skin studio updates, save sync CLOSES #1533

docs/new-features.md

@@ -13,7 +13,6 @@ Features intentionally added beyond the original Pokémon Red, Blue, and Yellow
 * **Mobile touch controls** with editable layouts, vibration, and orientation settings
 * **Touch skins** in RetroArch overlay format, with bezel art, per-button press states, and Super Game Boy borders
 * **Pokédex diploma and printer image exports**
-* **Mod download counts** from the index feed, with Most-downloaded and Trending sorts
 
 ## Gen 2 Specifics
 

docs/skin-studio.md

@@ -4,17 +4,23 @@ A **skin** replaces the on-screen controls wholesale: a bezel image, a
 control layout, and the rectangle the Game Boy screen is drawn into. Engine:
 `src/core/TouchSkin.lua` (model, parsers, zip export), `src/core/TouchControls.lua`
 (draw and input), `src/render/Renderer.lua` (the screen viewport),
+`src/core/DeltaSkin.lua` (Delta `.deltaskin` import and export),
 `src/ui/SkinStudio.lua` (the desktop editor). Tests:
 `tests/engine/touch_skin_test.lua`, `tests/engine/skin_studio_test.lua`,
+`tests/engine/skin_studio_ux.lua`,
 `tests/engine/skin_studio_image_import.lua`,
-`tests/engine/launcher_skins_tab.lua`.
+`tests/engine/skin_format_import_test.lua`,
+`tests/engine/launcher_skins_tab.lua`,
+`tests/engine/launcher_skins_ux.lua`.
 
 Skins are picked in the launcher's **Skins** tab, which also imports them and
 opens the studio. `options.touchControls.skin` holds the folder name.
 
 ## Formats
 
-Two load. `skin.lua` wins when a folder has both.
+Three load: the native `skin.lua`, a RetroArch overlay `.cfg`, and a Delta
+`.deltaskin`. `skin.lua` wins when a folder has more than one. The launcher
+badges each installed skin with the format it was read from.
 
 **RetroArch overlay `.cfg`.** The libretro `common-overlays` collection loads
 as-is. Supported keys:
@@ -41,6 +47,15 @@ Hitboxes are `radial` or `rect`. Pipe-separated binds (`left|down`) are one
 control that holds both. A `nul` desc is decoration: it draws and never
 captures a touch.
 
+The area desc types are expanded rather than ignored: `dpad_area`,
+`abxy_area`, `analog_left` and `analog_right` each become eight hitboxes over
+the same area, one per 45 degree sector measured from its centre, the way
+RetroArch resolves them: there is no neutral middle, and the four corner
+sectors fire two inputs. Any `_up` / `_down` / `_left` / `_right` override and
+the per-side reach are honoured, and the desc's own art is kept as decoration
+over the top. Exporting a cfg folds the eight back into the one area desc they
+came from. `retrok_<key>` is a keyboard bind.
+
 Alpha follows RetroArch (`input_driver.c`, `input_overlay_post_poll`): every
 image sits at the overlay opacity, and a pressed control's image swaps to
 `opacity * alpha_mod`. So `alpha_mod` above 1 lights a control up and below 1
@@ -71,6 +86,28 @@ return {
 }
 ```
 
+**Delta `.deltaskin`.** A zip (any wrapping folder is stripped) holding an
+`info.json` plus its art. The `representations` tree is walked
+device / display type / orientation, and every orientation that exists becomes
+a page; `page.orient` is the orientation key, so a portrait/landscape pair
+auto-rotates like a RetroArch one. Item `frame` rects are top-left plus size in
+`mappingSize` points and are converted to the native centre plus half extent;
+`extendedEdges` merge per key into the reach fields; `mask: "circle"` becomes a
+radial hitbox. A `dpad` or `thumbstick` item expands into the 3x3 grid, so the
+corners fire two directions. `screens[1].outputFrame` (or the legacy
+`gameScreenFrame`) becomes the screen cutout, and the skin stretches to the
+window the way Delta does rather than letterboxing. Host functions map to
+engine hotkeys: `menu` to `menu_toggle`, `fastForward` to
+`hold_fast_forward`, `toggleFastForward` to `toggle_fast_forward`;
+`quickSave` and `quickLoad` have nothing to bind to and drop to decoration.
+Both `com.rileytestut.delta.game.*` and Manic's `public.aoshuang.game.*`
+identifiers are accepted, and a non Game Boy system warns instead of failing.
+
+PDF artwork is the one thing that does not come across: Delta's own templates
+are all-PDF and this engine has no rasterizer, so such a skin is refused with
+the message asking for a PNG version. GBA4iOS `.gbcskin` / `.gbaskin` files are
+an older, incompatible schema and are refused by name.
+
 ## Bindable actions
 
 The eight Game Boy buttons: `a`, `b`, `start`, `select`, `up`, `down`,
@@ -119,10 +156,22 @@ them. Anything that binds a button still follows the usual mobile /
 
 ## Installing
 
-Drop a folder or a `.zip` into `skins/` in the save directory, or drop a zip on
+Four roads, all of them landing in `skins/` in the save directory:
-the launcher window while the Skins tab is open. A zip is mounted in place, so
+
-there is nothing to unpack. The folder needs one `skin.lua` or `.cfg`
+* **Import** on the Skins tab opens the host file picker for a `.zip` or a
-(`overlay.cfg` is preferred when there are several) and the images it names.
+  `.deltaskin`.
+* **Paste a skin link** in the tab's URL row, then **Add**. The download runs
+  on the fetch pool (`src/net/Fetch.lua`), so the launcher stays live, and the
+  row shows a spinner until it lands. A link to a bare `overlay.cfg` is wrapped
+  into an archive on the way in. This is the road that works on a phone, where
+  there is no file picker to speak of.
+* Drop a `.zip` or `.deltaskin` on the launcher window while the Skins tab is
+  open.
+* Copy a folder or archive into `skins/` by hand.
+
+An archive is mounted in place, so there is nothing to unpack. It needs one
+`skin.lua`, `.cfg` (`overlay.cfg` is preferred when there are several) or
+`info.json`, plus the images it names.
 
 Two ship bundled, both from libretro's `common-overlays` under CC-BY-4.0:
 
@@ -157,23 +206,40 @@ The Super Game Boy preset locks the viewport to the real screen window,
 160x144 at (48,40), so an SGB border cannot be drawn out of register.
 
 **Editing.** Click a control to select it, drag to move, eight handles to
-resize. X / Y / W / H are in canvas pixels, so a control can be typed to the
+resize. Arrow keys nudge the selection one canvas pixel, shift-arrow ten. While
-coordinate its art was drawn at. Bind, hitbox shape, hit reach and idle and
+a control is dragged it snaps to the centres and edges of the other controls
+and of the page itself when it comes within a few pixels, and the guide it
+snapped to is drawn. X / Y / W / H are in canvas pixels, so a control can be
+typed to the coordinate its art was drawn at. **Back** and **Front** move the
+selection through the draw order. Bind, hitbox shape, hit reach and idle and
 pressed images are per control; the bezel, the pages and the screen cutout are
 per page. The cutout is itself a draggable element with a 10:9 lock.
 
+**Bind** opens a grid of every bind the engine understands: the eight Game Boy
+buttons, the diagonal pairs, every hotkey, a few `key:` entries, and
+decoration. The COMBINE chips at the top toggle one part at a time, which is
+how a pipe bind like `left|down` is built without typing it.
+
+**Undo** and **Redo** in the top bar cover every edit (ctrl+Z / ctrl+Y, or
+`u` / shift+`u` without a keyboard modifier). The stack holds the last 50
+actions. `L` toggles the bind captions drawn on the canvas.
+
 Each page can **Lock** to portrait or landscape. With **Match canvas** on
-(the default), Next page picks a matching mock device and the canvas preset
+(the default), the page list picks a matching mock device and the canvas preset
 picks a matching page. Turn Match canvas off to look at a portrait page on a
-landscape device.
+landscape device. **Pages** opens the page list, where a page is selected,
+renamed or deleted.
+
+Starting a new skin, opening another one or closing the studio with unsaved
+edits prompts first, with Save first / Discard / Cancel.
 
 A RetroArch overlay whose pages are already named portrait / landscape
 (the auto-rotate convention) locks those pages and turns Match canvas on
 when you open it. You do not have to click Lock first.
 
-**Art.** The **Bezel**, **Idle art** and **Pressed art** rows cycle through the
+**Art.** The **Bezel**, **Idle art** and **Pressed art** rows open a
-images already in the skin folder; the **Import** button beside each one opens
+thumbnail grid of the images already in the skin folder, with `(none)` first;
-the host file picker (`src/core/FilePicker.lua`: osascript, PowerShell,
+the **Import** button there and beside each row opens the host file picker (`src/core/FilePicker.lua`: osascript, PowerShell,
 zenity/kdialog) and copies the chosen PNG or JPG into `img/` under the name in
 the SKIN field, then assigns it to that slot. Dropping a PNG or JPG on the
 window does the same for whichever slot was last touched. A new bezel does not
@@ -185,11 +251,23 @@ buttons and the footer reports what is held. **Play** saves the skin, selects
 it, and boots the game with it.
 
 **Saving.** **Save** writes `skins/<name>/skin.lua` and copies every image the
-skin names, so the folder stands alone. **Export** packs it as one zip
+skin names, so the folder stands alone. **Export** offers three formats, and
-(`src/core/SkinZip.lua`, store-only) carrying the native `skin.lua`, the
+the Skins tab's gear offers the same three for any installed skin:
-images, and the original `.cfg` when it came from one. An exported skin drops
+
-straight back into `skins/` and still opens in RetroArch.
+| Export | Contents |
+| --- | --- |
+| gen1recomp `.zip` | the native `skin.lua`, the images, and the original `.cfg` when it came from one |
+| RetroArch `.zip` | an `overlay.cfg` generated from the model, plus the images |
+| Delta `.deltaskin` | an `info.json` generated from the model, plus the images |
+
+All three are written store-only (`src/core/SkinZip.lua`) into `skins/_export/`
+in the save directory, which is outside the folder the skin list scans, so an
+export can never shadow the skin it came from. The notice names the full path
+so a phone can find the file in its own file manager. On desktop **Show the
+exported file** opens that folder.
 
 ## Not implemented
 
-RetroArch's `analog_*`, `dpad_area`, `abxy_area` and `retrok_*` desc types.
+Delta skins whose art is PDF only. Rasterizing them needs a PDF renderer this
+engine does not carry, so they are refused with a message rather than imported
+half-drawn.

mobile/android/love/src/jni/love/src/common/android.cpp

@@ -378,6 +378,104 @@ bool httpPost(const char *url, const char *body, int bodyLen, const char *conten
 	return result;
 }
 
+bool httpRequest(const char *url, const char *method,
+	const char *const *headerPairs, int headerPairCount,
+	const char *body, int bodyLen, const char *userAgent, std::string &out)
+{
+	out.clear();
+	if (url == nullptr)
+		return false;
+	if (headerPairCount < 0 || (headerPairCount > 0 && headerPairs == nullptr))
+		return false;
+
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	// Same resolution rule as httpDownload: the activity's own class via
+	// SDL_AndroidGetActivity, never FindClass for an app class -- save sync
+	// runs on a love.thread worker, whose class loader cannot see them.
+	jobject activityObj = (jobject) SDL_AndroidGetActivity();
+	if (activityObj == nullptr)
+		return false;
+	jclass activity = env->GetObjectClass(activityObj);
+	env->DeleteLocalRef(activityObj);
+
+	// Old APK / new liblove skew: report "no transport" instead of aborting
+	// on a missing method (#597).
+	jmethodID method_id = env->GetStaticMethodID(activity, "httpRequest",
+		"(Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;[BLjava/lang/String;)[B");
+	if (method_id == nullptr)
+	{
+		env->ExceptionClear();
+		env->DeleteLocalRef(activity);
+		return false;
+	}
+
+	jobjectArray jheaders = nullptr;
+	if (headerPairCount > 0)
+	{
+		// java/lang/String, unlike an app class, resolves from any thread.
+		jclass stringClass = env->FindClass("java/lang/String");
+		if (stringClass == nullptr)
+		{
+			env->ExceptionClear();
+			env->DeleteLocalRef(activity);
+			return false;
+		}
+		jheaders = env->NewObjectArray((jsize) headerPairCount, stringClass, nullptr);
+		env->DeleteLocalRef(stringClass);
+		if (jheaders == nullptr)
+		{
+			env->ExceptionClear();
+			env->DeleteLocalRef(activity);
+			return false;
+		}
+		for (int i = 0; i < headerPairCount; i++)
+		{
+			jstring field = env->NewStringUTF(headerPairs[i] != nullptr ? headerPairs[i] : "");
+			env->SetObjectArrayElement(jheaders, (jsize) i, field);
+			if (field != nullptr)
+				env->DeleteLocalRef(field);
+		}
+	}
+
+	jstring jurl = env->NewStringUTF(url);
+	jstring jmethod = env->NewStringUTF(method != nullptr ? method : "GET");
+	// raw bytes across the bridge, as httpPost does: a request body is JSON
+	// carrying a base64 save, and a jstring would run it through modified UTF-8
+	jbyteArray jbody = nullptr;
+	if (body != nullptr && bodyLen >= 0)
+	{
+		jbody = env->NewByteArray((jsize) bodyLen);
+		if (jbody != nullptr && bodyLen > 0)
+			env->SetByteArrayRegion(jbody, 0, (jsize) bodyLen, (const jbyte*) body);
+	}
+	jstring jua = env->NewStringUTF(userAgent != nullptr ? userAgent : "gen1recomp");
+
+	jobject result = env->CallStaticObjectMethod(activity, method_id, jurl, jmethod,
+		jheaders, jbody, jua);
+
+	env->DeleteLocalRef(jurl);
+	env->DeleteLocalRef(jmethod);
+	if (jheaders != nullptr)
+		env->DeleteLocalRef(jheaders);
+	if (jbody != nullptr)
+		env->DeleteLocalRef(jbody);
+	env->DeleteLocalRef(jua);
+	env->DeleteLocalRef(activity);
+
+	if (result == nullptr)
+		return false;
+
+	jbyteArray bytes = (jbyteArray) result;
+	jsize length = env->GetArrayLength(bytes);
+	if (length > 0)
+	{
+		out.resize((size_t) length);
+		env->GetByteArrayRegion(bytes, 0, length, (jbyte*) &out[0]);
+	}
+	env->DeleteLocalRef(result);
+	return true;
+}
+
 /*
  * TLS sockets. Same resolution rule as httpDownload above -- the activity's
  * own class, never FindClass -- and the same tolerance for an old APK: a

mobile/android/love/src/jni/love/src/common/android.h

@@ -106,6 +106,21 @@ bool httpDownload(const char *url, const char *destPath, const char *userAgent,
  **/
 bool httpPost(const char *url, const char *body, int bodyLen, const char *contentType, const char *userAgent);
 
+/**
+ * Blocking HTTPS request with a method, headers and a byte body
+ * (GameActivity.httpRequest). What save sync needs and neither of the two
+ * above can give it: PUT, per-request auth headers, and the response body of
+ * a 4xx as well as a 2xx. headerPairs is a flat name, value array of
+ * headerPairCount entries; body/userAgent may be null. `out` receives the
+ * Java side's envelope -- a head line of "STATUS <code>" or "ERROR <text>",
+ * a newline, then the raw response bytes. False means the platform has no
+ * such bridge at all (an old APK under a newer liblove), which the Lua side
+ * reports as "update the app" rather than as a failed request.
+ **/
+bool httpRequest(const char *url, const char *method,
+	const char *const *headerPairs, int headerPairCount,
+	const char *body, int bodyLen, const char *userAgent, std::string &out);
+
 /**
  * TLS client sockets (GameActivity.tls*, implemented by TlsSocket.java).
  * LuaSocket, which is what LOVE ships, does TCP only, so wss:// is otherwise

mobile/android/love/src/jni/love/src/modules/system/System.cpp

@@ -274,6 +274,27 @@ bool System::httpPost(const char *url, const char *body, int bodyLen,
 #endif
 }
 
+bool System::httpRequest(const char *url, const char *method,
+	const char *const *headerPairs, int headerPairCount,
+	const char *body, int bodyLen, const char *userAgent,
+	std::string &out) const
+{
+#ifdef LOVE_ANDROID
+	return love::android::httpRequest(url, method, headerPairs, headerPairCount,
+		body, bodyLen, userAgent, out);
+#else
+	LOVE_UNUSED(url);
+	LOVE_UNUSED(method);
+	LOVE_UNUSED(headerPairs);
+	LOVE_UNUSED(headerPairCount);
+	LOVE_UNUSED(body);
+	LOVE_UNUSED(bodyLen);
+	LOVE_UNUSED(userAgent);
+	out.clear();
+	return false;
+#endif
+}
+
 int System::tlsOpen(const char *host, int port) const
 {
 #ifdef LOVE_ANDROID

mobile/android/love/src/jni/love/src/modules/system/System.h

@@ -159,6 +159,18 @@ public:
 	virtual bool httpPost(const char *url, const char *body, int bodyLen,
 		const char *contentType = nullptr, const char *userAgent = nullptr) const;
 
+	/**
+	 * Blocking HTTPS request with a method, headers and a byte body (Android
+	 * only; false elsewhere). Save sync needs PUT, auth headers and the body
+	 * of a 4xx, none of which the two bridges above can express. headerPairs
+	 * is a flat name, value array; `out` receives the response envelope
+	 * ("STATUS <code>" or "ERROR <text>", a newline, then the raw body).
+	 **/
+	virtual bool httpRequest(const char *url, const char *method,
+		const char *const *headerPairs, int headerPairCount,
+		const char *body, int bodyLen, const char *userAgent,
+		std::string &out) const;
+
 	/**
 	 * TLS client sockets (Android only; every call fails elsewhere, where
 	 * LuaSec or another provider is the answer). Non-blocking by contract:

mobile/android/love/src/jni/love/src/modules/system/wrap_System.cpp

@@ -22,6 +22,9 @@
 #include "wrap_System.h"
 #include "sdl/System.h"
 
+#include <string>
+#include <vector>
+
 namespace love
 {
 namespace system
@@ -150,6 +153,57 @@ int w_httpPost(lua_State *L)
 	return 1;
 }
 
+/*
+ * love.system.httpRequest(url, method, headers, body, userAgent) -> envelope
+ *
+ * `headers` is a flat array of alternating header name and value strings, so
+ * it maps straight onto the Java bridge's String[] without any parsing here.
+ * The single return is the response envelope -- a head line of
+ * "STATUS <code>" or "ERROR <text>", a newline, then the raw body -- or nil
+ * where the build has no bridge, which src/core/HostShell.lua turns into an
+ * "update the app" notice rather than a failed request.
+ */
+int w_httpRequest(lua_State *L)
+{
+	const char *url = luaL_checkstring(L, 1);
+	const char *method = luaL_optstring(L, 2, "GET");
+
+	std::vector<std::string> fields;
+	if (!lua_isnoneornil(L, 3))
+	{
+		luaL_checktype(L, 3, LUA_TTABLE);
+		size_t count = luax_objlen(L, 3);
+		for (size_t i = 1; i <= count; i++)
+		{
+			lua_rawgeti(L, 3, (int) i);
+			const char *field = lua_tostring(L, -1);
+			fields.push_back(field != nullptr ? field : "");
+			lua_pop(L, 1);
+		}
+	}
+	std::vector<const char *> pairs;
+	for (size_t i = 0; i < fields.size(); i++)
+		pairs.push_back(fields[i].c_str());
+
+	size_t bodyLen = 0;
+	const char *body = nullptr;
+	if (!lua_isnoneornil(L, 4))
+		body = luaL_checklstring(L, 4, &bodyLen);
+	const char *ua = luaL_optstring(L, 5, nullptr);
+
+	std::string out;
+	bool ok = instance()->httpRequest(url, method,
+		pairs.empty() ? nullptr : &pairs[0], (int) pairs.size(),
+		body, (int) bodyLen, ua, out);
+	if (!ok)
+	{
+		lua_pushnil(L);
+		return 1;
+	}
+	lua_pushlstring(L, out.data(), out.size());
+	return 1;
+}
+
 int w_hasBackgroundMusic(lua_State *L)
 {
 	lua_pushboolean(L, instance()->hasBackgroundMusic());
@@ -245,6 +299,7 @@ static const luaL_Reg functions[] =
 	{ "restartApp", w_restartApp },
 	{ "httpDownload", w_httpDownload },
 	{ "httpPost", w_httpPost },
+	{ "httpRequest", w_httpRequest },
 	{ "tlsOpen", w_tlsOpen },
 	{ "tlsStatus", w_tlsStatus },
 	{ "tlsSend", w_tlsSend },

mobile/android/love/src/main/java/org/love2d/android/GameActivity.java

@@ -24,6 +24,7 @@ import org.libsdl.app.SDLActivity;
 
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -36,6 +37,7 @@ import java.net.URL;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import android.Manifest;
@@ -847,6 +849,149 @@ public class GameActivity extends SDLActivity {
         }
     }
 
+    /** Response ceiling for httpRequest; anything larger is refused, not buffered. */
+    private static final int HTTP_REQUEST_MAX_RESPONSE = 4 * 1024 * 1024;
+
+    /** Builds an httpRequest envelope: one head line, a newline, then the body. */
+    private static byte[] httpEnvelope(String head, byte[] payload) {
+        byte[] prefix;
+        try {
+            prefix = (head + "\n").getBytes("UTF-8");
+        } catch (Exception e) {
+            prefix = (head + "\n").getBytes();
+        }
+        if (payload == null || payload.length == 0) return prefix;
+        byte[] out = new byte[prefix.length + payload.length];
+        System.arraycopy(prefix, 0, out, 0, prefix.length);
+        System.arraycopy(payload, 0, out, prefix.length, payload.length);
+        return out;
+    }
+
+    /** One-line, CR/LF-free failure text, so an envelope head stays one line. */
+    private static String httpErrorText(Exception e) {
+        String text = e.getMessage();
+        if (text == null || text.length() == 0) text = e.getClass().getSimpleName();
+        text = text.replace('\r', ' ').replace('\n', ' ');
+        if (text.length() > 160) text = text.substring(0, 160);
+        return text;
+    }
+
+    /**
+     * Blocking HTTPS request with a chosen method, headers and byte body,
+     * exposed as love.system.httpRequest and used by src/core/HostShell.lua
+     * for save sync. Sync needs PUT, per-request auth headers and the response
+     * body of a 4xx as well as a 2xx (a conflict answers 409 with the save
+     * that won), none of which httpDownload or httpPost above can express.
+     *
+     * Same rules as those two: https only, redirects followed by hand
+     * (re-sending method and body on each hop), 15s connect / 60s read, and
+     * blocking on the Lua/worker thread -- never the UI thread. Headers arrive
+     * as a flat name, value array; a field carrying CR or LF is refused rather
+     * than sent, so a header value can never inject a second header.
+     *
+     * The reply is an envelope: a head line of "STATUS <code>" or
+     * "ERROR <text>", a newline, then the raw response bytes.
+     */
+    @Keep
+    public static byte[] httpRequest(String url, String method, String[] headerPairs,
+                                     byte[] body, String userAgent) {
+        if (url == null) return httpEnvelope("ERROR missing url", null);
+        String verb = method == null ? "GET" : method.toUpperCase(Locale.US);
+        if (!"GET".equals(verb) && !"POST".equals(verb)
+                && !"PUT".equals(verb) && !"DELETE".equals(verb)) {
+            return httpEnvelope("ERROR unsupported request method", null);
+        }
+        if (headerPairs != null) {
+            if ((headerPairs.length % 2) != 0) {
+                return httpEnvelope("ERROR bad request header", null);
+            }
+            for (int i = 0; i < headerPairs.length; i++) {
+                String field = headerPairs[i];
+                if (field == null) return httpEnvelope("ERROR bad request header", null);
+                if (field.indexOf('\r') >= 0 || field.indexOf('\n') >= 0) {
+                    return httpEnvelope("ERROR bad request header", null);
+                }
+                if ((i % 2) == 0 && field.length() == 0) {
+                    return httpEnvelope("ERROR bad request header", null);
+                }
+            }
+        }
+        HttpURLConnection conn = null;
+        try {
+            String current = url;
+            for (int hop = 0; hop < 5; hop++) {
+                URL parsed = new URL(current);
+                if (!"https".equalsIgnoreCase(parsed.getProtocol())) {
+                    return httpEnvelope("ERROR https only", null);
+                }
+                conn = (HttpURLConnection) parsed.openConnection();
+                conn.setInstanceFollowRedirects(false);
+                conn.setConnectTimeout(15000);
+                conn.setReadTimeout(60000);
+                conn.setRequestMethod(verb);
+                conn.setRequestProperty("User-Agent",
+                    userAgent == null ? "gen1recomp" : userAgent);
+                if (headerPairs != null) {
+                    for (int i = 0; i + 1 < headerPairs.length; i += 2) {
+                        conn.setRequestProperty(headerPairs[i], headerPairs[i + 1]);
+                    }
+                }
+                if (body != null && !"GET".equals(verb)) {
+                    conn.setDoOutput(true);
+                    conn.setFixedLengthStreamingMode(body.length);
+                    OutputStream out = new BufferedOutputStream(conn.getOutputStream());
+                    try {
+                        out.write(body);
+                    } finally {
+                        try { out.close(); } catch (IOException ignored) {}
+                    }
+                }
+                int code = conn.getResponseCode();
+                if (code == 301 || code == 302 || code == 303 || code == 307 || code == 308) {
+                    String next = conn.getHeaderField("Location");
+                    conn.disconnect();
+                    conn = null;
+                    if (next == null) {
+                        return httpEnvelope("ERROR redirect without a location", null);
+                    }
+                    current = new URL(parsed, next).toString();
+                    continue;
+                }
+                // A rejection's body is the diagnosis the caller wants, so 4xx
+                // and 5xx are read through getErrorStream rather than dropped.
+                InputStream in;
+                try {
+                    in = conn.getInputStream();
+                } catch (IOException e) {
+                    in = conn.getErrorStream();
+                }
+                ByteArrayOutputStream sink = new ByteArrayOutputStream();
+                if (in != null) {
+                    InputStream reader = new BufferedInputStream(in);
+                    try {
+                        byte[] buf = new byte[16384];
+                        int n;
+                        while ((n = reader.read(buf)) > 0) {
+                            if (sink.size() + n > HTTP_REQUEST_MAX_RESPONSE) {
+                                return httpEnvelope("ERROR the reply was too large", null);
+                            }
+                            sink.write(buf, 0, n);
+                        }
+                    } finally {
+                        try { reader.close(); } catch (IOException ignored) {}
+                    }
+                }
+                return httpEnvelope("STATUS " + code, sink.toByteArray());
+            }
+            return httpEnvelope("ERROR too many redirects", null);
+        } catch (Exception e) {
+            Log.d("GameActivity", "httpRequest failed: " + e.getMessage());
+            return httpEnvelope("ERROR " + httpErrorText(e), null);
+        } finally {
+            if (conn != null) conn.disconnect();
+        }
+    }
+
     /**
      * Shows ACTION_CREATE_DOCUMENT so the player can save a staged export
      * (pending_export.sav in the app save identity) to Downloads / Drive /

mobile/ios/native/GRPickerBridge.swift

@@ -67,6 +67,124 @@ public final class GRPickerBridge: NSObject {
         return succeeded
     }
 
+    // MARK: - General HTTP request (love.system.httpRequest)
+
+    private static let httpMaxResponse = 4 * 1024 * 1024
+
+    // URLSession turns a 301/302/303 POST into a GET on its own. Save sync
+    // signs a method and a body, so every hop re-sends the original request
+    // against the new URL instead, and only over https.
+    private final class GRRedirectKeeper: NSObject, URLSessionTaskDelegate {
+        func urlSession(_ session: URLSession, task: URLSessionTask,
+                        willPerformHTTPRedirection response: HTTPURLResponse,
+                        newRequest request: URLRequest,
+                        completionHandler: @escaping (URLRequest?) -> Void) {
+            guard let original = task.originalRequest,
+                  let target = request.url,
+                  target.scheme?.lowercased() == "https" else {
+                completionHandler(nil)
+                return
+            }
+            var next = original
+            next.url = target
+            completionHandler(next)
+        }
+    }
+
+    private static let httpSession = URLSession(configuration: .ephemeral,
+                                                delegate: GRRedirectKeeper(),
+                                                delegateQueue: nil)
+
+    private static func httpEnvelope(_ head: String, _ payload: Data?) -> NSData {
+        var out = Data((head + "\n").utf8)
+        if let payload { out.append(payload) }
+        return out as NSData
+    }
+
+    private static func httpErrorText(_ error: Error) -> String {
+        var text = error.localizedDescription
+            .replacingOccurrences(of: "\r", with: " ")
+            .replacingOccurrences(of: "\n", with: " ")
+        if text.isEmpty { text = "the request failed" }
+        if text.count > 160 { text = String(text.prefix(160)) }
+        return text
+    }
+
+    /// Blocking HTTPS request with a chosen method, headers and byte body, the
+    /// iOS half of love.system.httpRequest (see the Android GameActivity one).
+    /// Headers arrive as "name: value" lines joined by newlines. The reply is
+    /// an envelope: a head line of "STATUS <code>" or "ERROR <text>", a
+    /// newline, then the raw response bytes -- read for 4xx and 5xx as well,
+    /// because a sync conflict answers 409 with the save that won.
+    @objc(httpRequestWithUrl:method:headers:body:bodyLength:userAgent:)
+    public static func httpRequest(url: UnsafePointer<CChar>?,
+                                   method: UnsafePointer<CChar>?,
+                                   headers: UnsafePointer<CChar>?,
+                                   body: UnsafePointer<UInt8>?,
+                                   bodyLength: Int32,
+                                   userAgent: UnsafePointer<CChar>?) -> NSData? {
+        guard let url, let requestURL = URL(string: String(cString: url)) else {
+            return httpEnvelope("ERROR missing url", nil)
+        }
+        guard requestURL.scheme?.lowercased() == "https" else {
+            return httpEnvelope("ERROR https only", nil)
+        }
+        let verb = (method.map { String(cString: $0) } ?? "GET").uppercased()
+        guard ["GET", "POST", "PUT", "DELETE"].contains(verb) else {
+            return httpEnvelope("ERROR unsupported request method", nil)
+        }
+
+        var request = URLRequest(url: requestURL)
+        request.httpMethod = verb
+        request.timeoutInterval = 60
+        request.setValue(userAgent.map { String(cString: $0) } ?? "gen1recomp",
+                         forHTTPHeaderField: "User-Agent")
+        if let headers, headers.pointee != 0 {
+            for line in String(cString: headers).split(separator: "\n") {
+                guard let colon = line.firstIndex(of: ":") else {
+                    return httpEnvelope("ERROR bad request header", nil)
+                }
+                let name = line[line.startIndex..<colon]
+                    .trimmingCharacters(in: .whitespaces)
+                let value = line[line.index(after: colon)...]
+                    .trimmingCharacters(in: .whitespaces)
+                if name.isEmpty {
+                    return httpEnvelope("ERROR bad request header", nil)
+                }
+                request.setValue(value, forHTTPHeaderField: name)
+            }
+        }
+        if verb != "GET", let body, bodyLength > 0 {
+            request.httpBody = Data(bytes: body, count: Int(bodyLength))
+        }
+
+        let semaphore = DispatchSemaphore(value: 0)
+        var envelope = httpEnvelope("ERROR no response", nil)
+        let task = httpSession.dataTask(with: request) { data, response, error in
+            defer { semaphore.signal() }
+            if let error {
+                envelope = httpEnvelope("ERROR " + httpErrorText(error), nil)
+                return
+            }
+            guard let http = response as? HTTPURLResponse else {
+                envelope = httpEnvelope("ERROR no response", nil)
+                return
+            }
+            let payload = data ?? Data()
+            if payload.count > httpMaxResponse {
+                envelope = httpEnvelope("ERROR the reply was too large", nil)
+                return
+            }
+            envelope = httpEnvelope("STATUS \(http.statusCode)", payload)
+        }
+        task.resume()
+        guard semaphore.wait(timeout: .now() + 65) == .success else {
+            task.cancel()
+            return httpEnvelope("ERROR the request timed out", nil)
+        }
+        return envelope
+    }
+
     // MARK: - Entry points called from liblove (C strings on purpose)
 
     @objc(presentPickerWithKind:saveDir:)

mobile/ios/patch_love_src.py

@@ -9,7 +9,8 @@ What it does:
   1. Copies mobile/ios/native/ (GRPickerBridge.swift, GRHealthBridge.swift,
      GRBootstrap.m) and the HealthKit entitlements into the LÖVE tree.
   2. Patches liblove's wrap_System.cpp to expose love.system.pickFile,
-     love.system.createFile, and love.system.syncHealthSteps on iOS (each
+     love.system.createFile, love.system.syncHealthSteps,
+     love.system.httpDownload and love.system.httpRequest on iOS (each
      calls a GR*Bridge Swift class through the Objective-C runtime, so
      liblove never links against Swift directly).
   3. Patches love.xcodeproj so the love-ios app target compiles the native
@@ -50,6 +51,7 @@ WRAP_INCLUDES = """
 #include <objc/runtime.h>
 #include <objc/message.h>
 #include <string>
+#include <vector>
 #include "filesystem/Filesystem.h"
 #endif
 """ % MARKER
@@ -159,6 +161,7 @@ WRAP_REGISTRATION = """#ifdef LOVE_IOS
 	{ "createFile", w_createFile },
 	{ "syncHealthSteps", w_syncHealthSteps },
 	{ "httpDownload", w_httpDownload },
+	{ "httpRequest", w_httpRequest },
 #endif
 """
 
@@ -201,6 +204,7 @@ int w_syncHealthSteps(lua_State *L)
 WRAP_SYNC_REGISTRATION = """#ifdef LOVE_IOS
 	{ "syncHealthSteps", w_syncHealthSteps },
 	{ "httpDownload", w_httpDownload },
+	{ "httpRequest", w_httpRequest },
 #endif
 """
 
@@ -226,6 +230,80 @@ int w_httpDownload(lua_State *L)
 	lua_pushboolean(L, ok != 0);
 	return 1;
 }
+
+// love.system.httpRequest(url, method, headers, body, userAgent) -> envelope
+//
+// The transport save sync needs: a chosen method, per-request auth headers,
+// and the response body of a 4xx as well as a 2xx. `headers` is a flat array
+// of alternating name and value strings, joined into "name: value" lines here
+// because the Swift bridge takes C strings and no Foundation type may be
+// NAMED in this translation unit (see w_pickFileKinds above).
+//
+// The single return is the response envelope -- a head line of
+// "STATUS <code>" or "ERROR <text>", a newline, then the raw body -- or nil
+// where the build carries no bridge at all, which src/core/HostShell.lua
+// turns into an "update the app" notice rather than a failed request.
+int w_httpRequest(lua_State *L)
+{
+	const char *url = luaL_checkstring(L, 1);
+	const char *method = luaL_optstring(L, 2, "GET");
+
+	std::string headerBlob;
+	if (!lua_isnoneornil(L, 3))
+	{
+		luaL_checktype(L, 3, LUA_TTABLE);
+		std::vector<std::string> fields;
+		size_t count = luax_objlen(L, 3);
+		for (size_t i = 1; i <= count; i++)
+		{
+			lua_rawgeti(L, 3, (int) i);
+			const char *field = lua_tostring(L, -1);
+			fields.push_back(field != nullptr ? field : "");
+			lua_pop(L, 1);
+		}
+		for (size_t i = 0; i + 1 < fields.size(); i += 2)
+			headerBlob += fields[i] + ": " + fields[i + 1] + "\\n";
+	}
+
+	size_t bodyLen = 0;
+	const char *body = nullptr;
+	if (!lua_isnoneornil(L, 4))
+		body = luaL_checklstring(L, 4, &bodyLen);
+	const char *ua = luaL_optstring(L, 5, "gen1recomp");
+
+	Class cls = objc_getClass("GRPickerBridge");
+	if (cls == nullptr)
+	{
+		lua_pushnil(L);
+		return 1;
+	}
+	typedef id (*GRRequest)(Class, SEL, const char *, const char *,
+	                        const char *, const unsigned char *, int,
+	                        const char *);
+	id reply = ((GRRequest)objc_msgSend)(
+		cls,
+		sel_registerName("httpRequestWithUrl:method:headers:body:bodyLength:userAgent:"),
+		url, method, headerBlob.c_str(), (const unsigned char *) body,
+		(int) bodyLen, ua);
+	if (reply == nullptr)
+	{
+		lua_pushnil(L);
+		return 1;
+	}
+	// NSData read through the runtime, for the same reason as above: the
+	// bytes are copied out immediately, before any autorelease pool drains.
+	typedef const void *(*GRBytes)(id, SEL);
+	typedef unsigned long (*GRLength)(id, SEL);
+	const void *bytes = ((GRBytes)objc_msgSend)(reply, sel_registerName("bytes"));
+	unsigned long length = ((GRLength)objc_msgSend)(reply, sel_registerName("length"));
+	if (bytes == nullptr || length == 0)
+	{
+		lua_pushnil(L);
+		return 1;
+	}
+	lua_pushlstring(L, (const char *) bytes, (size_t) length);
+	return 1;
+}
 #endif
 """
 
@@ -308,7 +386,7 @@ def patch_wrap_system():
     text = text.replace(reg_anchor, reg_anchor + registration, 1)
     WRAP_SYSTEM.write_text(text)
     print("patch_love_src: wrap_System.cpp patched "
-          "(pickFile/createFile/syncHealthSteps/httpDownload)")
+          "(pickFile/createFile/syncHealthSteps/httpDownload/httpRequest)")
 
 
 def patch_public_documents():

src/core/DeltaSkin.lua

@@ -0,0 +1,523 @@
+local Json = require("src.link.Json")
+local TouchSkin = require("src.core.TouchSkin")
+
+local DeltaSkin = {}
+
+DeltaSkin.INFO_NAME = "info.json"
+DeltaSkin.MAX_INFO_BYTES = 4 * 1024 * 1024
+
+DeltaSkin.GAME_TYPE_PREFIXES = {
+  "com.rileytestut.delta.game.",
+  "public.aoshuang.game.",
+}
+
+DeltaSkin.SYSTEMS = { gb = true, gbc = true }
+
+DeltaSkin.LEGACY_EXTS = { gbcskin = true, gbaskin = true, gbskin = true }
+
+DeltaSkin.DEVICE_ORDER = { "iphone", "ipad", "tv" }
+DeltaSkin.DISPLAY_ORDER = { "edgeToEdge", "standard", "splitView" }
+DeltaSkin.ORIENTATIONS = { "portrait", "landscape" }
+DeltaSkin.SIDES = { "up", "down", "left", "right" }
+
+DeltaSkin.ASSET_LADDER = { "small", "medium", "large" }
+DeltaSkin.ASSET_WIDTHS = { small = 640, medium = 750, large = 1080 }
+DeltaSkin.DEFAULT_TARGET_WIDTH = 1080
+
+DeltaSkin.INPUTS = {
+  a = "a", b = "b", start = "start", select = "select",
+  up = "up", down = "down", left = "left", right = "right",
+  menu = "menu_toggle",
+  fastforward = "hold_fast_forward",
+  togglefastforward = "toggle_fast_forward",
+}
+
+DeltaSkin.OUTPUT_HOTKEYS = {
+  menu = "menu",
+  fast_forward_hold = "fastForward",
+  fast_forward_toggle = "toggleFastForward",
+}
+
+DeltaSkin.MAPPING = {
+  portrait = { width = 1080, height = 1920 },
+  landscape = { width = 1920, height = 1080 },
+}
+
+DeltaSkin.SCREEN_WIDTH = 160
+DeltaSkin.SCREEN_HEIGHT = 144
+
+local function pick(t, key)
+  if type(t) ~= "table" then return nil end
+  local direct = t[key]
+  if direct ~= nil then return direct end
+  local want = tostring(key):lower()
+  for k, v in pairs(t) do
+    if tostring(k):lower() == want then return v end
+  end
+  return nil
+end
+
+local function numOr(v, fallback)
+  local n = tonumber(v)
+  if not n or n ~= n then return fallback end
+  return n
+end
+
+local function round(n)
+  return math.floor(numOr(n, 0) + 0.5)
+end
+
+local function isArray(t)
+  return type(t) == "table" and t[1] ~= nil
+end
+
+local function addWarning(list, text)
+  if type(list) ~= "table" then return end
+  for _, existing in ipairs(list) do
+    if existing == text then return end
+  end
+  list[#list + 1] = text
+end
+
+function DeltaSkin.findInfo(root)
+  local direct = root .. "/" .. DeltaSkin.INFO_NAME
+  if TouchSkin.readFile(direct) then return direct, "" end
+  local items = TouchSkin.listDir(root)
+  for _, name in ipairs(items) do
+    if tostring(name):lower() == DeltaSkin.INFO_NAME then
+      return root .. "/" .. name, ""
+    end
+  end
+  table.sort(items)
+  for _, name in ipairs(items) do
+    local nested = root .. "/" .. name .. "/" .. DeltaSkin.INFO_NAME
+    if TouchSkin.readFile(nested) then return nested, name .. "/" end
+  end
+  return nil
+end
+
+function DeltaSkin.resolveName(name, opts)
+  name = tostring(name or ""):gsub("\\", "/"):gsub("^%./", "")
+  if name == "" then return nil end
+  local names = opts and opts.names
+  if type(names) == "table" then
+    local want = name:lower()
+    for _, entry in ipairs(names) do
+      if tostring(entry):lower() == want then
+        name = tostring(entry)
+        break
+      end
+    end
+  end
+  return ((opts and opts.prefix) or "") .. name
+end
+
+function DeltaSkin.pickAsset(assets, opts, pdfFiles)
+  if type(assets) ~= "table" then return nil end
+  pdfFiles = pdfFiles or {}
+  local raster = {}
+  for _, key in ipairs(DeltaSkin.ASSET_LADDER) do
+    local name = pick(assets, key)
+    if key == "medium" and type(name) ~= "string" then name = pick(assets, "normal") end
+    if type(name) == "string" and name ~= "" then
+      if name:lower():match("%.pdf$") then
+        pdfFiles[#pdfFiles + 1] = name
+      else
+        raster[#raster + 1] = { key = key, name = name }
+      end
+    end
+  end
+  local resizable = pick(assets, "resizable")
+  if type(resizable) == "string" and resizable ~= "" then
+    if resizable:lower():match("%.pdf$") then
+      pdfFiles[#pdfFiles + 1] = resizable
+    else
+      raster[#raster + 1] = { key = "large", name = resizable }
+    end
+  end
+  if #raster == 0 then return nil end
+
+  local target = numOr(opts and opts.targetWidth, DeltaSkin.DEFAULT_TARGET_WIDTH)
+  local chosen
+  for _, cand in ipairs(raster) do
+    if not chosen and (DeltaSkin.ASSET_WIDTHS[cand.key] or 0) >= target then
+      chosen = cand.name
+    end
+  end
+  if not chosen then chosen = raster[#raster].name end
+  return DeltaSkin.resolveName(chosen, opts)
+end
+
+function DeltaSkin.mergeEdges(base, item)
+  local out = { top = 0, bottom = 0, left = 0, right = 0 }
+  for _, side in ipairs({ "top", "bottom", "left", "right" }) do
+    local v = pick(item, side)
+    if v == nil then v = pick(base, side) end
+    out[side] = numOr(v, 0)
+  end
+  return out
+end
+
+function DeltaSkin.representation(reps, orient)
+  for _, device in ipairs(DeltaSkin.DEVICE_ORDER) do
+    local dev = pick(reps, device)
+    if type(dev) == "table" then
+      for _, display in ipairs(DeltaSkin.DISPLAY_ORDER) do
+        local shown = pick(dev, display)
+        if type(shown) == "table" then
+          local obj = pick(shown, orient)
+          if type(obj) == "table" then return obj, device, display end
+        end
+      end
+      local flat = pick(dev, orient)
+      if type(flat) == "table" and (pick(flat, "items") or pick(flat, "mappingSize")) then
+        return flat, device, nil
+      end
+    end
+  end
+  return nil
+end
+
+function DeltaSkin.directionalInputs(inputs)
+  if type(inputs) ~= "table" or isArray(inputs) then return nil end
+  local out, found = {}, 0
+  for _, side in ipairs(DeltaSkin.SIDES) do
+    local v = pick(inputs, side)
+    if type(v) == "string" then
+      local lower = v:lower()
+      local mapped = DeltaSkin.INPUTS[lower]
+      if not mapped and lower:find(side, 1, true) then mapped = side end
+      if mapped then
+        out[side] = mapped
+        found = found + 1
+      end
+    end
+  end
+  if found >= 2 then return out end
+  return nil
+end
+
+function DeltaSkin.specFor(inputs)
+  local parts = {}
+  local function add(v)
+    if type(v) ~= "string" then return end
+    local mapped = DeltaSkin.INPUTS[v:lower()]
+    if mapped then parts[#parts + 1] = mapped end
+  end
+  if type(inputs) == "string" then
+    add(inputs)
+  elseif type(inputs) == "table" then
+    if isArray(inputs) then
+      for _, v in ipairs(inputs) do add(v) end
+    else
+      local keys = {}
+      for k in pairs(inputs) do keys[#keys + 1] = tostring(k) end
+      table.sort(keys)
+      for _, k in ipairs(keys) do add(inputs[k]) end
+    end
+  end
+  if #parts == 0 then return "nul" end
+  return table.concat(parts, "|")
+end
+
+function DeltaSkin.screenRect(obj, mapW, mapH)
+  local frame
+  local screens = pick(obj, "screens")
+  if type(screens) == "table" and type(screens[1]) == "table" then
+    frame = pick(screens[1], "outputFrame")
+  end
+  if type(frame) ~= "table" then frame = pick(obj, "gameScreenFrame") end
+  if type(frame) ~= "table" then return nil end
+  local w = numOr(pick(frame, "width"), 0)
+  local h = numOr(pick(frame, "height"), 0)
+  if w <= 0 or h <= 0 then return nil end
+  return {
+    x = numOr(pick(frame, "x"), 0) / mapW,
+    y = numOr(pick(frame, "y"), 0) / mapH,
+    w = w / mapW, h = h / mapH,
+  }
+end
+
+function DeltaSkin.addItem(page, item, baseEdges, mapW, mapH)
+  if type(item) ~= "table" then return end
+  local frame = pick(item, "frame")
+  if type(frame) ~= "table" then return end
+  local fw = numOr(pick(frame, "width"), 0)
+  local fh = numOr(pick(frame, "height"), 0)
+  if fw <= 0 or fh <= 0 then return end
+  local fx = numOr(pick(frame, "x"), 0)
+  local fy = numOr(pick(frame, "y"), 0)
+
+  local edges = DeltaSkin.mergeEdges(baseEdges, pick(item, "extendedEdges"))
+  local cx, cy = (fx + fw * 0.5) / mapW, (fy + fh * 0.5) / mapH
+  local w, h = fw / mapW, fh / mapH
+  local reachLeft = 1 + edges.left / (fw * 0.5)
+  local reachRight = 1 + edges.right / (fw * 0.5)
+  local reachUp = 1 + edges.top / (fh * 0.5)
+  local reachDown = 1 + edges.bottom / (fh * 0.5)
+
+  local inputs = pick(item, "inputs")
+  local dirs = DeltaSkin.directionalInputs(inputs)
+  if dirs then
+    local base = {
+      x = cx, y = cy, rangeX = w * 0.5, rangeY = h * 0.5,
+      rangeMod = 1, alphaMod = page.alphaMod, shape = "rect",
+      reachLeft = reachLeft, reachRight = reachRight,
+      reachUp = reachUp, reachDown = reachDown,
+    }
+    for _, ctl in ipairs(TouchSkin.expandDirectional(base, dirs)) do
+      page.controls[#page.controls + 1] = ctl
+    end
+    return
+  end
+
+  local shape = tostring(pick(item, "mask") or ""):lower() == "circle" and "radial" or "rect"
+  local ctl = TouchSkin.newControl(DeltaSkin.specFor(inputs), cx, cy, w, h, shape)
+  ctl.alphaMod = page.alphaMod
+  ctl.reachLeft, ctl.reachRight = reachLeft, reachRight
+  ctl.reachUp, ctl.reachDown = reachUp, reachDown
+  page.controls[#page.controls + 1] = ctl
+end
+
+function DeltaSkin.buildPage(obj, orient, opts, warnings, pdfFiles)
+  local mapping = pick(obj, "mappingSize")
+  local mapW = numOr(pick(mapping, "width"), 0)
+  local mapH = numOr(pick(mapping, "height"), 0)
+  if mapW <= 0 or mapH <= 0 then
+    mapW, mapH = 320, 240
+    addWarning(warnings, orient .. " has no mappingSize; assuming 320x240")
+  end
+
+  local page = {
+    name = orient,
+    orient = orient,
+    imagePath = DeltaSkin.pickAsset(pick(obj, "assets"), opts, pdfFiles),
+    fullScreen = true,
+    normalized = true,
+    pixelCoords = false,
+    rangeMod = 1,
+    alphaMod = pick(obj, "translucent") == true and 0.7 or 1,
+    aspect = mapW / mapH,
+    aspectFromCfg = false,
+    rect = { x = 0, y = 0, w = 1, h = 1 },
+    mappingWidth = mapW,
+    mappingHeight = mapH,
+    controls = {},
+  }
+
+  local screen = DeltaSkin.screenRect(obj, mapW, mapH)
+  if screen then
+    page.viewport = screen
+    page.viewportFill = false
+  end
+
+  local baseEdges = pick(obj, "extendedEdges")
+  local items = pick(obj, "items")
+  if type(items) == "table" then
+    for _, item in ipairs(items) do
+      DeltaSkin.addItem(page, item, baseEdges, mapW, mapH)
+    end
+  end
+  return page
+end
+
+function DeltaSkin.systemOf(gameType)
+  if type(gameType) ~= "string" or gameType == "" then return nil end
+  for _, prefix in ipairs(DeltaSkin.GAME_TYPE_PREFIXES) do
+    if gameType:sub(1, #prefix) == prefix then
+      return gameType:sub(#prefix + 1):lower()
+    end
+  end
+  return nil
+end
+
+function DeltaSkin.parse(text, opts)
+  opts = opts or {}
+  local info, err = Json.decode(tostring(text or ""), DeltaSkin.MAX_INFO_BYTES)
+  if type(info) ~= "table" then
+    return nil, "info.json does not parse: " .. tostring(err)
+  end
+
+  local gameType = info.gameTypeIdentifier
+  if type(gameType) ~= "string" or gameType == "" then
+    return nil, "old GBA4iOS skin, not supported: info.json has no gameTypeIdentifier"
+  end
+  if gameType:lower():find("gba4ios", 1, true) then
+    return nil, "old GBA4iOS skin, not supported"
+  end
+  local system = DeltaSkin.systemOf(gameType)
+  if not system then
+    return nil, "not a Delta skin: unknown gameTypeIdentifier " .. gameType
+  end
+
+  local warnings = {}
+  if not DeltaSkin.SYSTEMS[system] then
+    addWarning(warnings, "this skin is for " .. system .. ", not Game Boy")
+  end
+
+  local reps = info.representations
+  if type(reps) ~= "table" then return nil, "info.json has no representations" end
+
+  local pdfFiles, pages = {}, {}
+  for _, orient in ipairs(DeltaSkin.ORIENTATIONS) do
+    local obj = DeltaSkin.representation(reps, orient)
+    if obj then
+      local page = DeltaSkin.buildPage(obj, orient, opts, warnings, pdfFiles)
+      page.index = #pages + 1
+      pages[#pages + 1] = page
+    end
+  end
+  if #pages == 0 then return nil, "info.json has no usable representation" end
+  if #pdfFiles > 0 then
+    addWarning(warnings, "PDF artwork cannot be imported yet")
+  end
+
+  return {
+    pages = pages,
+    name = info.name,
+    author = info.author,
+    notes = info.notes,
+    format = "delta",
+    system = system,
+    identifier = info.identifier,
+    warnings = warnings,
+    pdfFiles = pdfFiles,
+  }
+end
+
+function DeltaSkin.needsConversion(skin)
+  if type(skin) ~= "table" then return nil end
+  local files = skin.pdfFiles
+  if type(files) ~= "table" or #files == 0 then return nil end
+  for _, page in ipairs(skin.pages or {}) do
+    if page.imagePath then return nil end
+  end
+  return { pdfOnly = true, files = files }
+end
+
+function DeltaSkin.outputInputs(ctl)
+  local out = {}
+  for _, b in ipairs(ctl.buttons or {}) do out[#out + 1] = b end
+  for _, h in ipairs(ctl.hotkeys or {}) do
+    local mapped = DeltaSkin.OUTPUT_HOTKEYS[h]
+    if mapped then out[#out + 1] = mapped end
+  end
+  return out
+end
+
+function DeltaSkin.buildRepresentation(page, orient, warnings)
+  local map = DeltaSkin.MAPPING[orient] or DeltaSkin.MAPPING.portrait
+  local mapW, mapH = map.width, map.height
+  local items, files = {}, {}
+
+  for _, ctl in ipairs(page.controls or {}) do
+    local names = DeltaSkin.outputInputs(ctl)
+    if ctl.sector and ctl.sector ~= 1 then
+      names = {}
+    elseif ctl.sector and ctl.areaNames then
+      local TouchSkin = require("src.core.TouchSkin")
+      local dirs = {}
+      for _, side in ipairs({ "up", "down", "left", "right" }) do
+        local mapped = TouchSkin.GB_BUTTONS[tostring(ctl.areaNames[side]):lower()]
+        if mapped then dirs[side] = mapped end
+      end
+      names = next(dirs) and dirs or {}
+    end
+    if names.up or names.down or names.left or names.right or #names > 0 then
+      local item = {
+        inputs = names,
+        frame = {
+          x = round((ctl.x - ctl.rangeX) * mapW),
+          y = round((ctl.y - ctl.rangeY) * mapH),
+          width = round(ctl.rangeX * 2 * mapW),
+          height = round(ctl.rangeY * 2 * mapH),
+        },
+      }
+      if ctl.shape == "radial" then item.mask = "circle" end
+      local edges, any = {}, false
+      local pairsList = {
+        { key = "left", reach = ctl.reachLeft, half = ctl.rangeX * mapW },
+        { key = "right", reach = ctl.reachRight, half = ctl.rangeX * mapW },
+        { key = "top", reach = ctl.reachUp, half = ctl.rangeY * mapH },
+        { key = "bottom", reach = ctl.reachDown, half = ctl.rangeY * mapH },
+      }
+      for _, side in ipairs(pairsList) do
+        local reach = numOr(side.reach, 1)
+        if reach ~= 1 then
+          edges[side.key] = round((reach - 1) * side.half)
+          any = true
+        end
+      end
+      if any then item.extendedEdges = edges end
+      items[#items + 1] = item
+    elseif ctl.imagePath then
+      addWarning(warnings, "per-button art is dropped: Delta keeps all art in one image")
+    end
+  end
+
+  local obj = {
+    items = items,
+    mappingSize = { width = mapW, height = mapH },
+    extendedEdges = { top = 0, bottom = 0, left = 0, right = 0 },
+    translucent = false,
+  }
+  if page.imagePath then
+    obj.assets = {
+      small = page.imagePath, medium = page.imagePath, large = page.imagePath,
+    }
+    files[#files + 1] = page.imagePath
+  end
+  if page.viewport then
+    obj.screens = { {
+      inputFrame = { x = 0, y = 0,
+                     width = DeltaSkin.SCREEN_WIDTH, height = DeltaSkin.SCREEN_HEIGHT },
+      outputFrame = {
+        x = round(page.viewport.x * mapW), y = round(page.viewport.y * mapH),
+        width = round(page.viewport.w * mapW), height = round(page.viewport.h * mapH),
+      },
+    } }
+  end
+  return obj, files
+end
+
+function DeltaSkin.build(skin, opts)
+  if type(skin) ~= "table" or not skin.pages or not skin.pages[1] then
+    return nil, "skin has no pages"
+  end
+  opts = opts or {}
+  local standard, edgeToEdge = {}, {}
+  local assets, warnings, used = {}, {}, {}
+
+  for _, page in ipairs(skin.pages) do
+    local orient = TouchSkin.pageOrient(page)
+    if orient ~= "portrait" and orient ~= "landscape" then
+      orient = (numOr(page.aspect, 1) < 1) and "portrait" or "landscape"
+    end
+    if not used[orient] then
+      used[orient] = true
+      local obj, files = DeltaSkin.buildRepresentation(page, orient, warnings)
+      standard[orient] = obj
+      edgeToEdge[orient] = obj
+      for _, rel in ipairs(files) do assets[#assets + 1] = rel end
+    end
+  end
+
+  local system = tostring(opts.system or "gbc")
+  local info = {
+    name = skin.name or skin.id or "skin",
+    identifier = opts.identifier
+      or ("com.gen1recomp.skin." .. tostring(skin.id or "skin")),
+    gameTypeIdentifier = DeltaSkin.GAME_TYPE_PREFIXES[1] .. system,
+    debug = false,
+    representations = { iphone = { standard = standard, edgeToEdge = edgeToEdge } },
+  }
+  return info, assets, warnings
+end
+
+function DeltaSkin.encodeInfo(skin, opts)
+  local info, assets, warnings = DeltaSkin.build(skin, opts)
+  if not info then return nil, assets end
+  return Json.encode(info), assets, warnings
+end
+
+return DeltaSkin

src/core/Game.lua

@@ -34,6 +34,7 @@ end
 
 function Game:load()
   self.data = Data
+  self.sessionStartedAt = os.time()
   Data:load()
 
   -- Mods are a native engine subsystem.  They load after the verified ROM
@@ -155,6 +156,7 @@ function Game:makeTitleState()
     onNewGame = function()
       while self.stack:top() do self.stack:pop() end
       -- New Game keeps the standalone options.lua preferences
+      self.sessionStartedAt = os.time()
       self.save = SaveData.newGame(self:bootConfig())
       -- no bucket carry-over: mod state from an abandoned session must
       -- not leak into a fresh slot; mods seed via save.created instead
@@ -356,6 +358,7 @@ function Game:update(dt)
   -- reason: they are presentational, so fast-forward must not speed them up
   require("src.render.Pipelines").update(dt)
   pcall(function() require("src.core.DiscordPresence").update(dt) end)
+  self:updateSync(dt)
   -- Steady-state memory backstop: advance the incremental collector one
   -- small step every rendered frame.  The heavy GPU objects are now freed
   -- explicitly (map eviction, battle exit, canvas/renderer swaps), so this
@@ -1178,11 +1181,41 @@ function Game:writeSave()
   -- stamp here so the save.writing payload carries the exact meta the
   -- file gets; mods snapshot runtime state into their namespace now
   self.save.meta = SaveData.buildMeta(
-    self.modStatus and self.modStatus.loaded, self.save.meta)
+    self.modStatus and self.modStatus.loaded, self.save.meta,
+    self.sessionStartedAt)
   if ModRuntime.wants("save.writing") then
     ModRuntime.emit("save.writing", { save = self.save, meta = self.save.meta })
   end
-  return SaveData.save(self.save)
+  local written = SaveData.save(self.save)
+  if written then
+    local eng = self:syncEngine()
+    if eng then pcall(eng.noteSaveWritten, eng) end
+  end
+  return written
+end
+
+function Game:syncEngine()
+  if self._syncOff then return nil end
+  if self._syncEngineRef then return self._syncEngineRef end
+  local ok, SyncEngine = pcall(require, "src.sync.SyncEngine")
+  if not ok or type(SyncEngine) ~= "table" then
+    self._syncOff = true
+    return nil
+  end
+  local eng = SyncEngine.shared()
+  if not eng then
+    self._syncOff = true
+    return nil
+  end
+  self._syncEngineRef = eng
+  return eng
+end
+
+function Game:updateSync(dt)
+  local eng = self:syncEngine()
+  if not eng then return end
+  if not (eng.state.enabled and eng:linked()) and not eng:busy() then return end
+  pcall(eng.update, eng, dt)
 end
 
 -- Persist options.lua only (Options menu / hotkeys 2-5).  Keeps settings
@@ -1241,6 +1274,7 @@ function Game:applyOptions(opts)
 end
 
 function Game:restoreSave(loaded, recovered, opts)
+  self.sessionStartedAt = os.time()
   if ModRuntime.wants("save.loading") then
     ModRuntime.emit("save.loading", { raw = loaded })
   end

src/core/Game2.lua

@@ -36,6 +36,7 @@ local World = require("src.world.gen2.World")
 -- other engine file, so a call site here is the same call site Gen 1 has.
 local ModRuntime = require("src.mods.Runtime")
 local GameViewport = require("src.render.GameViewport")
+local Playfield = require("src.render.Playfield")
 -- Only for the mod-supplied save migrations and the mods-changed report, which
 -- are keyed off save.meta and know nothing about a generation; Gold's own save
 -- IO is src/core/gen2/Save.lua.
@@ -195,6 +196,7 @@ end
 function Game2:persistOptions()
   pcall(Save.saveOptions, self.options)
 end
+Game2.writeOptions = Game2.persistOptions
 
 -- Point the loader's mod.save backing at this save's modData so per-mod state
 -- persists with the slot.  Same contract and same three call sites as Gen 1
@@ -1160,7 +1162,8 @@ end
 -- (Renderer:endFrame's Sp).  Following the zoom used to shrink the LCD grid to
 -- one screen pixel a cell out at survey range.
 function Game2:pixelScale(w, h)
-  return math.max(1, math.floor(math.min(w / 160, h / 144)))
+  local _, _, pw, ph = Playfield.rect(w, h)
+  return math.max(1, math.floor(math.min(pw / 160, ph / 144)))
 end
 
 -- A window-sized canvas the whole frame is composed into, so the post passes
@@ -1277,7 +1280,8 @@ end
 function Game2:blitZones(canvas, zones, w, h)
   local G = love.graphics
   local GbcPalette = require("src.render.GbcPalette")
-  local sx, sy = w / 160, h / 144
+  local px, py, pw, ph = Playfield.rect(w, h)
+  local sx, sy = pw / 160, ph / 144
   G.setColor(1, 1, 1, 1)
   for _, z in ipairs(zones) do
     -- a colors == false zone is the true-colour opt-out; anything the shader
@@ -1296,11 +1300,11 @@ function Game2:blitZones(canvas, zones, w, h)
     -- whose contract differs from Gen 1's.  Whole-screen and half-screen zones
     -- come out of this at exactly the pixels the plain floor/ceil pair gave
     -- them, so the vanilla picture is untouched.
-    local zx, zy = (z.x or 0) * sx, (z.y or 0) * sy
+    local zx, zy = px + (z.x or 0) * sx, py + (z.y or 0) * sy
-    local x1 = math.floor(math.max(zx, 0))
+    local x1 = math.floor(math.max(zx, px))
-    local y1 = math.floor(math.max(zy, 0))
+    local y1 = math.floor(math.max(zy, py))
-    local x2 = math.ceil(math.min(zx + (z.w or 160) * sx, w))
+    local x2 = math.ceil(math.min(zx + (z.w or 160) * sx, px + pw))
-    local y2 = math.ceil(math.min(zy + (z.h or 144) * sy, h))
+    local y2 = math.ceil(math.min(zy + (z.h or 144) * sy, py + ph))
     if x2 > x1 and y2 > y1 then
       G.setScissor(x1, y1, x2 - x1, y2 - y1)
       G.draw(canvas, 0, 0)
@@ -1402,7 +1406,7 @@ function Game2:drawViewportFrame()
     scene = self:presentCanvas(1, w, h)
   end
   if not scene then
-    self:drawScene(w, h)
+    self:drawContained(w, h)
     self:drawHud(w, h)
     return
   end
@@ -1413,7 +1417,7 @@ function Game2:drawViewportFrame()
   G.origin()
   G.setCanvas(scene)
   G.clear(0, 0, 0, 1)
-  self:drawScene(w, h)
+  self:drawContained(w, h)
   G.setCanvas(previous)
 
   if composing and self:compose(scene, zones, w, h) then
@@ -1462,6 +1466,8 @@ function Game2:drawViewportFrame()
         generation = 2,
       }) == true
     if not outputHandled then
+      local cx, cy, cw, ch = Playfield.cutout(w, h)
+      if cx then G.setScissor(cx, cy, cw, ch) end
       if fx then
         GBCFX.present(source, self:pixelScale(w, h))
       else
@@ -1469,6 +1475,7 @@ function Game2:drawViewportFrame()
         G.draw(source, 0, 0)
         G.setShader()
       end
+      if cx then G.setScissor() end
     end
   end
   G.pop()
@@ -1499,6 +1506,13 @@ function Game2:textboxPaper()
   return nil
 end
 
+function Game2:drawContained(w, h)
+  local pw, ph = Playfield.push(w, h)
+  local ok, err = pcall(self.drawScene, self, pw, ph)
+  Playfield.pop()
+  if not ok then error(err, 0) end
+end
+
 function Game2:drawScene(w, h)
   local G = love.graphics
   -- render.compose reads this after the scene is drawn; the plain overworld

src/core/HostShell.lua

@@ -350,11 +350,23 @@ local function haveBridge()
   return osName == "Android" or osName == "iOS" or osName == "UWP"
 end
 
+local function haveRequestBridge()
+  if not (love and love.system and type(love.system.httpRequest) == "function") then
+    return false
+  end
+  local osName = love.system.getOS and love.system.getOS()
+  return osName == "Android" or osName == "iOS" or osName == "UWP"
+end
+
 -- Is any transport available at all?  Callers gate on this, never on curl.
 function HostShell.canFetch()
   return HostShell.haveCurl() or haveBridge()
 end
 
+function HostShell.canHttpRequest()
+  return (HostShell.haveCurl() or haveRequestBridge()) and true or false
+end
+
 -- Download url to an absolute host path.  Returns true, or nil plus an error.
 -- The curl branch deliberately ignores curl's exit code, as the download paths
 -- always did: callers judge the result by the file they got.
@@ -557,4 +569,173 @@ function HostShell.httpPost(url, body, contentType, userAgent, maxTime)
   return nil, "no POST transport on this platform"
 end
 
+local function requestHeaderList(headers)
+  local out = {}
+  if type(headers) == "table" then
+    if #headers > 0 then
+      for _, line in ipairs(headers) do
+        if type(line) == "string" then out[#out + 1] = line end
+      end
+    else
+      local names = {}
+      for name in pairs(headers) do names[#names + 1] = tostring(name) end
+      table.sort(names)
+      for _, name in ipairs(names) do
+        out[#out + 1] = name .. ": " .. tostring(headers[name])
+      end
+    end
+  end
+  for _, line in ipairs(out) do
+    if line:find("[\r\n]") or not line:find(":", 1, true) then return nil end
+  end
+  return out
+end
+
+local BRIDGE_METHODS = { GET = true, POST = true, PUT = true, DELETE = true }
+
+local function requestHeaderPairs(lines)
+  local out = {}
+  for _, line in ipairs(lines) do
+    local name, value = line:match("^%s*([^:]-)%s*:%s*(.-)%s*$")
+    if not name or name == "" then return nil end
+    if name:find("[\r\n]") or value:find("[\r\n]") then return nil end
+    out[#out + 1] = name
+    out[#out + 1] = value
+  end
+  return out
+end
+
+local function bridgeRequest(url, method, headers, body, userAgent)
+  if not BRIDGE_METHODS[method] then
+    return nil, "no request transport for " .. method .. " on this platform"
+  end
+  local fields = requestHeaderPairs(headers)
+  if not fields then return nil, "bad request header" end
+  local ok, envelope = pcall(love.system.httpRequest, url, method, fields,
+                             body, userAgent)
+  if not ok or type(envelope) ~= "string" or envelope == "" then
+    return nil, "this app build cannot make signed requests: update the app to use save sync"
+  end
+  local head, rest = envelope:match("^([^\n]*)\n(.*)$")
+  if not head then
+    return nil, fetchError(url, nil, "unreadable reply from the network bridge")
+  end
+  local status = tonumber(head:match("^STATUS (%d+)$"))
+  if status then return rest or "", nil, status end
+  return nil, fetchError(url, nil, head:match("^ERROR (.*)$") or head)
+end
+
+local requestSeq = 0
+
+local function requestStagingPath(kind)
+  local dir
+  if love and love.filesystem and love.filesystem.getSaveDirectory then
+    local ok, saveDir = pcall(love.filesystem.getSaveDirectory)
+    if ok and type(saveDir) == "string" and saveDir ~= "" then dir = saveDir end
+  end
+  if not dir then
+    dir = os.getenv("TEMP") or os.getenv("TMP")
+    if not dir or dir == "" then dir = os.getenv("TMPDIR") or "/tmp" end
+  end
+  local sep = dir:find("\\") and "\\" or "/"
+  requestSeq = requestSeq + 1
+  return dir .. sep .. ("gen1recomp-req-%s-%d-%d-%d.tmp"):format(
+    kind, os.time() % 1000000, requestSeq, math.random(0, 999999))
+end
+
+local function writeStagingFile(kind, text)
+  local path = requestStagingPath(kind)
+  local file, openErr = io.open(path, "wb")
+  if not file then
+    return nil, "could not create the request " .. kind .. ": " .. tostring(openErr)
+  end
+  local wrote, writeErr = pcall(function()
+    assert(file:write(text))
+    assert(file:close())
+  end)
+  if not wrote then
+    pcall(function() file:close() end)
+    pcall(os.remove, path)
+    return nil, "could not write the request " .. kind .. ": " .. tostring(writeErr)
+  end
+  return path
+end
+
+function HostShell.httpRequest(url, opts)
+  opts = type(opts) == "table" and opts or {}
+  if type(url) ~= "string" or url == "" then return nil, "missing url" end
+  local method = tostring(opts.method or "GET"):upper()
+  if not method:match("^%u+$") then return nil, "bad request method" end
+  local headers = requestHeaderList(opts.headers)
+  if not headers then return nil, "bad request header" end
+  local body = opts.body
+  if body ~= nil and type(body) ~= "string" then return nil, "bad request body" end
+  local userAgent = opts.userAgent or "gen1recomp"
+  local maxTime = tonumber(opts.maxTime) or 30
+
+  if not HostShell.haveCurl() then
+    if haveRequestBridge() then
+      return bridgeRequest(url, method, headers, body, userAgent)
+    end
+    if method == "GET" and #headers == 0 then
+      local got, err = HostShell.httpGet(url, userAgent, opts.accept, maxTime)
+      if not got then return nil, err end
+      return got, nil, 200
+    end
+    if haveBridge() then
+      return nil, "this app build cannot make signed requests: update the app to use save sync"
+    end
+    return nil, "no request transport on this platform"
+  end
+
+  local bodyPath, stageErr
+  if body then
+    bodyPath, stageErr = writeStagingFile("body", body)
+    if not bodyPath then return nil, stageErr end
+  end
+
+  local lines = { "User-Agent: " .. userAgent }
+  for _, line in ipairs(headers) do lines[#lines + 1] = line end
+  if body then
+    lines[#lines + 1] = "Content-Length: " .. tostring(#body)
+  end
+  local headerPath
+  headerPath, stageErr = writeStagingFile("head",
+    table.concat(lines, "\n") .. "\n")
+  if not headerPath then
+    if bodyPath then pcall(os.remove, bodyPath) end
+    return nil, stageErr
+  end
+
+  local function cleanup()
+    if bodyPath then pcall(os.remove, bodyPath) end
+    pcall(os.remove, headerPath)
+  end
+
+  local cmd = ("curl -sSL --proto =http,https --proto-redir =http,https "
+    .. "--connect-timeout 10 --max-time %d "):format(maxTime)
+    .. "-X " .. HostShell.quote(method) .. " "
+    .. "-H " .. HostShell.quote("@" .. headerPath) .. " "
+  if body then
+    cmd = cmd .. "--data-binary " .. HostShell.quote("@" .. bodyPath) .. " "
+  end
+  cmd = cmd .. "-w " .. HostShell.quote(HTTP_MARK_FMT) .. " "
+    .. HostShell.quote(url) .. " 2>&1"
+
+  local pipe = HostShell.popen(cmd)
+  if not pipe then
+    cleanup()
+    return nil, "could not run curl"
+  end
+  local readOk, out = pcall(function() return pipe:read("*a") end)
+  HostShell.pclose(pipe)
+  cleanup()
+  if not readOk then
+    return nil, fetchError(url, nil, tostring(out))
+  end
+  local respBody, status, noise = splitCurlOutput(out)
+  if not status then return nil, fetchError(url, nil, noise) end
+  return respBody or "", nil, status
+end
+
 return HostShell

src/core/SaveData.lua

@@ -356,6 +356,8 @@ function SaveData.defaultOptions()
     -- rewind presentation preferences.
     dateFormat = "device", -- device | dmy | mdy | ymd
     timeFormat = "device", -- device | 24h | 12h
+    saveSync = { enabled = false, lastSyncAt = 0, revs = {}, stamps = {},
+                 pendingConflicts = {} },
   }
 end
 
@@ -1013,6 +1015,22 @@ function SaveData.listSlots(version)
   return out
 end
 
+function SaveData.readSlotSource(version, slotId, injectedFs)
+  version = version or GameVersion.get()
+  if not knownVersion(version) or type(slotId) ~= "string" then return nil end
+  local fs = persistFs(injectedFs)
+  local main, bak, tmp = slotNames(version, slotId)
+  for _, name in ipairs({ main, tmp, bak }) do
+    if fs.getInfo(name) then
+      local body = fs.read(name)
+      if type(body) == "string" and body ~= "" then
+        if SaveSerializer.decode(body) then return body end
+      end
+    end
+  end
+  return nil
+end
+
 -- Give a registered slot a custom label (#205: "a way to name save slots so
 -- you can see that in the launcher").  The label lives in the options
 -- registry next to list/active, never in the save file itself, so renaming
@@ -1327,7 +1345,7 @@ end
 -- loaded list sorted by id and is the ground truth for the load-time
 -- mod-set diff.  A nil mods list keeps the previous stamp's set so a
 -- headless writer (the save editor) never wipes it.
-function SaveData.buildMeta(mods, previous)
+function SaveData.buildMeta(mods, previous, sessionStart)
   local list
   if mods ~= nil then
     list = {}
@@ -1338,10 +1356,18 @@ function SaveData.buildMeta(mods, previous)
   else
     list = (type(previous) == "table" and previous.mods) or {}
   end
+  local started = tonumber(sessionStart)
+  if not started or started ~= started or started <= 0
+      or started == math.huge then
+    started = type(previous) == "table" and tonumber(previous.sessionStart) or nil
+  end
+  local savedAt = os.time()
+  if started and started > savedAt then started = savedAt end
   return {
     format = Version.saveFormat,
     engine = Version.engine,
-    savedAt = os.time(),
+    savedAt = savedAt,
+    sessionStart = started,
     playthroughId = type(previous) == "table" and previous.playthroughId or nil,
     mods = list,
   }

src/core/TouchControls.lua

@@ -616,13 +616,15 @@ local function exitControl(self, ctl)
   for _, action in ipairs(ctl.hotkeys) do fireHotkey(self, action, false, ctl) end
 end
 
-function skinHitSet(self, x, y)
+function skinHitSet(self, x, y, prev)
   local page = TouchSkin.page()
   if not page then return nil end
   local ww, wh, ox, oy = surfaceRect()
   local set = nil
   for _, ctl in ipairs(page.controls) do
-    if not ctl.decorative and TouchSkin.hits(page, ctl, ww, wh, x, y, ox, oy) then
+    local held = (prev and prev[ctl]) == true
+    if not ctl.decorative
+       and TouchSkin.hits(page, ctl, ww, wh, x, y, ox, oy, held) then
       set = set or {}
       set[ctl] = true
     end
@@ -665,7 +667,7 @@ function TouchControls:touchpressed(id, x, y)
     return
   end
   if TouchSkin.active then
-    local set = skinHitSet(self, x, y)
+    local set = skinHitSet(self, x, y, nil)
     if not set then return end
     local touch = { control = "skin" }
     self.touches[id] = touch
@@ -698,7 +700,7 @@ function TouchControls:touchmoved(id, x, y)
   local touch = self.touches[id]
   if not touch then return end
   if touch.control == "skin" then
-    applySkinSet(self, touch, skinHitSet(self, x, y))
+    applySkinSet(self, touch, skinHitSet(self, x, y, touch.set))
     return
   end
   -- only the d-pad tracks movement (slide between directions without

src/core/TouchSkin.lua

@@ -2,6 +2,7 @@ local TouchSkin = {}
 
 TouchSkin.BUNDLED_ROOT = "assets/skins"
 TouchSkin.USER_ROOT = "skins"
+TouchSkin.EXPORT_ROOT = "skins/_export"
 
 TouchSkin.GB_BUTTONS = {
   a = "a", b = "b", start = "start", select = "select",
@@ -83,6 +84,110 @@ local function parseBinds(spec)
   return buttons, hotkeys, keys, decorative
 end
 
+TouchSkin.AREA_DEFAULTS = {
+  dpad_area = { up = "up", down = "down", left = "left", right = "right" },
+  abxy_area = { up = "x", down = "b", left = "y", right = "a" },
+  analog_left = { up = "up", down = "down", left = "left", right = "right" },
+  analog_right = { up = "up", down = "down", left = "left", right = "right" },
+}
+
+local DIRECTIONAL_CELLS = {
+  { col = 1, row = 1, h = "left", v = "up" },
+  { col = 2, row = 1, v = "up" },
+  { col = 3, row = 1, h = "right", v = "up" },
+  { col = 1, row = 2, h = "left" },
+  { col = 3, row = 2, h = "right" },
+  { col = 1, row = 3, h = "left", v = "down" },
+  { col = 2, row = 3, v = "down" },
+  { col = 3, row = 3, h = "right", v = "down" },
+}
+
+local function outwardReach(reach)
+  return 1 + 3 * ((num(reach, 1)) - 1)
+end
+
+function TouchSkin.expandDirectional(base, names)
+  names = names or {}
+  local cellX = math.abs(num(base.rangeX, 0.05)) / 3
+  local cellY = math.abs(num(base.rangeY, 0.05)) / 3
+  local out = {}
+  for _, cell in ipairs(DIRECTIONAL_CELLS) do
+    local parts = {}
+    if cell.h and names[cell.h] then parts[#parts + 1] = names[cell.h] end
+    if cell.v and names[cell.v] then parts[#parts + 1] = names[cell.v] end
+    local spec = #parts > 0 and table.concat(parts, "|") or "nul"
+    local ctl = TouchSkin.newControl(spec,
+      num(base.x, 0.5) + (cell.col - 2) * cellX * 2,
+      num(base.y, 0.5) + (cell.row - 2) * cellY * 2,
+      cellX * 2, cellY * 2, "rect")
+    ctl.rangeMod = num(base.rangeMod, 1)
+    ctl.alphaMod = num(base.alphaMod, 1)
+    ctl.reachLeft = cell.col == 1 and outwardReach(base.reachLeft) or 1
+    ctl.reachRight = cell.col == 3 and outwardReach(base.reachRight) or 1
+    ctl.reachUp = cell.row == 1 and outwardReach(base.reachUp) or 1
+    ctl.reachDown = cell.row == 3 and outwardReach(base.reachDown) or 1
+    ctl.pixelCoords = base.pixelCoords
+    ctl.movable = base.movable
+    ctl.exclusive = base.exclusive
+    out[#out + 1] = ctl
+  end
+  return out
+end
+
+local SECTOR_CELLS = {
+  { h = "right" },
+  { h = "right", v = "down" },
+  { v = "down" },
+  { h = "left", v = "down" },
+  { h = "left" },
+  { h = "left", v = "up" },
+  { v = "up" },
+  { h = "right", v = "up" },
+}
+
+TouchSkin.SECTOR_SPAN = math.pi / 4
+
+function TouchSkin.sectorHit(sector, dx, dy)
+  local span = TouchSkin.SECTOR_SPAN
+  local start = (sector - 1) * span - span * 0.5
+  local a = (math.atan2(dy, dx) - start) % (math.pi * 2)
+  return a < span
+end
+
+function TouchSkin.expandSectors(base, names)
+  names = names or {}
+  local out = {}
+  for i, cell in ipairs(SECTOR_CELLS) do
+    local parts = {}
+    if cell.h and names[cell.h] then parts[#parts + 1] = names[cell.h] end
+    if cell.v and names[cell.v] then parts[#parts + 1] = names[cell.v] end
+    local spec = #parts > 0 and table.concat(parts, "|") or "nul"
+    local ctl = TouchSkin.newControl(spec, num(base.x, 0.5), num(base.y, 0.5),
+      math.abs(num(base.rangeX, 0.05)) * 2, math.abs(num(base.rangeY, 0.05)) * 2,
+      base.shape)
+    ctl.sector = i
+    ctl.areaKind = base.areaKind
+    ctl.areaNames = base.areaNames
+    ctl.rangeMod = num(base.rangeMod, 1)
+    ctl.alphaMod = num(base.alphaMod, 1)
+    ctl.reachLeft = num(base.reachLeft, 1)
+    ctl.reachRight = num(base.reachRight, 1)
+    ctl.reachUp = num(base.reachUp, 1)
+    ctl.reachDown = num(base.reachDown, 1)
+    ctl.pixelCoords = base.pixelCoords
+    ctl.movable = base.movable
+    ctl.exclusive = base.exclusive
+    out[#out + 1] = ctl
+  end
+  return out
+end
+
+local function areaSide(kv, prefix, side, fallback)
+  local v = kv[prefix .. "_" .. side]
+  if v == nil or trim(v) == "" then return fallback end
+  return trim(v)
+end
+
 local function parseDesc(kv, prefix, page)
   local spec = kv[prefix]
   if not spec then return nil end
@@ -116,9 +221,28 @@ local function parseDesc(kv, prefix, page)
     imagePath = kv[prefix .. "_overlay"],
     pressedImagePath = kv[prefix .. "_overlay_pressed"],
     nextTarget = kv[prefix .. "_next_target"],
+    movable = toBool(kv[prefix .. "_movable"]) or nil,
+    exclusive = (toBool(kv[prefix .. "_exclusive"])
+                 or toBool(kv[prefix .. "_range_mod_exclusive"])) or nil,
+    saturatePct = num(kv[prefix .. "_saturate_pct"], nil),
   }
   if ctl.imagePath == "" then ctl.imagePath = nil end
   if ctl.pressedImagePath == "" then ctl.pressedImagePath = nil end
+
+  local normalized = kv[prefix .. "_normalized"]
+  if normalized ~= nil then ctl.pixelCoords = not toBool(normalized) end
+
+  local areaKind = trim(t[1]):lower()
+  local defaults = TouchSkin.AREA_DEFAULTS[areaKind]
+  if defaults then
+    ctl.areaKind = areaKind
+    ctl.areaNames = {
+      up = areaSide(kv, prefix, "up", defaults.up),
+      down = areaSide(kv, prefix, "down", defaults.down),
+      left = areaSide(kv, prefix, "left", defaults.left),
+      right = areaSide(kv, prefix, "right", defaults.right),
+    }
+  end
   return ctl
 end
 
@@ -127,7 +251,14 @@ function TouchSkin.parse(text)
   local count = math.floor(num(kv.overlays, 0))
   if count <= 0 then return nil, "no overlays" end
 
-  local pages = {}
+  local pages, warnings = {}, {}
+  local function warn(text)
+    for _, existing in ipairs(warnings) do
+      if existing == text then return end
+    end
+    warnings[#warnings + 1] = text
+  end
+
   for i = 0, count - 1 do
     local p = "overlay" .. i
     local page = {
@@ -166,10 +297,34 @@ function TouchSkin.parse(text)
       page.viewportExpand = toBool(kv[p .. "_viewport_expand"])
     end
 
+    page.pixelCoords = not page.normalized
+    if page.pixelCoords and not page.imagePath then
+      page.pixelCoords = false
+      warn(page.name .. " has no base image: desc coordinates read as normalized")
+    end
+
     local descs = math.floor(num(kv[p .. "_descs"], 0))
     for d = 0, descs - 1 do
       local ctl = parseDesc(kv, p .. "_desc" .. d, page)
-      if ctl then page.controls[#page.controls + 1] = ctl end
+      if not ctl then
+        warn(page.name .. " is missing desc " .. d)
+      elseif ctl.areaKind then
+        if ctl.imagePath or ctl.pressedImagePath then
+          local art = TouchSkin.newControl("nul", ctl.x, ctl.y,
+            ctl.rangeX * 2, ctl.rangeY * 2, ctl.shape)
+          art.imagePath = ctl.imagePath
+          art.pressedImagePath = ctl.pressedImagePath
+          art.rangeMod, art.alphaMod = ctl.rangeMod, ctl.alphaMod
+          art.pixelCoords = ctl.pixelCoords
+          art.movable, art.exclusive = ctl.movable, ctl.exclusive
+          page.controls[#page.controls + 1] = art
+        end
+        for _, cell in ipairs(TouchSkin.expandSectors(ctl, ctl.areaNames)) do
+          page.controls[#page.controls + 1] = cell
+        end
+      else
+        page.controls[#page.controls + 1] = ctl
+      end
     end
     pages[#pages + 1] = page
   end
@@ -180,7 +335,7 @@ function TouchSkin.parse(text)
     if not page.orient then page.orient = TouchSkin.pageOrient(page) end
   end
 
-  return { pages = pages }
+  return { pages = pages, warnings = warnings }
 end
 
 local function readFile(path)
@@ -219,18 +374,26 @@ end
 
 TouchSkin.NATIVE_NAME = "skin.lua"
 
+TouchSkin.readFile = readFile
+TouchSkin.listDir = listDir
+TouchSkin.isDir = isDir
+
 local function findConfig(root)
   if readFile(root .. "/" .. TouchSkin.NATIVE_NAME) then
-    return root .. "/" .. TouchSkin.NATIVE_NAME, "native"
+    return root .. "/" .. TouchSkin.NATIVE_NAME, "native", ""
   end
   local named = { "overlay.cfg", "skin.cfg", "layout.cfg" }
   for _, name in ipairs(named) do
-    if readFile(root .. "/" .. name) then return root .. "/" .. name, "retroarch" end
+    if readFile(root .. "/" .. name) then
+      return root .. "/" .. name, "retroarch", ""
     end
+  end
+  local infoPath, prefix = require("src.core.DeltaSkin").findInfo(root)
+  if infoPath then return infoPath, "delta", prefix end
   local items = listDir(root)
   table.sort(items)
   for _, name in ipairs(items) do
-    if name:match("%.cfg$") then return root .. "/" .. name, "retroarch" end
+    if name:match("%.cfg$") then return root .. "/" .. name, "retroarch", "" end
   end
   return nil
 end
@@ -262,6 +425,7 @@ function TouchSkin.parseNative(text)
       imagePath = raw.image,
       fullScreen = raw.fullScreen ~= false,
       normalized = true,
+      pixelCoords = false,
       rangeMod = num(raw.rangeMod, 1),
       alphaMod = num(raw.alphaMod, 1),
       aspect = num(raw.aspect, DEFAULT_ASPECT),
@@ -283,7 +447,24 @@ function TouchSkin.parseNative(text)
     end
     for _, c in ipairs(raw.controls or {}) do
       local buttons, hotkeys, keys, decorative = parseBinds(c.bind or "nul")
+      local sector = tonumber(c.sector)
+      if sector then
+        sector = math.floor(sector)
+        if sector < 1 or sector > #SECTOR_CELLS then sector = nil end
+      end
+      local areaNames
+      if type(c.areaNames) == "table" then
+        areaNames = {}
+        for _, side in ipairs({ "up", "down", "left", "right" }) do
+          if type(c.areaNames[side]) == "string" then
+            areaNames[side] = c.areaNames[side]
+          end
+        end
+      end
       page.controls[#page.controls + 1] = {
+        sector = sector,
+        areaKind = type(c.areaKind) == "string" and c.areaKind or nil,
+        areaNames = areaNames,
         spec = tostring(c.bind or "nul"),
         buttons = buttons, hotkeys = hotkeys, keys = keys,
         decorative = decorative,
@@ -298,6 +479,8 @@ function TouchSkin.parseNative(text)
         imagePath = c.image,
         pressedImagePath = c.imagePressed,
         nextTarget = c.nextTarget,
+        movable = c.movable == true or nil,
+        exclusive = c.exclusive == true or nil,
       }
     end
     if not page.orient then page.orient = TouchSkin.pageOrient(page) end
@@ -355,6 +538,14 @@ function TouchSkin.toNative(skin)
         image = ctl.imagePath,
         imagePressed = ctl.pressedImagePath,
         nextTarget = ctl.nextTarget,
+        movable = ctl.movable or nil,
+        exclusive = ctl.exclusive or nil,
+        sector = ctl.sector,
+        areaKind = ctl.areaKind,
+        areaNames = ctl.areaNames and {
+          up = ctl.areaNames.up, down = ctl.areaNames.down,
+          left = ctl.areaNames.left, right = ctl.areaNames.right,
+        } or nil,
       }
     end
     out.pages[#out.pages + 1] = p
@@ -379,14 +570,44 @@ local function loadImage(path)
   return img
 end
 
+local function pixelScalePending(page)
+  if page.pixelCoords then return true end
+  for _, ctl in ipairs(page.controls or {}) do
+    if ctl.pixelCoords then return true end
+  end
+  return false
+end
+
+local function applyPixelScale(page)
+  if not pixelScalePending(page) then return true end
+  if not page.image or not page.image.getDimensions then return false end
+  local iw, ih = page.image:getDimensions()
+  if not iw or not ih or iw <= 0 or ih <= 0 then return false end
+  for _, ctl in ipairs(page.controls or {}) do
+    local pixel = ctl.pixelCoords
+    if pixel == nil then pixel = page.pixelCoords end
+    if pixel then
+      ctl.x, ctl.y = ctl.x / iw, ctl.y / ih
+      ctl.rangeX, ctl.rangeY = ctl.rangeX / iw, ctl.rangeY / ih
+      ctl.pixelCoords = false
+    end
+  end
+  page.pixelCoords = false
+  return true
+end
+
 function TouchSkin.load(root, id)
-  local cfgPath, format = findConfig(root)
+  local cfgPath, format, prefix = findConfig(root)
-  if not cfgPath then return nil, "no skin.lua or .cfg in " .. root end
+  if not cfgPath then return nil, "no skin.lua, .cfg or info.json in " .. root end
   local text = readFile(cfgPath)
   if not text then return nil, "unreadable " .. cfgPath end
   local skin, err
   if format == "native" then
     skin, err = TouchSkin.parseNative(text)
+  elseif format == "delta" then
+    local dir = cfgPath:match("^(.*)/[^/]+$") or root
+    skin, err = require("src.core.DeltaSkin").parse(text,
+      { prefix = prefix or "", names = listDir(dir) })
   else
     skin, err = TouchSkin.parse(text)
   end
@@ -402,6 +623,10 @@ function TouchSkin.load(root, id)
     if page.imagePath then
       page.image = loadImage(joinPath(root, page.imagePath))
     end
+    if not applyPixelScale(page) then
+      return nil, "could not read " .. tostring(page.imagePath)
+        .. ", which " .. page.name .. " measures its coordinates against"
+    end
     for _, ctl in ipairs(page.controls) do
       if ctl.imagePath then ctl.image = loadImage(joinPath(root, ctl.imagePath)) end
       if ctl.pressedImagePath then
@@ -418,14 +643,30 @@ local function mountZip(archive, point)
   return ok and mounted == true
 end
 
+TouchSkin.ARCHIVE_EXTS = { zip = true, deltaskin = true }
+TouchSkin.LEGACY_EXTS = { gbcskin = true, gbaskin = true, gbskin = true }
+TouchSkin.PDF_ONLY_MESSAGE =
+  "This skin uses PDF artwork, which cannot be imported yet. "
+  .. "Ask the author for a PNG version."
+
+function TouchSkin.archiveId(name)
+  name = tostring(name or "")
+  local ext = name:match("%.([%w]+)$")
+  if not ext or not TouchSkin.ARCHIVE_EXTS[ext:lower()] then return nil end
+  local id = name:sub(1, #name - #ext - 1)
+  if id == "" then return nil end
+  return id, ext:lower()
+end
+
 function TouchSkin.list()
   local out, seen = {}, {}
   local function scan(root, source)
     for _, name in ipairs(listDir(root)) do
-      local id = name:gsub("%.zip$", "")
+      local archiveId = TouchSkin.archiveId(name)
-      if not seen[id] then
+      local id = archiveId or name
+      if not seen[id] and name:sub(1, 1) ~= "_" then
         local path = root .. "/" .. name
-        if name:match("%.zip$") then
+        if archiveId then
           local point = TouchSkin.USER_ROOT .. "/_mounted/" .. id
           if mountZip(path, point) and findConfig(point) then
             seen[id] = true
@@ -447,17 +688,20 @@ function TouchSkin.list()
   return out
 end
 
--- Drop a .zip into <save>/skins and report the id it will list under.
+-- Drop a .zip or .deltaskin into <save>/skins and report the id it lists under.
 function TouchSkin.installArchive(name, data)
   if not data or data == "" then return nil, "empty archive" end
   if not (love and love.filesystem and love.filesystem.write) then
     return nil, "no writable filesystem"
   end
   name = tostring(name or ""):match("([^/\\]+)$") or ""
-  name = name:gsub("[^%w%._%-]", "_")
+  name = name:gsub("[^%w%._%-]", "_"):gsub("^_+", "")
-  if not name:lower():match("%.zip$") then return nil, "not a .zip" end
+  local legacy = name:match("%.([%w]+)$")
-  local id = name:gsub("%.[Zz][Ii][Pp]$", "")
+  if legacy and TouchSkin.LEGACY_EXTS[legacy:lower()] then
-  if id == "" then return nil, "bad archive name" end
+    return nil, "old GBA4iOS skin, not supported"
+  end
+  local id = TouchSkin.archiveId(name)
+  if not id then return nil, "not a .zip or .deltaskin" end
 
   pcall(love.filesystem.createDirectory, TouchSkin.USER_ROOT)
   local dest = TouchSkin.USER_ROOT .. "/" .. name
@@ -467,9 +711,14 @@ function TouchSkin.installArchive(name, data)
   local entry = TouchSkin.find(id)
   if not entry then
     love.filesystem.remove(dest)
-    return nil, "no skin.lua or .cfg inside " .. name
+    return nil, "no skin.lua, .cfg or info.json inside " .. name
   end
-  return id
+  local skin = TouchSkin.load(entry.root, entry.id)
+  if skin and require("src.core.DeltaSkin").needsConversion(skin) then
+    love.filesystem.remove(dest)
+    return nil, TouchSkin.PDF_ONLY_MESSAGE
+  end
+  return id, skin and skin.warnings or nil
 end
 
 function TouchSkin.find(id)
@@ -498,29 +747,13 @@ function TouchSkin.assetPaths(skin)
   return out
 end
 
-function TouchSkin.export(skin, destPath)
+local function writeArchive(entries, destPath)
-  if not skin then return nil, "no skin" end
+  local blob = require("src.core.SkinZip").encode(entries)
-  local SkinZip = require("src.core.SkinZip")
-  local entries = { { name = TouchSkin.NATIVE_NAME, data = TouchSkin.serialize(skin) } }
-  local missing = {}
-  for _, rel in ipairs(TouchSkin.assetPaths(skin)) do
-    local data = readFile(joinPath(skin.root, rel))
-    if data then
-      entries[#entries + 1] = { name = rel, data = data }
-    else
-      missing[#missing + 1] = rel
-    end
-  end
-  if skin.configPath and skin.format == "retroarch" then
-    local cfg = readFile(skin.configPath)
-    if cfg then
-      entries[#entries + 1] =
-        { name = skin.configPath:match("([^/]+)$") or "overlay.cfg", data = cfg }
-    end
-  end
-  local blob = SkinZip.encode(entries)
-  destPath = destPath or (TouchSkin.USER_ROOT .. "/" .. skin.id .. "-export.zip")
   local absolute = destPath:sub(1, 1) == "/" or destPath:match("^%a:[/\\]") ~= nil
+  if not absolute and love and love.filesystem and love.filesystem.createDirectory then
+    local dir = destPath:match("^(.*)/[^/]+$")
+    if dir then pcall(love.filesystem.createDirectory, dir) end
+  end
   if not absolute and love and love.filesystem and love.filesystem.write then
     local ok, err = love.filesystem.write(destPath, blob)
     if not ok then return nil, tostring(err) end
@@ -530,9 +763,167 @@ function TouchSkin.export(skin, destPath)
     handle:write(blob)
     handle:close()
   end
+  return destPath
+end
+
+local function collectAssets(skin, rels)
+  local entries, missing = {}, {}
+  for _, rel in ipairs(rels) do
+    local data = readFile(joinPath(skin.root, rel))
+    if data then
+      entries[#entries + 1] = { name = rel, data = data }
+    else
+      missing[#missing + 1] = rel
+    end
+  end
+  return entries, missing
+end
+
+function TouchSkin.export(skin, destPath)
+  if not skin then return nil, "no skin" end
+  local entries = { { name = TouchSkin.NATIVE_NAME, data = TouchSkin.serialize(skin) } }
+  local assets, missing = collectAssets(skin, TouchSkin.assetPaths(skin))
+  for _, entry in ipairs(assets) do entries[#entries + 1] = entry end
+  if skin.configPath and skin.format == "retroarch" then
+    local cfg = readFile(skin.configPath)
+    if cfg then
+      entries[#entries + 1] =
+        { name = skin.configPath:match("([^/]+)$") or "overlay.cfg", data = cfg }
+    end
+  end
+  destPath = destPath or (TouchSkin.EXPORT_ROOT .. "/" .. skin.id .. "-export.zip")
+  local written, err = writeArchive(entries, destPath)
+  if not written then return nil, err end
   return destPath, missing
 end
 
+local function fmtNum(n)
+  n = tonumber(n) or 0
+  if n == math.floor(n) then return string.format("%d", n) end
+  local s = string.format("%.6f", n):gsub("0+$", ""):gsub("%.$", "")
+  return s
+end
+
+local function fmtRect(r)
+  return ('"%s,%s,%s,%s"'):format(fmtNum(r.x), fmtNum(r.y), fmtNum(r.w), fmtNum(r.h))
+end
+
+local function cfgSpec(spec)
+  local parts = {}
+  for raw in tostring(spec or ""):gmatch("[^|]+") do
+    local name = trim(raw)
+    local key = name:lower():match("^key:(.+)$")
+    parts[#parts + 1] = key and ("retrok_" .. key) or name
+  end
+  return table.concat(parts, "|")
+end
+
+function TouchSkin.toRetroArchConfig(skin)
+  local pages = (skin and skin.pages) or {}
+  local out = { "overlays = " .. #pages }
+  for i, page in ipairs(pages) do
+    local p = "overlay" .. (i - 1)
+    out[#out + 1] = ""
+    out[#out + 1] = p .. '_name = "' .. tostring(page.name or ("overlay" .. (i - 1))) .. '"'
+    if page.imagePath then out[#out + 1] = p .. "_overlay = " .. page.imagePath end
+    out[#out + 1] = p .. "_full_screen = " .. (page.fullScreen ~= false and "true" or "false")
+    out[#out + 1] = p .. "_normalized = true"
+    if num(page.rangeMod, 1) ~= 1 then
+      out[#out + 1] = p .. "_range_mod = " .. fmtNum(page.rangeMod)
+    end
+    if num(page.alphaMod, 1) ~= 1 then
+      out[#out + 1] = p .. "_alpha_mod = " .. fmtNum(page.alphaMod)
+    end
+    if page.aspectFromCfg and page.aspect and page.aspect > 0 then
+      out[#out + 1] = p .. "_aspect_ratio = " .. fmtNum(page.aspect)
+    end
+    local r = page.rect
+    if r and (r.x ~= 0 or r.y ~= 0 or r.w ~= 1 or r.h ~= 1) then
+      out[#out + 1] = p .. "_rect = " .. fmtRect(r)
+    end
+    if page.viewport then
+      out[#out + 1] = p .. "_viewport = " .. fmtRect(page.viewport)
+      if page.viewportFill then out[#out + 1] = p .. "_viewport_fill = true" end
+      if page.viewportExpand then out[#out + 1] = p .. "_viewport_expand = true" end
+    end
+    local controls = {}
+    for _, ctl in ipairs(page.controls or {}) do
+      if not ctl.sector or ctl.sector == 1 then controls[#controls + 1] = ctl end
+    end
+    out[#out + 1] = p .. "_descs = " .. #controls
+    for j, ctl in ipairs(controls) do
+      local d = p .. "_desc" .. (j - 1)
+      local spec = ctl.areaKind and ctl.sector and ctl.areaKind
+        or cfgSpec(ctl.spec)
+      if spec == "" then spec = "nul" end
+      out[#out + 1] = ('%s = "%s,%s,%s,%s,%s,%s"'):format(d, spec,
+        fmtNum(ctl.x), fmtNum(ctl.y),
+        ctl.shape == "radial" and "radial" or "rect",
+        fmtNum(ctl.rangeX), fmtNum(ctl.rangeY))
+      if ctl.imagePath then out[#out + 1] = d .. "_overlay = " .. ctl.imagePath end
+      if ctl.pressedImagePath then
+        out[#out + 1] = d .. "_overlay_pressed = " .. ctl.pressedImagePath
+      end
+      if num(ctl.rangeMod, 1) ~= num(page.rangeMod, 1) then
+        out[#out + 1] = d .. "_range_mod = " .. fmtNum(ctl.rangeMod)
+      end
+      if num(ctl.alphaMod, 1) ~= num(page.alphaMod, 1) then
+        out[#out + 1] = d .. "_alpha_mod = " .. fmtNum(ctl.alphaMod)
+      end
+      for key, value in pairs({ up = ctl.reachUp, down = ctl.reachDown,
+                                left = ctl.reachLeft, right = ctl.reachRight }) do
+        if num(value, 1) ~= 1 then
+          out[#out + 1] = d .. "_reach_" .. key .. " = " .. fmtNum(value)
+        end
+      end
+      if ctl.movable then out[#out + 1] = d .. "_movable = true" end
+      if ctl.exclusive then out[#out + 1] = d .. "_exclusive = true" end
+      if ctl.nextTarget then
+        out[#out + 1] = d .. '_next_target = "' .. tostring(ctl.nextTarget) .. '"'
+      end
+      if ctl.areaKind and ctl.sector and ctl.areaNames then
+        local defaults = TouchSkin.AREA_DEFAULTS[ctl.areaKind] or {}
+        for _, side in ipairs({ "up", "down", "left", "right" }) do
+          local name = ctl.areaNames[side]
+          if name and name ~= defaults[side] then
+            out[#out + 1] = d .. "_" .. side .. ' = "' .. name .. '"'
+          end
+        end
+      end
+    end
+  end
+  return table.concat(out, "\n") .. "\n"
+end
+
+function TouchSkin.exportRetroArch(skin, destPath)
+  if not skin then return nil, "no skin" end
+  local entries = { { name = "overlay.cfg", data = TouchSkin.toRetroArchConfig(skin) } }
+  local assets, missing = collectAssets(skin, TouchSkin.assetPaths(skin))
+  for _, entry in ipairs(assets) do entries[#entries + 1] = entry end
+  destPath = destPath or (TouchSkin.EXPORT_ROOT .. "/" .. skin.id .. "-retroarch.zip")
+  local written, err = writeArchive(entries, destPath)
+  if not written then return nil, err end
+  return destPath, missing
+end
+
+function TouchSkin.exportDelta(skin, opts)
+  if not skin then return nil, "no skin" end
+  opts = opts or {}
+  local DeltaSkin = require("src.core.DeltaSkin")
+  local info, assetRels, warnings = DeltaSkin.build(skin, opts)
+  if not info then return nil, assetRels end
+  local entries = {
+    { name = DeltaSkin.INFO_NAME, data = require("src.link.Json").encode(info) },
+  }
+  local assets, missing = collectAssets(skin, assetRels)
+  for _, entry in ipairs(assets) do entries[#entries + 1] = entry end
+  local destPath = opts.path
+    or (TouchSkin.EXPORT_ROOT .. "/" .. skin.id .. ".deltaskin")
+  local written, err = writeArchive(entries, destPath)
+  if not written then return nil, err end
+  return destPath, missing, warnings
+end
+
 TouchSkin.BINDS = {
   "nul",
   "up", "down", "left", "right",
@@ -597,6 +988,7 @@ function TouchSkin.clone(skin)
     id = skin.id, name = skin.name, root = skin.root, format = skin.format,
     author = skin.author, notes = skin.notes, configPath = skin.configPath,
     source = skin.source, pages = {},
+    warnings = skin.warnings and copyTable(skin.warnings) or nil,
   }
   for i, page in ipairs(skin.pages or {}) do
     local p = copyTable(page)
@@ -676,7 +1068,8 @@ function TouchSkin.listImages(root)
   local function scan(dir, prefix)
     for _, name in ipairs(listDir(dir)) do
       local path = dir .. "/" .. name
-      if name:lower():match("%.png$") or name:lower():match("%.jpg$") then
+      local lower = name:lower()
+      if lower:match("%.png$") or lower:match("%.jpg$") or lower:match("%.jpeg$") then
         out[#out + 1] = prefix .. name
       elseif isDir(path) and prefix == "" then
         scan(path, name .. "/")
@@ -872,17 +1265,21 @@ function TouchSkin.controlGeometry(page, ctl, w, h, ox, oy)
   return cx, cy, halfW, halfH
 end
 
-function TouchSkin.hits(page, ctl, w, h, px, py, ox, oy)
+function TouchSkin.hits(page, ctl, w, h, px, py, ox, oy, held)
   local cx, cy, halfW, halfH = TouchSkin.controlGeometry(page, ctl, w, h, ox, oy)
-  local left = halfW * ctl.reachLeft * ctl.rangeMod
+  local mod = held == false and 1 or ctl.rangeMod
-  local right = halfW * ctl.reachRight * ctl.rangeMod
+  local left = halfW * ctl.reachLeft * mod
-  local up = halfH * ctl.reachUp * ctl.rangeMod
+  local right = halfW * ctl.reachRight * mod
-  local down = halfH * ctl.reachDown * ctl.rangeMod
+  local up = halfH * ctl.reachUp * mod
+  local down = halfH * ctl.reachDown * mod
   local dx = px - cx
   local dy = py - cy
   local rx = dx < 0 and left or right
   local ry = dy < 0 and up or down
   if rx <= 0 or ry <= 0 then return false end
+  if ctl.sector and not TouchSkin.sectorHit(ctl.sector, dx, dy) then
+    return false
+  end
   if ctl.shape == "radial" then
     return (dx * dx) / (rx * rx) + (dy * dy) / (ry * ry) <= 1
   end

src/core/gen2/Save.lua

@@ -301,6 +301,13 @@ end
 -- gear edit these before the game starts (src/import/LauncherSettings.lua).
 Save.OPTIONS_KEY = "gold"
 
+local SHARED_KEYS = {
+  touchControls = true, haptics = true,
+  mods = true, modsByVersion = true, modsGen2 = true,
+  modOptions = true, modProfiles = true, modProfilesSeeded = true,
+  activeProfile = true,
+}
+
 function Save.loadOptions(fs)
   local options = Save.defaultOptions()
   local ok, SaveData = pcall(require, "src.core.SaveData")
@@ -308,7 +315,21 @@ function Save.loadOptions(fs)
   local loaded = SaveData.loadOptions(fs)
   local stored = loaded and loaded[Save.OPTIONS_KEY]
   if type(stored) == "table" then
-    for key, value in pairs(stored) do options[key] = value end
+    for key, value in pairs(stored) do
+      if not SHARED_KEYS[key] then options[key] = value end
+    end
+  end
+  if type(loaded) == "table" then
+    for key in pairs(SHARED_KEYS) do
+      if loaded[key] ~= nil then options[key] = loaded[key] end
+    end
+  end
+  if type(stored) == "table" then
+    for key in pairs(SHARED_KEYS) do
+      if options[key] == nil and stored[key] ~= nil then
+        options[key] = stored[key]
+      end
+    end
   end
   return options
 end
@@ -321,7 +342,13 @@ function Save.saveOptions(options, fs)
   if not ok then return false end
   local file = SaveData.loadOptions(fs) or {}
   local block = {}
-  for key, value in pairs(options) do block[key] = value end
+  for key, value in pairs(options) do
+    if SHARED_KEYS[key] then
+      file[key] = value
+    else
+      block[key] = value
+    end
+  end
   file[Save.OPTIONS_KEY] = block
   SaveData.saveOptions(file, fs)
   return true

src/import/LauncherView.lua

@@ -48,6 +48,14 @@ local TAP_SLOP2 = 16 * 16
 -- Installed mods should not turn into a one- or two-item pager on a compact
 -- display.  Keep a useful page size, then let the list viewport scroll.
 local MIN_MODS_PER_PAGE = 10
+local MIN_SKIN_ROWS = 4
+local SKIN_FORMAT_LABEL = {
+  native = "GEN1",
+  retroarch = "RETROARCH",
+  delta = "DELTA",
+}
+local MIN_FIND_ROWS = 3
+local PANEL_OVERSCAN = 0.75
 
 local function clamp(v, lo, hi) return math.max(lo, math.min(hi, v)) end
 
@@ -56,6 +64,32 @@ local function inRect(rect, x, y)
     and y >= rect.y and y <= rect.y + rect.h
 end
 
+local function tabKeyOf(imp) return imp.tab or "red" end
+
+local function tabScrollMax(imp)
+  local t = imp._tabScrollMax
+  return (t and t[tabKeyOf(imp)]) or 0
+end
+
+local function tabScrollAt(imp)
+  local t = imp._tabScroll
+  return clamp((t and t[tabKeyOf(imp)]) or 0, 0, tabScrollMax(imp))
+end
+
+local function setTabScroll(imp, value)
+  imp._tabScroll = imp._tabScroll or {}
+  imp._tabScroll[tabKeyOf(imp)] = clamp(value, 0, tabScrollMax(imp))
+end
+
+local function modListWantsWheel(imp, wheel)
+  if imp.tab ~= "mods" or (imp._modScrollMax or 0) <= 0 then return false end
+  if not inRect(imp._modListRect, Kit.mouseX, Kit.mouseY) then return false end
+  if not inRect(imp._tabRegionRect, Kit.mouseX, Kit.mouseY) then return false end
+  local at = clamp(imp.modScroll or 0, 0, imp._modScrollMax)
+  if wheel < 0 then return at < imp._modScrollMax end
+  return at > 0
+end
+
 -- ------------------------------------------------------------- lifecycle
 
 local function ensureState(imp)
@@ -65,6 +99,9 @@ local function ensureState(imp)
     imp._actAt = imp._actAt or {}
     imp._uiActions = imp._uiActions or {}
     imp._pages = imp._pages or {}
+    imp._tabScroll = imp._tabScroll or {}
+    imp._tabScrollMax = imp._tabScrollMax or {}
+    imp._tabContentH = imp._tabContentH or {}
     -- Held backspace/arrows must repeat in the text fields; restored on
     -- detach because the game's Input does its own per-step edge detection
     -- and never expects repeated keypressed events.
@@ -155,7 +192,10 @@ function LauncherView.touchpressed(imp, id, x, y)
   imp._touchAt = imp._touchAt or {}
   imp._touchAt[tostring(id)] = {
     x = x, y = y,
-    modsList = (imp._modScrollMax or 0) > 0 and inRect(imp._modListRect, x, y),
+    modsList = imp.tab == "mods" and (imp._modScrollMax or 0) > 0
+      and inRect(imp._modListRect, x, y)
+      and inRect(imp._tabRegionRect, x, y),
+    region = tabScrollMax(imp) > 0 and inRect(imp._tabRegionRect, x, y),
   }
 end
 
@@ -170,13 +210,25 @@ function LauncherView.touchmoved(imp, id, x, y)
     -- A drag that began in the installed-mod viewport scrolls that page's
     -- rows.  Its pager remains available for moving to the next ten-plus
     -- entries; a drag elsewhere keeps the normal short-window page scroll.
-    if start.dragged and start.modsList then
+    if start.dragged then
       local last = start.lastY or start.y
-      imp.modScroll = clamp((imp.modScroll or 0) - (y - last), 0,
+      local move = -(y - last)
-        imp._modScrollMax or 0)
+      if start.modsList then
-    elseif start.dragged and (imp._pageScrollMax or 0) > 0 then
+        local listMax = imp._modScrollMax or 0
-      local last = start.lastY or start.y
+        local at, leftover = Kit.scrollHandoff(
-      imp._pageScroll = (imp._pageScroll or 0) - (y - last)
+          clamp(imp.modScroll or 0, 0, listMax), listMax, move)
+        imp.modScroll = at
+        move = leftover
+      end
+      if move ~= 0 and start.region then
+        local at, leftover = Kit.scrollHandoff(tabScrollAt(imp),
+          tabScrollMax(imp), move)
+        setTabScroll(imp, at)
+        move = leftover
+      end
+      if move ~= 0 and (imp._pageScrollMax or 0) > 0 then
+        imp._pageScroll = (imp._pageScroll or 0) + move
+      end
     end
     start.lastY = y
   end
@@ -796,6 +848,34 @@ local function drawSkinGlyph(x, y, w, h, hot)
   Theme.fillRounded(bx + pad + ow * 0.80, by + pad + oh * 0.50, r * 2, r * 2, ink, a, r)
 end
 
+local function drawSyncGlyph(x, y, w, h, hot)
+  local box = math.min(w, h)
+  local bx = x + (w - box) / 2
+  local by = y + (h - box) / 2
+  local pad = box * 0.24
+  local ink = hot and PAL.inverse or PAL.ink
+  local left, right = bx + pad, bx + box - pad
+  local head = box * 0.15
+  local bar = math.max(1, box * 0.09)
+  local topY, botY = by + box * 0.34, by + box * 0.58
+  Theme.fill(left, topY, math.max(0, right - left - head * 0.5), bar, ink, 1)
+  Theme.fill(left + head * 0.5, botY, math.max(0, right - left - head * 0.5),
+    bar, ink, 1)
+  if love.graphics.line then
+    love.graphics.push("all")
+    Theme.col(ink, 1)
+    if love.graphics.setLineWidth then
+      love.graphics.setLineWidth(math.max(1.5, bar))
+    end
+    local ty, byy = topY + bar / 2, botY + bar / 2
+    love.graphics.line(right - head, ty - head, right, ty, right - head,
+      ty + head)
+    love.graphics.line(left + head, byy - head, left, byy, left + head,
+      byy + head)
+    love.graphics.pop()
+  end
+end
+
 local function drawCross(x, y, size, color)
   love.graphics.push("all")
   love.graphics.setColor(color)
@@ -885,6 +965,8 @@ local function headerChrome(imp)
           hot and QUIT_INK_HOT or QUIT_INK_REST)
       end },
     tab = {},
+    sync = { face = "tab", drawFn = drawSyncGlyph,
+      action = function() imp:_openSync() end },
     game = { face = "tab", font = "tab",
       action = function()
         local g = currentGame(imp)
@@ -1050,6 +1132,27 @@ local function buildHeader(imp, m)
     tx = tx + w + tabGap
   end
 
+  do
+    local w = tabH
+    if tx > tabLeft and tx + w > tabRight then
+      tx = tabLeft
+      ty = ty + tabH + tabRowGap
+    end
+    local o = chrome.sync
+    o.active = imp._syncModal ~= nil
+    btn(imp, tx, ty, w, tabH, "tab-sync", "", o)
+    local bh = math.floor(11 * m.s)
+    local bw = math.min(w, Kit.textWidth("micro", "BETA") + math.floor(10 * m.s))
+    Kit.tag(tx + (w - bw) / 2, ty + tabH - bh - math.floor(2 * m.s), bw, bh,
+      "BETA", o.active and PAL.inverse or PAL.yellow)
+    local eng = imp._sync
+    if eng and eng.busy and eng:busy() then
+      Kit.spinner(tx + w - math.floor(8 * m.s), ty + math.floor(8 * m.s),
+        math.max(2, math.floor(4 * m.s)))
+    end
+    tx = tx + w + tabGap
+  end
+
   -- `ty` has walked down with the wraps, so this stays correct at one row too.
   y = ty + tabH + math.floor(8 * m.s)
   Theme.fill(m.x, y, m.w, 1, PAL.line, Theme.A.hairline)
@@ -1481,7 +1584,7 @@ local function buildSlotCard(imp, x, y, w, availH, m, version, ready)
   return h
 end
 
-local function buildGamePanel(imp, x, y, w, availH, m, version)
+local function buildGamePanel(imp, x, y, w, availH, m, version, budgetH)
   imp.panelVersion = version
   local info = GameVersion.info(version)
   local locked = info == nil
@@ -1527,12 +1630,15 @@ local function buildGamePanel(imp, x, y, w, availH, m, version)
   local afterTitle = math.floor((ready and 22 or 12) * m.s)
   local cy = y + titleH + afterTitle
   local remaining = availH - (titleH + afterTitle)
+  local budgetLeft = math.max(remaining,
+    (budgetH or availH) - (titleH + afterTitle))
 
   local gap = m.gap
   local lx, lw, rx2, rw
   if m.twoCol then
-    lx, lw = x, m.colW
+    local colW = math.floor((w - m.colGap) / 2)
-    rx2, rw = x + m.colW + m.colGap, m.colW
+    lx, lw = x, colW
+    rx2, rw = x + colW + m.colGap, colW
   else
     lx, lw, rx2, rw = x, w, x, w
   end
@@ -1579,15 +1685,19 @@ local function buildGamePanel(imp, x, y, w, availH, m, version)
   -- Save slots.  Two columns put them beside the left stack; ONE column
   -- stacks them underneath.  Either way the card is clipped to the room it
   -- actually has, and sizes its own list to that budget.
+  local bottom = ly
   if not locked then
     local slotY = m.twoCol and cy or ly
-    local slotAvail = m.twoCol and remaining or (cy + remaining - ly)
+    local slotAvail = m.twoCol and budgetLeft or (cy + budgetLeft - ly)
     if slotAvail > 80 * m.s then
       Kit.pushClip(rx2, slotY, rw, math.max(0, slotAvail))
-      buildSlotCard(imp, rx2, slotY, rw, slotAvail, m, version, ready)
+      local slotH = buildSlotCard(imp, rx2, slotY, rw, slotAvail, m, version,
+        ready)
       Kit.popClip()
+      bottom = math.max(bottom, slotY + math.min(slotH or 0, slotAvail))
     end
   end
+  return bottom - y
 end
 
 -- --------------------------------------------------------------- mods panel
@@ -1821,7 +1931,7 @@ local function buildModsPanel(imp, x, y, w, availH, m)
   if #mods == 0 then
     imp.modScroll, imp._modScrollMax, imp._modListRect = 0, 0, nil
     Kit.emptyBox(x, cy, w, math.floor(110 * m.s), imp:_modsEmptyHint())
-    return
+    return (cy - y) + math.floor(110 * m.s)
   end
 
   local sortKey = currentSort(imp, "mods")
@@ -1882,7 +1992,8 @@ local function buildModsPanel(imp, x, y, w, availH, m)
   if not lr then lr = {}; imp._modListRect = lr end
   lr.x, lr.y, lr.w, lr.h = x, listTop, w, listH
   imp._modScrollMax = scrollMax
-  if scrollMax > 0 and (Kit.wheelY or 0) ~= 0 and Kit.hit(x, listTop, w, listH) then
+  if scrollMax > 0 and (Kit.wheelY or 0) ~= 0 and not Kit.blockClicks
+      and Kit.hit(x, listTop, w, listH) then
     scroll = clamp(scroll - Kit.wheelY * math.floor(48 * m.s), 0, scrollMax)
     Kit.wheelY = 0
   elseif scrollMax == 0 then
@@ -2008,9 +2119,10 @@ local function buildModsPanel(imp, x, y, w, availH, m)
   Kit.popClip()
 
   local pagerY = listTop + listH + gap
-  local newPage = Kit.pager(x, pagerY, w, cur, #mods, perPage, "mods")
+  local newPage, newPagerH = Kit.pager(x, pagerY, w, cur, #mods, perPage, "mods")
   if newPage ~= cur then imp.modScroll = 0 end
   setPage(imp, "mods", newPage)
+  return pagerY + newPagerH - y
 end
 
 -- ---------------------------------------------------------- find mods panel
@@ -2044,6 +2156,32 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
       imp._skinNotice.ok and PAL.green or PAL.red, 2) + math.floor(8 * m.s)
   end
 
+  local urlH = m.btnH
+  local addLabel = Strings("Add")
+  local addW = Kit.textWidth("small", addLabel) + math.floor(24 * m.s)
+  local pasteLabel = Strings("Paste")
+  local pasteW = Kit.textWidth("small", pasteLabel) + math.floor(20 * m.s)
+  if imp._skinFetch then
+    Loader.inline(x, cy, w, urlH,
+      Strings("Downloading %s...", tostring(imp._skinFetch.name or "")))
+  else
+    local urlPlace = Layout.rightCluster(x, w, math.floor(6 * m.s))
+    btn(imp, urlPlace(addW), cy, addW, urlH, "skins-url-add", addLabel, {
+      kind = "accent", font = "small",
+      action = function() imp:_addSkinFromUrl() end })
+    if w - addW - pasteW > math.floor(140 * m.s) then
+      btn(imp, urlPlace(pasteW), cy, pasteW, urlH, "skins-url-paste",
+        pasteLabel, {
+          font = "small", action = function() imp:_pasteSkinUrl() end })
+    end
+    local fieldW = math.max(0, urlPlace(0) - x - math.floor(6 * m.s))
+    textField(imp, x, cy, fieldW, urlH, "skins-url", imp.skinUrl or "",
+      Strings("Paste a skin link (.zip, .cfg, .deltaskin)"),
+      imp._skinUrlFocus == true,
+      function() imp:_toggleSkinUrlFocus() end)
+  end
+  cy = cy + urlH + math.floor(8 * m.s)
+
   -- Studio button.  Desktop only: the host supplies the hook nowhere else.
   if imp.onOpenSkinStudio then
     local label = Strings("Open Skin Studio")
@@ -2071,7 +2209,7 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
   -- The row itself is "use this skin"; the gear beside it configures that
   -- entry -- the built-in pad opens the drag-a-button layout editor, a skin
   -- opens the studio, so neither lands on a screen that cannot edit it.
-  local function skinRow(key, id, title, detail, selected, configure)
+  local function skinRow(key, id, title, detail, selected, configure, format)
     local gearW = configure and rowH or 0
     local rowW = w - (gearW > 0 and (gearW + math.floor(6 * m.s)) or 0)
     local ink = rowHit(imp, x, cy, rowW, rowH, selected, key,
@@ -2079,7 +2217,17 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
     local tagW = selected
       and (Kit.textWidth("small", Strings("IN USE")) + math.floor(20 * m.s))
       or math.floor(12 * m.s)
-    local textW = rowW - math.floor(24 * m.s) - tagW
+    local badge = format and SKIN_FORMAT_LABEL[format] or nil
+    local badgeW = 0
+    if badge then
+      badgeW = Kit.textWidth("micro", badge) + math.floor(16 * m.s)
+      local badgeH = math.floor(16 * m.s)
+      Kit.tag(x + rowW - tagW - badgeW - math.floor(12 * m.s),
+        cy + (rowH - badgeH) / 2, badgeW, badgeH, badge,
+        format == "native" and PAL.green or PAL.blue)
+      badgeW = badgeW + math.floor(10 * m.s)
+    end
+    local textW = math.max(0, rowW - math.floor(24 * m.s) - tagW - badgeW)
     local tx = x + math.floor(12 * m.s)
     local ty = cy + math.floor(7 * m.s)
     Kit.text("mono", Kit.ellipsize("mono", title, textW), tx, ty,
@@ -2102,7 +2250,7 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
 
   local TouchSkin = require("src.core.TouchSkin")
   local hint = Strings(
-    "You can also drop a skin .zip on this window, or put a folder in %s/ of your save directory. RetroArch overlay .cfg files work as-is.",
+    "You can also drop a skin .zip or .deltaskin on this window, or put a folder in %s/ of your save directory. RetroArch overlay .cfg files and Delta skins work as-is.",
     TouchSkin.USER_ROOT)
   local hintH = Kit.wrapHeight("small", hint, w, 3)
   local importH = math.floor(10 * m.s) + hintH
@@ -2111,9 +2259,10 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
   local pagerH = math.max(Kit.tapMin(), math.floor(30 * m.s))
   local listTop = cy
   local listH = availH - (cy - y) - importH
-  local perPage = Kit.rowsThatFit(listH, rowH, rowGap, 1, 20)
+  local perPage = Kit.rowsThatFit(listH, rowH, rowGap, MIN_SKIN_ROWS, 20)
   if #entries > perPage then
-    perPage = Kit.rowsThatFit(listH - pagerH - gap, rowH, rowGap, 1, 20)
+    perPage = Kit.rowsThatFit(listH - pagerH - gap, rowH, rowGap,
+      MIN_SKIN_ROWS, 20)
   end
   local first, last, cur, pages = Kit.pageBounds(page(imp, "skins"),
     #entries, perPage)
@@ -2142,11 +2291,10 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
         bits[#bits + 1] = entry.pages .. " " .. Strings("pages")
       end
       if entry.screen then bits[#bits + 1] = Strings("screen cutout") end
-      local configure = imp.onOpenSkinStudio and function()
+      local configure = function() imp._skinActions = { id = entry.id } end
-        imp.onOpenSkinStudio(imp.modScope or "red", entry.id)
-      end or nil
       skinRow("skin-" .. entry.id, entry.id, entry.id,
-        table.concat(bits, "  \194\183  "), active == entry.id, configure)
+        table.concat(bits, "  \194\183  "), active == entry.id, configure,
+        entry.format)
     end
   end
 
@@ -2164,6 +2312,7 @@ local function buildSkinsPanel(imp, x, y, w, availH, m)
 
   cy = cy + math.floor(10 * m.s)
   Kit.textWrapped("small", hint, x, cy, w, PAL.muted, 3)
+  return cy + hintH - y
 end
 
 local function buildFindPanel(imp, x, y, w, availH, m)
@@ -2201,7 +2350,7 @@ local function buildFindPanel(imp, x, y, w, availH, m)
       aw, m.btnH, "find-add", Strings("Add an index"), {
         kind = "accent", font = "small",
         action = function() imp._indexManage = true end })
-    return
+    return (cy - y) + h
   end
 
   -- One row: the search field, then Filter / Sort / Indexes popup buttons.
@@ -2232,7 +2381,7 @@ local function buildFindPanel(imp, x, y, w, availH, m)
     Kit.emptyBox(x, cy, w, math.floor(110 * m.s),
       (total == 0) and Strings("This index lists no mods yet.")
         or Strings("No mods match that search."))
-    return
+    return (cy - y) + math.floor(110 * m.s)
   end
 
   local sortKey = currentSort(imp, "find")
@@ -2283,7 +2432,7 @@ local function buildFindPanel(imp, x, y, w, availH, m)
     + math.floor(8 * m.s)
   local pagerH = math.max(Kit.tapMin(), math.floor(30 * m.s))
   local listH = availH - (cy - y) - pagerH - gap
-  local perPage = Kit.rowsThatFit(listH, rowH, gap, 1, 20)
+  local perPage = Kit.rowsThatFit(listH, rowH, gap, MIN_FIND_ROWS, 20)
   local first, last, cur, pages = Kit.pageBounds(page(imp, "find"), #rows, perPage)
   setPage(imp, "find", cur)
   local listTop = cy
@@ -2384,7 +2533,10 @@ local function buildFindPanel(imp, x, y, w, availH, m)
   end
 
   local pagerY = listTop + (last - first + 1) * (rowH + gap)
-  setPage(imp, "find", Kit.pager(x, pagerY, w, cur, #rows, perPage, "find"))
+  local findPage, findPagerH = Kit.pager(x, pagerY, w, cur, #rows, perPage,
+    "find")
+  setPage(imp, "find", findPage)
+  local bottom = pagerY + findPagerH
 
   -- Aggregate progress.  Enrichment happens a page at a time and each row says
   -- so for itself, but with nothing summarising it the panel looked idle while
@@ -2398,7 +2550,9 @@ local function buildFindPanel(imp, x, y, w, availH, m)
     Kit.text("micro", Strings("Checking %d of %d on this page...",
       waiting, last - first + 1),
       x + dh + math.floor(6 * m.s), py, PAL.muted)
+    bottom = math.max(bottom, py + dh)
   end
+  return bottom - y
 end
 
 -- ------------------------------------------------------------------ footer
@@ -3161,6 +3315,75 @@ end
 
 -- Per-mod actions for the MODS tab: the row itself only carries the enable
 -- toggle, everything episodic (update check, versions, delete) lives here.
+local SKIN_EXPORTS = {
+  { id = "native", key = "skinact-exp-native", label = "Export as gen1recomp .zip" },
+  { id = "retroarch", key = "skinact-exp-ra", label = "Export as RetroArch .zip" },
+  { id = "delta", key = "skinact-exp-delta", label = "Export as Delta .deltaskin" },
+}
+
+local function buildSkinActionsModal(imp, m)
+  local id = imp._skinActions and imp._skinActions.id
+  if not id then imp._skinActions = nil return end
+  local entry
+  for _, e in ipairs(imp:_ensureSkins()) do
+    if e.id == id then entry = e break end
+  end
+  if not entry then imp._skinActions = nil return end
+  local pad = math.floor(18 * m.s)
+  local gap = math.floor(8 * m.s)
+  local rows = #SKIN_EXPORTS + 2 + (imp.onOpenSkinStudio and 1 or 0)
+    + (imp._skinExport and imp._skinExport.dir and 1 or 0)
+  local h = pad + Kit.textHeight("button") + math.floor(4 * m.s)
+    + Kit.textHeight("small") + math.floor(12 * m.s)
+    + rows * (m.btnH + gap) - gap + pad
+  local px, py, pw = modalPanel(m, math.floor(440 * m.s), h)
+  local cy = py + pad
+  Kit.text("button", Kit.ellipsize("button", entry.id, pw - 2 * pad),
+    px + pad, cy, PAL.heading)
+  cy = cy + Kit.textHeight("button") + math.floor(4 * m.s)
+  local fmt = SKIN_FORMAT_LABEL[entry.format or ""] or Strings("unknown format")
+  Kit.text("small", Kit.ellipsize("small",
+    fmt .. "  \194\183  " .. entry.pages .. " " .. Strings("pages")
+      .. "  \194\183  " .. entry.controls .. " " .. Strings("buttons"),
+    pw - 2 * pad), px + pad, cy, PAL.muted)
+  cy = cy + Kit.textHeight("small") + math.floor(12 * m.s)
+
+  btn(imp, px + pad, cy, pw - 2 * pad, m.btnH, "skinact-use",
+    Strings("Use this skin"), { kind = "primary", font = "small",
+      action = function()
+        imp:_useSkin(id)
+        imp._skinActions = nil
+      end })
+  cy = cy + m.btnH + gap
+  if imp.onOpenSkinStudio then
+    btn(imp, px + pad, cy, pw - 2 * pad, m.btnH, "skinact-edit",
+      Strings("Open in Skin Studio"), { kind = "accent", font = "small",
+        action = function()
+          imp._skinActions = nil
+          imp.onOpenSkinStudio(imp.modScope or "red", id)
+        end })
+    cy = cy + m.btnH + gap
+  end
+  for _, spec in ipairs(SKIN_EXPORTS) do
+    btn(imp, px + pad, cy, pw - 2 * pad, m.btnH, spec.key, Strings(spec.label), {
+      font = "small",
+      action = function()
+        imp:_exportSkin(id, spec.id)
+        imp._skinActions = nil
+      end })
+    cy = cy + m.btnH + gap
+  end
+  if imp._skinExport and imp._skinExport.dir then
+    btn(imp, px + pad, cy, pw - 2 * pad, m.btnH, "skinact-reveal",
+      Strings("Show the exported file"), { font = "small",
+        action = function() imp:_revealSkinExport() end })
+    cy = cy + m.btnH + gap
+  end
+  btn(imp, px + pad, cy, pw - 2 * pad, m.btnH, "skinact-close",
+    Strings("Close"), { font = "small",
+      action = function() imp._skinActions = nil end })
+end
+
 local function buildModActionsModal(imp, m)
   local mod
   for _, mm in ipairs(imp.mods or {}) do
@@ -3907,6 +4130,335 @@ local function buildDepResolverModal(imp, m)
   end
 end
 
+local SYNC_HINT = "Save sync keeps your saves and your mod list on our server so another device can pick them up. It is brand new, so keep your own backups too."
+
+local function syncTitle(imp, m, px, py, pw, pad)
+  local label = Strings("SAVE SYNC")
+  Kit.text("button", label, px + pad, py, PAL.heading)
+  local bh = math.floor(15 * m.s)
+  local bw = Kit.textWidth("micro", "BETA") + math.floor(14 * m.s)
+  Kit.tag(px + pad + Kit.textWidth("button", label) + math.floor(8 * m.s),
+    py + (Kit.textHeight("button") - bh) / 2, bw, bh, "BETA", PAL.yellow)
+  return py + Kit.textHeight("button") + math.floor(12 * m.s)
+end
+
+local function syncStatus(imp, m, x, y, w, eng)
+  if eng:busy() then
+    Loader.inline(x, y, w, m.btnH, eng.status)
+    return m.btnH + math.floor(8 * m.s)
+  end
+  Kit.text("small", Kit.ellipsize("small", eng.status or "", w), x, y,
+    eng.phase == "error" and PAL.red or PAL.muted)
+  return Kit.textHeight("small") + math.floor(10 * m.s)
+end
+
+local function syncRow(imp, m, x, y, w, key, label, opts)
+  opts = opts or {}
+  opts.font = "small"
+  btn(imp, x, y, w, m.btnH, key, label, opts)
+  return y + m.btnH + math.floor(8 * m.s)
+end
+
+function LauncherView.syncSideText(meta)
+  meta = type(meta) == "table" and meta or {}
+  local summary = type(meta.summary) == "table" and meta.summary or {}
+  local bits = {}
+  if type(summary.name) == "string" and summary.name ~= "" then
+    bits[#bits + 1] = summary.name
+  end
+  if tonumber(summary.badges) then
+    bits[#bits + 1] = tostring(math.floor(summary.badges)) .. " "
+      .. Strings("badges")
+  end
+  if type(summary.timeText) == "string" and summary.timeText ~= "" then
+    bits[#bits + 1] = summary.timeText
+  end
+  if tonumber(summary.dexCount) then
+    bits[#bits + 1] = tostring(math.floor(summary.dexCount)) .. " "
+      .. Strings("seen")
+  end
+  local when = tonumber(meta.savedAt)
+  if when then
+    bits[#bits + 1] = Strings("saved") .. " " .. os.date("%Y-%m-%d %H:%M", when)
+  end
+  if #bits == 0 then return Strings("no details") end
+  return table.concat(bits, "  \194\183  ")
+end
+
+local function buildSyncConflict(imp, m, eng)
+  local row = eng.conflicts[1]
+  local pad = math.floor(18 * m.s)
+  local w = math.floor(520 * m.s)
+  local innerW = w - 2 * pad
+  local lead = row.overlap
+    and Strings("These saves were played at the same time.")
+    or Strings("This save also changed on another device.")
+  local leadH = Kit.wrapHeight("small", lead, innerW, 2)
+  local sideH = Kit.textHeight("small") + math.floor(2 * m.s)
+    + Kit.wrapHeight("micro", "x", innerW, 2)
+  local h = pad + Kit.textHeight("button") + math.floor(12 * m.s) + leadH
+    + math.floor(10 * m.s) + 2 * (sideH + math.floor(10 * m.s))
+    + 4 * (m.btnH + math.floor(8 * m.s)) + pad
+  local px, py, pw = modalPanel(m, w, h)
+  local cy = syncTitle(imp, m, px, py + pad, pw, pad)
+  cy = cy + Kit.textWrapped("small", lead, px + pad, cy, pw - 2 * pad,
+    PAL.detail, 2) + math.floor(10 * m.s)
+
+  local function side(title, meta)
+    Kit.text("small", title, px + pad, cy, PAL.heading)
+    cy = cy + Kit.textHeight("small") + math.floor(2 * m.s)
+    cy = cy + Kit.textWrapped("micro", LauncherView.syncSideText(meta),
+      px + pad, cy, pw - 2 * pad, PAL.muted, 2) + math.floor(10 * m.s)
+  end
+  side(Strings("This device") .. "  \194\183  " .. tostring(row.version or "?"),
+    row.localMeta)
+  side(Strings("Other device"), row.remoteMeta)
+
+  local key = row.key
+  cy = syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-keep-this",
+    Strings("Keep this device"), { kind = "primary",
+      action = function() imp:_syncResolve(key, "local") end })
+  cy = syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-keep-other",
+    Strings("Keep the other device"), { kind = "accent",
+      action = function() imp:_syncResolve(key, "remote") end })
+  cy = syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-keep-both",
+    Strings("Keep both"), {
+      action = function() imp:_syncResolve(key, "both") end })
+  syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-conflict-close",
+    Strings("Close"), { action = function() imp:_closeSync() end })
+end
+
+local function buildSyncLink(imp, m, eng)
+  local mo = imp._syncModal
+  local pad = math.floor(18 * m.s)
+  local w = math.floor(460 * m.s)
+  local fieldH = math.max(Kit.tapMin(), math.floor(36 * m.s))
+  local hint = Strings("Enter the two codes the other device is showing.")
+  local hintH = Kit.wrapHeight("small", hint, w - 2 * pad, 2)
+  local h = pad + Kit.textHeight("button") + math.floor(12 * m.s) + hintH
+    + math.floor(10 * m.s) + 2 * (fieldH + math.floor(8 * m.s))
+    + Kit.textHeight("small") + math.floor(10 * m.s)
+    + 2 * (m.btnH + math.floor(8 * m.s)) + pad
+  local px, py, pw = modalPanel(m, w, h)
+  local cy = syncTitle(imp, m, px, py + pad, pw, pad)
+  cy = cy + Kit.textWrapped("small", hint, px + pad, cy, pw - 2 * pad,
+    PAL.detail, 2) + math.floor(10 * m.s)
+  textField(imp, px + pad, cy, pw - 2 * pad, fieldH, "sync-code1",
+    mo.code1 or "", Strings("First code"), imp._syncFocus == "code1",
+    function() imp:_syncFocusField("code1") end)
+  cy = cy + fieldH + math.floor(8 * m.s)
+  textField(imp, px + pad, cy, pw - 2 * pad, fieldH, "sync-code2",
+    mo.code2 or "", Strings("Second code"), imp._syncFocus == "code2",
+    function() imp:_syncFocusField("code2") end)
+  cy = cy + fieldH + math.floor(8 * m.s)
+  cy = cy + syncStatus(imp, m, px + pad, cy, pw - 2 * pad, eng)
+  cy = syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-link-go",
+    Strings("Link this device"), { kind = "primary", enabled = not eng:busy(),
+      action = function() imp:_syncLink() end })
+  syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-link-back",
+    Strings("Back"), { action = function() imp:_syncView("home") end })
+end
+
+local function buildSyncMods(imp, m, eng)
+  local mo = imp._syncModal
+  local pad = math.floor(18 * m.s)
+  local w = math.floor(500 * m.s)
+  local fieldH = math.max(Kit.tapMin(), math.floor(36 * m.s))
+  local plan = eng.modPlan
+  local rows = 4 + (plan and 1 or 0)
+  local h = pad + Kit.textHeight("button") + math.floor(12 * m.s)
+    + 3 * (Kit.textHeight("small") + math.floor(8 * m.s))
+    + fieldH + math.floor(8 * m.s)
+    + rows * (m.btnH + math.floor(8 * m.s)) + pad
+  local px, py, pw = modalPanel(m, w, h)
+  local cy = syncTitle(imp, m, px, py + pad, pw, pad)
+  local innerW = pw - 2 * pad
+
+  if eng.shareCode then
+    Kit.text("small", Strings("Share this code:"), px + pad, cy, PAL.muted)
+    cy = cy + Kit.textHeight("small") + math.floor(4 * m.s)
+    Kit.text("stat", eng.shareCode, px + pad, cy, PAL.heading)
+    cy = cy + Kit.textHeight("stat") + math.floor(4 * m.s)
+    Kit.text("micro", Kit.ellipsize("micro",
+      Strings("Enter this code in Save Sync > Get mod list"), innerW),
+      px + pad, cy, PAL.muted)
+    cy = cy + Kit.textHeight("micro") + math.floor(10 * m.s)
+  end
+  cy = syncRow(imp, m, px + pad, cy, innerW, "sync-share-mods",
+    Strings("Share mod list"), { kind = "accent", enabled = not eng:busy(),
+      action = function() imp:_syncShareMods() end })
+
+  textField(imp, px + pad, cy, innerW, fieldH, "sync-share-code",
+    mo.share or "", Strings("Paste a 6-character mod code"),
+    imp._syncFocus == "share", function() imp:_syncFocusField("share") end)
+  cy = cy + fieldH + math.floor(8 * m.s)
+  cy = syncRow(imp, m, px + pad, cy, innerW, "sync-get-mods",
+    Strings("Get mod list"), { kind = "accent", enabled = not eng:busy(),
+      action = function() imp:_syncGetShare() end })
+
+  if plan then
+    local line = Strings("%d mods, %d indexes to add",
+      #(plan.toInstall or {}) + #(plan.toEnable or {}), #(plan.indexes or {}))
+    if #(plan.missing or {}) > 0 then
+      line = line .. "  \194\183  " .. Strings("%d not in your indexes",
+        #plan.missing)
+    end
+    Kit.text("small", Kit.ellipsize("small", line, innerW), px + pad, cy,
+      PAL.detail)
+    cy = cy + Kit.textHeight("small") + math.floor(8 * m.s)
+    local prog = mo.progress
+    if prog then
+      Loader.inline(px + pad, cy, innerW, m.btnH,
+        Strings("%d of %d", prog.done or 0, prog.total or 0))
+      cy = cy + m.btnH + math.floor(8 * m.s)
+    else
+      cy = syncRow(imp, m, px + pad, cy, innerW, "sync-apply-mods",
+        Strings("Apply these mods"), { kind = "primary",
+          enabled = not eng:busy(),
+          action = function() imp:_syncApplyMods() end })
+    end
+  end
+  cy = cy + syncStatus(imp, m, px + pad, cy, innerW, eng)
+  syncRow(imp, m, px + pad, cy, innerW, "sync-mods-back", Strings("Back"),
+    { action = function() imp:_syncView("home") end })
+end
+
+function LauncherView.syncDeviceRows(eng, limit)
+  local out = {}
+  if not eng or type(eng.devices) ~= "table" then return out end
+  for _, row in ipairs(eng.devices) do
+    if #out >= (limit or 6) then break end
+    if type(row) == "table" and type(row.id) == "string" then
+      out[#out + 1] = {
+        id = row.id,
+        current = row.current == true,
+        label = type(row.label) == "string" and row.label ~= "" and row.label
+          or "device",
+      }
+    end
+  end
+  return out
+end
+
+local function buildSyncHome(imp, m, eng)
+  local pad = math.floor(18 * m.s)
+  local w = math.floor(460 * m.s)
+  local linked = eng:linked()
+  local codes = eng.codes
+  local body = linked
+    and Strings("This device is linked. Saves and the mod list sync when the launcher opens and a few seconds after each save.")
+    or Strings(SYNC_HINT)
+  local innerW = w - 2 * pad
+  local hintH = Kit.wrapHeight("small", body, innerW, 5)
+  local codesH = codes
+    and (Kit.textHeight("small") + math.floor(6 * m.s)
+      + 2 * (Kit.textHeight("title") + math.floor(4 * m.s))
+      + math.floor(8 * m.s)) or 0
+  local devices = linked and LauncherView.syncDeviceRows(eng) or {}
+  local devicesH = #devices > 0
+    and (Kit.textHeight("small") + math.floor(6 * m.s)) or 0
+  local rows = (linked and 5 or 3) + #devices
+  local h = pad + Kit.textHeight("button") + math.floor(12 * m.s) + hintH
+    + math.floor(10 * m.s) + codesH + devicesH + m.btnH + math.floor(10 * m.s)
+    + rows * (m.btnH + math.floor(8 * m.s)) + pad
+  local px, py, pw = modalPanel(m, w, h)
+  local cy = syncTitle(imp, m, px, py + pad, pw, pad)
+  cy = cy + Kit.textWrapped("small", body, px + pad, cy, innerW, PAL.detail, 5)
+    + math.floor(10 * m.s)
+
+  if codes then
+    Kit.text("small", Strings("Enter these on your other device:"), px + pad,
+      cy, PAL.muted)
+    cy = cy + Kit.textHeight("small") + math.floor(6 * m.s)
+    Kit.text("title", codes.code1, px + pad, cy, PAL.heading)
+    cy = cy + Kit.textHeight("title") + math.floor(4 * m.s)
+    Kit.text("title", codes.code2, px + pad, cy, PAL.heading)
+    cy = cy + Kit.textHeight("title") + math.floor(8 * m.s)
+  end
+  cy = cy + syncStatus(imp, m, px + pad, cy, innerW, eng)
+
+  if #devices > 0 then
+    Kit.text("small", Strings("Devices on this account:"), px + pad, cy,
+      PAL.muted)
+    cy = cy + Kit.textHeight("small") + math.floor(6 * m.s)
+    for i, device in ipairs(devices) do
+      local id = device.id
+      if device.current then
+        cy = syncRow(imp, m, px + pad, cy, innerW, "sync-device-" .. i,
+          device.label .. "  \194\183  " .. Strings("this device"),
+          { enabled = false })
+      else
+        cy = syncRow(imp, m, px + pad, cy, innerW, "sync-device-" .. i,
+          Strings("Unlink %s", device.label), { kind = "danger",
+            enabled = not eng:busy(),
+            action = function() imp:_syncUnlinkDevice(id) end })
+      end
+    end
+  end
+
+  if linked then
+    cy = syncRow(imp, m, px + pad, cy, innerW, "sync-now", Strings("Sync now"),
+      { kind = "primary", enabled = not eng:busy(),
+        action = function() imp:_syncNow() end })
+    cy = syncRow(imp, m, px + pad, cy, innerW, "sync-mods",
+      Strings("Share or get a mod list"), { kind = "accent",
+        action = function() imp:_syncView("mods") end })
+    cy = syncRow(imp, m, px + pad, cy, innerW, "sync-unlink",
+      Strings("Unlink this device"), { kind = "danger",
+        action = function() imp:_syncUnlink() end })
+  else
+    cy = syncRow(imp, m, px + pad, cy, innerW, "sync-create",
+      Strings("Create sync account"), { kind = "primary",
+        enabled = not eng:busy(),
+        action = function() imp:_syncCreate() end })
+    cy = syncRow(imp, m, px + pad, cy, innerW, "sync-link",
+      Strings("Link this device"), { kind = "accent",
+        action = function() imp:_syncView("link") end })
+  end
+  syncRow(imp, m, px + pad, cy, innerW, "sync-close", Strings("Close"),
+    { action = function() imp:_closeSync() end })
+end
+
+local function buildSyncUnavailable(imp, m, msg)
+  local pad = math.floor(18 * m.s)
+  local w = math.floor(420 * m.s)
+  local h = pad + Kit.textHeight("button") + math.floor(12 * m.s)
+    + Kit.wrapHeight("small", msg, w - 2 * pad, 4) + math.floor(10 * m.s)
+    + m.btnH + pad
+  local px, py, pw = modalPanel(m, w, h)
+  local cy = syncTitle(imp, m, px, py + pad, pw, pad)
+  cy = cy + Kit.textWrapped("small", msg, px + pad, cy, pw - 2 * pad,
+    PAL.detail, 4) + math.floor(10 * m.s)
+  syncRow(imp, m, px + pad, cy, pw - 2 * pad, "sync-close",
+    Strings("Close"), { action = function() imp:_closeSync() end })
+end
+
+local function buildSyncModal(imp, m)
+  if not imp:_syncSupported() then
+    buildSyncUnavailable(imp, m, Strings(
+      "Save sync cannot run on this build: it has no way to send the signed requests it needs. Update to the latest app build, or use a desktop build."))
+    return
+  end
+  local eng = imp._sync
+  if not eng then
+    buildSyncUnavailable(imp, m,
+      Strings("Save sync is not available in this build."))
+    return
+  end
+  if eng.phase == "conflict" and eng.conflicts and #eng.conflicts > 0 then
+    buildSyncConflict(imp, m, eng)
+    return
+  end
+  local view = imp._syncModal and imp._syncModal.view or "home"
+  if view == "link" then
+    buildSyncLink(imp, m, eng)
+  elseif view == "mods" then
+    buildSyncMods(imp, m, eng)
+  else
+    buildSyncHome(imp, m, eng)
+  end
+end
+
 -- Whether ANY modal will draw this frame.  draw() consults this BEFORE the
 -- panels build: immediate mode hit-tests each control as it draws, so the
 -- panels underneath a modal must run with Kit.blockClicks already raised or
@@ -3919,7 +4471,7 @@ local function modalUp(imp)
     or imp._findDetails or imp._modVersions or imp._modDepResolver or imp._sortPopup
     or imp._filterPopup or imp._modScopePopup or imp._indexManage
     or imp._gamePopup
-    or imp._modActions or imp._modImports
+    or imp._modActions or imp._modImports or imp._skinActions or imp._syncModal
     or imp._modHeaderActionsPopup or imp._profilesPopup or imp._singleProfileActions or imp._profileSavePrompt
     or imp._profileRenamePrompt or imp._findEntry or imp._gameManage) ~= nil
 end
@@ -4064,6 +4616,8 @@ local function buildModals(imp, m)
   if imp._modScopePopup then buildModScopeModal(imp, m) return true end
   if imp._filterPopup then buildFilterModal(imp, m) return true end
   if imp._indexManage then buildIndexesModal(imp, m) return true end
+  if imp._syncModal then buildSyncModal(imp, m) return true end
+  if imp._skinActions then buildSkinActionsModal(imp, m) return true end
   if imp._modActions then buildModActionsModal(imp, m) return true end
   if imp._findEntry then buildFindEntryModal(imp, m) return true end
   if imp._gameManage then buildGameManageModal(imp, m) return true end
@@ -4173,13 +4727,6 @@ function LauncherView.draw(imp)
   local footH = footerHeight(imp, m)
   local naturalAvail = m.h - headerHeight(m) - footH - m.gap
   local scrollMax = math.max(0, minPanelHeight(m) - naturalAvail)
-  local scroll = math.max(0, math.min(imp._pageScroll or 0, scrollMax))
-  if scrollMax > 0 and (imp._wheelY or 0) ~= 0 then
-    scroll = math.max(0, math.min(
-      scroll - imp._wheelY * math.floor(48 * m.s), scrollMax))
-    imp._wheelY = 0  -- the page consumed the wheel; lists page by tap here
-  end
-  imp._pageScroll, imp._pageScrollMax = scroll, scrollMax
 
   Kit.beginFrame(mx, my, click ~= nil, imp._wheelY or 0)
   imp._clickPt = nil
@@ -4192,6 +4739,35 @@ function LauncherView.draw(imp)
   -- one is up; buildModals lowers the shield for the modal's own controls.
   Kit.blockClicks = modalUp(imp)
 
+  local step = Kit.scrollStep(m.s)
+  local nested = modListWantsWheel(imp, Kit.wheelY or 0)
+  if not nested then
+    local rect = imp._tabRegionRect
+    if rect then
+      setTabScroll(imp, (Kit.scrollWheel(tabScrollAt(imp), tabScrollMax(imp),
+        rect.x, rect.y, rect.w, rect.h, step)))
+    end
+  end
+  local scroll = math.max(0, math.min(imp._pageScroll or 0, scrollMax))
+  if scrollMax > 0 and (Kit.wheelY or 0) ~= 0 and not nested
+      and not Kit.blockClicks then
+    local moved = math.max(0, math.min(scroll - Kit.wheelY * step, scrollMax))
+    if moved ~= scroll then
+      scroll = moved
+      Kit.wheelY = 0
+    end
+  end
+  imp._pageScroll, imp._pageScrollMax = scroll, scrollMax
+  if (Kit.wheelY or 0) ~= 0 and not nested and not Kit.blockClicks
+      and tabScrollMax(imp) > 0 then
+    local was = tabScrollAt(imp)
+    local to = Kit.scrollClamp(was - Kit.wheelY * step, tabScrollMax(imp))
+    if to ~= was then
+      setTabScroll(imp, to)
+      Kit.wheelY = 0
+    end
+  end
+
   -- The header is the only block that moves with the page scroll, so shift
   -- m.top across the call and put it back rather than wrapping `m` in a
   -- proxy: the proxy cost two tables a frame and put a metatable lookup on
@@ -4210,15 +4786,31 @@ function LauncherView.draw(imp)
   end
 
   local x, w = m.contentX, m.contentW
+  local viewH = math.max(0, availH)
+  local rect = imp._tabRegionRect
+  if not rect then rect = {}; imp._tabRegionRect = rect end
+  rect.x, rect.y, rect.w, rect.h = x, contentY, w, viewH
+
+  local at = tabScrollAt(imp)
+  local py = Kit.scrollBegin(x, contentY, w, viewH, at, tabScrollMax(imp))
+  local budgetH = math.floor(viewH * (1 + PANEL_OVERSCAN))
+  local panelW = math.max(0, w - Kit.scrollGutter(m.s))
+  local contentH
   if imp.tab == "mods" then
-    buildModsPanel(imp, x, contentY, w, availH, m)
+    contentH = buildModsPanel(imp, x, py, panelW, budgetH, m)
   elseif imp.tab == "find" then
-    buildFindPanel(imp, x, contentY, w, availH, m)
+    contentH = buildFindPanel(imp, x, py, panelW, budgetH, m)
   elseif imp.tab == "skins" then
-    buildSkinsPanel(imp, x, contentY, w, availH, m)
+    contentH = buildSkinsPanel(imp, x, py, panelW, budgetH, m)
   else
-    buildGamePanel(imp, x, contentY, w, availH, m, imp.tab)
+    contentH = buildGamePanel(imp, x, py, panelW, availH, m, imp.tab, budgetH)
   end
+  contentH = contentH or availH
+  imp._tabContentH[tabKeyOf(imp)] = contentH
+  imp._tabScrollMax[tabKeyOf(imp)] = Kit.scrollExtent(contentH, viewH)
+  at = clamp(at, 0, tabScrollMax(imp))
+  imp._tabScroll[tabKeyOf(imp)] = at
+  Kit.scrollEnd(x, contentY, w, viewH, at, tabScrollMax(imp))
 
   buildFooter(imp, m, footY)
   Kit.blockClicks = false

src/import/RomImporter.lua

@@ -1111,18 +1111,18 @@ local function chooseZip()
 end
 
 local function chooseSkinZip()
-  local prompt = shellSafe(Strings("Choose a skin .zip"))
+  local prompt = shellSafe(Strings("Choose a skin .zip or .deltaskin"))
   local platform = love.system.getOS()
   if platform == "OS X" then
     return commandOutput(
-      ([[osascript -e 'POSIX path of (choose file with prompt "%s" of type {"zip"})' 2>/dev/null]])
+      ([[osascript -e 'POSIX path of (choose file with prompt "%s" of type {"zip", "deltaskin"})' 2>/dev/null]])
         :format(prompt))
   elseif platform == "Windows" then
     local script = table.concat({
       "Add-Type -AssemblyName System.Windows.Forms;",
       "$d=New-Object System.Windows.Forms.OpenFileDialog;",
       "$d.Title='" .. prompt .. "';",
-      "$d.Filter='Skin archive (*.zip)|*.zip|All files (*.*)|*.*';",
+      "$d.Filter='Skin archive (*.zip;*.deltaskin)|*.zip;*.deltaskin|All files (*.*)|*.*';",
       "if($d.ShowDialog() -eq 'OK'){",
       "$n=[IO.Path]::GetFileName($d.FileName) -replace '[^\\x20-\\x7E]','_';",
       "$t=Join-Path $env:TEMP $n;",
@@ -1134,11 +1134,11 @@ local function chooseSkinZip()
       'powershell -NoProfile -STA -Command "' .. script .. '"')
   elseif platform == "Linux" then
     local path = commandOutput(
-      ([[zenity --file-selection --title="%s" --file-filter="Skin archive | *.zip" 2>/dev/null]])
+      ([[zenity --file-selection --title="%s" --file-filter="Skin archive | *.zip *.deltaskin" 2>/dev/null]])
         :format(prompt))
     if path then return path end
     return commandOutput(
-      [[kdialog --getopenfilename "$HOME" "*.zip|Skin archive" 2>/dev/null]])
+      [[kdialog --getopenfilename "$HOME" "*.zip *.deltaskin|Skin archive" 2>/dev/null]])
   end
   return nil
 end
@@ -1349,6 +1349,7 @@ function RomImporter.new(onComplete, opts)
     findLoaded = false, findSources = nil, findIndex = nil,
     findScroll = 0, findNotice = nil, findQuery = "", findCategory = nil,
     _findSearchFocus = false, _findThumbs = nil,
+    skinUrl = "", _skinUrlFocus = false,
     -- Page scroll offset (px) for the column under the tab bar -- panel, updater
     -- banner and footer -- used only while that column is taller than the window
     -- (see draw()).  Clamped against content in draw, reset on a tab change.
@@ -1851,10 +1852,14 @@ end
 function RomImporter:filedropped(file)
   if self.workState == "working" then return end
   -- A dropped .zip is a mod archive: hand it straight to the mods installer
-  -- (which mounts + validates it).  Everything else is treated as a ROM.  The
+  -- (which mounts + validates it).  A .deltaskin is only ever a skin, and
-  -- dropped file itself is passed through -- installZip opens it the same way
+  -- everything else is treated as a ROM.  The dropped file itself is passed
-  -- readDroppedFile does here.
+  -- through -- installZip opens it the same way readDroppedFile does here.
   local name = file:getFilename() or ""
+  if name:lower():match("%.deltaskin$") then
+    self:_installSkinZip(file)
+    return
+  end
   if name:lower():match("%.zip$") then
     -- On the SKINS tab a zip is a skin; everywhere else it is a mod archive.
     if self.tab == "skins" then
@@ -2481,6 +2486,8 @@ function RomImporter:update(dt)
   self:_pumpModInfoFetch()
   self:_pumpFindStats()
   self:_pumpFindThumbs()
+  self:_pumpSkinFetch()
+  self:_pumpSync(dt)
   self:_pumpModCheck()
   self:_pumpModInstall()
   self:_pumpExtract()
@@ -3082,6 +3089,8 @@ end
 function RomImporter:_switchTab(id)
   self.tab = id
   self._findSearchFocus = false
+  self._skinUrlFocus = false
+  self._modScrollMax, self._modListRect = 0, nil
   self:_disarmTextInput()
   -- the skins list is cheap and can change behind the launcher's back
   -- (an export, a hand-dropped folder), so re-read it on every visit
@@ -3107,6 +3116,7 @@ function RomImporter:_ensureSkins(force)
     out[#out + 1] = {
       id = entry.id,
       source = entry.source,
+      format = skin and skin.format or nil,
       pages = skin and #skin.pages or 0,
       controls = controls,
       screen = page ~= nil and page.viewport ~= nil,
@@ -3140,7 +3150,6 @@ end
 function RomImporter:_installSkinZip(source)
   if self.workState == "working" then return end
   self.tab = "skins"
-  local TouchSkin = require("src.core.TouchSkin")
   local name, data, readError
   if type(source) == "string" then
     name = source
@@ -3160,13 +3169,368 @@ function RomImporter:_installSkinZip(source)
         .. tostring(readError or name) }
     return
   end
-  local id, err = TouchSkin.installArchive(name, data)
+  self:_installSkinData(name, data)
+end
+
+local MAX_SKIN_URL = 300
+local SKIN_TEMP_DIR = "skins/_download"
+
+function RomImporter.skinUrlName(url)
+  local path = tostring(url or ""):gsub("[?#].*$", "")
+  local base = (path:match("([^/\\]+)$") or ""):gsub("[^%w%._%-]", "_")
+  local ext = base:match("%.([%w]+)$")
+  if not ext then
+    return (base ~= "" and base or "skin") .. ".zip"
+  end
+  ext = ext:lower()
+  local TouchSkin = require("src.core.TouchSkin")
+  if TouchSkin.ARCHIVE_EXTS[ext] or ext == "cfg" then return base end
+  return (base:gsub("%.[%w]+$", "")) .. ".zip"
+end
+
+function RomImporter.wrapSkinPayload(name, data)
+  name = tostring(name or "")
+  if not name:lower():match("%.cfg$") then return name, data end
+  if not data then return name, data end
+  if data:sub(1, 2) == "PK" then
+    return (name:gsub("%.[Cc][Ff][Gg]$", "")) .. ".zip", data
+  end
+  local blob = require("src.core.SkinZip").encode({
+    { name = "overlay.cfg", data = data },
+  })
+  return (name:gsub("%.[Cc][Ff][Gg]$", "")) .. ".zip", blob
+end
+
+function RomImporter:_installSkinData(name, data)
+  local TouchSkin = require("src.core.TouchSkin")
+  if not data or data == "" then
+    self._skinNotice = { ok = false, text = Strings("The skin file was empty.") }
+    return nil
+  end
+  local wrappedName, payload = RomImporter.wrapSkinPayload(name, data)
+  local id, note = TouchSkin.installArchive(wrappedName, payload)
   self:_ensureSkins(true)
   if not id then
-    self._skinNotice = { ok = false, text = "Import failed: " .. tostring(err) }
+    self._skinNotice = { ok = false, text = "Import failed: " .. tostring(note) }
+    return nil
+  end
+  local text = "Imported " .. id
+  if type(note) == "table" and note[1] then
+    text = text .. ": " .. tostring(note[1])
+  end
+  self._skinNotice = { ok = true, text = text }
+  return id
+end
+
+function RomImporter:_toggleSkinUrlFocus()
+  self._skinUrlFocus = not self._skinUrlFocus
+  if self._skinUrlFocus then
+    self:_armTextInput()
+  else
+    self:_disarmTextInput()
+  end
+end
+
+function RomImporter:_pasteSkinUrl()
+  local ok, text = pcall(love.system.getClipboardText)
+  if ok and type(text) == "string" then
+    self.skinUrl = utf8Cap((self.skinUrl or "") .. text:gsub("%s", ""),
+      MAX_SKIN_URL)
+  end
+end
+
+function RomImporter:_addSkinFromUrl(url)
+  if self._skinFetch then return false end
+  url = tostring(url or self.skinUrl or ""):gsub("%s", "")
+  if url == "" then
+    self._skinNotice = { ok = false,
+      text = Strings("Paste a link to a skin archive first.") }
+    return false
+  end
+  if not url:match("^https?://") then
+    self._skinNotice = { ok = false,
+      text = Strings("A skin link has to start with http:// or https://") }
+    return false
+  end
+  if not require("src.core.Platform").canFetchRemote() then
+    self._skinNotice = { ok = false,
+      text = Strings("Downloading needs a network transport this build has not got.") }
+    return false
+  end
+  local name = RomImporter.skinUrlName(url)
+  local Fetch = require("src.net.Fetch")
+  self._skinFetch = {
+    url = url, name = name, dest = SKIN_TEMP_DIR .. "/" .. name,
+    job = Fetch.download(url, SKIN_TEMP_DIR .. "/" .. name,
+      { userAgent = "gen1recomp-skin", maxSeconds = 90 }),
+  }
+  self._skinNotice = { ok = true, text = Strings("Downloading %s...", name) }
+  return true
+end
+
+function RomImporter:_pumpSkinFetch()
+  local f = self._skinFetch
+  if not f then return end
+  local Fetch = require("src.net.Fetch")
+  local st = Fetch.poll(f.job)
+  if st.status == "pending" then
+    self._skinFetchProgress = st.progress
     return
   end
-  self._skinNotice = { ok = true, text = "Imported " .. id }
+  Fetch.release(f.job)
+  self._skinFetch, self._skinFetchProgress = nil, nil
+  if st.status ~= "ok" or not st.path then
+    self._skinNotice = { ok = false,
+      text = "Download failed: " .. tostring(st.err or "no data") }
+    return
+  end
+  local data = love.filesystem.read(st.path)
+  love.filesystem.remove(st.path)
+  if self:_installSkinData(f.name, data) then
+    self.skinUrl = ""
+  end
+end
+
+function RomImporter:_exportSkin(id, kind)
+  local TouchSkin = require("src.core.TouchSkin")
+  local entry = id and TouchSkin.find(id)
+  if not entry then
+    self._skinNotice = { ok = false, text = Strings("That skin is gone.") }
+    return nil
+  end
+  local skin = TouchSkin.load(entry.root, entry.id)
+  if not skin then
+    self._skinNotice = { ok = false,
+      text = Strings("Could not read %s", tostring(id)) }
+    return nil
+  end
+  local path, missing, warnings
+  if kind == "retroarch" then
+    path, missing = TouchSkin.exportRetroArch(skin)
+  elseif kind == "delta" then
+    path, missing, warnings = TouchSkin.exportDelta(skin)
+  else
+    path, missing = TouchSkin.export(skin)
+  end
+  if not path then
+    self._skinNotice = { ok = false,
+      text = "Export failed: " .. tostring(missing) }
+    return nil
+  end
+  local dir = love.filesystem.getSaveDirectory
+    and love.filesystem.getSaveDirectory() or nil
+  self._skinExport = { path = path, dir = dir }
+  local text = Strings("Exported to %s", (dir and (dir .. "/") or "") .. path)
+  if type(missing) == "table" and missing[1] then
+    text = text .. " (" .. #missing .. " image(s) missing)"
+  end
+  if type(warnings) == "table" and warnings[1] then
+    text = text .. " " .. tostring(warnings[1])
+  end
+  self._skinNotice = { ok = true, text = text }
+  return path
+end
+
+function RomImporter:_revealSkinExport()
+  local e = self._skinExport
+  if not e or not e.dir then return false end
+  if love.system and love.system.openURL then
+    pcall(love.system.openURL, fileUrl(e.dir))
+  end
+  return true
+end
+
+local MAX_SYNC_CODE = 8
+local MAX_SHARE_CODE = 6
+
+function RomImporter.syncDigits(text)
+  local digits = tostring(text or ""):gsub("[^%d]", "")
+  return digits:sub(1, MAX_SYNC_CODE)
+end
+
+function RomImporter.syncShareCode(text)
+  local out = tostring(text or ""):upper():gsub("[^A-Z2-9]", "")
+  return out:sub(1, MAX_SHARE_CODE)
+end
+
+function RomImporter:_syncDeviceLabel()
+  local name = love.system and love.system.getOS and love.system.getOS()
+  if type(name) ~= "string" or name == "" then return "device" end
+  return name
+end
+
+function RomImporter:_syncEngine()
+  if self._sync ~= nil then return self._sync or nil end
+  local ok, SyncEngine = pcall(require, "src.sync.SyncEngine")
+  if not ok or type(SyncEngine) ~= "table" then
+    self._sync = false
+    return nil
+  end
+  local made, eng = pcall(SyncEngine.shared)
+  if not made or type(eng) ~= "table" then
+    self._sync = false
+    return nil
+  end
+  self._sync = eng
+  return eng
+end
+
+function RomImporter:_syncSupported()
+  if self._syncTransportOk ~= nil then return self._syncTransportOk end
+  local ok, HostShell = pcall(require, "src.core.HostShell")
+  if not ok or type(HostShell) ~= "table"
+      or type(HostShell.canHttpRequest) ~= "function" then
+    self._syncTransportOk = true
+    return true
+  end
+  local asked, can = pcall(HostShell.canHttpRequest)
+  self._syncTransportOk = (not asked) or (can and true or false)
+  return self._syncTransportOk
+end
+
+function RomImporter:_pumpSync(dt)
+  if self._sync == nil then
+    if not self.launcher or self._syncBooted then return end
+    if not self:_syncSupported() then return end
+    self._syncBooted = true
+    local booted = self:_syncEngine()
+    if booted and booted.state.enabled and booted:linked() then
+      pcall(booted.syncNow, booted)
+    end
+  end
+  local eng = self._sync
+  if not eng then return end
+  pcall(eng.update, eng, dt)
+  if eng.phase == "conflict" and eng.conflicts and #eng.conflicts > 0 then
+    if not self._syncModal and not self._syncConflictShown then
+      self._syncConflictShown = true
+      self:_openSync()
+    end
+  else
+    self._syncConflictShown = nil
+  end
+end
+
+function RomImporter:_openSync()
+  self:_syncEngine()
+  self._syncModal = self._syncModal
+    or { view = "home", code1 = "", code2 = "", share = "" }
+  self._syncFocus = nil
+  self:_disarmTextInput()
+end
+
+function RomImporter:_closeSync()
+  self._syncModal = nil
+  self._syncFocus = nil
+  self:_disarmTextInput()
+end
+
+function RomImporter:_syncView(view)
+  if not self._syncModal then return end
+  self._syncModal.view = view
+  self._syncFocus = nil
+  self:_disarmTextInput()
+end
+
+function RomImporter:_syncFocusField(field)
+  if not self._syncModal then return end
+  if self._syncFocus == field then
+    self._syncFocus = nil
+    self:_disarmTextInput()
+    return
+  end
+  self._syncFocus = field
+  self:_armTextInput()
+end
+
+function RomImporter:_syncTypeInto(field, text)
+  local mo = self._syncModal
+  if not mo or not field then return end
+  if field == "share" then
+    mo.share = RomImporter.syncShareCode((mo.share or "") .. tostring(text or ""))
+  else
+    mo[field] = RomImporter.syncDigits((mo[field] or "") .. tostring(text or ""))
+  end
+end
+
+function RomImporter:_syncPaste()
+  local field = self._syncFocus
+  if not field then return end
+  local ok, text = pcall(love.system.getClipboardText)
+  if ok and type(text) == "string" then self:_syncTypeInto(field, text) end
+end
+
+function RomImporter:_syncCreate()
+  local eng = self:_syncEngine()
+  if not eng then return false end
+  return eng:createAccount(self:_syncDeviceLabel())
+end
+
+function RomImporter:_syncLink()
+  local eng, mo = self:_syncEngine(), self._syncModal
+  if not eng or not mo then return false end
+  local ok = eng:linkDevice(mo.code1, mo.code2, self:_syncDeviceLabel())
+  if ok then
+    mo.code1, mo.code2, mo.view = "", "", "home"
+    self._syncFocus = nil
+    self:_disarmTextInput()
+  end
+  return ok
+end
+
+function RomImporter:_syncNow()
+  local eng = self:_syncEngine()
+  if not eng then return false end
+  return eng:syncNow()
+end
+
+function RomImporter:_syncUnlink()
+  local eng = self:_syncEngine()
+  if not eng then return false end
+  eng:unlink()
+  if self._syncModal then self._syncModal.view = "home" end
+  return true
+end
+
+function RomImporter:_syncUnlinkDevice(deviceId)
+  local eng = self:_syncEngine()
+  if not eng or type(eng.unlinkDevice) ~= "function" then return false end
+  return eng:unlinkDevice(deviceId)
+end
+
+function RomImporter:_syncShareMods()
+  local eng = self:_syncEngine()
+  if not eng then return false end
+  return eng:shareMods()
+end
+
+function RomImporter:_syncGetShare()
+  local eng, mo = self:_syncEngine(), self._syncModal
+  if not eng or not mo then return false end
+  return eng:fetchShare(mo.share or "")
+end
+
+function RomImporter:_syncApplyMods()
+  local eng, mo = self:_syncEngine(), self._syncModal
+  if not eng then return false end
+  local ok, err = eng:applyModPlan(function(done, total, label, finished)
+    if not mo then return end
+    if finished then
+      mo.progress = nil
+      if self._refreshMods then self:_refreshMods() end
+    else
+      mo.progress = { done = done, total = total, label = label }
+    end
+  end)
+  if mo then mo.progress = nil end
+  if ok and self._refreshMods then self:_refreshMods() end
+  return ok, err
+end
+
+function RomImporter:_syncResolve(key, choice)
+  local eng = self:_syncEngine()
+  if not eng then return false end
+  return eng:resolveConflict(key, choice)
 end
 
 function RomImporter:_skinsImportButtonLabel()
@@ -3338,6 +3702,27 @@ function RomImporter:keypressed(key)
     if key == "escape" then self:_closeSettings() end
     return
   end
+  if self._syncModal then
+    local field = self._syncFocus
+    if field then
+      local mo = self._syncModal
+      if key == "backspace" then
+        mo[field] = tostring(mo[field] or ""):sub(1, -2)
+      elseif key == "return" or key == "kpenter" or key == "escape" then
+        self._syncFocus = nil
+        self:_disarmTextInput()
+      elseif key == "v"
+          and love.keyboard.isDown("lctrl", "rctrl", "lgui", "rgui") then
+        self:_syncPaste()
+      end
+      return
+    end
+    if self._flex and require("src.import.LauncherView").keypressed(self, key) then
+      return
+    end
+    if key == "escape" then self:_closeSync() end
+    return
+  end
   if self._rename then
     if key == "backspace" then
       self._rename.text = utf8Back(self._rename.text)
@@ -3387,6 +3772,21 @@ function RomImporter:keypressed(key)
     end
     return
   end
+  if self._skinUrlFocus then
+    if key == "backspace" then
+      self.skinUrl = utf8Back(self.skinUrl or "")
+    elseif key == "return" or key == "kpenter" then
+      self._skinUrlFocus = false
+      self:_disarmTextInput()
+      self:_addSkinFromUrl()
+    elseif key == "escape" then
+      self._skinUrlFocus = false
+      self:_disarmTextInput()
+    elseif key == "v" and love.keyboard.isDown("lctrl", "rctrl", "lgui", "rgui") then
+      self:_pasteSkinUrl()
+    end
+    return
+  end
   if self._findSearchFocus then
     if key == "backspace" then
       self.findQuery = utf8Back(self.findQuery or "")
@@ -3494,6 +3894,10 @@ function RomImporter:_commitRename()
 end
 
 function RomImporter:textinput(text)
+  if self._syncModal and self._syncFocus then
+    self:_syncTypeInto(self._syncFocus, text)
+    return
+  end
   if self._profileSavePrompt then
     self._profileSavePrompt.text = utf8Cap((self._profileSavePrompt.text or "") .. text, MAX_SLOT_LABEL)
     return
@@ -3514,6 +3918,11 @@ function RomImporter:textinput(text)
       utf8Cap(self._indexPrompt.text .. text:gsub("%s", ""), MAX_INDEX_URL)
     return
   end
+  if self._skinUrlFocus then
+    self.skinUrl = utf8Cap((self.skinUrl or "") .. text:gsub("%s", ""),
+      MAX_SKIN_URL)
+    return
+  end
   if self._findSearchFocus then
     self.findQuery = utf8Cap((self.findQuery or "") .. text, MAX_FIND_QUERY)
     self.findScroll = 0

src/net/Fetch.lua

@@ -86,6 +86,7 @@ local function drain()
         else
           j.status = msg.ok and "ok" or "error"
           j.body, j.err, j.path = msg.body, msg.err, msg.path
+          j.code = msg.code
           j.progress = msg.ok and 1 or j.progress
         end
       end
@@ -143,6 +144,14 @@ function Fetch.post(url, body, opts)
     contentType = opts.contentType, maxSeconds = opts.maxSeconds })
 end
 
+function Fetch.request(url, opts)
+  opts = opts or {}
+  return submit({ kind = "request", url = url,
+    method = opts.method, body = opts.body, headers = opts.headers,
+    userAgent = opts.userAgent or "gen1recomp",
+    maxSeconds = opts.maxSeconds })
+end
+
 -- Download a URL to `saveRel`, a path relative to the LOVE save directory.
 -- Progress is reported as a 0..1 fraction when `size` is known.
 function Fetch.download(url, saveRel, opts)

src/net/fetch_worker.lua

@@ -113,6 +113,22 @@ local function doPost(job)
   post({ id = job.id, ok = true, done = true })
 end
 
+local function doRequest(job)
+  if not HostShell then
+    post({ id = job.id, ok = false, err = "no transport" })
+    return
+  end
+  local body, err, code = HostShell.httpRequest(job.url, {
+    method = job.method, body = job.body, headers = job.headers,
+    userAgent = job.userAgent,
+    maxTime = tonumber(job.maxSeconds) or GET_MAX_SECONDS })
+  if not code then
+    post({ id = job.id, ok = false, err = err or "request failed" })
+    return
+  end
+  post({ id = job.id, ok = true, body = body or "", code = code, done = true })
+end
+
 while true do
   local job = cmdCh:demand()
   -- The flag is checked before the job's KIND, so a worker woken by a
@@ -131,6 +147,9 @@ while true do
     elseif job.kind == "post" then
       local ok, err = pcall(doPost, job)
       if not ok then post({ id = job.id, ok = false, err = tostring(err) }) end
+    elseif job.kind == "request" then
+      local ok, err = pcall(doRequest, job)
+      if not ok then post({ id = job.id, ok = false, err = tostring(err) }) end
     elseif job.kind == "download" then
       local ok, err = pcall(doDownload, job)
       if not ok then post({ id = job.id, ok = false, err = tostring(err) }) end

src/render/Playfield.lua

@@ -0,0 +1,81 @@
+local GameViewport = require("src.render.GameViewport")
+local TouchSkin = require("src.core.TouchSkin")
+
+local Playfield = {}
+
+Playfield.WIDTH, Playfield.HEIGHT = 160, 144
+
+Playfield.entered = false
+Playfield.box = nil
+
+local function clampRect(x, y, w, h, sw, sh)
+  if type(w) ~= "number" or type(h) ~= "number" then return nil end
+  if w ~= w or h ~= h then return nil end
+  x = math.floor(tonumber(x) or 0)
+  y = math.floor(tonumber(y) or 0)
+  w, h = math.floor(w), math.floor(h)
+  if x < 0 then w, x = w + x, 0 end
+  if y < 0 then h, y = h + y, 0 end
+  if x + w > sw then w = sw - x end
+  if y + h > sh then h = sh - y end
+  if w < 1 or h < 1 then return nil end
+  return x, y, w, h
+end
+
+function Playfield.cutout(sw, sh)
+  if Playfield.entered then return nil end
+  if type(sw) ~= "number" or type(sh) ~= "number" then return nil end
+  if sw < 1 or sh < 1 then return nil end
+  if type(TouchSkin.viewport) ~= "function" then return nil end
+  local ok, x, y, w, h, fill, expand = pcall(TouchSkin.viewport, sw, sh)
+  if not ok then return nil end
+  local cx, cy, cw, ch = clampRect(x, y, w, h, sw, sh)
+  if not cx then return nil end
+  return cx, cy, cw, ch, fill == true, expand == true
+end
+
+function Playfield.rect(sw, sh)
+  local x, y, w, h, _, expand = Playfield.cutout(sw, sh)
+  if not x then return 0, 0, sw or 0, sh or 0, false end
+  if expand then return x, y, w, h, true end
+  local s = math.max(1, math.floor(math.min(w / Playfield.WIDTH,
+    h / Playfield.HEIGHT)))
+  local pw = math.min(w, Playfield.WIDTH * s)
+  local ph = math.min(h, Playfield.HEIGHT * s)
+  return x + math.floor((w - pw) / 2), y + math.floor((h - ph) / 2), pw, ph, true
+end
+
+function Playfield.enter(x, y, w, h)
+  Playfield.entered = true
+  Playfield.box = { x = x, y = y, w = w, h = h }
+end
+
+function Playfield.leave()
+  Playfield.entered = false
+  Playfield.box = nil
+end
+
+function Playfield.dimensions()
+  if Playfield.entered and Playfield.box then
+    return Playfield.box.w, Playfield.box.h
+  end
+  return GameViewport.dimensions()
+end
+
+function Playfield.push(sw, sh)
+  local x, y, w, h, active = Playfield.rect(sw, sh)
+  local G = love.graphics
+  G.push("all")
+  if active then G.setScissor(x, y, w, h) end
+  G.translate(x, y)
+  Playfield.enter(x, y, w, h)
+  return w, h, x, y, active
+end
+
+function Playfield.pop()
+  Playfield.leave()
+  love.graphics.setScissor()
+  love.graphics.pop()
+end
+
+return Playfield

src/render/Renderer.lua

@@ -15,7 +15,7 @@ local Runtime = require("src.mods.Runtime")
 local GameViewport = require("src.render.GameViewport")
 -- leaf module (no renderer dependency), so requiring it here cannot cycle
 local FaithfulRes = require("src.core.FaithfulRes")
-local TouchSkin = require("src.core.TouchSkin")
+local Playfield = require("src.render.Playfield")
 
 local Renderer = {}
 
@@ -86,12 +86,12 @@ local function displayMetrics()
   if dpiX < 1e-6 then dpiX = 1 end
   if dpiY < 1e-6 then dpiY = 1 end
   local vx, vy = 0, 0
-  local sx, sy, sw, sh = TouchSkin.viewport(pw, ph)
+  local cut, grow = false, false
-  if sw and sw >= 1 and sh >= 1 then
+  local sx, sy, sw, sh, _, expand = Playfield.cutout(pw, ph)
-    vx, vy = math.floor(sx), math.floor(sy)
+  if sx then
-    pw, ph = math.floor(sw), math.floor(sh)
+    vx, vy, pw, ph, cut, grow = sx, sy, sw, sh, true, expand
   end
-  return ww, wh, pw, ph, dpiX, dpiY, vx, vy
+  return ww, wh, pw, ph, dpiX, dpiY, vx, vy, cut, grow
 end
 
 function Renderer:init()
@@ -269,7 +269,7 @@ end
 -- corners; flat mode returns exactly today's size (growth factor is 1 when
 -- tilt is inactive).
 function Renderer:worldViewSize()
-  local _, _, pw, ph = displayMetrics()
+  local _, _, pw, ph, _, _, _, _, cut, grow = displayMetrics()
   -- FAITHFUL RATIO on mobile.  The world pass deliberately expands to cover the
   -- WHOLE display, so letterbox voids become more map instead of black bars.
   -- That is why the lock appeared to do nothing in the overworld: it shrank
@@ -281,13 +281,11 @@ function Renderer:worldViewSize()
   -- this is the same sum with the viewport standing in for the window, so
   -- both platforms show the same map area at the same zoom.
   local cap = FaithfulRes.scaleCap()
-  if not cap and TouchSkin.hasViewport() then
+  if not cap and cut and not grow then cap = self:fitScale() end
-    local page = TouchSkin.page()
-    if not page.viewportExpand then cap = self:fitScale() end
-  end
   if cap then
     local uiw, uih = self:uiSize()
-    pw, ph = uiw * cap, uih * cap
+    pw = cut and math.min(pw, uiw * cap) or uiw * cap
+    ph = cut and math.min(ph, uih * cap) or uih * cap
   end
   local sp = Zoom.scale(self:fitScale())
   local vw, vh = math.ceil(pw / sp), math.ceil(ph / sp)
@@ -346,19 +344,20 @@ end
 -- window is the classic wipe unchanged.
 --
 -- Sx/Sy are LOVE-unit scales (Sy defaults to Sx on uniform surfaces).
-function Renderer:drawBattleWipe(wipe, ww, wh, ox, oy, vpw, vph, Sx, Sy)
+function Renderer:drawBattleWipe(wipe, ww, wh, ox, oy, vpw, vph, Sx, Sy, wx, wy)
   if not wipe or not wipe.prog or wipe.prog <= 0 then return end
   Sy = Sy or Sx
+  wx, wy = wx or 0, wy or 0
   local TW, TH = 8 * Sx, 8 * Sy
   if TW < 1 then TW = 1 end
   if TH < 1 then TH = 1 end
   local prog = math.min(1, wipe.prog)
 
   love.graphics.setColor(0, 0, 0, 1)
-  love.graphics.setScissor(0, 0, ww, wh)
+  love.graphics.setScissor(wx, wy, ww, wh)
 
   if prog >= 1 then
-    love.graphics.rectangle("fill", 0, 0, ww, wh)
+    love.graphics.rectangle("fill", wx, wy, ww, wh)
     love.graphics.setScissor()
     love.graphics.setColor(1, 1, 1, 1)
     return
@@ -366,10 +365,10 @@ function Renderer:drawBattleWipe(wipe, ww, wh, ox, oy, vpw, vph, Sx, Sy)
 
   -- whole-tile padding out to each window edge, keeping the grid in phase
   -- with the letterbox's tiles
-  local padL = math.max(0, math.ceil(ox / TW))
+  local padL = math.max(0, math.ceil((ox - wx) / TW))
-  local padT = math.max(0, math.ceil(oy / TH))
+  local padT = math.max(0, math.ceil((oy - wy) / TH))
-  local padR = math.max(0, math.ceil((ww - ox - vpw) / TW))
+  local padR = math.max(0, math.ceil((wx + ww - ox - vpw) / TW))
-  local padB = math.max(0, math.ceil((wh - oy - vph) / TH))
+  local padB = math.max(0, math.ceil((wy + wh - oy - vph) / TH))
   local lbCols = math.max(1, math.floor(vpw / TW + 0.5))
   local lbRows = math.max(1, math.floor(vph / TH + 0.5))
   local cols, rows = padL + lbCols + padR, padT + lbRows + padB
@@ -396,9 +395,9 @@ function Renderer:drawBattleWipe(wipe, ww, wh, ox, oy, vpw, vph, Sx, Sy)
       for row = 0, rows - 1 do
         local y = y0 + row * TH
         if row % 2 == 0 then
-          love.graphics.rectangle("fill", 0, y, w, TH)
+          love.graphics.rectangle("fill", wx, y, w, TH)
         else
-          love.graphics.rectangle("fill", ww - w, y, w, TH)
+          love.graphics.rectangle("fill", wx + ww - w, y, w, TH)
         end
       end
     elseif style == "vstripes" then
@@ -406,21 +405,21 @@ function Renderer:drawBattleWipe(wipe, ww, wh, ox, oy, vpw, vph, Sx, Sy)
       for col = 0, cols - 1 do
         local x = x0 + col * TW
         if col % 2 == 0 then
-          love.graphics.rectangle("fill", x, 0, TW, h)
+          love.graphics.rectangle("fill", x, wy, TW, h)
         else
-          love.graphics.rectangle("fill", x, wh - h, TW, h)
+          love.graphics.rectangle("fill", x, wy + wh - h, TW, h)
         end
       end
     elseif style == "shrink" then
       local h, w = wh / 2 * prog, ww / 2 * prog
-      love.graphics.rectangle("fill", 0, 0, ww, h)
+      love.graphics.rectangle("fill", wx, wy, ww, h)
-      love.graphics.rectangle("fill", 0, wh - h, ww, h)
+      love.graphics.rectangle("fill", wx, wy + wh - h, ww, h)
-      love.graphics.rectangle("fill", 0, 0, w, wh)
+      love.graphics.rectangle("fill", wx, wy, w, wh)
-      love.graphics.rectangle("fill", ww - w, 0, w, wh)
+      love.graphics.rectangle("fill", wx + ww - w, wy, w, wh)
     else -- split: a black cross growing out of the centre in both axes
       local h, w = wh / 2 * prog, ww / 2 * prog
-      love.graphics.rectangle("fill", 0, wh / 2 - h, ww, h * 2)
+      love.graphics.rectangle("fill", wx, wy + wh / 2 - h, ww, h * 2)
-      love.graphics.rectangle("fill", ww / 2 - w, 0, w * 2, wh)
+      love.graphics.rectangle("fill", wx + ww / 2 - w, wy, w * 2, wh)
     end
   end
   love.graphics.setScissor()
@@ -542,7 +541,8 @@ end
 -- into (nil = default framebuffer; presentCanvas when CRT is on).
 -- Returns true on success; false (no shader/mesh) tells endFrame to fall
 -- back to the flat blit unchanged.
-function Renderer:drawTiltedWorld(zoneList, sx, sy, wox, woy, target)
+function Renderer:drawTiltedWorld(zoneList, sx, sy, wox, woy, target,
+                                 boxX, boxY, boxW, boxH)
   local shader = self:tiltShader()
   local mesh = self:tiltMesh()
   if not (shader and mesh) then return false end
@@ -593,12 +593,16 @@ function Renderer:drawTiltedWorld(zoneList, sx, sy, wox, woy, target)
   mesh:setTexture(self.tiltCanvas)
   mesh:setVertices(Tilt.meshCorners(wvw, wvh))
   love.graphics.push()
+  if boxW and boxH and boxW > 0 and boxH > 0 then
+    love.graphics.setScissor(boxX, boxY, boxW, boxH)
+  end
   love.graphics.translate(wox, woy)
   love.graphics.scale(sx, sy)
   love.graphics.setColor(1, 1, 1, 1)
   love.graphics.setShader(shader)
   love.graphics.draw(mesh)
   love.graphics.setShader()
+  love.graphics.setScissor()
   love.graphics.pop()
   return true
 end
@@ -755,20 +759,23 @@ end
 -- scissored through the shade-remap shader, later zones on top.
 -- When GBC FX is active the composite is drawn into presentCanvas and
 -- presented through the GBC FX shader as a final pass.
-function Renderer:endFrame(zones, worldZones)
+function Renderer:frameRects()
-  GameViewport.setTarget()
+  local ww, wh, pw, ph, dpiX, dpiY, vx, vy, cut = displayMetrics()
-  local ww, wh, pw, ph, dpiX, dpiY, vx, vy = displayMetrics()
+  local r = {
-  local vux, vuy = vx / dpiX, vy / dpiY
+    ww = ww, wh = wh, pw = pw, ph = ph, dpiX = dpiX, dpiY = dpiY,
-  local vuw, vuh = pw / dpiX, ph / dpiY
+    vx = vx, vy = vy, cut = cut,
+    vux = vx / dpiX, vuy = vy / dpiY, vuw = pw / dpiX, vuh = ph / dpiY,
+  }
   -- Sp = integer framebuffer pixels per GB pixel;
   -- Sx/Sy = LOVE-unit draw scales (may differ when dpiX ≠ dpiY).
   local Sp = self:fitScale()
-  local Sx, Sy = Sp / dpiX, Sp / dpiY
+  r.Sp, r.Sx, r.Sy = Sp, Sp / dpiX, Sp / dpiY
   local uiw, uih = self:uiSize()
-  local vpw, vph = uiw * Sx, uih * Sy
+  r.uiw, r.uih = uiw, uih
+  r.vpw, r.vph = uiw * r.Sx, uih * r.Sy
   -- Snap the letterbox origin to a framebuffer pixel, then convert to units.
-  local ox = (vx + math.floor((pw - uiw * Sp) / 2)) / dpiX
+  r.ox = (vx + math.floor((pw - uiw * Sp) / 2)) / dpiX
-  local oy = (vy + math.floor((ph - uih * Sp) / 2)) / dpiY
+  r.oy = (vy + math.floor((ph - uih * Sp) / 2)) / dpiY
   -- The UI has its own scale: it steps down as the survey zoom goes out (see
   -- uiScale), so it can be smaller than the world letterbox.  Un-zoomed these
   -- are identical to Sp/ox/oy and every rect below is what it always was.
@@ -782,10 +789,38 @@ function Renderer:endFrame(zones, worldZones)
   if self.uiFill then
     Up = math.min(ph / uih, pw / uiw)
   end
-  local Ux, Uy = Up / dpiX, Up / dpiY
+  if uiw * Up > pw or uih * Up > ph then
-  local uvpw, uvph = uiw * Ux, uih * Uy
+    Up = math.min(ph / uih, pw / uiw)
-  local uox = (vx + math.floor((pw - uiw * Up) / 2)) / dpiX
+  end
-  local uoy = (vy + math.floor((ph - uih * Up) / 2)) / dpiY
+  r.Up, r.Ux, r.Uy = Up, Up / dpiX, Up / dpiY
+  r.uvpw, r.uvph = uiw * r.Ux, uih * r.Uy
+  r.uox = (vx + math.floor((pw - uiw * Up) / 2)) / dpiX
+  r.uoy = (vy + math.floor((ph - uih * Up) / 2)) / dpiY
+  return r
+end
+
+function Renderer.clipToView(r, x, y, w, h)
+  local x2, y2 = math.min(x + w, r.vux + r.vuw), math.min(y + h, r.vuy + r.vuh)
+  x, y = math.max(x, r.vux), math.max(y, r.vuy)
+  return x, y, math.max(0, x2 - x), math.max(0, y2 - y)
+end
+
+function Renderer:playfieldRect()
+  local r = self:frameRects()
+  return r.vux, r.vuy, r.vuw, r.vuh, r.cut
+end
+
+function Renderer:endFrame(zones, worldZones)
+  GameViewport.setTarget()
+  local R = self:frameRects()
+  local ww, wh, pw, ph = R.ww, R.wh, R.pw, R.ph
+  local dpiX, dpiY, vx, vy, cut = R.dpiX, R.dpiY, R.vx, R.vy, R.cut
+  local vux, vuy, vuw, vuh = R.vux, R.vuy, R.vuw, R.vuh
+  local Sp, Sx, Sy = R.Sp, R.Sx, R.Sy
+  local uiw, uih = R.uiw, R.uih
+  local vpw, vph, ox, oy = R.vpw, R.vph, R.ox, R.oy
+  local Ux, Uy = R.Ux, R.Uy
+  local uvpw, uvph, uox, uoy = R.uvpw, R.uvph, R.uox, R.uoy
   local GBCFX = require("src.render.GBCFX")
   -- Forced mono/Classic modes still need a whole-screen zone when a state
   -- exposes no SGB packets (raw DMG canvas), so sendColors can remap.
@@ -814,6 +849,7 @@ function Renderer:endFrame(zones, worldZones)
       ww = ww, wh = wh, pw = pw, ph = ph, ox = ox, oy = oy,
       vpw = vpw, vph = vph, uiw = uiw, uih = uih,
       scale = Sp, Sx = Sx, Sy = Sy, dpiX = dpiX, dpiY = dpiY,
+      viewX = vux, viewY = vuy, viewWidth = vuw, viewHeight = vuh,
       secondScreen = require("src.render.SecondScreen"),
     }
     if Runtime.call("render.compose", function() return false end, self, ctx) == true then
@@ -901,23 +937,29 @@ function Renderer:endFrame(zones, worldZones)
       clearR, clearG, clearB = PaletteFX.paperShade(Game and Game.data)
     end
   end
-  love.graphics.setColor(clearR, clearG, clearB, 1)
+  if cut then
+    love.graphics.setColor(0, 0, 0, 1)
     love.graphics.rectangle("fill", 0, 0, ww, wh)
+  end
+  love.graphics.setColor(clearR, clearG, clearB, 1)
+  love.graphics.rectangle("fill", vux, vuy, vuw, vuh)
   if extendedBlackBand then
     love.graphics.setColor(bandR, bandG, bandB, 1)
-    love.graphics.rectangle("fill", uox, 0, uvpw, wh)
+    love.graphics.rectangle("fill", uox, vuy, uvpw, vuh)
   end
   love.graphics.setColor(1, 1, 1, 1)
   -- render.letterbox: SGB borders / custom void art in the bars around the
   -- 160x144 (or world) blit.  Drawn after the clear and before the game
   -- canvas so the playfield sits on top of the border.
   if Runtime.wantsHook("render.letterbox") then
+    if cut then love.graphics.setScissor(vux, vuy, vuw, vuh) end
     Runtime.call("render.letterbox", function() end, {
       ww = ww, wh = wh, pw = pw, ph = ph,
       ox = ox, oy = oy, vpw = vpw, vph = vph,
       scale = Sp, dpiX = dpiX, dpiY = dpiY,
       worldActive = self.worldActive and true or false,
     })
+    if cut then love.graphics.setScissor() end
   end
 
   -- see Renderer:blitCanvas; bound here to the frame's dpi so the composite
@@ -928,6 +970,10 @@ function Renderer:endFrame(zones, worldZones)
                            bx, by, boxX, boxY, boxW, boxH, dpiX, dpiY)
   end
 
+  local function clipToView(x, y, w, h)
+    return Renderer.clipToView(R, x, y, w, h)
+  end
+
   if self.worldOverride then
     -- A render pipeline already produced the whole world -- terrain,
     -- characters and its own FX overlay -- as one window-resolution image,
@@ -938,9 +984,9 @@ function Renderer:endFrame(zones, worldZones)
     love.graphics.setScissor(vux, vuy, vuw, vuh)
     local loveMajor = love.getVersion()
     if love.system and love.system.getOS and love.system.getOS() == "iOS" and loveMajor >= 12 then
-      love.graphics.draw(self.worldOverride, 0, wh, 0, 1 / dpiX, -1 / dpiY)
+      love.graphics.draw(self.worldOverride, vux, vuy + vuh, 0, 1 / dpiX, -1 / dpiY)
     else
-      love.graphics.draw(self.worldOverride, 0, 0, 0, 1 / dpiX, 1 / dpiY)
+      love.graphics.draw(self.worldOverride, vux, vuy, 0, 1 / dpiX, 1 / dpiY)
     end
     love.graphics.setScissor()
     -- the screen-space overlays the flat path draws over its composite
@@ -964,7 +1010,8 @@ function Renderer:endFrame(zones, worldZones)
     -- falls through to the flat blit, keeping the flat frame byte-for-byte
     -- identical to today.
     local projected =
-      Tilt.active() and self:drawTiltedWorld(worldZones or zones, sx, sy, wox, woy, present)
+      Tilt.active() and self:drawTiltedWorld(worldZones or zones, sx, sy, wox, woy,
+                                             present, vux, vuy, vuw, vuh)
     if not projected then
       if worldZones then
         blit(self.worldCanvas, sx, sy, worldZones, sx, sy, wox, woy, vux, vuy, vuw, vuh)
@@ -1061,7 +1108,7 @@ function Renderer:endFrame(zones, worldZones)
      and not FaithfulRes.scaleCap() then
     local ok, Game = pcall(require, "src.core.Game")
     love.graphics.setColor(PaletteFX.paperShade(ok and Game and Game.data))
-    love.graphics.rectangle("fill", uox, 0, uvpw, wh)
+    love.graphics.rectangle("fill", uox, vuy, uvpw, vuh)
     love.graphics.setColor(1, 1, 1, 1)
   end
 
@@ -1070,9 +1117,9 @@ function Renderer:endFrame(zones, worldZones)
   -- always been.
   local anchors = self.uiAnchors
   if not anchors or #anchors == 0 then
-    blit(self.canvas, Ux, Uy, zones, Ux, Uy, uox, uoy, uox, uoy, uvpw, uvph)
+    blit(self.canvas, Ux, Uy, zones, Ux, Uy, uox, uoy, clipToView(uox, uoy, uvpw, uvph))
   else
-    local rest = { { uox, uoy, uvpw, uvph } }
+    local rest = { { clipToView(uox, uoy, uvpw, uvph) } }
     local placed = {}
     for _, a in ipairs(anchors) do
       local dw, dh = a.w * Ux, a.h * Uy
@@ -1086,19 +1133,19 @@ function Renderer:endFrame(zones, worldZones)
       local dx, dy
       if a.anchor == "bottom" then
         dx = uox + a.x * Ux -- horizontally it stays with the letterbox
-        dy = wh - gapB - dh
+        dy = vuy + vuh - gapB - dh
       elseif a.anchor == "top" then
         dx = uox + a.x * Ux -- horizontally it stays with the letterbox
-        dy = a.y * Uy
+        dy = vuy + a.y * Uy
       elseif a.anchor == "topright" then
-        dx = ww - gapR - dw
+        dx = vux + vuw - gapR - dw
-        dy = a.y * Uy
+        dy = vuy + a.y * Uy
       else -- unknown anchor: leave it where it is
         dx, dy = uox + a.x * Ux, uoy + a.y * Uy
       end
       if a.windowClamped then
-        dx = math.max(0, math.min(math.max(0, ww - dw), dx))
+        dx = math.max(vux, math.min(math.max(vux, vux + vuw - dw), dx))
-        dy = math.max(0, math.min(math.max(0, wh - dh), dy))
+        dy = math.max(vuy, math.min(math.max(vuy, vuy + vuh - dh), dy))
       end
       placed[#placed + 1] = { a = a, dx = dx, dy = dy, dw = dw, dh = dh }
       if a.extract then
@@ -1113,13 +1160,14 @@ function Renderer:endFrame(zones, worldZones)
       -- The zone scissors are computed from the same origin, so an SGB
       -- region travels with the element instead of staying in the letterbox.
       blit(p.a.canvas or self.canvas, Ux, Uy, zones, Ux, Uy,
-           p.dx - p.a.x * Ux, p.dy - p.a.y * Uy, p.dx, p.dy, p.dw, p.dh)
+           p.dx - p.a.x * Ux, p.dy - p.a.y * Uy,
+           clipToView(p.dx, p.dy, p.dw, p.dh))
     end
   end
   local uiRedraws = PaletteFX.uiSpriteRedraws()
   if uiRedraws[1] then
     love.graphics.setColor(1, 1, 1, 1)
-    love.graphics.setScissor(uox, uoy, uvpw, uvph)
+    love.graphics.setScissor(clipToView(uox, uoy, uvpw, uvph))
     for _, r in ipairs(uiRedraws) do
       if r.quad then
         love.graphics.draw(r.image, r.quad, uox + r.x * Ux, uoy + r.y * Uy,
@@ -1135,7 +1183,8 @@ function Renderer:endFrame(zones, worldZones)
   -- over the finished composite rather than under the UI blit.  On hardware
   -- it is the tilemap being overwritten -- there is nothing it does not cover.
   if self.battleWipe then
-    self:drawBattleWipe(self.battleWipe, ww, wh, ox, oy, vpw, vph, Sx, Sy)
+    self:drawBattleWipe(self.battleWipe, vuw, vuh, ox, oy, vpw, vph, Sx, Sy,
+                        vux, vuy)
   end
 
   -- Palette-register effects (BattleTransition_FlashScreen's rBGP writes, the
@@ -1157,7 +1206,7 @@ function Renderer:endFrame(zones, worldZones)
     if FaithfulRes.scaleCap() then
       love.graphics.rectangle("fill", ox, oy, vpw, vph)
     else
-      love.graphics.rectangle("fill", 0, 0, ww, wh)
+      love.graphics.rectangle("fill", vux, vuy, vuw, vuh)
     end
     love.graphics.setColor(1, 1, 1, 1)
   end
@@ -1181,6 +1230,7 @@ function Renderer:endFrame(zones, worldZones)
         generation = 1,
       }) == true
     if not outputHandled then
+      if cut then love.graphics.setScissor(vux, vuy, vuw, vuh) end
       if GBCFX.active() then
         -- shader grid/shadow math is in framebuffer pixels
         GBCFX.present(composed, Sp)
@@ -1190,6 +1240,7 @@ function Renderer:endFrame(zones, worldZones)
         love.graphics.setColor(1, 1, 1, 1)
         love.graphics.draw(composed, 0, 0)
       end
+      if cut then love.graphics.setScissor() end
     end
   end
   self.worldActive = false
@@ -1202,6 +1253,7 @@ function Renderer:endFrame(zones, worldZones)
     gameWidth = vpw, gameHeight = vph,
     scale = Sp,
     dpiX = dpiX, dpiY = dpiY,
+    viewX = vux, viewY = vuy, viewWidth = vuw, viewHeight = vuh,
   }
 end
 

src/sync/SyncClient.lua

@@ -0,0 +1,197 @@
+local Json = require("src.link.Json")
+
+local SyncClient = {}
+SyncClient.__index = SyncClient
+
+SyncClient.DEFAULT_URL = os.getenv("POKEPORT_SYNC_URL")
+  or "https://sync.147.182.215.255.sslip.io"
+SyncClient.MAX_BLOB = 2 * 1024 * 1024
+SyncClient.MAX_RESPONSE = 4 * 1024 * 1024
+SyncClient.TIMEOUT = 25
+
+function SyncClient.normalizeCode(code)
+  if type(code) ~= "string" and type(code) ~= "number" then return nil end
+  local digits = tostring(code):gsub("[^%d]", "")
+  if #digits ~= 8 then return nil end
+  return digits
+end
+
+function SyncClient.formatCode(code)
+  local digits = SyncClient.normalizeCode(code)
+  if not digits then return nil end
+  return digits:sub(1, 4) .. "-" .. digits:sub(5, 8)
+end
+
+local function escape(s)
+  return (tostring(s):gsub("[^%w%-%._~]", function(c)
+    return ("%%%02X"):format(c:byte())
+  end))
+end
+
+local function query(params)
+  local names = {}
+  for name in pairs(params or {}) do names[#names + 1] = tostring(name) end
+  table.sort(names)
+  local out = {}
+  for _, name in ipairs(names) do
+    out[#out + 1] = escape(name) .. "=" .. escape(params[name])
+  end
+  if #out == 0 then return "" end
+  return "?" .. table.concat(out, "&")
+end
+
+function SyncClient.new(opts)
+  opts = opts or {}
+  local base = opts.baseUrl or SyncClient.DEFAULT_URL
+  base = tostring(base):gsub("/+$", "")
+  local transport = opts.transport
+  if not transport then
+    transport = require("src.sync.SyncTransport").new()
+  end
+  return setmetatable({
+    baseUrl = base,
+    transport = transport,
+    account = opts.account,
+    token = opts.token,
+  }, SyncClient)
+end
+
+function SyncClient:setAuth(account, token)
+  self.account = type(account) == "string" and account ~= "" and account or nil
+  self.token = type(token) == "string" and token ~= "" and token or nil
+end
+
+function SyncClient:clearAuth()
+  self.account, self.token = nil, nil
+end
+
+function SyncClient:isLinked()
+  return self.account ~= nil and self.token ~= nil
+end
+
+function SyncClient:send(method, path, body, opts)
+  opts = opts or {}
+  local headers = { ["Accept"] = "application/json" }
+  local payload
+  if body ~= nil then
+    local ok, encoded = pcall(Json.encode, body)
+    if not ok then return nil, "could not encode the request" end
+    payload = encoded
+    headers["Content-Type"] = "application/json"
+  end
+  if not opts.noAuth then
+    if not self:isLinked() then return nil, "this device is not linked" end
+    headers["x-sync-account"] = self.account
+    headers["x-sync-token"] = self.token
+  end
+  local url = self.baseUrl .. path .. query(opts.params)
+  local handle = self.transport:begin({
+    url = url, method = method, body = payload, headers = headers,
+    maxSeconds = opts.maxSeconds or SyncClient.TIMEOUT,
+  })
+  if handle == nil then return nil, "no network transport" end
+  return handle
+end
+
+function SyncClient:poll(handle)
+  if handle == nil then return { status = "error", err = "no request" } end
+  local res = self.transport:poll(handle)
+  if res.status == "pending" then return { status = "pending" } end
+  if res.status ~= "ok" then
+    return { status = "error", err = res.err or "sync request failed" }
+  end
+  local raw = res.body or ""
+  local code = tonumber(res.code) or 0
+  if #raw > SyncClient.MAX_RESPONSE then
+    return { status = "error", code = code, err = "the reply was too large" }
+  end
+  local data, decodeErr = Json.decode(raw, SyncClient.MAX_RESPONSE)
+  if type(data) ~= "table" then
+    local why = Json.describeUnexpected(raw) or decodeErr or "unreadable reply"
+    if code >= 400 then
+      return { status = "error", code = code,
+        err = ("the server answered %d"):format(code) }
+    end
+    return { status = "error", code = code, err = why }
+  end
+  if code >= 400 or data.error then
+    local err = data.error
+    if type(err) ~= "string" or err == "" then
+      err = ("the server answered %d"):format(code)
+    end
+    return { status = "error", code = code, data = data, err = err }
+  end
+  return { status = "ok", code = code, data = data }
+end
+
+function SyncClient:release(handle)
+  if handle ~= nil then self.transport:release(handle) end
+end
+
+function SyncClient:create(deviceLabel)
+  return self:send("POST", "/sync/create",
+    { device = deviceLabel or "device" }, { noAuth = true })
+end
+
+function SyncClient:link(code1, code2, deviceLabel)
+  local a = SyncClient.normalizeCode(code1)
+  local b = SyncClient.normalizeCode(code2)
+  if not a or not b then return nil, "both codes are 8 digits" end
+  return self:send("POST", "/sync/link",
+    { code1 = a, code2 = b, device = deviceLabel or "device" },
+    { noAuth = true })
+end
+
+function SyncClient:fetchState()
+  return self:send("GET", "/sync/state")
+end
+
+function SyncClient:putSave(entry)
+  if type(entry) ~= "table" then return nil, "missing save entry" end
+  if type(entry.blob) ~= "string" or entry.blob == "" then
+    return nil, "missing save data"
+  end
+  if #entry.blob > SyncClient.MAX_BLOB then
+    return nil, "this save is too large to sync"
+  end
+  return self:send("PUT", "/sync/save", {
+    version = entry.version,
+    slot = entry.slot,
+    meta = entry.meta,
+    blob = entry.blob,
+    baseRev = entry.baseRev,
+    force = entry.force and true or nil,
+  })
+end
+
+function SyncClient:getSave(version, id)
+  return self:send("GET", "/sync/save", nil,
+    { params = { version = version, id = id } })
+end
+
+function SyncClient:putMods(manifest)
+  return self:send("PUT", "/sync/mods", { manifest = manifest })
+end
+
+function SyncClient:getMods()
+  return self:send("GET", "/sync/mods")
+end
+
+function SyncClient:shareMods(manifest)
+  return self:send("POST", "/sync/modshare", { manifest = manifest })
+end
+
+function SyncClient:fetchShare(code)
+  local trimmed = tostring(code or ""):gsub("%s", ""):upper()
+  if not trimmed:match("^[A-Z2-9]+$") or #trimmed ~= 6 then
+    return nil, "share codes are 6 characters"
+  end
+  return self:send("GET", "/sync/modshare", nil,
+    { noAuth = true, params = { code = trimmed } })
+end
+
+function SyncClient:unlink(device)
+  return self:send("POST", "/sync/unlink", { device = device })
+end
+
+return SyncClient

src/sync/SyncEngine.lua

@@ -0,0 +1,690 @@
+local SyncClient = require("src.sync.SyncClient")
+local SyncState = require("src.sync.SyncState")
+local SyncMods = require("src.sync.SyncMods")
+
+local SyncEngine = {}
+SyncEngine.__index = SyncEngine
+
+SyncEngine.UPLOAD_DEBOUNCE = 5
+SyncEngine.AUTO_INTERVAL = 300
+SyncEngine.MAX_STEPS_PER_UPDATE = 8
+
+local IDLE_STATUS = "Ready"
+local UNLINKED_STATUS = "Not set up"
+
+local function saveApi()
+  return require("src.core.SaveData")
+end
+
+local function gameVersions()
+  return require("src.core.GameVersion").ORDER
+end
+
+local function slotForPlaythrough(options, version, playthroughId)
+  local byVersion = options.playthroughIds and options.playthroughIds[version]
+  for slotId, id in pairs(byVersion or {}) do
+    if id == playthroughId then return slotId end
+  end
+  return nil
+end
+
+function SyncEngine.defaultSaves()
+  return {
+    list = function()
+      local SaveData = saveApi()
+      local options = SaveData.loadOptions()
+      local out = {}
+      for _, version in ipairs(gameVersions()) do
+        for _, slot in ipairs(SaveData.listSlots(version)) do
+          if slot.exists then
+            local source = SaveData.readSlotSource(version, slot.id)
+            local save = source and SaveData.decode(source)
+            if type(save) == "table" then
+              local meta = type(save.meta) == "table" and save.meta or {}
+              local id = meta.playthroughId
+              if type(id) ~= "string" or id == "" then
+                local byVersion = options.playthroughIds
+                  and options.playthroughIds[version]
+                id = byVersion and byVersion[slot.id] or nil
+              end
+              if id then
+                local name, summary = SaveData.slotSummary(save)
+                out[#out + 1] = {
+                  version = version,
+                  slot = slot.id,
+                  playthroughId = id,
+                  blob = source,
+                  meta = {
+                    savedAt = tonumber(meta.savedAt),
+                    sessionStart = tonumber(meta.sessionStart),
+                    playthroughId = id,
+                    format = meta.format,
+                    engine = meta.engine,
+                    playTime = tonumber(save.playTime),
+                    summary = {
+                      name = name,
+                      badges = summary and summary.badges,
+                      timeText = summary and summary.timeText,
+                      dexCount = summary and summary.dexCount,
+                    },
+                  },
+                }
+              end
+            end
+          end
+        end
+      end
+      return out
+    end,
+
+    write = function(version, playthroughId, blob, mode)
+      local SaveData = saveApi()
+      local save = SaveData.decode(blob)
+      if type(save) ~= "table" then return nil, "the downloaded save is unreadable" end
+      save.version = save.version or version
+      local options = SaveData.loadOptions()
+      local slotId
+      if mode == "new" then
+        save.meta = type(save.meta) == "table" and save.meta or {}
+        save.meta.playthroughId = SaveData.newPlaythroughId()
+      else
+        slotId = slotForPlaythrough(options, version, playthroughId)
+      end
+      if not slotId then
+        slotId = SaveData.createSlot(version)
+        if not slotId then return nil, "could not make a save slot" end
+      end
+      local ok, err = SaveData.writeSlot(version, slotId, save)
+      if not ok then return nil, err or "could not write the save" end
+      options = SaveData.loadOptions()
+      options.playthroughIds = options.playthroughIds or {}
+      options.playthroughIds[version] = options.playthroughIds[version] or {}
+      options.playthroughIds[version][slotId] =
+        save.meta and save.meta.playthroughId or playthroughId
+      SaveData.saveOptions(options)
+      return slotId
+    end,
+  }
+end
+
+function SyncEngine.overlaps(a, b)
+  if type(a) ~= "table" or type(b) ~= "table" then return false end
+  local aStart, aEnd = tonumber(a.sessionStart), tonumber(a.savedAt)
+  local bStart, bEnd = tonumber(b.sessionStart), tonumber(b.savedAt)
+  if not (aStart and aEnd and bStart and bEnd) then return false end
+  return aStart <= bEnd and bStart <= aEnd
+end
+
+function SyncEngine.new(opts)
+  opts = opts or {}
+  local eng = setmetatable({}, SyncEngine)
+  eng.fs = opts.fs
+  eng.state = opts.state or SyncState.load(eng.fs)
+  eng.client = opts.client or SyncClient.new({
+    baseUrl = opts.baseUrl, transport = opts.transport })
+  eng.saves = opts.saves or SyncEngine.defaultSaves()
+  eng.modDeps = opts.modDeps
+  eng.now = opts.now or os.time
+  eng.persist = opts.persist ~= false
+  eng.phase = "idle"
+  eng.error = nil
+  eng.conflicts = {}
+  eng.codes = nil
+  eng.modPlan = nil
+  eng.shareCode = nil
+  eng.clock = 0
+  eng.queue = {}
+  eng.pending = nil
+  eng.uploadAt = nil
+  eng.client:setAuth(eng.state.account, eng.state.deviceToken)
+  eng.status = eng:defaultStatus()
+  return eng
+end
+
+function SyncEngine.shared(opts)
+  if SyncEngine._shared == nil then
+    local ok, eng = pcall(SyncEngine.new, opts or {})
+    SyncEngine._shared = (ok and type(eng) == "table") and eng or false
+  end
+  return SyncEngine._shared or nil
+end
+
+function SyncEngine.forgetShared()
+  SyncEngine._shared = nil
+end
+
+function SyncEngine:defaultStatus()
+  if not SyncState.linked(self.state) then return UNLINKED_STATUS end
+  return IDLE_STATUS
+end
+
+function SyncEngine:linked()
+  return SyncState.linked(self.state)
+end
+
+function SyncEngine:busy()
+  return self.pending ~= nil or #self.queue > 0 or self.modApply ~= nil
+end
+
+function SyncEngine:_persist()
+  if not self.persist then return end
+  SyncState.save(self.state, self.fs)
+end
+
+function SyncEngine:_fail(message)
+  self.phase = "error"
+  self.error = tostring(message or "sync failed")
+  self.status = "Sync failed: " .. self.error
+  self.queue = {}
+  self.pending = nil
+end
+
+function SyncEngine:_finish()
+  if #self.conflicts > 0 then
+    self.phase = "conflict"
+    local overlap = false
+    for _, row in ipairs(self.conflicts) do
+      if row.overlap then overlap = true end
+    end
+    self.status = overlap
+      and "These saves were played at the same time."
+      or "This save also changed on another device."
+    return
+  end
+  self.phase = "idle"
+  self.error = nil
+  self.state.lastSyncAt = self.now()
+  self.status = self:defaultStatus()
+  self:_persist()
+end
+
+function SyncEngine:_request(handle, err, onOk, onErr)
+  if not handle then
+    self:_fail(err or "could not start the request")
+    return false
+  end
+  self.pending = { handle = handle, onOk = onOk, onErr = onErr }
+  return true
+end
+
+function SyncEngine:_enqueue(fn)
+  self.queue[#self.queue + 1] = fn
+end
+
+function SyncEngine:cancel()
+  if self.pending then self.client:release(self.pending.handle) end
+  self.pending = nil
+  self.queue = {}
+  self.modApply = nil
+  self.uploadAt = nil
+  if self.phase ~= "conflict" then
+    self.phase = "idle"
+    self.status = self:defaultStatus()
+  end
+end
+
+function SyncEngine:noteSaveWritten()
+  if not (self.state.enabled and self:linked()) then return end
+  self.uploadAt = self.clock + SyncEngine.UPLOAD_DEBOUNCE
+end
+
+function SyncEngine:update(dt)
+  self.clock = self.clock + (tonumber(dt) or 0)
+  if self.pending then
+    local res = self.client:poll(self.pending.handle)
+    if res.status == "pending" then return end
+    local job = self.pending
+    self.pending = nil
+    self.client:release(job.handle)
+    if res.status == "ok" then
+      local ok, err = pcall(job.onOk, self, res)
+      if not ok then self:_fail(err) end
+    else
+      local handled = false
+      if job.onErr then
+        local ok, result = pcall(job.onErr, self, res)
+        if not ok then self:_fail(result) return end
+        handled = result == true
+      end
+      if not handled then self:_fail(res.err) end
+    end
+  end
+  if self.pending then return end
+  if self.modApply then
+    self:_stepModApply()
+    return
+  end
+  if self.uploadAt and self.clock >= self.uploadAt and not self:busy() then
+    self.uploadAt = nil
+    if self.state.enabled and self:linked() then self:syncNow() end
+  end
+  local steps = 0
+  while not self.pending and #self.queue > 0
+      and steps < SyncEngine.MAX_STEPS_PER_UPDATE do
+    steps = steps + 1
+    local task = table.remove(self.queue, 1)
+    local ok, err = pcall(task, self)
+    if not ok then self:_fail(err) return end
+    if not self.pending and #self.queue == 0 and self.phase ~= "error" then
+      self:_finish()
+    end
+  end
+end
+
+function SyncEngine:createAccount(label)
+  if self:busy() then return false, "sync is busy" end
+  self.phase = "checking"
+  self.status = "Creating a sync account..."
+  self.error = nil
+  local handle, err = self.client:create(label)
+  return self:_request(handle, err, function(eng, res)
+    local data = res.data or {}
+    if type(data.account) ~= "string" or type(data.deviceToken) ~= "string" then
+      eng:_fail("the server sent an unexpected reply")
+      return
+    end
+    eng.codes = {
+      code1 = SyncClient.formatCode(data.code1) or tostring(data.code1 or ""),
+      code2 = SyncClient.formatCode(data.code2) or tostring(data.code2 or ""),
+    }
+    eng.state.account = data.account
+    eng.state.deviceToken = data.deviceToken
+    eng.state.deviceId = type(data.device) == "string" and data.device or nil
+    eng.state.deviceLabel = label
+    eng.state.enabled = true
+    eng.client:setAuth(data.account, data.deviceToken)
+    eng.phase = "idle"
+    eng.status = "Sync account created"
+    eng:_persist()
+  end)
+end
+
+function SyncEngine:linkDevice(code1, code2, label)
+  if self:busy() then return false, "sync is busy" end
+  local a = SyncClient.normalizeCode(code1)
+  local b = SyncClient.normalizeCode(code2)
+  if not a or not b then
+    self:_fail("both codes are 8 digits")
+    return false, "both codes are 8 digits"
+  end
+  self.phase = "checking"
+  self.status = "Linking this device..."
+  self.error = nil
+  local handle, err = self.client:link(a, b, label)
+  return self:_request(handle, err, function(eng, res)
+    local data = res.data or {}
+    if type(data.account) ~= "string" or type(data.deviceToken) ~= "string" then
+      eng:_fail("the server sent an unexpected reply")
+      return
+    end
+    eng.state.account = data.account
+    eng.state.deviceToken = data.deviceToken
+    eng.state.deviceId = type(data.device) == "string" and data.device or nil
+    eng.state.deviceLabel = label
+    eng.state.enabled = true
+    eng.client:setAuth(data.account, data.deviceToken)
+    eng.status = "This device is linked"
+    eng:_persist()
+    eng:syncNow()
+  end)
+end
+
+function SyncEngine:_forgetLocal()
+  self.state = SyncState.defaults()
+  self.client:clearAuth()
+  self.codes = nil
+  self.conflicts = {}
+  self.devices = nil
+  self.phase = "idle"
+  self.status = UNLINKED_STATUS
+  self:_persist()
+end
+
+function SyncEngine:unlink()
+  if not self:linked() then
+    self:_forgetLocal()
+    return true
+  end
+  if self:busy() then return false, "sync is busy" end
+  self.phase = "checking"
+  self.status = "Unlinking this device..."
+  self.error = nil
+  local handle, err = self.client:unlink(self.state.deviceId)
+  return self:_request(handle, err, function(eng)
+    eng:_forgetLocal()
+  end, function(eng, res)
+    if res.code == 401 or res.code == 404 then
+      eng:_forgetLocal()
+      return true
+    end
+    return false
+  end)
+end
+
+function SyncEngine:unlinkDevice(deviceId)
+  if type(deviceId) ~= "string" or deviceId == "" then
+    return false, "no such device"
+  end
+  if not self:linked() then return false, "this device is not linked" end
+  if deviceId == self.state.deviceId then return self:unlink() end
+  if self:busy() then return false, "sync is busy" end
+  self.phase = "checking"
+  self.status = "Unlinking that device..."
+  self.error = nil
+  local handle, err = self.client:unlink(deviceId)
+  return self:_request(handle, err, function(eng)
+    eng.status = "That device was unlinked"
+    eng.phase = "idle"
+    eng:syncNow()
+  end)
+end
+
+function SyncEngine:setEnabled(enabled)
+  self.state.enabled = enabled and true or false
+  self:_persist()
+  return self.state.enabled
+end
+
+function SyncEngine:syncNow()
+  if not self:linked() then return false, "this device is not linked" end
+  if self.pending then return false, "sync is busy" end
+  self.queue = {}
+  self.conflicts = {}
+  self.state.pendingConflicts = {}
+  self.phase = "checking"
+  self.status = "Checking for changes..."
+  self.error = nil
+  local handle, err = self.client:fetchState()
+  return self:_request(handle, err, function(eng, res)
+    eng:_planFrom(res.data or {})
+  end)
+end
+
+function SyncEngine:_planFrom(remoteState)
+  self.devices = nil
+  if type(remoteState.devices) == "table" then
+    local list = {}
+    for _, row in ipairs(remoteState.devices) do
+      if type(row) == "table" and type(row.id) == "string" and row.id ~= "" then
+        list[#list + 1] = {
+          id = row.id,
+          label = type(row.label) == "string" and row.label ~= "" and row.label
+            or "device",
+          createdAt = tonumber(row.createdAt),
+          current = row.current == true or row.id == self.state.deviceId,
+        }
+      end
+    end
+    self.devices = list
+  end
+  local remote = type(remoteState.saves) == "table" and remoteState.saves or {}
+  local locals = self.saves.list() or {}
+  local seen = {}
+  for _, entry in ipairs(locals) do
+    local key = SyncState.key(entry.version, entry.playthroughId)
+    if key then
+      seen[key] = true
+      local row = remote[key]
+      local knownRev = SyncState.rev(self.state, key)
+      local stamp = SyncState.stamp(self.state, key)
+      local localChanged = stamp == nil
+        or tonumber(entry.meta and entry.meta.savedAt) ~= stamp
+      local remoteRev = row and tonumber(row.rev)
+      local remoteChanged = row ~= nil and remoteRev ~= knownRev
+      if not row then
+        self:_queueUpload(entry, key, false)
+      elseif localChanged and remoteChanged then
+        self:_addConflict(entry, key, row)
+      elseif localChanged then
+        self:_queueUpload(entry, key, false)
+      elseif remoteChanged then
+        self:_queueDownload(key, entry.version, entry.playthroughId, "replace")
+      end
+    end
+  end
+  for key, row in pairs(remote) do
+    if not seen[key] then
+      local version, id = SyncState.splitKey(key)
+      if version and id then
+        self:_queueDownload(key, version, id, "replace", tonumber(row.rev))
+      end
+    end
+  end
+  if #self.queue == 0 then self:_finish() end
+end
+
+function SyncEngine:_addConflict(entry, key, row)
+  local remoteMeta = row
+  if type(row.meta) == "table" then
+    remoteMeta = row.meta
+  elseif type(row.remoteMeta) == "table" then
+    remoteMeta = row.remoteMeta
+  end
+  self.conflicts[#self.conflicts + 1] = {
+    key = key,
+    version = entry.version,
+    playthroughId = entry.playthroughId,
+    slot = entry.slot,
+    entry = entry,
+    localMeta = entry.meta,
+    remoteMeta = remoteMeta,
+    remoteRev = tonumber(row.rev),
+    overlap = SyncEngine.overlaps(entry.meta, remoteMeta),
+  }
+  local pending = self.state.pendingConflicts or {}
+  self.state.pendingConflicts = pending
+  for _, row in ipairs(pending) do
+    if row.key == key then return end
+  end
+  pending[#pending + 1] = {
+    key = key,
+    version = entry.version,
+    playthroughId = entry.playthroughId,
+    overlap = SyncEngine.overlaps(entry.meta, remoteMeta),
+  }
+end
+
+function SyncEngine:_queueUpload(entry, key, force)
+  self:_enqueue(function(eng)
+    eng.phase = "uploading"
+    eng.status = "Uploading saves..."
+    local handle, err = eng.client:putSave({
+      version = entry.version,
+      slot = entry.slot,
+      meta = entry.meta,
+      blob = entry.blob,
+      baseRev = SyncState.rev(eng.state, key),
+      force = force,
+    })
+    eng:_request(handle, err, function(e, res)
+      local data = res.data or {}
+      SyncState.setRev(e.state, key, tonumber(data.rev),
+        entry.meta and entry.meta.savedAt)
+      e:_persist()
+      if not e:busy() then e:_finish() end
+    end, function(e, res)
+      if res.code == 409 then
+        local row = res.data or {}
+        e:_addConflict(entry, key, row)
+        if not e:busy() then e:_finish() end
+        return true
+      end
+      return false
+    end)
+  end)
+end
+
+function SyncEngine:_queueDownload(key, version, playthroughId, mode, knownRev)
+  self:_enqueue(function(eng)
+    eng.phase = "downloading"
+    eng.status = "Downloading saves..."
+    local handle, err = eng.client:getSave(version, playthroughId)
+    eng:_request(handle, err, function(e, res)
+      local data = res.data or {}
+      if type(data.blob) ~= "string" or data.blob == "" then
+        e:_fail("the server sent no save data")
+        return
+      end
+      local slotId, writeErr = e.saves.write(version, playthroughId, data.blob, mode)
+      if not slotId then
+        e:_fail(writeErr or "could not write the downloaded save")
+        return
+      end
+      if mode ~= "new" then
+        local meta = type(data.meta) == "table" and data.meta or {}
+        SyncState.setRev(e.state, key, tonumber(data.rev) or knownRev,
+          tonumber(meta.savedAt))
+      end
+      e:_persist()
+      if not e:busy() then e:_finish() end
+    end)
+  end)
+end
+
+function SyncEngine:resolveConflict(key, choice)
+  local index
+  for i, row in ipairs(self.conflicts) do
+    if row.key == key then index = i break end
+  end
+  if not index then return false, "no such conflict" end
+  local conflict = table.remove(self.conflicts, index)
+  local kept = {}
+  for _, row in ipairs(self.state.pendingConflicts or {}) do
+    if row.key ~= key then kept[#kept + 1] = row end
+  end
+  self.state.pendingConflicts = kept
+
+  if choice == "local" then
+    SyncState.setRev(self.state, key, conflict.remoteRev, nil)
+    self:_queueUpload(conflict.entry, key, true)
+  elseif choice == "remote" then
+    self:_queueDownload(key, conflict.version, conflict.playthroughId,
+      "replace", conflict.remoteRev)
+  elseif choice == "both" then
+    self:_queueDownload(key, conflict.version, conflict.playthroughId,
+      "new", conflict.remoteRev)
+    SyncState.setRev(self.state, key, conflict.remoteRev, nil)
+    self:_queueUpload(conflict.entry, key, true)
+  else
+    return false, "unknown resolution"
+  end
+  self.phase = "uploading"
+  self.status = "Applying your choice..."
+  return true
+end
+
+function SyncEngine:uploadMods()
+  if not self:linked() then return false, "this device is not linked" end
+  if self:busy() then return false, "sync is busy" end
+  local manifest = SyncMods.build(self.modDeps)
+  self.phase = "uploading"
+  self.status = "Uploading the mod list..."
+  local handle, err = self.client:putMods(manifest)
+  return self:_request(handle, err, function(eng)
+    eng.phase = "idle"
+    eng.status = "Mod list synced"
+  end)
+end
+
+function SyncEngine:fetchModPlan()
+  if not self:linked() then return false, "this device is not linked" end
+  if self:busy() then return false, "sync is busy" end
+  self.phase = "downloading"
+  self.status = "Reading the mod list..."
+  local handle, err = self.client:getMods()
+  return self:_request(handle, err, function(eng, res)
+    local data = res.data or {}
+    local manifest = type(data.manifest) == "table" and data.manifest or data
+    eng.modPlan = SyncMods.plan(manifest, eng.modDeps)
+    eng.phase = "idle"
+    eng.status = SyncMods.planEmpty(eng.modPlan)
+      and "Mods already match" or "Mod changes ready to apply"
+  end)
+end
+
+function SyncEngine:shareMods()
+  if not self:linked() then return false, "this device is not linked" end
+  if self:busy() then return false, "sync is busy" end
+  local manifest = SyncMods.build(self.modDeps)
+  self.phase = "uploading"
+  self.status = "Sharing the mod list..."
+  local handle, err = self.client:shareMods(manifest)
+  return self:_request(handle, err, function(eng, res)
+    local data = res.data or {}
+    eng.shareCode = type(data.code) == "string" and data.code or nil
+    eng.phase = "idle"
+    eng.status = eng.shareCode and ("Share code " .. eng.shareCode)
+      or "The server sent no share code"
+  end)
+end
+
+function SyncEngine:fetchShare(code)
+  if self:busy() then return false, "sync is busy" end
+  self.phase = "downloading"
+  self.status = "Fetching that mod list..."
+  local handle, err = self.client:fetchShare(code)
+  return self:_request(handle, err, function(eng, res)
+    local data = res.data or {}
+    local manifest = type(data.manifest) == "table" and data.manifest or data
+    eng.modPlan = SyncMods.plan(manifest, eng.modDeps)
+    eng.phase = "idle"
+    eng.status = SyncMods.planEmpty(eng.modPlan)
+      and "Mods already match" or "Mod changes ready to apply"
+  end)
+end
+
+function SyncEngine:applyModPlan(progress)
+  if not self.modPlan then return false, "no mod plan" end
+  if self.modApply then return false, "the mods are already being applied" end
+  local steps = SyncMods.steps(self.modPlan, self.modDeps)
+  if #steps == 0 then
+    self.modPlan = nil
+    self.status = "Mods already match"
+    if progress then progress(0, 0, nil, true) end
+    return true
+  end
+  self.modApply = { steps = steps, index = 0, failures = {},
+                    progress = progress }
+  self.phase = "applying"
+  self.status = ("Applying mods... 0 of %d"):format(#steps)
+  return true
+end
+
+function SyncEngine:applyingMods()
+  return self.modApply ~= nil
+end
+
+function SyncEngine:_stepModApply()
+  local job = self.modApply
+  local step = job.steps[job.index + 1]
+  job.index = job.index + 1
+  local ok, res, why = pcall(step.run)
+  if not ok then
+    job.failures[#job.failures + 1] = tostring(res)
+  elseif not res then
+    job.failures[#job.failures + 1] = tostring(why or step.label)
+  end
+  local total = #job.steps
+  local done = job.index >= total
+  if not done then
+    self.status = ("Applying mods... %d of %d"):format(job.index, total)
+    if job.progress then
+      pcall(job.progress, job.index, total, step.label, false)
+    end
+    return
+  end
+  self.modApply = nil
+  self.modPlan = nil
+  self.phase = "idle"
+  if #job.failures > 0 then
+    self.status = "Some mods could not be applied: "
+      .. table.concat(job.failures, "; ")
+  else
+    self.status = "Mods applied"
+  end
+  if job.progress then
+    pcall(job.progress, job.index, total, step.label, true)
+  end
+end
+
+return SyncEngine

src/sync/SyncMods.lua

@@ -0,0 +1,196 @@
+local SyncMods = {}
+
+SyncMods.REV = 1
+
+local function versions()
+  local ok, GameVersion = pcall(require, "src.core.GameVersion")
+  if ok and GameVersion and GameVersion.ORDER then return GameVersion.ORDER end
+  return { "red", "blue", "yellow", "gold" }
+end
+
+local function defaultDeps()
+  return {
+    installed = function()
+      return require("src.mods.LauncherMods").list()
+    end,
+    indexes = function()
+      return require("src.mods.ModIndex").sources()
+    end,
+    addIndex = function(url)
+      return require("src.mods.ModIndex").addSource(url)
+    end,
+    findEntry = function(id)
+      local ModIndex = require("src.mods.ModIndex")
+      for _, source in ipairs(ModIndex.sources()) do
+        local cached = ModIndex.readCache(source.feed)
+        for _, entry in ipairs((cached and cached.mods) or {}) do
+          if entry.id == id then return entry end
+        end
+      end
+      return nil
+    end,
+    install = function(entry)
+      return require("src.mods.LauncherMods").installFromIndex(entry)
+    end,
+    setEnabled = function(id, enabled, version)
+      return require("src.mods.LauncherMods").setEnabled(id, enabled, version)
+    end,
+  }
+end
+
+local function deps(given)
+  local out = defaultDeps()
+  if type(given) == "table" then
+    for k, v in pairs(given) do out[k] = v end
+  end
+  return out
+end
+
+local function sourceOf(row)
+  local github = row.github
+    or (type(row.manifest) == "table" and row.manifest.github)
+  if type(github) == "string" and github ~= "" then
+    return "github:" .. github
+  end
+  return "local"
+end
+
+function SyncMods.build(given)
+  local d = deps(given)
+  local manifest = { rev = SyncMods.REV, indexes = {}, mods = {} }
+  for _, row in ipairs(d.indexes() or {}) do
+    local url = row.url or row.feed
+    if type(url) == "string" and url ~= "" then
+      manifest.indexes[#manifest.indexes + 1] = url
+    end
+  end
+  table.sort(manifest.indexes)
+  for _, row in ipairs(d.installed() or {}) do
+    if type(row) == "table" and type(row.id) == "string" then
+      local enabledFor = {}
+      local answers = row.enabledByVersion or {}
+      for _, version in ipairs(versions()) do
+        if answers[version] then enabledFor[#enabledFor + 1] = version end
+      end
+      manifest.mods[#manifest.mods + 1] = {
+        id = row.id,
+        version = row.version,
+        source = sourceOf(row),
+        enabledFor = enabledFor,
+      }
+    end
+  end
+  table.sort(manifest.mods, function(a, b) return a.id < b.id end)
+  return manifest
+end
+
+function SyncMods.plan(manifest, given)
+  local d = deps(given)
+  local plan = { indexes = {}, toInstall = {}, toEnable = {}, missing = {} }
+  if type(manifest) ~= "table" then return plan end
+
+  local haveIndex = {}
+  for _, row in ipairs(d.indexes() or {}) do
+    if type(row.url) == "string" then haveIndex[row.url] = true end
+    if type(row.feed) == "string" then haveIndex[row.feed] = true end
+  end
+  for _, url in ipairs(manifest.indexes or {}) do
+    if type(url) == "string" and url ~= "" and not haveIndex[url] then
+      plan.indexes[#plan.indexes + 1] = url
+      haveIndex[url] = true
+    end
+  end
+
+  local installed = {}
+  for _, row in ipairs(d.installed() or {}) do
+    if type(row) == "table" and type(row.id) == "string" then
+      installed[row.id] = row
+    end
+  end
+
+  for _, mod in ipairs(manifest.mods or {}) do
+    if type(mod) == "table" and type(mod.id) == "string" then
+      local here = installed[mod.id]
+      local available = here ~= nil
+      if not here then
+        local entry = d.findEntry(mod.id)
+        if entry then
+          available = true
+          plan.toInstall[#plan.toInstall + 1] =
+            { id = mod.id, version = mod.version, entry = entry }
+        else
+          plan.missing[#plan.missing + 1] =
+            { id = mod.id, version = mod.version, source = mod.source }
+        end
+      end
+      if available then
+        local answers = (here and here.enabledByVersion) or {}
+        for _, version in ipairs(mod.enabledFor or {}) do
+          if answers[version] ~= true then
+            plan.toEnable[#plan.toEnable + 1] = { id = mod.id, version = version }
+          end
+        end
+      end
+    end
+  end
+  return plan
+end
+
+function SyncMods.planEmpty(plan)
+  if type(plan) ~= "table" then return true end
+  return #(plan.indexes or {}) == 0 and #(plan.toInstall or {}) == 0
+    and #(plan.toEnable or {}) == 0
+end
+
+function SyncMods.steps(plan, given)
+  local d = deps(given)
+  local out = {}
+  if type(plan) ~= "table" then return out end
+  local broken = {}
+
+  for _, url in ipairs(plan.indexes or {}) do
+    out[#out + 1] = { label = url, run = function()
+      local ok, err = d.addIndex(url)
+      if not ok then return nil, tostring(err or url) end
+      return true
+    end }
+  end
+  for _, mod in ipairs(plan.toInstall or {}) do
+    out[#out + 1] = { label = mod.id, run = function()
+      local ok, err = d.install(mod.entry)
+      if not ok then
+        broken[mod.id] = true
+        return nil, mod.id .. ": " .. tostring(err or "install failed")
+      end
+      return true
+    end }
+  end
+  for _, want in ipairs(plan.toEnable or {}) do
+    out[#out + 1] = { label = want.id, run = function()
+      if broken[want.id] then return true end
+      local ok, err = d.setEnabled(want.id, true, want.version)
+      if ok == false then
+        return nil, want.id .. ": " .. tostring(err or "could not enable")
+      end
+      return true
+    end }
+  end
+  return out
+end
+
+function SyncMods.apply(plan, progress, given)
+  if type(plan) ~= "table" then return false, "nothing to apply" end
+  local steps = SyncMods.steps(plan, given)
+  local failures = {}
+  for i, step in ipairs(steps) do
+    local ok, err = step.run()
+    if not ok then failures[#failures + 1] = err end
+    if progress then progress(i, #steps, step.label) end
+  end
+  if #failures > 0 then
+    return false, table.concat(failures, "; ")
+  end
+  return true
+end
+
+return SyncMods

src/sync/SyncState.lua

@@ -0,0 +1,129 @@
+local SaveData = require("src.core.SaveData")
+
+local SyncState = {}
+
+SyncState.KEY = "saveSync"
+
+function SyncState.defaults()
+  return {
+    enabled = false,
+    lastSyncAt = 0,
+    revs = {},
+    stamps = {},
+    pendingConflicts = {},
+  }
+end
+
+local function str(v)
+  if type(v) == "string" and v ~= "" then return v end
+  return nil
+end
+
+local function num(v)
+  local n = tonumber(v)
+  if type(n) ~= "number" or n ~= n or n == math.huge or n == -math.huge then
+    return nil
+  end
+  return n
+end
+
+function SyncState.sanitize(raw)
+  local out = SyncState.defaults()
+  if type(raw) ~= "table" then return out end
+  out.enabled = raw.enabled == true
+  out.account = str(raw.account)
+  out.deviceToken = str(raw.deviceToken)
+  out.deviceId = str(raw.deviceId)
+  out.deviceLabel = str(raw.deviceLabel)
+  out.lastSyncAt = num(raw.lastSyncAt) or 0
+  if type(raw.revs) == "table" then
+    for key, rev in pairs(raw.revs) do
+      local n = num(rev)
+      if type(key) == "string" and n then out.revs[key] = n end
+    end
+  end
+  if type(raw.stamps) == "table" then
+    for key, at in pairs(raw.stamps) do
+      local n = num(at)
+      if type(key) == "string" and n then out.stamps[key] = n end
+    end
+  end
+  if type(raw.pendingConflicts) == "table" then
+    for _, row in ipairs(raw.pendingConflicts) do
+      if type(row) == "table" and str(row.key) then
+        out.pendingConflicts[#out.pendingConflicts + 1] = {
+          key = row.key,
+          version = str(row.version),
+          playthroughId = str(row.playthroughId),
+          overlap = row.overlap == true,
+        }
+      end
+    end
+  end
+  return out
+end
+
+function SyncState.load(fs)
+  local opts = SaveData.loadOptions(fs)
+  return SyncState.sanitize(opts and opts[SyncState.KEY])
+end
+
+function SyncState.save(state, fs)
+  local opts = SaveData.loadOptions(fs)
+  opts[SyncState.KEY] = SyncState.sanitize(state)
+  SaveData.saveOptions(opts, fs)
+  return opts[SyncState.KEY]
+end
+
+function SyncState.update(fn, fs)
+  local state = SyncState.load(fs)
+  fn(state)
+  return SyncState.save(state, fs)
+end
+
+function SyncState.clear(fs)
+  return SyncState.save(SyncState.defaults(), fs)
+end
+
+function SyncState.linked(state)
+  return type(state) == "table" and str(state.account) ~= nil
+    and str(state.deviceToken) ~= nil
+end
+
+function SyncState.key(version, playthroughId)
+  if type(version) ~= "string" or version == "" then return nil end
+  if type(playthroughId) ~= "string" or playthroughId == "" then return nil end
+  return version .. "/" .. playthroughId
+end
+
+function SyncState.splitKey(key)
+  if type(key) ~= "string" then return nil end
+  local version, id = key:match("^([^/]+)/(.+)$")
+  return version, id
+end
+
+function SyncState.rev(state, key)
+  if type(state) ~= "table" or type(state.revs) ~= "table" then return nil end
+  return state.revs[key]
+end
+
+function SyncState.stamp(state, key)
+  if type(state) ~= "table" or type(state.stamps) ~= "table" then return nil end
+  return state.stamps[key]
+end
+
+function SyncState.setRev(state, key, rev, savedAt)
+  if type(state) ~= "table" or type(key) ~= "string" then return end
+  state.revs = state.revs or {}
+  state.stamps = state.stamps or {}
+  state.revs[key] = num(rev)
+  state.stamps[key] = num(savedAt)
+end
+
+function SyncState.forget(state, key)
+  if type(state) ~= "table" or type(key) ~= "string" then return end
+  if type(state.revs) == "table" then state.revs[key] = nil end
+  if type(state.stamps) == "table" then state.stamps[key] = nil end
+end
+
+return SyncState

src/sync/SyncTransport.lua

@@ -0,0 +1,41 @@
+local Transport = {}
+Transport.__index = Transport
+
+function Transport.new(fetch)
+  return setmetatable({ fetch = fetch or require("src.net.Fetch") }, Transport)
+end
+
+function Transport:begin(req)
+  return self.fetch.request(req.url, {
+    method = req.method,
+    body = req.body,
+    headers = req.headers,
+    maxSeconds = req.maxSeconds,
+  })
+end
+
+function Transport:poll(handle)
+  local st = self.fetch.poll(handle)
+  if st.status == "pending" then return { status = "pending" } end
+  if st.status == "cancelled" then
+    return { status = "error", err = "sync request cancelled" }
+  end
+  if st.status ~= "ok" then
+    return { status = "error", err = st.err or "sync request failed" }
+  end
+  return { status = "ok", body = st.body or "", code = tonumber(st.code) }
+end
+
+function Transport:release(handle)
+  if handle ~= nil and self.fetch.release then self.fetch.release(handle) end
+end
+
+function Transport:cancel(handle)
+  if handle ~= nil and self.fetch.cancel then self.fetch.cancel(handle) end
+end
+
+function Transport:available()
+  return self.fetch.available and self.fetch.available() or false
+end
+
+return Transport

src/ui/gen2/BattleTransition.lua

@@ -28,7 +28,7 @@
 -- covered by tests; the state at the bottom is the only part that draws.
 
 local GbcPalette = require("src.render.GbcPalette")
-local GameViewport = require("src.render.GameViewport")
+local Playfield = require("src.render.Playfield")
 local Palettes = require("src.world.gen2.Palettes")
 local Runtime = require("src.mods.Runtime")
 local SpriteAnims = require("src.ui.gen2.SpriteAnims")
@@ -510,7 +510,7 @@ function BattleTransition:blackAt(col, row)
 end
 
 function BattleTransition:draw()
-  local w, h = GameViewport.dimensions()
+  local w, h = Playfield.dimensions()
   self:drawWidescreen(w, h)
 end
 

src/ui/gen2/Chrome.lua

@@ -43,16 +43,29 @@ end
 -- pixel rows out of glyphs.  This is the same rule src/render/Renderer.lua
 -- fitScale applies to the Gen 1 UI canvas; the surround a widescreen screen
 -- paints still fills the window, the PANEL is what stays on the grid.
+local function playfieldRect(winW, winH)
+  local ok, Playfield = pcall(require, "src.render.Playfield")
+  if ok and Playfield.rect then
+    local okv, x, y, w, h = pcall(Playfield.rect, winW, winH)
+    if okv and w and w >= 1 and h and h >= 1 then
+      return x, y, w, h
+    end
+  end
+  return 0, 0, winW or 0, winH or 0
+end
+
 function Chrome.fitScale(winW, winH)
-  return math.max(1, math.floor(math.min((winW or 0) / (Chrome.SCREEN_W * 8),
+  local _, _, w, h = playfieldRect(winW, winH)
-    (winH or 0) / (Chrome.SCREEN_H * 8))))
+  return math.max(1, math.floor(math.min(w / (Chrome.SCREEN_W * 8),
+    h / (Chrome.SCREEN_H * 8))))
 end
 
 -- The centred origin that goes with it, so a caller does not re-derive it.
 function Chrome.fitOrigin(winW, winH, scale)
   scale = scale or Chrome.fitScale(winW, winH)
-  return math.floor((winW - Chrome.SCREEN_W * 8 * scale) / 2),
+  local x, y, w, h = playfieldRect(winW, winH)
-    math.floor((winH - Chrome.SCREEN_H * 8 * scale) / 2)
+  return x + math.floor((w - Chrome.SCREEN_W * 8 * scale) / 2),
+    y + math.floor((h - Chrome.SCREEN_H * 8 * scale) / 2)
 end
 
 -- A bordered box, tile coords.  Leaves the draw color black for text.

src/ui/kit/Kit.lua

@@ -856,8 +856,8 @@ end
 
 -- -------------------------------------------------------------------- pager
 -- Prev / Next / "1-12 of 151".  Drawn even for a single page, so a list is
--- never silently truncated.  This is the ONLY way the launcher moves through
+-- never silently truncated.  A long list still PAGES rather than scrolling:
--- a long list: no scrollbars, no momentum, bounded row count per frame.
+-- no momentum, bounded row count per frame.
 -- Returns the new page (1-based) and the row height consumed.
 local pagerLabels = {}
 
@@ -930,6 +930,64 @@ function Kit.wheelPage(x, y, w, h, page, total, perPage)
   return math.floor(moved)
 end
 
+function Kit.scrollExtent(contentH, viewH)
+  return math.max(0, (contentH or 0) - math.max(0, viewH or 0))
+end
+
+function Kit.scrollClamp(offset, maxScroll)
+  return math.max(0, math.min(offset or 0, math.max(0, maxScroll or 0)))
+end
+
+function Kit.scrollStep(scale)
+  return math.floor(48 * (scale or Kit.scale))
+end
+
+function Kit.scrollBarW(scale)
+  return math.max(2, math.floor(4 * (scale or Kit.scale)))
+end
+
+function Kit.scrollGutter(scale)
+  return Kit.scrollBarW(scale) + math.max(2, math.floor(4 * (scale or Kit.scale)))
+end
+
+function Kit.scrollHandoff(offset, maxScroll, delta)
+  local want = (offset or 0) + (delta or 0)
+  local at = Kit.scrollClamp(want, maxScroll)
+  return at, want - at
+end
+
+function Kit.scrollWheel(offset, maxScroll, x, y, w, h, step)
+  local at = Kit.scrollClamp(offset, maxScroll)
+  local wheel = Kit.wheelY or 0
+  if Kit.blockClicks or wheel == 0 or (maxScroll or 0) <= 0 then
+    return at, false
+  end
+  if not Kit.hit(x, y, w, h) then return at, false end
+  local moved = Kit.scrollClamp(at - wheel * (step or Kit.scrollStep()),
+    maxScroll)
+  if moved == at then return at, false end
+  Kit.wheelY = 0
+  return moved, true
+end
+
+function Kit.scrollBegin(x, y, w, h, offset, maxScroll)
+  Kit.pushClip(x, y, math.max(0, w or 0), math.max(0, h or 0))
+  return y - Kit.scrollClamp(offset, maxScroll)
+end
+
+function Kit.scrollEnd(x, y, w, h, offset, maxScroll)
+  Kit.popClip()
+  if (maxScroll or 0) <= 0 or (h or 0) <= 0 or (w or 0) <= 0 then return end
+  local barW = Kit.scrollBarW()
+  local barX = x + w - barW
+  local at = Kit.scrollClamp(offset, maxScroll)
+  local thumbH = math.max(math.floor(20 * Kit.scale),
+    math.floor(h * (h / (h + maxScroll))))
+  local thumbY = y + (h - thumbH) * (at / maxScroll)
+  Theme.fill(barX, y, barW, h, PAL.bg, 0.35)
+  Theme.fill(barX, thumbY, barW, thumbH, PAL.muted, 0.7)
+end
+
 -- ------------------------------------------------------------------ spinner
 -- The one animated element in the UI: a rotating arc of ticks.  Drawn as N
 -- short lines at descending alpha, which needs no shader, no canvas and no

src/world/OverworldController.lua

@@ -9,7 +9,6 @@ local Collision = require("src.world.Collision")
 local Encounter = require("src.world.Encounter")
 local FieldDefaults = require("src.world.FieldDefaults")
 local GameVersion = require("src.core.GameVersion")
-local GameViewport = require("src.render.GameViewport")
 local Logger = require("src.core.Logger")
 local Map = require("src.world.Map")
 local MapLoader = require("src.world.MapLoader")
@@ -5196,7 +5195,7 @@ function OverworldState:drawWorld()
     -- point projects under the pipeline's own camera.  That is the direct
     -- analogue of what :billboard does for tilt, and it keeps exactly one
     -- copy of every effect: the closures above are the ones that run.
-    local pw, ph = GameViewport.dimensions()
+    local _, _, pw, ph = Game.renderer:playfieldRect()
     local pscale = Zoom.scale(Game.renderer:fitScale())
     local ctx = {
       state = self, cam = cam, vw = vw, vh = vh, bgY = bgY,

src/world/gen2/World.lua

@@ -34,7 +34,7 @@ local Font = require("src.render.Font")
 -- a mod has taken a facade (src/mods/Gen2Compat.lua).
 local Gen1Facade = require("src.mods.Gen2Compat")
 local GbcPalette = require("src.render.GbcPalette")
-local GameViewport = require("src.render.GameViewport")
+local Playfield = require("src.render.Playfield")
 local Gen2Save = require("src.core.gen2.Save")
 local HallOfFame = require("src.core.gen2.HallOfFame")
 local HiddenItems = require("src.world.gen2.HiddenItems")
@@ -7499,7 +7499,7 @@ function World:interactBody()
 end
 
 function World:fitScale()
-  local w, h = GameViewport.dimensions()
+  local w, h = Playfield.dimensions()
   return math.max(1, math.floor(math.min(w / 160, h / 144)))
 end
 
@@ -8336,7 +8336,7 @@ function World:rebuildNeighbors()
   self.neighbors = {}
   if not self.map then return end
   local s = self:zoomScale()
-  local ww, wh = GameViewport.dimensions()
+  local ww, wh = Playfield.dimensions()
   local vw = math.ceil(ww / s)
   local vh = math.ceil(wh / s)
   if vw % 2 ~= 0 then vw = vw + 1 end
@@ -9748,7 +9748,7 @@ function World:drawGround(s)
     if canvas then
       bw, bh = canvas:getDimensions()
     else
-      bw, bh = GameViewport.dimensions()
+      bw, bh = Playfield.dimensions()
     end
     if BorderFill.fillBlock(self.map.def) == false then
       -- BLACK: World:draw clears to a brown letterbox, so the void itself
@@ -10017,7 +10017,7 @@ end
 
 function World:draw()
   local G = love.graphics
-  local w, h = GameViewport.dimensions()
+  local w, h = Playfield.dimensions()
   self:refreshColorMode()
   G.clear(0.07, 0.05, 0.02, 1)
 

tests/drivers/launcher_sync_shot.lua

@@ -0,0 +1,128 @@
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local RomImporter = require("src.import.RomImporter")
+
+  local dir = os.getenv("SHOT_DIR") or "/tmp/syncmodal"
+  os.execute('mkdir -p "' .. dir .. '" 2>/dev/null')
+  love.window.setMode(1024, 768, { resizable = true, highdpi = true })
+  U.wait(2)
+
+  local eng = {
+    phase = "idle", status = "Ready", conflicts = {}, state = { enabled = true },
+    isLinked = false, isBusy = false,
+    linked = function(self) return self.isLinked end,
+    busy = function(self) return self.isBusy end,
+    createAccount = function(self)
+      self.isLinked = true
+      self.codes = { code1 = "1234-5678", code2 = "8765-4321" }
+      self.status = "Sync account created"
+      return true
+    end,
+    linkDevice = function(self) self.isLinked = true return true end,
+    syncNow = function(self) self.status = "Checking for changes..." return true end,
+    unlink = function(self) self.isLinked, self.codes = false, nil return true end,
+    shareMods = function(self) self.shareCode = "K7QW3M" return true end,
+    fetchShare = function(self) return true end,
+    applyModPlan = function(self) self.modPlan = nil return true end,
+    resolveConflict = function(self) self.conflicts = {} self.phase = "idle" return true end,
+  }
+
+  local imp = RomImporter.new(function() end, { launcher = true })
+  imp._sync = eng
+  imp._syncTransportOk = true
+
+  local pending = nil
+  love.draw = function()
+    imp:draw()
+    if pending then
+      local path = pending
+      pending = nil
+      love.graphics.captureScreenshot(function(imagedata)
+        local f = io.open(path, "wb")
+        if f then f:write(imagedata:encode("png"):getString()) f:close() end
+      end)
+    end
+  end
+  local function shot(name)
+    pending = dir .. "/" .. name
+    for _ = 1, 90 do
+      if not pending then break end
+      imp:update(1 / 60)
+      coroutine.yield()
+    end
+    U.wait(3)
+    local f = io.open(dir .. "/" .. name, "rb")
+    U.log(f and "shot" or "FAIL shot", name)
+    if f then f:close() end
+  end
+
+  imp:_openSync()
+  U.wait(3)
+  U.log("modal view:", imp._syncModal.view, "linked:", tostring(eng:linked()))
+  shot("sync_new.png")
+
+  imp:_syncView("link")
+  imp:_syncFocusField("code1")
+  imp:textinput("1234-5678")
+  imp:_syncFocusField("code2")
+  imp:textinput("8765ab4321")
+  U.wait(2)
+  U.log("codes typed:", imp._syncModal.code1, imp._syncModal.code2)
+  shot("sync_link.png")
+
+  imp:_syncView("home")
+  imp:_syncCreate()
+  U.wait(2)
+  U.log("codes shown:", eng.codes.code1, eng.codes.code2)
+  shot("sync_codes.png")
+
+  eng.isBusy = true
+  eng.status = "Uploading saves..."
+  U.wait(2)
+  shot("sync_busy.png")
+  eng.isBusy = false
+  eng.status = "Ready"
+
+  imp:_syncView("mods")
+  imp:_syncShareMods()
+  eng.modPlan = {
+    indexes = { "https://example.invalid/index.json" },
+    toInstall = { { id = "jp_green" }, { id = "randomizer" } },
+    toEnable = { { id = "jp_green", version = "red" } },
+    missing = { { id = "gone" } },
+  }
+  U.wait(2)
+  U.log("share code:", tostring(eng.shareCode))
+  shot("sync_mods.png")
+
+  eng.phase = "conflict"
+  eng.status = "These saves were played at the same time."
+  eng.conflicts = { {
+    key = "red/abcd1234", version = "red", overlap = true,
+    localMeta = { savedAt = os.time(), sessionStart = os.time() - 3600,
+      summary = { name = "ASH", badges = 3, timeText = "5:42", dexCount = 40 } },
+    remoteMeta = { savedAt = os.time() - 600, sessionStart = os.time() - 4200,
+      summary = { name = "ASH", badges = 4, timeText = "6:10", dexCount = 44 } },
+  } }
+  U.wait(2)
+  shot("sync_conflict.png")
+
+  love.window.setMode(520, 760, { resizable = true, highdpi = true })
+  U.wait(3)
+  shot("sync_conflict_narrow.png")
+
+  eng.phase = "idle"
+  eng.conflicts = {}
+  imp:_syncView("home")
+  U.wait(2)
+  shot("sync_home_narrow.png")
+
+  imp:_closeSync()
+  U.wait(2)
+  U.log("closed:", tostring(imp._syncModal == nil))
+  shot("sync_closed.png")
+
+  U.log("done")
+  love.event.quit()
+  while true do coroutine.yield() end
+end

tests/drivers/skin_add_by_url_shot.lua

@@ -0,0 +1,115 @@
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local RomImporter = require("src.import.RomImporter")
+  local TouchSkin = require("src.core.TouchSkin")
+  local Fetch = require("src.net.Fetch")
+
+  local dir = os.getenv("SHOT_DIR") or "/tmp/skinurl"
+  os.execute('mkdir -p "' .. dir .. '" 2>/dev/null')
+  love.window.setMode(1024, 768, { resizable = true, highdpi = true })
+  U.wait(2)
+
+  local imp = RomImporter.new(function() end, {
+    launcher = true,
+    onOpenSkinStudio = function() end,
+  })
+
+  local pending = nil
+  love.draw = function()
+    imp:draw()
+    if pending then
+      local path = pending
+      pending = nil
+      love.graphics.captureScreenshot(function(imagedata)
+        local f = io.open(path, "wb")
+        if f then f:write(imagedata:encode("png"):getString()) f:close() end
+      end)
+    end
+  end
+  local function shot(name)
+    pending = dir .. "/" .. name
+    for _ = 1, 90 do
+      if not pending then break end
+      imp:update(1 / 60)
+      coroutine.yield()
+    end
+    U.wait(3)
+    local f = io.open(dir .. "/" .. name, "rb")
+    U.log(f and "shot" or "FAIL shot", name)
+    if f then f:close() end
+  end
+
+  imp:_switchTab("skins")
+  U.wait(3)
+
+  U.log("name from url:", RomImporter.skinUrlName(
+    "https://example.com/pads/Neon.deltaskin"))
+  U.log("name from cfg:", RomImporter.skinUrlName(
+    "https://example.com/overlay.cfg"))
+
+  imp.skinUrl = "https://example.com/pads/neon.deltaskin"
+  imp._skinUrlFocus = true
+  U.wait(2)
+  shot("skins_url_typed.png")
+
+  local realDownload, realPoll, realRelease =
+    Fetch.download, Fetch.poll, Fetch.release
+  local state = { status = "pending", progress = 0.4 }
+  Fetch.download = function(url, dest)
+    U.log("download:", url, "->", dest)
+    return 1
+  end
+  Fetch.poll = function() return state end
+  Fetch.release = function() end
+
+  imp._skinUrlFocus = false
+  imp:_addSkinFromUrl()
+  U.log("in flight:", tostring(imp._skinFetch ~= nil))
+  U.wait(2)
+  shot("skins_url_downloading.png")
+
+  state = { status = "error", err = "could not resolve host" }
+  imp:_pumpSkinFetch()
+  U.log("failure notice:", imp._skinNotice.text)
+  U.wait(2)
+  shot("skins_url_failed.png")
+
+  Fetch.download, Fetch.poll, Fetch.release = realDownload, realPoll, realRelease
+
+  local staged = TouchSkin.export(
+    assert(TouchSkin.load("assets/skins/gb_anim", "gb_anim")),
+    "skins/url_probe.zip")
+  local raw = love.filesystem.read("skins/url_probe.zip")
+  love.filesystem.remove("skins/url_probe.zip")
+  U.log("staged:", tostring(staged), "bytes:", raw and #raw or 0)
+  imp:_installSkinData("downloaded_pad.zip", raw)
+  U.log("install notice:", imp._skinNotice.text)
+  U.wait(2)
+  shot("skins_url_installed.png")
+
+  local skins = imp:_ensureSkins(true)
+  for _, e in ipairs(skins) do
+    U.log(("  %s  format=%s buttons=%d"):format(e.id, tostring(e.format),
+      e.controls))
+  end
+
+  imp._skinActions = { id = skins[1] and skins[1].id }
+  U.wait(2)
+  shot("skins_actions_sheet.png")
+
+  for _, kind in ipairs({ "native", "retroarch", "delta" }) do
+    local path = imp:_exportSkin(skins[1].id, kind)
+    U.log("export " .. kind .. ":", tostring(path))
+  end
+  imp._skinActions = nil
+  U.wait(2)
+  shot("skins_exported.png")
+
+  love.window.setMode(520, 820, { resizable = true, highdpi = true })
+  U.wait(3)
+  shot("skins_url_narrow.png")
+
+  U.log("done")
+  love.event.quit()
+  while true do coroutine.yield() end
+end

tests/drivers/skin_containment_shot.lua

@@ -0,0 +1,227 @@
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local TouchControls = require("src.core.TouchControls")
+  local TouchSkin = require("src.core.TouchSkin")
+  local Playfield = require("src.render.Playfield")
+
+  local dir = os.getenv("SHOT_DIR") or "/tmp/skin-cutout"
+  local gen2 = game.overworld == nil
+  local failures, checks = 0, 0
+
+  local SKIN = [[
+return {
+  name = "containment_probe",
+  pages = {
+    {
+      name = "probe",
+      fullScreen = true,
+      viewport = { x = 0.25, y = 0.1, w = 0.5, h = 0.6 },
+      controls = { { bind = "nul", x = 0.5, y = 0.92, w = 0.04, h = 0.04 } },
+    },
+  },
+}
+]]
+  love.filesystem.createDirectory("skins/containment_probe")
+  assert(love.filesystem.write("skins/containment_probe/skin.lua", SKIN))
+
+  love.window.setMode(1280, 720, { resizable = true, highdpi = true })
+  love.graphics.setBackgroundColor(0, 0, 0, 1)
+  U.wait(2)
+
+  local options = gen2 and game.options or game.save.options
+  options.touchControls = { enabled = true, skin = "containment_probe" }
+  options.tilt = 0
+  options.zoom = 0
+  options.pipelines = {}
+  options.videoMode = "windowed"
+  options.faithfulRes = 0
+  game:applyOptions()
+  love.window.setMode(1280, 720, { resizable = true, highdpi = true })
+  U.wait(4)
+
+  U.log("gen:", gen2 and 2 or 1, "skin:", tostring(TouchControls.skinId),
+        "err:", tostring(TouchControls.skinError))
+  U.log("drawable:", TouchSkin.drawable(), "hasViewport:", TouchSkin.hasViewport())
+
+  local function cutoutPx()
+    local pw, ph = love.graphics.getPixelDimensions()
+    local x, y, w, h = Playfield.cutout(pw, ph)
+    return x, y, w, h, pw, ph
+  end
+
+  local cx, cy, cw, ch, pw, ph = cutoutPx()
+  if not cx then
+    U.log("FAIL no cutout is active; nothing to prove")
+    love.event.quit()
+    while true do coroutine.yield() end
+  end
+  U.log(("cutout px: %d,%d %dx%d in %dx%d"):format(cx, cy, cw, ch, pw, ph))
+
+  local INSET = 4
+  local function scan(label, data)
+    local w, h = data:getWidth(), data:getHeight()
+    local sx, sy = w / pw, h / ph
+    local x1, y1 = math.floor(cx * sx) - INSET, math.floor(cy * sy) - INSET
+    local x2 = math.ceil((cx + cw) * sx) + INSET
+    local y2 = math.ceil((cy + ch) * sy) + INSET
+    local bad, firstX, firstY, worst = 0, nil, nil, 0
+    local inked = 0
+    local step = math.max(2, math.floor(math.min(w, h) / 360))
+    for y = 0, h - 1, step do
+      for x = 0, w - 1, step do
+        local r, g, b = data:getPixel(x, y)
+        local lit = math.max(r, g, b)
+        local outside = x < x1 or x >= x2 or y < y1 or y >= y2
+        if outside then
+          if lit > 0.02 then
+            bad = bad + 1
+            if not firstX then firstX, firstY = x, y end
+            if lit > worst then worst = lit end
+          end
+        elseif lit > 0.02 then
+          inked = inked + 1
+        end
+      end
+    end
+    checks = checks + 1
+    if bad > 0 then
+      failures = failures + 1
+      U.log(("FAIL %s: %d lit samples outside the cutout (first %d,%d, max %.2f)")
+        :format(label, bad, firstX, firstY, worst))
+    elseif inked == 0 then
+      failures = failures + 1
+      U.log("FAIL " .. label .. ": nothing drew inside the cutout either")
+    else
+      U.log(("ok   %s: contained (%d lit samples inside)"):format(label, inked))
+    end
+  end
+
+  local pending = nil
+  local function probe(label)
+    U.wait(2)
+    pending = label
+    love.graphics.captureScreenshot(function(data)
+      scan(pending, data)
+      pending = nil
+    end)
+    for _ = 1, 180 do
+      if not pending then break end
+      coroutine.yield()
+    end
+    if pending then
+      failures = failures + 1
+      U.log("FAIL " .. tostring(pending) .. ": screenshot never arrived")
+      pending = nil
+    end
+    if os.getenv("SHOT_PNG") == "1" then
+      U.shot(game, ("%s/%s.png"):format(dir, label:gsub("[^%w]+", "_")))
+    end
+  end
+
+  if gen2 then
+    for i = 1, 2 do
+      probe("gold_boot_" .. i)
+      U.wait(60)
+    end
+    for _ = 1, 240 do
+      if game.world and game.world.map then break end
+      game.input.pressQueue[#game.input.pressQueue + 1] = "start"
+      U.wait(4)
+    end
+    if game.world and game.world.map then
+      probe("gold_overworld")
+      local Zoom = require("src.render.Zoom")
+      Zoom.allowSurvey = true
+      for _, off in ipairs({ -2, -1, 1, 2 }) do
+        Zoom.offset = off
+        probe("gold_zoom_" .. (off < 0 and "out" or "in") .. math.abs(off))
+      end
+      Zoom.offset = 0
+      local function tap(button, frames)
+        game.input.pressQueue[#game.input.pressQueue + 1] = button
+        game.input.state[button] = true
+        U.wait(2)
+        game.input.state[button] = false
+        U.wait(frames or 12)
+      end
+      tap("start", 24)
+      probe("gold_start_menu")
+      tap("b", 12)
+      probe("gold_after_menu")
+    else
+      U.log("FAIL gold world never booted")
+      failures = failures + 1
+    end
+  else
+    local Pokemon = require("src.pokemon.Pokemon")
+    game.save.party = { Pokemon.new(game.data, "CHARIZARD", 50) }
+    game.save.player.name = "bryan"
+    U.teleport(game, "PALLET_TOWN", 10, 8, "down")
+    U.wait(12)
+    probe("red_overworld")
+
+    local Zoom = require("src.render.Zoom")
+    local Renderer = require("src.render.Renderer")
+    Zoom.allowSurvey = true
+    local lo, hi = Zoom.offsetRange(Renderer:fitScale())
+    for off = lo, hi do
+      Zoom.offset = off
+      probe("red_zoom_" .. Zoom.offsetLabel(off))
+    end
+    Zoom.offset = 0
+
+    U.tap(game, "start")
+    U.wait(20)
+    probe("red_start_menu")
+
+    local function stress(label, mutate)
+      local state = game.stack:top()
+      local original = state.draw
+      state.draw = function(...)
+        original(...)
+        mutate()
+      end
+      probe(label)
+      state.draw = original
+    end
+    stress("red_screen_veil", function()
+      Renderer.screenVeil = { 1, 0.85 }
+    end)
+    stress("red_battle_wipe", function()
+      Renderer.battleWipe = { style = "spiralin", prog = 0.45 }
+    end)
+    stress("red_letterbox_paper", function()
+      Renderer.extendedWorldBand = true
+    end)
+    stress("red_ui_anchor", function()
+      Renderer.uiCentered = false
+      Renderer:setUIAnchor(0, 96, 160, 48, "bottom")
+    end)
+    U.tap(game, "b")
+    U.wait(10)
+
+    game.save.options.uiLayout = "dynamic"
+    game:applyOptions()
+    U.tap(game, "start")
+    U.wait(20)
+    probe("red_dynamic_start_menu")
+    U.tap(game, "b")
+    U.wait(10)
+    game.save.options.uiLayout = "centered"
+    game:applyOptions()
+
+    local Tilt = require("src.render.Tilt")
+    game.save.options.tilt = 1
+    Tilt.applyOptions(game.save.options)
+    U.wait(30)
+    probe("red_tilt")
+    game.save.options.tilt = 0
+    Tilt.applyOptions(game.save.options)
+    U.wait(20)
+  end
+
+  U.log(("done: %d/%d frames contained, %d failures")
+    :format(checks - failures, checks, failures))
+  love.event.quit()
+  while true do coroutine.yield() end
+end

tests/engine/gen2_mod_options_persist.lua

@@ -0,0 +1,83 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+local SaveData = require("src.core.SaveData")
+local Save = require("src.core.gen2.Save")
+
+local function memfs()
+  local files = {}
+  return {
+    files = files,
+    write = function(path, content) files[path] = content return true end,
+    read = function(path) return files[path] end,
+    remove = function(path) files[path] = nil return true end,
+    getInfo = function(path)
+      if files[path] ~= nil then return { type = "file" } end
+      return nil
+    end,
+  }
+end
+
+local fs = memfs()
+SaveData.saveOptions(SaveData.defaultOptions(), fs)
+local opts = Save.loadOptions(fs)
+opts.modOptions = { nuzlocke = { dupes = true } }
+opts.modProfiles = { { name = "casual", enabled = {} } }
+opts.activeProfile = "casual"
+opts.mods = { nuzlocke = true }
+opts.modsByVersion = { gold = { hardmode = true } }
+opts.textSpeed = "SLOW"
+check(Save.saveOptions(opts, fs), "gold options write lands")
+
+local file = SaveData.loadOptions(fs)
+eq(file.modOptions and file.modOptions.nuzlocke and file.modOptions.nuzlocke.dupes,
+  true, "modOptions lands flat where gen1 and the launcher read it")
+eq(file.activeProfile, "casual", "activeProfile lands flat")
+eq(file.modProfiles and file.modProfiles[1] and file.modProfiles[1].name,
+  "casual", "modProfiles lands flat")
+eq(file.mods and file.mods.nuzlocke, true, "enable flags land flat")
+eq(file.modsByVersion and file.modsByVersion.gold
+  and file.modsByVersion.gold.hardmode, true, "per-version flags land flat")
+eq(file[Save.OPTIONS_KEY].modOptions, nil, "gold block no longer traps modOptions")
+eq(file[Save.OPTIONS_KEY].activeProfile, nil,
+  "gold block no longer traps activeProfile")
+eq(file[Save.OPTIONS_KEY].textSpeed, "SLOW", "gold-only keys stay in the gold block")
+
+local back = Save.loadOptions(fs)
+eq(back.modOptions.nuzlocke.dupes, true, "flat modOptions round-trips into gold's table")
+eq(back.activeProfile, "casual", "flat activeProfile round-trips")
+
+local fs2 = memfs()
+fs2.files["options.lua"] = [[return { gold = { textSpeed = "FAST",
+  modOptions = { nuzlocke = { dupes = true } }, activeProfile = "old" } }]]
+local legacy = Save.loadOptions(fs2)
+eq(legacy.modOptions and legacy.modOptions.nuzlocke
+  and legacy.modOptions.nuzlocke.dupes, true,
+  "modOptions trapped in the gold block migrates out")
+eq(legacy.activeProfile, "old", "trapped activeProfile migrates")
+eq(legacy.textSpeed, "FAST", "gold-only keys still merge")
+check(Save.saveOptions(legacy, fs2), "migrated write lands")
+local migrated = SaveData.loadOptions(fs2)
+eq(migrated.modOptions and migrated.modOptions.nuzlocke.dupes, true,
+  "migration lands the trapped store flat")
+eq(migrated[Save.OPTIONS_KEY].modOptions, nil, "migration empties the trap")
+
+local fs3 = memfs()
+fs3.files["options.lua"] = [[return { modOptions = { nuzlocke = { dupes = false } },
+  gold = { modOptions = { nuzlocke = { dupes = true } } } }]]
+local both = Save.loadOptions(fs3)
+eq(both.modOptions.nuzlocke.dupes, false, "flat modOptions wins over a trapped copy")
+
+local Game2 = require("src.core.Game2")
+check(type(Game2.writeOptions) == "function", "Game2 exposes writeOptions")
+eq(Game2.writeOptions, Game2.persistOptions, "writeOptions is the persist path")
+
+local ManagerState = require("src.mods.ManagerState")
+local wrote = false
+ManagerState.persistOptions({ game = { writeOptions = function() wrote = true end } })
+check(wrote, "ManagerState:persistOptions writes through game.writeOptions")
+
+T.finish("gen2_mod_options_persist")

tests/engine/gen2_touch_skin_options.lua

@@ -0,0 +1,85 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+local SaveData = require("src.core.SaveData")
+local Save = require("src.core.gen2.Save")
+
+local function memfs()
+  local files = {}
+  return {
+    files = files,
+    write = function(path, content) files[path] = content return true end,
+    read = function(path) return files[path] end,
+    remove = function(path) files[path] = nil return true end,
+    getInfo = function(path)
+      if files[path] ~= nil then return { type = "file" } end
+      return nil
+    end,
+  }
+end
+
+local fs = memfs()
+local seed = SaveData.defaultOptions()
+seed.touchControls = { enabled = true, skin = "gb_anim" }
+seed.haptics = "off"
+seed[Save.OPTIONS_KEY] = { textSpeed = "FAST", touchControls = { enabled = false } }
+check(SaveData.saveOptions(seed, fs) ~= nil, "seed write lands")
+
+local opts = Save.loadOptions(fs)
+eq(opts.touchControls and opts.touchControls.skin, "gb_anim",
+  "gold sees the skin the launcher picked")
+eq(opts.touchControls.enabled, true, "top-level touchControls wins over the gold block")
+eq(opts.haptics, "off", "top-level haptics wins over the gold default")
+eq(opts.textSpeed, "FAST", "gold-block keys still merge")
+
+local fs2 = memfs()
+fs2.files["options.lua"] =
+  "return { gold = { touchControls = { enabled = false } } }"
+local opts2 = Save.loadOptions(fs2)
+eq(opts2.touchControls and opts2.touchControls.enabled, true,
+  "shared touchControls (default-folded) wins over a stale gold-block copy")
+
+local fs3 = memfs()
+SaveData.saveOptions(SaveData.defaultOptions(), fs3)
+local gopts = Save.loadOptions(fs3)
+gopts.touchControls = { enabled = true, skin = "tv_crt" }
+gopts.haptics = "strong"
+gopts.textSpeed = "SLOW"
+check(Save.saveOptions(gopts, fs3), "gold options write lands")
+
+local file = SaveData.loadOptions(fs3)
+eq(file.touchControls and file.touchControls.skin, "tv_crt",
+  "gold's touch pick lands on the shared top-level key")
+eq(file.haptics, "strong", "gold's haptics lands on the shared top-level key")
+eq(file[Save.OPTIONS_KEY].touchControls, nil, "gold block no longer shadows touchControls")
+eq(file[Save.OPTIONS_KEY].haptics, nil, "gold block no longer shadows haptics")
+eq(file[Save.OPTIONS_KEY].textSpeed, "SLOW", "gold-only keys stay in the gold block")
+
+local g1 = Save.loadOptions(fs3)
+eq(g1.touchControls.skin, "tv_crt", "hoisted value round-trips back into gold")
+
+local TouchSkin = require("src.core.TouchSkin")
+local Chrome = require("src.ui.gen2.Chrome")
+
+local savedViewport = TouchSkin.viewport
+TouchSkin.viewport = function() return nil end
+eq(Chrome.fitScale(640, 576), 4, "no cutout: integer fit against the window")
+local ox, oy = Chrome.fitOrigin(640, 576)
+eq(ox, 0, "no cutout: centred x")
+eq(oy, 0, "no cutout: centred y")
+
+TouchSkin.viewport = function(w, h) return w * 0.25, h * 0.125, w * 0.5, h * 0.5 end
+eq(Chrome.fitScale(640, 576), 2, "cutout: integer fit against the cutout rect")
+local cx, cy = Chrome.fitOrigin(640, 576)
+eq(cx, 160 + (320 - 320) / 2, "cutout: origin starts at the cutout")
+eq(cy, 72 + math.floor((288 - 288) / 2), "cutout: origin starts at the cutout y")
+
+TouchSkin.viewport = function() error("boom") end
+eq(Chrome.fitScale(640, 576), 4, "a throwing viewport degrades to the window fit")
+
+TouchSkin.viewport = savedViewport
+
+T.finish("gen2_touch_skin_options")

tests/engine/host_shell_bridge_request.lua

@@ -0,0 +1,125 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+local HostShell = require("src.core.HostShell")
+
+local TOKEN = "0123456789abcdef0123456789abcdef"
+local BODY = '{"blob":"return {}"}'
+
+HostShell.haveCurl = function() return false end
+love.system.getOS = function() return "Android" end
+
+local calls = {}
+local reply = "STATUS 200\n" .. '{"ok":true}'
+
+love.system.httpRequest = function(url, method, headers, body, userAgent)
+  calls[#calls + 1] = { url = url, method = method, headers = headers,
+                        body = body, userAgent = userAgent }
+  if type(reply) == "function" then return reply() end
+  return reply
+end
+
+check(HostShell.canHttpRequest(),
+  "the bridge counts as a request transport where curl does not exist")
+
+local body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT",
+  body = BODY,
+  headers = {
+    ["x-sync-account"] = "aa11bb22cc33dd44",
+    ["x-sync-token"] = TOKEN,
+    ["Content-Type"] = "application/json",
+  },
+})
+
+eq(code, 200, "a bridge request completes: " .. tostring(err))
+eq(body, '{"ok":true}', "and the body arrives with the status line stripped")
+eq(err, nil, "with no error alongside it")
+
+eq(#calls, 1, "the bridge is called once")
+local sent = calls[1]
+eq(sent.url, "https://sync.example/sync/save", "the url goes through untouched")
+eq(sent.method, "PUT", "and so does the method curl would have taken with -X")
+eq(sent.body, BODY, "the save blob rides the body argument, not the url")
+eq(sent.userAgent, "gen1recomp", "with the default user agent")
+
+local seen = {}
+for i = 1, #sent.headers, 2 do seen[sent.headers[i]] = sent.headers[i + 1] end
+eq(seen["x-sync-token"], TOKEN, "auth headers arrive as flat name, value pairs")
+eq(seen["x-sync-account"], "aa11bb22cc33dd44", "for the account id too")
+eq(seen["Content-Type"], "application/json", "and for the content type")
+eq(seen["User-Agent"], nil,
+  "the user agent stays its own argument rather than a duplicate header")
+
+calls = {}
+reply = "STATUS 409\n" .. '{"error":"the save moved on"}'
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT", body = BODY, headers = { ["Accept"] = "application/json" },
+})
+eq(code, 409, "a conflict comes back as a status, not as a transport failure")
+eq(body, '{"error":"the save moved on"}',
+  "and its body survives, which is the whole point of the request arm")
+eq(err, nil, "a 4xx is the caller's to interpret")
+
+calls = {}
+reply = "ERROR the reply was too large\n"
+body, err, code = HostShell.httpRequest("https://sync.example/sync/state", {
+  method = "GET",
+})
+eq(code, nil, "an ERROR envelope has no status")
+eq(body, nil, "and no body")
+check(err and err:find("the reply was too large", 1, true) ~= nil,
+  "the bridge's own complaint reaches the caller: " .. tostring(err))
+check(err and err:find("https://sync.example/sync/state", 1, true) ~= nil,
+  "named with the url that failed")
+
+calls = {}
+reply = "STATUS 200\n" .. '{"ok":true}'
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT", body = BODY,
+  headers = { ["x-sync-token"] = TOKEN .. "\r\nx-sync-account: stolen" },
+})
+eq(code, nil, "a header value carrying CRLF is refused")
+eq(err, "bad request header", "with the same complaint the curl branch gives")
+eq(#calls, 0, "and the bridge is never reached")
+
+calls = {}
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PATCH", body = BODY,
+})
+eq(code, nil, "a method the bridge cannot express is refused")
+check(err and err:find("PATCH", 1, true) ~= nil,
+  "naming the method: " .. tostring(err))
+eq(#calls, 0, "without calling the bridge")
+
+calls = {}
+reply = function() return nil end
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT", body = BODY,
+})
+eq(code, nil, "an old app under a newer engine returns nothing")
+check(err and err:find("update the app", 1, true) ~= nil,
+  "and degrades to an update notice rather than a crash: " .. tostring(err))
+
+love.system.httpRequest = nil
+love.system.httpDownload = function() return false end
+check(not HostShell.canHttpRequest(),
+  "a build with only the download bridge cannot make signed requests")
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT", body = BODY,
+})
+eq(code, nil, "so the request does not go out")
+check(err and err:find("update the app", 1, true) ~= nil,
+  "and says what to do about it: " .. tostring(err))
+
+love.system.httpDownload = nil
+body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT", body = BODY,
+})
+eq(err, "no request transport on this platform",
+  "a platform with no bridge at all keeps its old answer")
+
+T.finish("host shell bridge request")

tests/engine/host_shell_request_headers.lua

@@ -0,0 +1,95 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+local HostShell = require("src.core.HostShell")
+
+local MARK = "\n__gen1recomp_http__"
+local SAVE_DIR = "/tmp/pokeport-stub-save"
+local TOKEN = "0123456789abcdef0123456789abcdef"
+local BODY = '{"blob":"return {}"}'
+
+local realOpen = io.open
+local realPopen = io.popen
+local realRemove = os.remove
+local realHaveCurl = HostShell.haveCurl
+
+local files, removed = {}, {}
+local popenCommand
+
+HostShell.haveCurl = function() return true end
+os.remove = function(path)
+  removed[path] = true
+  return true
+end
+io.open = function(path, mode)
+  local entry = { path = path, mode = mode, text = "" }
+  files[#files + 1] = entry
+  return {
+    write = function(_, value)
+      entry.text = entry.text .. value
+      return true
+    end,
+    close = function() return true end,
+  }
+end
+io.popen = function(command)
+  popenCommand = command
+  return {
+    read = function() return '{"ok":true}' .. MARK .. "200" end,
+    close = function() return true end,
+  }
+end
+
+local body, err, code = HostShell.httpRequest("https://sync.example/sync/save", {
+  method = "PUT",
+  body = BODY,
+  headers = {
+    ["x-sync-account"] = "aa11bb22cc33dd44",
+    ["x-sync-token"] = TOKEN,
+    ["Content-Type"] = "application/json",
+  },
+})
+
+io.open = realOpen
+io.popen = realPopen
+os.remove = realRemove
+HostShell.haveCurl = realHaveCurl
+
+eq(code, 200, "the request completes: " .. tostring(err))
+eq(body, '{"ok":true}', "and the response body comes back without the marker")
+
+check(popenCommand:find(TOKEN, 1, true) == nil,
+  "the device token never reaches the command line")
+check(popenCommand:find("aa11bb22cc33dd44", 1, true) == nil,
+  "and neither does the account id")
+check(popenCommand:find(BODY, 1, true) == nil,
+  "the save blob stays out of the command line too")
+
+local headerFile, bodyFile
+for _, entry in ipairs(files) do
+  if entry.text:find("x-sync-token", 1, true) then headerFile = entry end
+  if entry.text == BODY then bodyFile = entry end
+end
+check(headerFile ~= nil, "the headers are staged in a file")
+check(bodyFile ~= nil, "and so is the body")
+eq(headerFile.mode, "wb", "the header file is written as bytes")
+check(headerFile.text:find("x%-sync%-token: " .. TOKEN) ~= nil,
+  "with one header per line for curl to read")
+check(headerFile.text:find("User%-Agent: ") ~= nil,
+  "including the user agent curl would otherwise take on argv")
+check(popenCommand:find("-H '@" .. headerFile.path .. "'", 1, true) ~= nil,
+  "and curl is pointed at that file")
+
+check(headerFile.path:find(SAVE_DIR, 1, true) == 1,
+  "staging happens in the user-private save directory, not shared /tmp")
+check(bodyFile.path:find(SAVE_DIR, 1, true) == 1,
+  "for the body as well")
+check(headerFile.path ~= bodyFile.path,
+  "two concurrent requests cannot collide on one name")
+eq(removed[headerFile.path], true, "the staged headers are deleted afterwards")
+eq(removed[bodyFile.path], true, "and so is the staged body")
+
+T.finish("host shell request headers")

tests/engine/launcher_scroll_test.lua

@@ -0,0 +1,324 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+love.graphics.setLineJoin = love.graphics.setLineJoin or function() end
+love.graphics.newShader = love.graphics.newShader or function() return {} end
+
+local Kit = require("src.ui.kit.Kit")
+local RomImporter = require("src.import.RomImporter")
+local LauncherView = require("src.import.LauncherView")
+
+local function window(w, h)
+  love.graphics.getDimensions = function() return w, h end
+  love.graphics.getPixelDimensions = function() return w, h end
+end
+
+local function pointer(x, y)
+  love.mouse.getPosition = function() return x, y end
+end
+
+eq(Kit.scrollExtent(800, 500), 300, "the extent is exactly the overflow")
+eq(Kit.scrollExtent(400, 500), 0, "content that fits has no extent")
+eq(Kit.scrollExtent(400, -50), 400, "a negative viewport is no room, not more")
+eq(Kit.scrollExtent(nil, nil), 0, "an unmeasured region has no extent")
+
+eq(Kit.scrollClamp(-10, 300), 0, "an offset above the top clamps to it")
+eq(Kit.scrollClamp(5000, 300), 300, "an offset past the end clamps to it")
+eq(Kit.scrollClamp(120, 0), 0, "a region with no travel sits at the top")
+
+local at, left = Kit.scrollHandoff(0, 300, 120)
+eq(at, 120, "a move inside the extent is taken in full")
+eq(left, 0, "and hands nothing on")
+at, left = Kit.scrollHandoff(250, 300, 120)
+eq(at, 300, "a move past the end stops at the end")
+eq(left, 70, "and hands the remainder to whatever is behind it")
+at, left = Kit.scrollHandoff(0, 300, -80)
+eq(at, 0, "a move above the top stops at the top")
+eq(left, -80, "and hands that remainder on with its sign")
+
+local function wheelCase(offset, maxScroll, wheel, mx, my)
+  Kit.blockClicks = false
+  Kit.mouseX, Kit.mouseY = mx, my
+  Kit.wheelY = wheel
+  Kit._clipRect = nil
+  local moved, took = Kit.scrollWheel(offset, maxScroll, 0, 0, 100, 100, 50)
+  return moved, took, Kit.wheelY
+end
+
+local moved, took, leftWheel = wheelCase(0, 300, -1, 50, 50)
+eq(moved, 50, "a notch over the region moves it by one step")
+eq(took, true, "and reports the region took it")
+eq(leftWheel, 0, "so nothing reaches the surface behind it")
+
+moved, took, leftWheel = wheelCase(300, 300, -1, 50, 50)
+eq(moved, 300, "a region already at its bottom does not move")
+eq(took, false, "and does not claim the notch")
+eq(leftWheel, -1, "which is what lets the page scroll take over")
+
+moved, took, leftWheel = wheelCase(0, 300, 1, 50, 50)
+eq(moved, 0, "a region at the top ignores an upward notch")
+eq(leftWheel, 1, "and passes it on")
+
+moved, took, leftWheel = wheelCase(0, 300, -1, 400, 400)
+eq(took, false, "a notch outside the region is not the region's")
+eq(leftWheel, -1, "and stays queued")
+
+Kit.blockClicks = true
+Kit.mouseX, Kit.mouseY, Kit.wheelY = 50, 50, -1
+moved, took = Kit.scrollWheel(0, 300, 0, 0, 100, 100, 50)
+eq(took, false, "a shielded frame (modal up) leaves the region alone")
+eq(Kit.wheelY, -1, "so the modal's own scroller still sees the notch")
+Kit.blockClicks = false
+
+local function skinLauncher(count)
+  local imp = RomImporter.new(function() end, { launcher = true })
+  imp.tab = "skins"
+  local skins = {}
+  for i = 1, count do
+    skins[i] = { id = "skin" .. i, source = "user", controls = 8, pages = 1 }
+  end
+  imp._skins = skins
+  imp._ensureSkins = function() return skins end
+  return imp
+end
+
+window(360, 780)
+local imp = skinLauncher(12)
+LauncherView.draw(imp)
+LauncherView.draw(imp)
+local rect = imp._tabRegionRect
+check(rect ~= nil, "the panel publishes the rect its region occupies")
+check((imp._tabScrollMax.skins or 0) > 0,
+  "a panel with more rows than its viewport scrolls")
+eq(imp._tabScroll.skins, 0, "a freshly drawn panel sits at the top")
+check(imp._tabContentH.skins > rect.h,
+  "the region's content is taller than the viewport it is clipped to")
+
+pointer(rect.x + 10, rect.y + 10)
+imp._wheelY = -1
+LauncherView.draw(imp)
+local step = math.floor(48 * Kit.scale)
+eq(imp._tabScroll.skins, step, "one notch scrolls the panel by one step")
+eq(imp._pageScroll, 0,
+  "and the page under it does not move while the panel still can")
+
+for _ = 1, 30 do
+  imp._wheelY = -1
+  LauncherView.draw(imp)
+end
+eq(imp._tabScroll.skins, imp._tabScrollMax.skins,
+  "held down, the panel reaches its own bottom")
+eq(imp._pageScroll, imp._pageScrollMax,
+  "and only then does the leftover scroll the page")
+
+for _ = 1, 40 do
+  imp._wheelY = 1
+  LauncherView.draw(imp)
+end
+eq(imp._tabScroll.skins, 0, "scrolling back up returns the panel to the top")
+eq(imp._pageScroll, 0, "and the page with it")
+
+imp._wheelY = -1
+LauncherView.draw(imp)
+local parked = imp._tabScroll.skins
+check(parked > 0, "the skins panel is parked mid-scroll")
+imp:_switchTab("red")
+LauncherView.draw(imp)
+eq(imp._tabScroll.red or 0, 0, "the game tab has its own offset")
+eq(imp._tabScroll.skins, parked, "and the skins offset survives the switch")
+imp:_switchTab("skins")
+LauncherView.draw(imp)
+eq(imp._tabScroll.skins, parked, "coming back lands where the player left")
+
+imp._skins = {}
+imp._ensureSkins = function() return {} end
+LauncherView.draw(imp)
+LauncherView.draw(imp)
+eq(imp._tabScrollMax.skins, 0, "a panel that now fits has no travel")
+eq(imp._tabScroll.skins, 0, "and its offset comes back with it")
+
+local mods = {}
+for i = 1, 60 do
+  mods[#mods + 1] = {
+    id = "mod" .. i, name = "Mod " .. i, version = "1.0.0",
+    status = "ok", badge = "gameplay", description = "a mod",
+    enabledByVersion = { red = true },
+  }
+end
+window(360, 780)
+local modImp = RomImporter.new(function() end, { launcher = true })
+modImp.tab = "mods"
+modImp.mods = mods
+modImp._ensureMods = function() return mods end
+LauncherView.draw(modImp)
+LauncherView.draw(modImp)
+check((modImp._modScrollMax or 0) > 0,
+  "60 mods overflow the list viewport inside the panel")
+local list = modImp._modListRect
+check(list.x + list.w
+    <= modImp._tabRegionRect.x + modImp._tabRegionRect.w - Kit.scrollBarW(),
+  "the rows stop short of the region's scrollbar gutter")
+pointer(list.x + 10, list.y + 10)
+modImp._wheelY = -1
+LauncherView.draw(modImp)
+check((modImp.modScroll or 0) > 0, "a notch over the mod list scrolls the list")
+eq(modImp._tabScroll.mods or 0, 0, "not the panel region around it")
+eq(modImp._pageScroll, 0, "and not the page behind that")
+
+modImp._modActions = "mod1"
+local shielded = modImp.modScroll
+local shieldedPage = modImp._pageScroll
+pointer(list.x + 10, list.y + 10)
+modImp._wheelY = -1
+LauncherView.draw(modImp)
+eq(modImp.modScroll, shielded, "a shielded mod list ignores the notch")
+eq(modImp._tabScroll.mods or 0, 0, "and so does the region under the scrim")
+eq(modImp._pageScroll, shieldedPage, "and the page behind that")
+modImp._modActions = nil
+modImp._wheelY = 0
+LauncherView.draw(modImp)
+
+window(360, 780)
+local gameImp = RomImporter.new(function() end, { launcher = true })
+gameImp.tab = "red"
+gameImp.ready = { red = true }
+gameImp.slots = { red = {} }
+for i = 1, 8 do
+  gameImp.slots.red[i] = { id = "slot" .. i, name = "Slot " .. i }
+end
+gameImp._ensureSlots = function() end
+LauncherView.draw(gameImp)
+LauncherView.draw(gameImp)
+check((gameImp._tabScrollMax.red or 0) > 0,
+  "a game tab whose cart and slots outgrow the viewport scrolls too")
+check(gameImp._tabContentH.red > gameImp._tabRegionRect.h,
+  "because it reports its NATURAL height, not the height it was given")
+pointer(gameImp._tabRegionRect.x + 10, gameImp._tabRegionRect.y + 10)
+gameImp._wheelY = -1
+LauncherView.draw(gameImp)
+check((gameImp._tabScroll.red or 0) > 0, "and a notch over it moves it")
+
+window(360, 780)
+local touchImp = skinLauncher(12)
+LauncherView.draw(touchImp)
+LauncherView.draw(touchImp)
+local treg = touchImp._tabRegionRect
+local tmax = touchImp._tabScrollMax.skins
+check(tmax > 0, "the touched panel has travel")
+LauncherView.touchpressed(touchImp, 1, treg.x + 20, treg.y + 40)
+LauncherView.touchmoved(touchImp, 1, treg.x + 20, treg.y + 40 - 200)
+eq(touchImp._tabScroll.skins, math.min(200, tmax),
+  "dragging up scrolls the panel by the finger's travel")
+eq(touchImp._pageScroll, 0, "while the panel still has travel, the page waits")
+LauncherView.touchmoved(touchImp, 1, treg.x + 20, treg.y + 40 - 200 - tmax * 2)
+eq(touchImp._tabScroll.skins, tmax, "a longer drag reaches the panel's bottom")
+check((touchImp._pageScroll or 0) > 0, "and spills into the page from there")
+LauncherView.touchreleased(touchImp, 1, treg.x + 20, treg.y - 400)
+
+window(360, 780)
+local dragMods = RomImporter.new(function() end, { launcher = true })
+dragMods.tab = "mods"
+dragMods.mods = mods
+dragMods._ensureMods = function() return mods end
+LauncherView.draw(dragMods)
+LauncherView.draw(dragMods)
+local dlist = dragMods._modListRect
+local dListMax = dragMods._modScrollMax
+local dRegionMax = dragMods._tabScrollMax.mods
+check(dListMax > 0 and dRegionMax > 0,
+  "the mods tab has both an inner list and a region to scroll")
+LauncherView.touchpressed(dragMods, 7, dlist.x + 20, dlist.y + 30)
+LauncherView.touchmoved(dragMods, 7, dlist.x + 20, dlist.y + 30 - 60)
+eq(dragMods.modScroll, math.min(60, dListMax),
+  "the first pixels of the drag move the list")
+eq(dragMods._tabScroll.mods or 0, 0, "and nothing else")
+LauncherView.touchmoved(dragMods, 7, dlist.x + 20,
+  dlist.y + 30 - 60 - dListMax - dRegionMax * 2)
+eq(dragMods.modScroll, dListMax, "carrying on saturates the list")
+eq(dragMods._tabScroll.mods, dRegionMax,
+  "then the same gesture walks the region to its bottom")
+check((dragMods._pageScroll or 0) > 0, "and only then reaches the page")
+LauncherView.touchreleased(dragMods, 7, dlist.x + 20, dlist.y - 900)
+
+dragMods._skins = { { id = "s1", source = "user", controls = 8, pages = 1 } }
+for i = 2, 12 do
+  dragMods._skins[i] = { id = "s" .. i, source = "user", controls = 8, pages = 1 }
+end
+dragMods._ensureSkins = function() return dragMods._skins end
+dragMods.modScroll = 0
+local heldModScroll = dragMods.modScroll
+local overList = dlist.y + 30
+dragMods:_switchTab("skins")
+LauncherView.draw(dragMods)
+LauncherView.draw(dragMods)
+local sreg = dragMods._tabRegionRect
+check((dragMods._tabScrollMax.skins or 0) > 0, "the skins tab has travel")
+LauncherView.touchpressed(dragMods, 9, sreg.x + 20, overList)
+LauncherView.touchmoved(dragMods, 9, sreg.x + 20, overList - 200)
+check((dragMods._tabScroll.skins or 0) > 0,
+  "a drag on the skins tab scrolls the skins tab")
+eq(dragMods.modScroll, heldModScroll,
+  "and leaves the mod list where the player parked it")
+LauncherView.touchreleased(dragMods, 9, sreg.x + 20, sreg.y - 400)
+
+love.graphics.polygon = love.graphics.polygon or function() end
+window(360, 780)
+local padImp = skinLauncher(12)
+LauncherView.draw(padImp)
+LauncherView.draw(padImp)
+local preg = padImp._tabRegionRect
+padImp._padCursorActive = true
+padImp._padCursor = { x = preg.x + 10, y = preg.y + preg.h - 4 }
+LauncherView.wheelmoved(padImp, 0, -1)
+LauncherView.draw(padImp)
+check((padImp._tabScroll.skins or 0) > 0,
+  "the pad's synthesized wheel scrolls the region its cursor sits in")
+eq(padImp._pageScroll, 0, "and not the page behind it")
+
+window(1280, 720)
+local edgeImp = skinLauncher(40)
+LauncherView.draw(edgeImp)
+LauncherView.draw(edgeImp)
+local ereg = edgeImp._tabRegionRect
+check((edgeImp._tabScrollMax.skins or 0) > 0, "the wide window still overflows")
+eq(edgeImp._pageScrollMax, 0, "with no page scroll left to catch the notch")
+check(ereg.y + ereg.h < 720, "and a region that ends above the safe area")
+edgeImp._padCursorActive = true
+edgeImp._padCursor = { x = ereg.x + 20, y = 719 }
+edgeImp._padAxis = { lefty = 1 }
+edgeImp._padDir = {}
+pointer(ereg.x + 20, 719)
+edgeImp:_updatePadCursor(0.5)
+check((edgeImp._wheelY or 0) < 0, "the edge push synthesizes a notch")
+LauncherView.draw(edgeImp)
+check((edgeImp._tabScroll.skins or 0) > 0,
+  "which reaches the tab region even though the cursor is below it")
+
+local function read(path)
+  local f = assert(io.open(path, "r"))
+  local src = f:read("*a")
+  f:close()
+  return src
+end
+
+local view = read("src/import/LauncherView.lua")
+check(view:find("Kit.scrollBegin(", 1, true) ~= nil,
+  "the panel dispatch opens a scroll region")
+check(view:find("Kit.scrollEnd(", 1, true) ~= nil, "and closes it")
+check(view:find("modListWantsWheel", 1, true) ~= nil,
+  "the nested mod list is asked before the region takes a notch")
+check(view:find("start.region", 1, true) ~= nil,
+  "a touch drag that began in the region scrolls the region")
+check(view:find("Kit.scrollGutter(", 1, true) ~= nil,
+  "the panels lay out inside a gutter, so the thumb covers no control")
+check(view:find("Kit.scrollHandoff(tabScrollAt(imp)", 1, true) ~= nil,
+  "and hands its leftover to the page, like the wheel does")
+
+local kit = read("src/ui/kit/Kit.lua")
+check(kit:find("function Kit.scrollWheel", 1, true) ~= nil,
+  "the kit owns the wheel rule, so no panel hand-rolls a fifth copy")
+
+T.finish("launcher scroll regions")

tests/engine/launcher_skins_ux.lua

@@ -0,0 +1,268 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+love.graphics.setLineJoin = love.graphics.setLineJoin or function() end
+love.graphics.newShader = love.graphics.newShader or function() return {} end
+
+local RomImporter = require("src.import.RomImporter")
+local LauncherView = require("src.import.LauncherView")
+local TouchSkin = require("src.core.TouchSkin")
+
+local function read(path)
+  local f = assert(io.open(path, "r"))
+  local src = f:read("*a")
+  f:close()
+  return src
+end
+
+local function window(w, h)
+  love.graphics.getDimensions = function() return w, h end
+  love.graphics.getPixelDimensions = function() return w, h end
+end
+
+local function launcher()
+  return RomImporter.new(function() end, { launcher = true })
+end
+
+eq(RomImporter.skinUrlName("https://example.com/pads/gbc.zip"), "gbc.zip",
+   "a direct .zip keeps its name")
+eq(RomImporter.skinUrlName("https://example.com/pads/Neon.deltaskin"),
+   "Neon.deltaskin", "and so does a .deltaskin")
+eq(RomImporter.skinUrlName("https://example.com/overlay.cfg"), "overlay.cfg",
+   "a bare RetroArch cfg is kept as a cfg")
+eq(RomImporter.skinUrlName("https://example.com/pads/gbc.zip?raw=1"), "gbc.zip",
+   "a query string is not part of the name")
+eq(RomImporter.skinUrlName("https://example.com/pads/gbc.zip#frag"), "gbc.zip",
+   "nor is a fragment")
+eq(RomImporter.skinUrlName("https://example.com/download"), "download.zip",
+   "an extension-less link is treated as an archive")
+eq(RomImporter.skinUrlName("https://example.com/a b/../pad.tar"), "pad.zip",
+   "an unknown extension is replaced, and the name is sanitized")
+check(RomImporter.skinUrlName("https://example.com/"):match("^[%w%._%-]+$"),
+      "the download name can never escape the skins folder")
+
+local name, payload = RomImporter.wrapSkinPayload("overlay.cfg",
+  "overlays = 1\noverlay0_descs = 0\n")
+eq(name, "overlay.zip", "a downloaded .cfg is wrapped into an archive")
+eq(payload:sub(1, 2), "PK", "which is a real zip")
+check(payload:find("overlays = 1", 1, true) ~= nil,
+      "carrying the cfg text inside it")
+check(payload:find("overlay.cfg", 1, true) ~= nil,
+      "under the name RetroArch parsing expects")
+
+local zipName, zipData = RomImporter.wrapSkinPayload("pad.zip", "PK\3\4stuff")
+eq(zipName, "pad.zip", "a zip is passed through untouched")
+eq(zipData, "PK\3\4stuff", "bytes and all")
+eq(select(1, RomImporter.wrapSkinPayload("pad.deltaskin", "PK\3\4x")),
+   "pad.deltaskin", "and so is a .deltaskin")
+local pkName, pkData = RomImporter.wrapSkinPayload("overlay.cfg", "PK\3\4real")
+eq(pkName, "overlay.zip", "a .cfg link that serves zip bytes is renamed, not refused")
+eq(pkData, "PK\3\4real", "and its bytes are left alone")
+
+local imp = launcher()
+check(not imp:_addSkinFromUrl(""), "an empty link is refused")
+check(imp._skinNotice and not imp._skinNotice.ok, "with a visible error")
+eq(imp._skinFetch, nil, "and no download is started")
+check(not imp:_addSkinFromUrl("file:///etc/passwd"),
+      "a non-http link is refused")
+eq(imp._skinFetch, nil, "and still starts nothing")
+check(not imp:_addSkinFromUrl("skins/local.zip"),
+      "a bare path is not a link either")
+
+local Fetch = require("src.net.Fetch")
+local realDownload, realPoll, realRelease = Fetch.download, Fetch.poll,
+  Fetch.release
+local asked
+Fetch.download = function(url, dest) asked = { url = url, dest = dest } return 7 end
+Fetch.poll = function() return { status = "pending", progress = 0.5 } end
+Fetch.release = function() end
+
+imp = launcher()
+imp.skinUrl = "https://example.com/pads/neon.deltaskin"
+check(imp:_addSkinFromUrl(), "a good link starts a download")
+check(imp._skinFetch ~= nil, "and parks the job on the importer")
+eq(asked.url, "https://example.com/pads/neon.deltaskin", "the url is fetched")
+check(asked.dest:find("neon.deltaskin", 1, true) ~= nil,
+      "into a file named after the link")
+check(asked.dest:find("%.%.") == nil, "with no traversal in the path")
+check(not imp:_addSkinFromUrl("https://example.com/other.zip"),
+      "a second add while one is in flight is ignored")
+
+imp:_pumpSkinFetch()
+check(imp._skinFetch ~= nil, "a pending download stays in flight")
+
+local installed
+imp._installSkinData = function(_, n, d) installed = { name = n, data = d } return "neon" end
+Fetch.poll = function()
+  return { status = "ok", path = "skins/_download/neon.deltaskin" }
+end
+love.filesystem.write("skins/_download/neon.deltaskin", "PK\3\4payload")
+imp:_pumpSkinFetch()
+eq(imp._skinFetch, nil, "a finished download is released")
+check(installed ~= nil, "and its bytes go to the installer")
+eq(installed.name, "neon.deltaskin", "under the downloaded name")
+eq(love.filesystem.read("skins/_download/neon.deltaskin"), nil,
+   "the temporary download is cleaned up")
+eq(imp.skinUrl, "", "and the field is cleared for the next one")
+
+imp = launcher()
+imp._installSkinData = function() return nil end
+Fetch.download = function() return 8 end
+Fetch.poll = function() return { status = "error", err = "404" } end
+imp:_addSkinFromUrl("https://example.com/missing.zip")
+imp:_pumpSkinFetch()
+eq(imp._skinFetch, nil, "a failed download is released too")
+check(imp._skinNotice and not imp._skinNotice.ok, "and reported")
+check(tostring(imp._skinNotice.text):find("404", 1, true) ~= nil,
+      "with the reason attached")
+
+Fetch.download, Fetch.poll, Fetch.release = realDownload, realPoll, realRelease
+
+imp = launcher()
+eq(imp:_installSkinData("pad.zip", ""), nil, "an empty payload is refused")
+check(imp._skinNotice and not imp._skinNotice.ok, "and says so")
+eq(imp:_installSkinData("notes.txt", "hello"), nil, "a non-archive is refused")
+
+love.filesystem.write("skins/warny.zip/overlay.cfg", [[
+overlays = 1
+overlay0_name = "warny"
+overlay0_normalized = true
+overlay0_descs = 2
+overlay0_desc0 = "a,0.5,0.5,rect,0.05,0.05"
+]])
+imp = launcher()
+eq(imp:_installSkinData("warny.zip", "PK\3\4stub"), "warny", "a skin installs")
+check(imp._skinNotice.ok, "with an ok notice")
+check(tostring(imp._skinNotice.text):find("missing desc", 1, true) ~= nil,
+      "that repeats what the importer had to complain about")
+
+love.filesystem.write("skins/vecty.deltaskin/info.json", [[
+{ "name": "Vecty", "gameTypeIdentifier": "com.rileytestut.delta.game.gbc",
+  "representations": { "iphone": { "standard": { "portrait": {
+    "assets": { "resizable": "iphone_portrait.pdf" },
+    "mappingSize": {"width":320,"height":480},
+    "items": [ { "inputs": ["a"], "frame": {"x":0,"y":0,"width":32,"height":32} } ]
+  } } } } }
+]])
+imp = launcher()
+eq(imp:_installSkinData("vecty.deltaskin", "PK\3\4stub"), nil,
+   "a PDF-only Delta skin does not install silently")
+check(imp._skinNotice and not imp._skinNotice.ok, "the tab reports the refusal")
+check(tostring(imp._skinNotice.text):find("PDF artwork", 1, true) ~= nil,
+      "and says why, instead of listing a skin with no buttons")
+
+local function dropped(fileName)
+  return { getFilename = function() return fileName end,
+           open = function() return false end }
+end
+
+local routed
+local function routeDrop(tab, fileName)
+  routed = nil
+  local drop = launcher()
+  drop.tab = tab
+  drop._installSkinZip = function() routed = "skin" end
+  drop._installMod = function() routed = "mod" end
+  drop.startData = function() routed = "rom" end
+  drop:filedropped(dropped(fileName))
+  return routed
+end
+
+eq(routeDrop("mods", "pad.deltaskin"), "skin",
+   "a dropped .deltaskin installs as a skin from any tab")
+eq(routeDrop("skins", "pad.deltaskin"), "skin", "and from the skins tab")
+eq(routeDrop("skins", "Neon.DeltaSkin"), "skin", "whatever its case")
+eq(routeDrop("skins", "pad.zip"), "skin", "a zip on the skins tab is still a skin")
+eq(routeDrop("mods", "pad.zip"), "mod", "and a mod anywhere else")
+
+check(TouchSkin.saveTo(TouchSkin.newSkin("uxskin"), "uxskin") ~= nil,
+      "a skin to list")
+imp = launcher()
+local entries = imp:_ensureSkins(true)
+check(#entries > 0, "the installed skins are listed")
+local byId = {}
+for _, entry in ipairs(entries) do
+  byId[entry.id] = entry
+  check(type(entry.format) == "string",
+        entry.id .. " reports the format it was parsed from")
+end
+eq(byId.uxskin and byId.uxskin.format, "native",
+   "a skin.lua skin is badged as the native format")
+
+imp = launcher()
+eq(imp:_exportSkin("no-such-skin", "native"), nil, "exporting a ghost fails")
+check(imp._skinNotice and not imp._skinNotice.ok, "with an error notice")
+
+local first = entries[1]
+imp = launcher()
+local path = imp:_exportSkin(first.id, "delta")
+check(path ~= nil and path:match("%.deltaskin$") ~= nil,
+      "a bundled skin exports as a .deltaskin")
+check(imp._skinNotice.ok, "and the tab reports where it landed")
+check(tostring(imp._skinNotice.text):find(path, 1, true) ~= nil,
+      "naming the path, which is the whole mobile story")
+check(imp._skinExport ~= nil and imp._skinExport.path == path,
+      "the export is remembered so Show file can reveal it")
+path = imp:_exportSkin(first.id, "retroarch")
+check(path ~= nil and path:match("%.zip$") ~= nil,
+      "and as a RetroArch .zip")
+path = imp:_exportSkin(first.id, "native")
+check(path ~= nil and path:match("%.zip$") ~= nil, "and as a gen1recomp .zip")
+
+window(420, 900)
+imp = launcher()
+imp.tab = "skins"
+LauncherView.draw(imp)
+LauncherView.draw(imp)
+check(true, "the skins tab draws with the URL row")
+imp._skinActions = { id = entries[1].id }
+LauncherView.draw(imp)
+check(imp._skinActions ~= nil, "the actions sheet stays up while it draws")
+imp._skinFetch = { name = "neon.zip" }
+LauncherView.draw(imp)
+imp._skinFetch = nil
+
+window(320, 640)
+LauncherView.draw(imp)
+LauncherView.draw(imp)
+check(true, "and on a phone-width window, where Paste gives up its room")
+
+local view = read("src/import/LauncherView.lua")
+local rom = read("src/import/RomImporter.lua")
+
+check(view:find('"skins-url"', 1, true) ~= nil,
+      "the skins tab carries an add-by-URL field")
+check(view:find('"skins-url-add"', 1, true) ~= nil, "with a button to submit it")
+check(view:find('"skins-url-paste"', 1, true) ~= nil,
+      "and a paste button, because a phone cannot type a URL")
+check(view:find("_addSkinFromUrl", 1, true) ~= nil,
+      "which reaches the importer's downloader")
+check(view:find("Loader.inline", 1, true) ~= nil,
+      "and the row shows progress while it runs")
+check(view:find("SKIN_FORMAT_LABEL", 1, true) ~= nil,
+      "rows carry a format badge")
+check(view:find("buildSkinActionsModal", 1, true) ~= nil,
+      "the gear opens an actions sheet")
+check(view:find("_exportSkin", 1, true) ~= nil, "which can export the skin")
+check(view:find("skinact-exp-delta", 1, true) ~= nil,
+      "including as a Delta skin")
+local modals = view:match("local function modalUp%(imp%)(.-)\nend")
+check(modals and modals:find("_skinActions", 1, true) ~= nil,
+      "the sheet raises the modal shield like every other popup")
+check(view:find("imp.onOpenSkinStudio(imp.modScope or \"red\", id)", 1, true)
+      ~= nil, "and still hands the studio a real game version")
+
+check(rom:find("deltaskin", 1, true) ~= nil,
+      "the desktop file picker offers .deltaskin")
+check(rom:find("_pumpSkinFetch", 1, true) ~= nil,
+      "the skin download is pumped from update()")
+local update = rom:match("function RomImporter:update%(dt%)(.-)\nend\n")
+check(update and update:find("_pumpSkinFetch", 1, true) ~= nil,
+      "from inside update itself, not just declared")
+check(TouchSkin.ARCHIVE_EXTS.deltaskin == true,
+      "and the installer accepts the extension")
+
+T.finish("launcher_skins_ux")

tests/engine/launcher_sync_modal.lua

@@ -0,0 +1,307 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+love.graphics.setLineJoin = love.graphics.setLineJoin or function() end
+love.graphics.polygon = love.graphics.polygon or function() end
+love.graphics.newShader = love.graphics.newShader or function() return {} end
+
+local Kit = require("src.ui.kit.Kit")
+local RomImporter = require("src.import.RomImporter")
+local LauncherView = require("src.import.LauncherView")
+
+local function read(path)
+  local f = assert(io.open(path, "r"))
+  local src = f:read("*a")
+  f:close()
+  return src
+end
+
+eq(RomImporter.syncDigits("1234-5678"), "12345678",
+   "the dash people read the code with is not part of it")
+eq(RomImporter.syncDigits(" 12 34 "), "1234", "spaces are dropped")
+eq(RomImporter.syncDigits("abc9"), "9", "letters cannot enter a digit code")
+eq(RomImporter.syncDigits("123456789012"), "12345678",
+   "a code is eight digits and no more")
+eq(RomImporter.syncDigits(nil), "", "an empty field stays empty")
+
+eq(RomImporter.syncShareCode("abc234"), "ABC234", "share codes are upper case")
+eq(RomImporter.syncShareCode("A1B0C-D"), "ABCD",
+   "1 and 0 are not in the share alphabet")
+eq(RomImporter.syncShareCode("ABCDEFGH"), "ABCDEF",
+   "a share code is six characters")
+
+local function fakeEngine(over)
+  local eng = {
+    phase = "idle", status = "Ready", conflicts = {}, state = { enabled = true },
+    calls = {},
+    isLinked = false,
+    linked = function(self) return self.isLinked end,
+    busy = function(self) return self.isBusy == true end,
+    createAccount = function(self, label)
+      self.calls[#self.calls + 1] = { "create", label }
+      self.isLinked = true
+      self.codes = { code1 = "1234-5678", code2 = "8765-4321" }
+      return true
+    end,
+    linkDevice = function(self, a, b, label)
+      self.calls[#self.calls + 1] = { "link", a, b, label }
+      if #tostring(a) ~= 8 or #tostring(b) ~= 8 then return false end
+      self.isLinked = true
+      return true
+    end,
+    syncNow = function(self)
+      self.calls[#self.calls + 1] = { "syncNow" }
+      return true
+    end,
+    unlink = function(self)
+      self.calls[#self.calls + 1] = { "unlink" }
+      self.isLinked, self.codes = false, nil
+      return true
+    end,
+    shareMods = function(self)
+      self.calls[#self.calls + 1] = { "shareMods" }
+      self.shareCode = "K7QW3M"
+      return true
+    end,
+    fetchShare = function(self, code)
+      self.calls[#self.calls + 1] = { "fetchShare", code }
+      return true
+    end,
+    applyModPlan = function(self, progress)
+      self.calls[#self.calls + 1] = { "applyModPlan" }
+      if progress then progress(1, 2, "a") progress(2, 2, "b") end
+      return true
+    end,
+    resolveConflict = function(self, key, choice)
+      self.calls[#self.calls + 1] = { "resolve", key, choice }
+      return true
+    end,
+  }
+  for k, v in pairs(over or {}) do eng[k] = v end
+  return eng
+end
+
+local function launcher(eng)
+  local imp = RomImporter.new(function() end, { launcher = true })
+  imp._sync = eng
+  imp._syncTransportOk = true
+  return imp
+end
+
+local eng = fakeEngine()
+local imp = launcher(eng)
+
+eq(imp._syncModal, nil, "the modal is closed until the header button opens it")
+imp:_openSync()
+check(imp._syncModal ~= nil, "the header button opens the modal")
+eq(imp._syncModal.view, "home", "and lands on the home view")
+eq(imp._syncFocus, nil, "with no field taking the keyboard")
+
+imp:_syncView("link")
+eq(imp._syncModal.view, "link", "Link this device swaps the view")
+imp:_syncFocusField("code1")
+eq(imp._syncFocus, "code1", "tapping a field focuses it")
+imp:textinput("12ab34")
+eq(imp._syncModal.code1, "1234", "typed letters never reach a code field")
+imp:textinput("5678")
+eq(imp._syncModal.code1, "12345678", "the field fills to eight digits")
+imp:textinput("9")
+eq(imp._syncModal.code1, "12345678", "and refuses a ninth")
+imp:keypressed("backspace")
+eq(imp._syncModal.code1, "1234567", "backspace drops one digit")
+imp:textinput("8")
+
+imp:_syncFocusField("code2")
+eq(imp._syncFocus, "code2", "focus moves to the second code")
+eq(imp._syncModal.code1, "12345678", "without disturbing the first")
+imp:_syncFocusField("code2")
+eq(imp._syncFocus, nil, "tapping the focused field again releases it")
+imp:_syncFocusField("code2")
+imp:textinput("87654321")
+
+imp:_syncLink()
+eq(eng.calls[#eng.calls][1], "link", "Link sends both codes to the engine")
+eq(eng.calls[#eng.calls][2], "12345678", "the first code as typed")
+eq(eng.calls[#eng.calls][3], "87654321", "and the second")
+eq(imp._syncModal.view, "home", "a linked device comes back to the home view")
+eq(imp._syncModal.code1, "", "and the codes are not left lying in the field")
+eq(imp._syncModal.code2, "", "either of them")
+eq(imp._syncFocus, nil, "with the keyboard released")
+
+local short = launcher(fakeEngine())
+short:_openSync()
+short:_syncView("link")
+short._syncModal.code1, short._syncModal.code2 = "1234", "87654321"
+eq(short:_syncLink(), false, "a short code does not link")
+eq(short._syncModal.code1, "1234",
+   "and what was typed stays put to be corrected")
+
+imp:_syncFocusField("code1")
+imp:keypressed("escape")
+eq(imp._syncFocus, nil, "escape out of a field releases the keyboard")
+check(imp._syncModal ~= nil, "and leaves the modal up")
+imp:keypressed("escape")
+eq(imp._syncModal, nil, "escape closes the modal")
+
+imp:_openSync()
+imp:_syncView("mods")
+imp:_syncShareMods()
+eq(eng.shareCode, "K7QW3M", "Share mod list asks the engine for a code")
+imp:_syncFocusField("share")
+imp:textinput("k7qw3m")
+eq(imp._syncModal.share, "K7QW3M", "a typed share code is normalized")
+imp:_syncGetShare()
+eq(eng.calls[#eng.calls][2], "K7QW3M", "and handed to the engine as typed")
+imp._syncModal.progress = nil
+imp:_syncApplyMods()
+eq(imp._syncModal.progress, nil,
+   "the progress line is cleared once the apply returns")
+
+imp:_syncResolve("red/abc", "both")
+eq(eng.calls[#eng.calls][1], "resolve", "the conflict buttons call the engine")
+eq(eng.calls[#eng.calls][3], "both", "with the choice the player pressed")
+
+imp:_syncUnlink()
+eq(eng.isLinked, false, "Unlink drops the device")
+eq(imp._syncModal.view, "home", "and the modal returns to the home view")
+
+local bare = RomImporter.new(function() end, { launcher = true })
+bare._sync = false
+bare._syncTransportOk = true
+bare:_openSync()
+check(bare._syncModal ~= nil, "the modal opens without an engine")
+bare:_closeSync()
+eq(bare._syncModal, nil, "and closes again")
+
+local function controls(imp2)
+  love.graphics.getDimensions = function() return 900, 780 end
+  love.graphics.getPixelDimensions = love.graphics.getDimensions
+  Kit.audit = {}
+  local ok, err = pcall(LauncherView.draw, imp2)
+  local labels = {}
+  for _, r in ipairs(Kit.audit or {}) do
+    if r.class == "control" then labels[r.label] = true end
+  end
+  Kit.audit = nil
+  check(ok, "the sync modal draws: " .. tostring(err))
+  return labels
+end
+
+local rEng = fakeEngine()
+local rImp = launcher(rEng)
+rImp:_openSync()
+local labels = controls(rImp)
+check(labels["Create sync account"], "an unlinked device is offered an account")
+check(labels["Link this device"], "and the link road")
+
+rEng:createAccount("mac")
+labels = controls(rImp)
+check(labels["Sync now"], "a linked device can sync on demand")
+check(labels["Unlink this device"], "and unlink")
+check(labels["Share or get a mod list"], "and reach the mod list road")
+
+rImp:_syncView("link")
+labels = controls(rImp)
+check(labels["Back"], "the link view can back out")
+
+rImp:_syncView("mods")
+rEng.shareCode = "K7QW3M"
+rEng.modPlan = { indexes = { "https://x" }, toInstall = { { id = "a" } },
+  toEnable = {}, missing = {} }
+labels = controls(rImp)
+check(labels["Share mod list"], "the mod view shares a list")
+check(labels["Get mod list"], "and fetches one")
+check(labels["Apply these mods"], "a fetched plan can be applied")
+
+rImp:_syncView("home")
+rEng.devices = {
+  { id = "0a1b2c3d", label = "OS X", current = true },
+  { id = "99998888", label = "Android" },
+}
+labels = controls(rImp)
+check(labels["Unlink Android"], "the other linked devices can be revoked here")
+check(labels["OS X  \194\183  this device"],
+      "and this one is named rather than offered twice")
+
+local devRows = LauncherView.syncDeviceRows(rEng)
+eq(#devRows, 2, "the modal reads the device list off the engine")
+eq(devRows[1].current, true, "knowing which one is this device")
+eq(#LauncherView.syncDeviceRows({}), 0,
+   "an engine that has not synced yet lists nothing")
+
+local offline = launcher(fakeEngine())
+offline._syncTransportOk = false
+offline:_openSync()
+labels = controls(offline)
+check(not labels["Create sync account"],
+      "a device with no way to send signed requests is not offered an account")
+check(labels["Close"], "it just explains itself and closes")
+
+rEng.devices = nil
+rEng.phase = "conflict"
+rEng.conflicts = { {
+  key = "red/abc", version = "red", overlap = true,
+  localMeta = { savedAt = 1700000000, sessionStart = 1699999000,
+    summary = { name = "ASH", badges = 3, timeText = "5:42", dexCount = 40 } },
+  remoteMeta = { savedAt = 1700000500, sessionStart = 1699999500,
+    summary = { name = "ASH", badges = 4, timeText = "6:10", dexCount = 44 } },
+} }
+labels = controls(rImp)
+check(labels["Keep this device"], "a conflict offers this device")
+check(labels["Keep the other device"], "the other device")
+check(labels["Keep both"], "and keeping both")
+check(not labels["Sync now"],
+      "a conflict takes over the modal until it is answered")
+
+local side = LauncherView.syncSideText({ savedAt = 1700000000,
+  summary = { name = "ASH", badges = 3, timeText = "5:42", dexCount = 40 } })
+check(side:find("ASH", 1, true) ~= nil, "a side summary names the trainer")
+check(side:find("3 badges", 1, true) ~= nil, "counts badges")
+check(side:find("5:42", 1, true) ~= nil, "and shows play time")
+eq(LauncherView.syncSideText(nil), "no details",
+   "a side with no metadata says so rather than drawing blank")
+
+local quiet = launcher(fakeEngine())
+quiet:_pumpSync(0.016)
+eq(quiet._syncModal, nil, "a quiet auto-sync never interrupts the launcher")
+
+local raised = launcher(fakeEngine({ phase = "conflict",
+  conflicts = { { key = "red/abc", version = "red" } } }))
+raised:_pumpSync(0.016)
+check(raised._syncModal ~= nil,
+      "a conflict found by the boot sync opens the prompt on its own")
+raised:_closeSync()
+raised:_pumpSync(0.016)
+eq(raised._syncModal, nil,
+   "and a prompt the player dismissed does not reopen every frame")
+
+local view = read("src/import/LauncherView.lua")
+local impSrc = read("src/import/RomImporter.lua")
+
+check(view:find('"tab-sync"', 1, true) ~= nil,
+      "the header tab row carries a Save Sync button")
+local header = view:match("local HEADER_TABS = %{(.-)%}\n")
+check(header and header:find('id = "skins"', 1, true) ~= nil,
+      "and it sits beside the skins tab")
+check(view:find('"BETA"', 1, true) ~= nil,
+      "the button and the modal are labelled BETA")
+check(view:find("buildSyncModal", 1, true) ~= nil,
+      "the sync UI is a modal, so it works from any tab")
+local modals = view:match("local function modalUp%(imp%)(.-)\nend")
+check(modals and modals:find("_syncModal", 1, true) ~= nil,
+      "the modal raises the click shield like every other one")
+check(view:find("if imp._syncModal then buildSyncModal", 1, true) ~= nil,
+      "and buildModals routes it")
+
+check(impSrc:find("_pumpSync(dt)", 1, true) ~= nil,
+      "the launcher pumps the sync engine every frame")
+local pump = impSrc:match("function RomImporter:_pumpSync%(dt%)(.-)\nend\n")
+check(pump and pump:find("self.launcher", 1, true) ~= nil,
+      "only the interactive launcher boots an engine of its own")
+check(impSrc:find("_syncTypeInto", 1, true) ~= nil,
+      "text input is routed through the code filter")
+
+T.finish("launcher_sync_modal")

tests/engine/skin_format_import_test.lua

@@ -0,0 +1,626 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+if not _G.love then _G.love = require("tests.love_stub") end
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+
+local TouchSkin = require("src.core.TouchSkin")
+local DeltaSkin = require("src.core.DeltaSkin")
+local Json = require("src.link.Json")
+
+local function near(got, want, msg)
+  return check(type(got) == "number" and math.abs(got - want) < 1e-6,
+    ("%s (got %s, want %s)"):format(msg, tostring(got), tostring(want)))
+end
+
+local function hasWarning(skin, fragment)
+  for _, w in ipairs(skin.warnings or {}) do
+    if tostring(w):find(fragment, 1, true) then return true end
+  end
+  return false
+end
+
+local function unzip(bytes)
+  local out, i = {}, 1
+  while bytes:sub(i, i + 3) == "PK\3\4" do
+    local function u16(off)
+      local a, b = bytes:byte(i + off, i + off + 1)
+      return a + b * 256
+    end
+    local function u32(off)
+      local a, b, c, d = bytes:byte(i + off, i + off + 3)
+      return a + b * 256 + c * 65536 + d * 16777216
+    end
+    local size, nameLen, extraLen = u32(18), u16(26), u16(28)
+    local name = bytes:sub(i + 30, i + 29 + nameLen)
+    local start = i + 30 + nameLen + extraLen
+    out[name] = bytes:sub(start, start + size - 1)
+    out[#out + 1] = name
+    i = start + size
+  end
+  return out
+end
+
+local function readBytes(path)
+  local f = assert(io.open(path, "rb"))
+  local data = f:read("*a")
+  f:close()
+  return data
+end
+
+local GAMEBOY_CFG = [[
+overlays = 4
+
+overlay0_name = "landscape"
+overlay0_full_screen = true
+overlay0_normalized = true
+overlay0_range_mod = 1.5
+overlay0_alpha_mod = 2.0
+overlay0_aspect_ratio = 2.22222222222222
+overlay0_descs = 13
+overlay0_desc0 = "nul,0.0985,0.6825,rect,0.0525,0.0875"
+overlay0_desc0_overlay = img/dpad.png
+overlay0_desc1 = "up,0.0985,0.5950,rect,0.0175,0.0292"
+overlay0_desc2 = "down,0.0985,0.7700,rect,0.0175,0.0292"
+overlay0_desc3 = "left,0.0460,0.6825,rect,0.0175,0.0292"
+overlay0_desc4 = "right,0.1510,0.6825,rect,0.0175,0.0292"
+overlay0_desc5 = "left|up,0.0460,0.5950,rect,0.0175,0.0292"
+overlay0_desc6 = "right|up,0.1510,0.5950,rect,0.0175,0.0292"
+overlay0_desc7 = "left|down,0.0460,0.7700,rect,0.0175,0.0292"
+overlay0_desc8 = "right|down,0.1510,0.7700,rect,0.0175,0.0292"
+overlay0_desc9 = "a,0.8975,0.6300,radial,0.0525,0.0875"
+overlay0_desc9_overlay = img/a.png
+overlay0_desc10 = "b,0.8100,0.7350,radial,0.0525,0.0875"
+overlay0_desc10_overlay = img/b.png
+overlay0_desc11 = "start,0.5500,0.9000,rect,0.0500,0.0400"
+overlay0_desc12 = "select,0.4500,0.9000,rect,0.0500,0.0400"
+
+overlay1_name = "portrait"
+overlay1_full_screen = true
+overlay1_normalized = true
+overlay1_aspect_ratio = 0.45
+overlay1_descs = 2
+overlay1_desc0 = "a,0.8975,0.6300,radial,0.0875,0.0525"
+overlay1_desc1 = "b,0.8100,0.7350,radial,0.0875,0.0525"
+
+overlay2_name = "menu"
+overlay2_full_screen = true
+overlay2_normalized = true
+overlay2_descs = 1
+overlay2_desc0 = "menu_toggle,0.5,0.5,rect,0.1,0.1"
+
+overlay3_name = "hide"
+overlay3_full_screen = true
+overlay3_normalized = true
+overlay3_descs = 1
+overlay3_desc0 = "overlay_next,0.95,0.05,radial,0.04,0.04"
+overlay3_desc0_next_target = "landscape"
+]]
+
+local gameboy = assert(TouchSkin.parse(GAMEBOY_CFG))
+eq(#gameboy.pages, 4, "the canonical gameboy overlay has four pages")
+eq(gameboy.pages[1].orient, "landscape", "page 1 auto-rotates landscape")
+eq(gameboy.pages[2].orient, "portrait", "page 2 auto-rotates portrait")
+check(TouchSkin.hasOrientPair(gameboy), "so it is an auto-rotate overlay")
+eq(gameboy.pages[3].orient, nil, "the menu page is not part of the pair")
+eq(#gameboy.pages[1].controls, 13, "every landscape desc parsed")
+check(gameboy.pages[1].controls[1].decorative, "the d-pad art desc binds nothing")
+eq(gameboy.pages[1].controls[1].imagePath, "img/dpad.png", "and carries the art")
+eq(gameboy.pages[1].imagePath, nil, "the overlay ships no page background")
+eq(gameboy.pages[4].controls[1].nextTarget, "landscape", "hide jumps back by name")
+local named = {}
+for _, ctl in ipairs(gameboy.pages[1].controls) do
+  for _, btn in ipairs(ctl.buttons) do named[btn] = true end
+end
+for _, btn in ipairs({ "a", "b", "start", "select", "up", "down", "left", "right" }) do
+  check(named[btn], "landscape binds GB " .. btn)
+end
+eq(#gameboy.warnings, 0, "a well-formed overlay warns about nothing")
+
+local SPACED_CFG = [[
+overlays = 1
+overlay0_name = "spaced"
+overlay0_normalized = true
+overlay0_descs = 2
+overlay0_desc0 = "a 0.5 0.5 rect 0.05 0.05"
+overlay0_desc0_saturate_pct = 0.6
+overlay0_desc0_exclusive = true
+overlay0_desc0_movable = true
+overlay0_desc1 = b,0.25,0.5,radial,0.05,0.05
+]]
+local spaced = assert(TouchSkin.parse(SPACED_CFG))
+near(spaced.pages[1].controls[1].saturatePct, 0.6, "_saturate_pct is parsed")
+check(spaced.pages[1].controls[1].exclusive, "_exclusive is parsed")
+check(spaced.pages[1].controls[1].movable, "_movable is parsed on a plain desc")
+eq(spaced.pages[1].controls[2].exclusive, nil, "and is not inherited")
+eq(#spaced.pages[1].controls, 2, "a space-separated desc still parses")
+eq(spaced.pages[1].controls[1].buttons[1], "a", "space-separated bind")
+near(spaced.pages[1].controls[1].x, 0.5, "space-separated position")
+eq(spaced.pages[1].controls[2].buttons[1], "b", "an unquoted desc parses too")
+eq(spaced.pages[1].controls[2].shape, "radial", "and keeps its hitbox shape")
+
+local SHORT_CFG = [[
+overlays = 1
+overlay0_name = "short"
+overlay0_normalized = true
+overlay0_descs = 2
+overlay0_desc0 = "a,0.5,0.5,rect,0.05,0.05"
+]]
+local short = assert(TouchSkin.parse(SHORT_CFG))
+eq(#short.pages[1].controls, 1, "a missing desc is skipped, not faked")
+check(hasWarning(short, "missing desc 1"), "and the importer says so")
+
+eq(select(1, TouchSkin.parse("overlay0_descs = 1\n")), nil,
+   "a cfg without the overlays key is refused")
+
+local AREA_CFG = [[
+overlays = 1
+overlay0_name = "portrait"
+overlay0_full_screen = true
+overlay0_normalized = true
+overlay0_descs = 3
+overlay0_desc0 = "dpad_area,0.2,0.7,rect,0.15,0.1"
+overlay0_desc0_overlay = img/dpad.png
+overlay0_desc0_reach_x = 1.5
+overlay0_desc0_movable = true
+overlay0_desc1 = "abxy_area,0.8,0.7,radial,0.12,0.08"
+overlay0_desc1_up = "start"
+overlay0_desc2 = "analog_left,0.2,0.3,radial,0.1,0.1"
+overlay0_desc2_saturate_pct = 0.6
+overlay0_desc2_exclusive = true
+]]
+local area = assert(TouchSkin.parse(AREA_CFG))
+local ap = area.pages[1]
+near(ap.aspect, 0.5625, "a portrait-named overlay defaults to 9:16")
+check(not ap.aspectFromCfg, "and that default is not a cfg aspect lock")
+eq(#ap.controls, 1 + 8 + 8 + 8, "each area desc expands into eight hitboxes")
+
+local art = ap.controls[1]
+check(art.decorative, "the dpad_area art is carried by a decoration")
+eq(art.imagePath, "img/dpad.png", "with the desc's own overlay image")
+near(art.rangeX, 0.15, "sized like the area it replaces")
+
+local sectorE = ap.controls[2]
+eq(sectorE.spec, "right", "the first sector is the one pointing right")
+near(sectorE.x, 0.2, "every sector sits on the area centre")
+near(sectorE.y, 0.7, "on both axes")
+near(sectorE.rangeX, 0.15, "and covers the whole area, not a ninth of it")
+near(sectorE.reachLeft, 1.5, "the desc reach_x rides onto the sectors as it is")
+near(sectorE.reachRight, 1.5, "on both sides")
+eq(sectorE.sector, 1, "the sector index is kept for the hit test")
+eq(ap.controls[3].spec, "right|down", "the next sector is the lower-right corner")
+eq(ap.controls[4].spec, "down", "then straight down, y growing downwards")
+eq(ap.controls[8].spec, "up", "and straight up seven sectors along")
+check(ap.controls[1].movable, "_movable is parsed")
+
+local abxy = ap.controls[10]
+eq(abxy.spec, "a", "abxy right is RetroPad a, which is GB A")
+eq(abxy.buttons[1], "a", "and reaches that GB button")
+eq(ap.controls[16].spec, "start", "abxy_area honours an _up override")
+eq(ap.controls[15].spec, "y|start", "the up-left sector combines both sides")
+check(ap.controls[15].exclusive == nil, "and inherits nothing the desc did not set")
+check(ap.controls[14].decorative, "RetroPad Y has no GB button, so that sector is inert")
+eq(abxy.shape, "radial", "a radial area keeps its ellipse")
+
+eq(ap.controls[18].spec, "right", "analog_left degrades to a directional pad")
+check(ap.controls[18].exclusive, "_exclusive rides onto the expanded sectors")
+eq(ap.controls[23].spec, "left|up", "with all eight sectors")
+near(ap.controls[18].rangeX, 0.1, "analog sectors share the whole stick area")
+
+local sq = { x = 0.5, y = 0.5, rangeX = 0.25, rangeY = 0.25, shape = "rect",
+             rangeMod = 1, alphaMod = 1,
+             reachUp = 1, reachDown = 1, reachLeft = 1, reachRight = 1 }
+local sectors = TouchSkin.expandSectors(sq, TouchSkin.AREA_DEFAULTS.dpad_area)
+eq(#sectors, 8, "a dpad area expands into eight sector hitboxes")
+local page = { rect = { x = 0, y = 0, w = 1, h = 1 }, fullScreen = true,
+               aspect = 1, controls = sectors }
+local function hitSpecs(px, py)
+  local out = {}
+  for _, ctl in ipairs(sectors) do
+    if TouchSkin.hits(page, ctl, 100, 100, px, py, 0, 0) then out[#out + 1] = ctl.spec end
+  end
+  return table.concat(out, "+")
+end
+eq(hitSpecs(50, 50), "right", "the exact centre still fires a direction: no dead zone")
+eq(hitSpecs(60, 50), "right", "a touch to the right of centre is right")
+eq(hitSpecs(50, 60), "down", "a touch below centre is down, y growing downwards")
+eq(hitSpecs(50, 40), "up", "a touch above centre is up")
+eq(hitSpecs(40, 40), "left|up", "a diagonal touch fires both directions")
+eq(hitSpecs(58, 52), "right", "17 degrees off the axis is still a pure direction")
+eq(hitSpecs(55, 53), "right|down", "and 31 degrees is the diagonal, not a grid corner")
+eq(hitSpecs(50, 80), "", "outside the area nothing fires")
+
+local PIXEL_NO_IMAGE = [[
+overlays = 1
+overlay0_name = "pixels"
+overlay0_descs = 1
+overlay0_desc0 = "a,120,80,rect,20,10"
+]]
+local noImage = assert(TouchSkin.parse(PIXEL_NO_IMAGE))
+check(hasWarning(noImage, "no base image"),
+      "pixel coords without a base image are called out")
+check(noImage.pages[1].pixelCoords == false,
+      "and read as normalized rather than dividing by nothing")
+
+love.filesystem.write("skins/px/overlay.cfg", [[
+overlays = 1
+overlay0_name = "px"
+overlay0_overlay = img/base.png
+overlay0_full_screen = true
+overlay0_descs = 2
+overlay0_desc0 = "a,4,4,rect,2,1"
+overlay0_desc1 = "b,6,2,rect,1,1"
+overlay0_desc1_normalized = true
+]])
+local px = assert(TouchSkin.load("skins/px", "px"))
+local pxPage = px.pages[1]
+check(pxPage.image ~= nil, "the base overlay image loads")
+local iw, ih = pxPage.image:getDimensions()
+near(pxPage.controls[1].x, 4 / iw, "pixel x is divided by the base image width")
+near(pxPage.controls[1].y, 4 / ih, "pixel y is divided by the base image height")
+near(pxPage.controls[1].rangeX, 2 / iw, "and so are the half extents")
+near(pxPage.controls[2].x, 6, "a per-desc normalized flag opts that desc out")
+check(pxPage.pixelCoords == false, "the page is normalized once converted")
+
+love.filesystem.write("skins/pxbad/overlay.cfg", [[
+overlays = 1
+overlay0_name = "pxbad"
+overlay0_overlay = img/broken.png
+overlay0_descs = 1
+overlay0_desc0 = "a,4,4,rect,2,1"
+]])
+local savedNewImage = love.graphics.newImage
+love.graphics.newImage = function() error("unreadable image") end
+local badPx, badPxErr = TouchSkin.load("skins/pxbad", "pxbad")
+love.graphics.newImage = savedNewImage
+eq(badPx, nil, "a skin whose pixel coordinates have no base image fails to load")
+check(tostring(badPxErr):find("img/broken.png", 1, true) ~= nil,
+      "and the error names the image it could not read")
+
+local DELTA_JSON = [[
+{
+  "name": "Test GBC",
+  "identifier": "com.example.gbc.test",
+  "gameTypeIdentifier": "com.rileytestut.delta.game.gbc",
+  "debug": false,
+  "representations": {
+    "iphone": {
+      "edgeToEdge": {
+        "portrait": {
+          "assets": { "small": "p_small.png", "medium": "p_medium.png",
+                      "large": "p_large.png" },
+          "items": [
+            { "inputs": ["a"], "frame": {"x":240,"y":320,"width":64,"height":64},
+              "mask": "circle" },
+            { "inputs": ["b"], "frame": {"x":160,"y":360,"width":64,"height":64},
+              "extendedEdges": {"right":16} },
+            { "inputs": {"up":"up","down":"down","left":"left","right":"right"},
+              "frame": {"x":16,"y":320,"width":96,"height":96} },
+            { "inputs": ["start","select"],
+              "frame": {"x":128,"y":448,"width":64,"height":32} },
+            { "inputs": ["menu"], "frame": {"x":0,"y":0,"width":32,"height":32} },
+            { "inputs": ["quickSave"],
+              "frame": {"x":288,"y":0,"width":32,"height":32} }
+          ],
+          "mappingSize": {"width":320,"height":480},
+          "extendedEdges": {"top":8,"bottom":8,"left":8,"right":8},
+          "translucent": false,
+          "screens": [{ "inputFrame": {"x":0,"y":0,"width":160,"height":144},
+                        "outputFrame": {"x":0,"y":32,"width":320,"height":288} }]
+        }
+      },
+      "standard": {
+        "portrait": { "items": [], "mappingSize": {"width":320,"height":480} }
+      }
+    }
+  }
+}
+]]
+
+local delta = assert(TouchSkin ~= nil and DeltaSkin.parse(DELTA_JSON))
+eq(delta.format, "delta", "a .deltaskin parses into the native model")
+eq(delta.name, "Test GBC", "info.json name")
+eq(delta.system, "gbc", "gbc covers both GB and GBC")
+eq(#delta.pages, 1, "only the orientations present become pages")
+local dp = delta.pages[1]
+eq(dp.name, "portrait", "the page is named for its orientation")
+eq(dp.orient, "portrait", "and locked to it")
+eq(dp.imagePath, "p_large.png", "the PNG ladder picks the largest for a phone")
+check(dp.fullScreen, "Delta stretches its skin over the whole surface")
+check(not dp.aspectFromCfg, "so nothing letterboxes it")
+near(dp.aspect, 320 / 480, "the page aspect is the mappingSize aspect")
+eq(#dp.controls, 13, "edgeToEdge wins over standard, so all six items parsed")
+
+local dA = dp.controls[1]
+eq(dA.buttons[1], "a", "an inputs array binds its button")
+eq(dA.shape, "radial", 'mask "circle" becomes a radial hitbox')
+near(dA.x, 0.85, "frame top-left plus half width is the native centre")
+near(dA.y, 352 / 480, "and the same for y")
+near(dA.rangeX, 0.1, "frame width halves into the native half extent")
+near(dA.reachLeft, 1.25, "orientation extendedEdges become reach")
+
+local dB = dp.controls[2]
+near(dB.reachRight, 1.5, "a per-item extendedEdges key overrides that side")
+near(dB.reachLeft, 1.25, "and leaves the others inherited")
+
+eq(dp.controls[3].spec, "left|up", "a dpad input object expands to a 3x3 grid")
+near(dp.controls[3].x, 0.1, "dpad top-left cell x")
+near(dp.controls[3].rangeX, 0.05, "dpad cells are a third of the frame")
+near(dp.controls[3].reachLeft, 1.5, "with the extended edge re-scaled onto them")
+eq(dp.controls[4].spec, "up", "dpad top-centre cell")
+eq(dp.controls[10].spec, "right|down", "dpad bottom-right cell")
+
+eq(dp.controls[11].spec, "start|select", "a multi-input item fires both")
+eq(dp.controls[12].hotkeys[1], "menu", "the Delta menu button becomes a hotkey")
+check(dp.controls[13].decorative,
+      "quickSave has no engine hotkey, so it is inert rather than a game button")
+
+check(dp.viewport ~= nil, "screens[] places the emulator picture")
+near(dp.viewport.y, 32 / 480, "outputFrame y normalizes by mappingSize")
+near(dp.viewport.h, 288 / 480, "outputFrame height normalizes by mappingSize")
+
+local bx, by, bw, bh = TouchSkin.pageBox(dp, 1000, 500)
+eq(bx, 0, "delta page box x") eq(by, 0, "delta page box y")
+eq(bw, 1000, "delta page box fills the width")
+eq(bh, 500, "delta page box fills the height")
+
+local LEGACY_SCREEN = [[
+{ "gameTypeIdentifier": "public.aoshuang.game.gbc",
+  "representations": { "iphone": { "standard": { "landscape": {
+    "mappingSize": {"width":640,"height":320},
+    "gameScreenFrame": {"x":160,"y":0,"width":320,"height":288},
+    "translucent": true,
+    "items": [ { "inputs": {"up":"analogStickUp","down":"analogStickDown",
+                            "left":"analogStickLeft","right":"analogStickRight"},
+                 "frame": {"x":0,"y":0,"width":120,"height":120} } ] } } } } }
+]]
+local legacy = assert(DeltaSkin.parse(LEGACY_SCREEN))
+eq(legacy.system, "gbc", "the Manic public.aoshuang prefix is accepted")
+eq(#legacy.pages, 1, "landscape only")
+eq(legacy.pages[1].orient, "landscape", "orientation key drives the lock")
+near(legacy.pages[1].viewport.x, 0.25, "gameScreenFrame is the legacy screen rect")
+near(legacy.pages[1].alphaMod, 0.7, "translucent dims the controls")
+eq(#legacy.pages[1].controls, 8, "a thumbstick degrades to a directional pad")
+eq(legacy.pages[1].controls[1].spec, "left|up", "with the analog names mapped")
+
+local snes = assert(DeltaSkin.parse([[
+{ "gameTypeIdentifier": "com.rileytestut.delta.game.snes",
+  "representations": { "iphone": { "standard": { "portrait": {
+    "mappingSize": {"width":320,"height":480}, "items": [] } } } } }
+]]))
+check(hasWarning(snes, "not Game Boy"), "a non Game Boy skin warns")
+eq(#snes.pages, 1, "but still imports")
+
+eq(select(1, DeltaSkin.parse([[
+{ "name": "old", "gameTypeIdentifier": "com.rileytestut.GBA4iOS.gba",
+  "representations": { "iphone": { "portrait": { "assets": {} } } } }
+]])), nil, "a GBA4iOS skin is refused")
+local _, gbaErr = DeltaSkin.parse([[
+{ "gameTypeIdentifier": "com.rileytestut.GBA4iOS.gbc", "representations": {} }
+]])
+check(tostring(gbaErr):find("GBA4iOS", 1, true) ~= nil,
+      "and the message names the old format")
+
+local _, noTypeErr = DeltaSkin.parse('{ "representations": {} }')
+check(tostring(noTypeErr):find("gameTypeIdentifier", 1, true) ~= nil,
+      "info.json without a gameTypeIdentifier is refused by name")
+eq(select(1, DeltaSkin.parse("not json at all")), nil, "garbage is refused")
+eq(select(1, DeltaSkin.parse([[
+{ "gameTypeIdentifier": "com.rileytestut.delta.game.gbc", "representations": {} }
+]])), nil, "an empty representations tree is refused")
+
+local PDF_JSON = [[
+{ "name": "Vector", "gameTypeIdentifier": "com.rileytestut.delta.game.gbc",
+  "representations": { "iphone": { "standard": { "portrait": {
+    "assets": { "resizable": "iphone_portrait.pdf" },
+    "mappingSize": {"width":320,"height":480},
+    "items": [ { "inputs": ["a"], "frame": {"x":0,"y":0,"width":32,"height":32} } ]
+  } } } } }
+]]
+local pdf = assert(DeltaSkin.parse(PDF_JSON))
+eq(pdf.pages[1].imagePath, nil, "a PDF asset is not pretended to be art")
+local convert = DeltaSkin.needsConversion(pdf)
+check(convert ~= nil, "PDF-only skins report that they need conversion")
+if convert then
+  check(convert.pdfOnly, "the report is flagged pdfOnly")
+  eq(convert.files[1], "iphone_portrait.pdf", "and names the file to convert")
+end
+eq(DeltaSkin.needsConversion(delta), nil, "a PNG skin needs no conversion")
+
+local mixed = assert(DeltaSkin.parse([[
+{ "gameTypeIdentifier": "com.rileytestut.delta.game.gb",
+  "representations": { "iphone": { "standard": { "portrait": {
+    "assets": { "resizable": "art.pdf", "medium": "art.png" },
+    "mappingSize": {"width":320,"height":480}, "items": [] } } } } }
+]]))
+eq(mixed.pages[1].imagePath, "art.png", "a raster asset beats the PDF")
+eq(DeltaSkin.needsConversion(mixed), nil, "so no conversion is needed")
+
+eq(DeltaSkin.pickAsset({ small = "s.png" }, { targetWidth = 1080 }, {}), "s.png",
+   "the ladder falls back to the largest shipped asset")
+eq(DeltaSkin.pickAsset({ small = "s.png", medium = "m.png", large = "l.png" },
+                       { targetWidth = 640 }, {}), "s.png",
+   "a small target takes the small asset")
+eq(DeltaSkin.pickAsset({ normal = "n.png" }, { targetWidth = 640 }, {}), "n.png",
+   'the Manic "normal" alias is accepted')
+
+love.filesystem.write("skins/wrapped.deltaskin/MySkin/info.json", [[
+{ "name": "Wrapped", "gameTypeIdentifier": "com.rileytestut.delta.game.gbc",
+  "representations": { "iphone": { "standard": { "portrait": {
+    "assets": { "large": "Portrait.PNG" },
+    "mappingSize": {"width":320,"height":480},
+    "items": [ { "inputs": ["a"], "frame": {"x":0,"y":0,"width":64,"height":64} } ]
+  } } } } }
+]])
+love.filesystem.write("skins/wrapped.deltaskin/MySkin/portrait.png", "\137PNG\r\n\26\n")
+
+local wrappedId, wrappedErr = TouchSkin.installArchive("wrapped.deltaskin", "PK\3\4stub")
+eq(wrappedId, "wrapped", "a .deltaskin installs under its bare name: " .. tostring(wrappedErr))
+local wrapped = assert(TouchSkin.load("skins/_mounted/wrapped", "wrapped"))
+eq(wrapped.format, "delta", "the mounted archive is recognised as a Delta skin")
+eq(wrapped.name, "Wrapped", "and its name comes from info.json")
+eq(wrapped.pages[1].imagePath, "MySkin/portrait.png",
+   "the wrapping folder is prefixed onto assets and the real file name wins")
+eq(#wrapped.pages[1].controls, 1, "the wrapped items parsed")
+
+love.filesystem.write("skins/vector.deltaskin/info.json", PDF_JSON)
+local vectorId, vectorErr = TouchSkin.installArchive("vector.deltaskin", "PK\3\4stub")
+eq(vectorId, nil, "a PDF-only skin is refused instead of installing invisible")
+check(tostring(vectorErr):find("PDF artwork", 1, true) ~= nil,
+      "with the message that asks for a PNG version")
+eq(love.filesystem.read("skins/vector.deltaskin"), nil,
+   "and the refused archive is not left behind")
+
+eq(select(1, TouchSkin.installArchive("skin.gbcskin", "PK\3\4stub")), nil,
+   "a GBA4iOS .gbcskin is refused at the door")
+local _, legacyErr = TouchSkin.installArchive("skin.gbaskin", "PK\3\4stub")
+check(tostring(legacyErr):find("GBA4iOS", 1, true) ~= nil,
+      "with a message that names the format")
+eq(select(1, TouchSkin.installArchive("skin.rar", "PK\3\4stub")), nil,
+   "an unknown archive extension is refused")
+eq(TouchSkin.archiveId("pad.deltaskin"), "pad", "archiveId strips .deltaskin")
+eq(TouchSkin.archiveId("pad.zip"), "pad", "archiveId strips .zip")
+eq(TouchSkin.archiveId("pad"), nil, "a bare name is not an archive")
+
+local AUTHORED = [[
+return { name = "Authored", pages = {
+  { name = "portrait", orient = "portrait", fullScreen = true,
+    viewport = { x = 0, y = 0, w = 1, h = 0.5 },
+    controls = {
+      { bind = "a", x = 0.8, y = 0.75, w = 0.2, h = 0.1, shape = "radial" },
+      { bind = "b", x = 0.6, y = 0.8, w = 0.2, h = 0.1, shape = "radial",
+        reachRight = 1.5 },
+      { bind = "start", x = 0.5, y = 0.95, w = 0.1, h = 0.04 },
+      { bind = "menu_toggle", x = 0.05, y = 0.05, w = 0.08, h = 0.04 },
+      { bind = "nul", x = 0.2, y = 0.7, w = 0.3, h = 0.2, image = "img/dpad.png" },
+    } },
+  { name = "landscape", orient = "landscape", fullScreen = true,
+    controls = {
+      { bind = "a", x = 0.9, y = 0.8, w = 0.1, h = 0.15, shape = "radial" },
+    } },
+} }
+]]
+local authored = assert(TouchSkin.parseNative(AUTHORED))
+authored.id = "authored"
+authored.root = "skins/authored"
+
+local cfgText = TouchSkin.toRetroArchConfig(authored)
+check(cfgText:find("overlays = 2", 1, true) ~= nil, "the cfg declares its overlays")
+local reparsed = assert(TouchSkin.parse(cfgText))
+eq(#reparsed.pages, 2, "the generated cfg round-trips both pages")
+eq(reparsed.pages[1].name, "portrait", "and their names")
+eq(#reparsed.pages[1].controls, 5, "and every desc")
+eq(reparsed.pages[1].controls[1].spec, "a", "binds survive the round trip")
+near(reparsed.pages[1].controls[1].x, 0.8, "centres survive the round trip")
+near(reparsed.pages[1].controls[1].rangeX, 0.1, "half extents survive")
+eq(reparsed.pages[1].controls[1].shape, "radial", "hitbox shape survives")
+near(reparsed.pages[1].controls[2].reachRight, 1.5, "per-side reach survives")
+eq(reparsed.pages[1].controls[4].hotkeys[1], "menu", "hotkeys survive")
+check(reparsed.pages[1].controls[5].decorative, "decoration stays decoration")
+eq(reparsed.pages[1].controls[5].imagePath, "img/dpad.png", "and keeps its art")
+near(reparsed.pages[1].viewport.h, 0.5, "the screen cutout survives")
+eq(reparsed.pages[1].orient, "portrait", "the orientation lock survives by name")
+
+local KEY_SKIN = [[
+return { name = "Keys", pages = {
+  { name = "portrait", fullScreen = true, controls = {
+      { bind = "key:escape", x = 0.5, y = 0.5, w = 0.1, h = 0.1 },
+    } },
+} }
+]]
+local keySkin = assert(TouchSkin.parseNative(KEY_SKIN))
+local keyCfg = TouchSkin.toRetroArchConfig(keySkin)
+check(keyCfg:find("retrok_escape", 1, true) ~= nil,
+      "a key bind exports in the grammar RetroArch understands")
+check(keyCfg:find("key:escape", 1, true) == nil, "and not in the native spelling")
+eq(assert(TouchSkin.parse(keyCfg)).pages[1].controls[1].keys[1], "escape",
+   "which this importer still reads back as the same key")
+
+local areaCfg = TouchSkin.toRetroArchConfig({ pages = area.pages })
+local areaBack = assert(TouchSkin.parse(areaCfg))
+eq(#areaBack.pages[1].controls, #ap.controls,
+   "an area desc exports as one desc, not eight overlapping ones")
+check(areaCfg:find("dpad_area", 1, true) ~= nil, "the area kind is written back")
+check(areaCfg:find('_up = "start"', 1, true) ~= nil, "with its output override")
+eq(areaBack.pages[1].controls[16].spec, "start", "which survives the round trip")
+
+local areaInfo = assert(DeltaSkin.build({ id = "area", pages = area.pages }))
+local areaRep = areaInfo.representations.iphone.edgeToEdge.portrait
+local dpadItem
+for _, item in ipairs(areaRep.items) do
+  if not dpadItem and type(item.inputs) == "table" and item.inputs.up then
+    dpadItem = item
+  end
+end
+check(dpadItem ~= nil, "the same area exports to Delta as one d-pad item")
+eq(dpadItem.inputs.left, "left", "carrying each direction")
+eq(#areaRep.items, 3, "one per area desc, not eight stacked on one another")
+
+local raPath = os.tmpname() .. "-ra.zip"
+local raWritten, raMissing = TouchSkin.exportRetroArch(authored, raPath)
+eq(raWritten, raPath, "exportRetroArch writes where it was told")
+eq(raMissing[1], "img/dpad.png", "and reports art it could not find")
+local raZip = unzip(readBytes(raPath))
+eq(raZip[1], "overlay.cfg", "the RetroArch zip leads with overlay.cfg")
+check(raZip["overlay.cfg"] ~= nil, "and the entry has bytes")
+check(TouchSkin.parse(raZip["overlay.cfg"]) ~= nil, "which RetroArch grammar accepts")
+os.remove(raPath)
+
+local dsPath = os.tmpname() .. ".deltaskin"
+local dsWritten, _, dsWarnings = TouchSkin.exportDelta(authored, { path = dsPath })
+eq(dsWritten, dsPath, "exportDelta writes where it was told")
+check(#dsWarnings > 0, "and warns that per-button art has nowhere to go")
+local dsZip = unzip(readBytes(dsPath))
+eq(dsZip[1], "info.json", "the .deltaskin leads with info.json")
+local info = assert(Json.decode(dsZip["info.json"]))
+eq(info.gameTypeIdentifier, "com.rileytestut.delta.game.gbc",
+   "the export claims the GBC game type")
+eq(info.name, "Authored", "and carries the skin name")
+check(info.identifier:find("authored", 1, true) ~= nil, "identifier names the skin")
+local rep = info.representations.iphone.edgeToEdge.portrait
+check(rep ~= nil, "an iPhone edgeToEdge portrait representation is emitted")
+eq(info.representations.iphone.standard.portrait.mappingSize.width, 1080,
+   "standard portrait maps 1080 wide")
+eq(rep.mappingSize.height, 1920, "portrait maps 1920 tall")
+eq(#rep.items, 4, "only bound controls become Delta items")
+eq(rep.items[1].inputs[1], "a", "the first item is A")
+eq(rep.items[1].mask, "circle", "a radial hitbox exports as a circle mask")
+eq(rep.items[1].frame.x, 756, "frame x is top-left, not centre")
+eq(rep.items[1].frame.width, 216, "frame width is the full extent")
+eq(rep.items[2].extendedEdges.right, 54, "reach exports as extendedEdges")
+eq(rep.items[4].inputs[1], "menu", "the menu hotkey exports as a Delta host input")
+eq(rep.screens[1].inputFrame.width, 160, "the screen crop is a full GB frame")
+eq(rep.screens[1].outputFrame.height, 960, "and the output frame follows the viewport")
+eq(info.representations.iphone.edgeToEdge.landscape.mappingSize.width, 1920,
+   "the landscape page maps 1920 wide")
+
+local back = assert(DeltaSkin.parse(dsZip["info.json"]))
+eq(#back.pages, 2, "the exported skin re-imports both orientations")
+local bp = back.pages[1]
+eq(#bp.controls, 4, "with every bound control")
+near(bp.controls[1].x, 0.8, "and the same centres it started with")
+near(bp.controls[1].rangeX, 0.1, "and the same half extents")
+eq(bp.controls[1].shape, "radial", "and the same hitbox shape")
+near(bp.controls[2].reachRight, 1.5, "and the same reach")
+near(bp.viewport.h, 0.5, "and the same screen cutout")
+os.remove(dsPath)
+
+love.filesystem.write("skins/collide/overlay.cfg", [[
+overlays = 1
+overlay0_name = "collide"
+overlay0_descs = 1
+overlay0_desc0 = "a,0.5,0.5,rect,0.05,0.05"
+]])
+local collide = assert(TouchSkin.load("skins/collide", "collide"))
+local defaultDelta = assert(TouchSkin.exportDelta(collide))
+eq(defaultDelta, "skins/_export/collide.deltaskin",
+   "a default export lands outside the folder the skin list scans")
+local listedRoot, listedExport
+for _, entry in ipairs(TouchSkin.list()) do
+  if entry.id == "collide" then listedRoot = entry.root end
+  if entry.id == "_export" then listedExport = true end
+end
+eq(listedRoot, "skins/collide", "so the export cannot shadow the skin it came from")
+check(not listedExport, "and the export folder is not a skin of its own")
+
+T.finish("skin_format_import")

tests/engine/skin_studio_ux.lua

@@ -0,0 +1,339 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+if not _G.love then _G.love = require("tests.love_stub") end
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+
+local TouchSkin = require("src.core.TouchSkin")
+local Studio = require("src.ui.SkinStudio")
+
+local function near(a, b, tol, msg)
+  check(math.abs(a - b) <= (tol or 1e-6), msg .. " (got " .. tostring(a) ..
+        ", want " .. tostring(b) .. ")")
+end
+
+local function session()
+  Studio.skin = TouchSkin.newSkin("t")
+  Studio.skinIdField = "t"
+  Studio.pageIndex = 1
+  Studio.selected = nil
+  Studio.canvasIndex = 1
+  Studio.aspectLock = true
+  Studio.drag = nil
+  Studio.dirty = false
+  Studio.images = {}
+  Studio.thumbs = {}
+  Studio.available = {}
+  Studio.availableMeta = {}
+  Studio.undoStack, Studio.redoStack = {}, {}
+  Studio.undoTag, Studio.undoAt = nil, nil
+  Studio.modal, Studio.confirm = nil, nil
+  Studio.status, Studio.statusErr = nil, false
+  Studio.imageTarget = "idle"
+  return Studio.skin
+end
+
+session()
+check(not Studio.canUndo(), "a fresh session has nothing to undo")
+Studio.addControl()
+eq(#Studio.page().controls, 1, "a control was added")
+check(Studio.canUndo(), "adding a control is undoable")
+Studio.undo()
+eq(#Studio.page().controls, 0, "undo takes the control back off")
+check(Studio.canRedo(), "and offers a redo")
+Studio.redo()
+eq(#Studio.page().controls, 1, "redo puts it back")
+check(not Studio.canRedo(), "the redo stack is spent")
+
+Studio.addControl()
+check(not Studio.canRedo(), "a fresh edit clears the redo stack")
+
+session()
+Studio.addControl()
+local before = Studio.page().controls[1]
+Studio.pushUndo()
+before.x = 0.9
+Studio.undo()
+check(Studio.page().controls[1] ~= before,
+      "undo restores a copy, not the edited table")
+near(Studio.page().controls[1].x, 0.5, 1e-6, "with the pre-edit position")
+
+session()
+for _ = 1, Studio.UNDO_CAP + 10 do Studio.pushUndo() end
+eq(#Studio.undoStack, Studio.UNDO_CAP, "the undo stack is capped")
+
+session()
+check(not Studio.undo(), "undo on an empty stack reports nothing to do")
+check(not Studio.redo(), "and so does redo")
+
+local realIsDown = love.keyboard and love.keyboard.isDown
+love.keyboard = love.keyboard or {}
+local held = {}
+love.keyboard.isDown = function(...)
+  for _, k in ipairs({ ... }) do if held[k] then return true end end
+  return false
+end
+session()
+Studio.addControl()
+Studio.addControl()
+held.lctrl = true
+Studio.keypressed("z")
+eq(#Studio.page().controls, 1, "ctrl+Z undoes one step")
+Studio.keypressed("z")
+eq(#Studio.page().controls, 0, "and again")
+held.lshift = true
+Studio.keypressed("z")
+eq(#Studio.page().controls, 1, "ctrl+shift+Z redoes instead of undoing further")
+held.lshift = nil
+Studio.keypressed("y")
+eq(#Studio.page().controls, 2, "and ctrl+Y redoes as well")
+held.lctrl = nil
+if realIsDown then love.keyboard.isDown = realIsDown end
+
+session()
+local ran = 0
+check(Studio.guard("lose it?", function() ran = ran + 1 end),
+      "a clean skin runs the action straight away")
+eq(ran, 1, "and does not prompt")
+check(Studio.confirm == nil, "no prompt is left up")
+
+Studio.dirty = true
+check(not Studio.guard("lose it?", function() ran = ran + 1 end),
+      "a dirty skin defers the action")
+eq(ran, 1, "the action has not run yet")
+check(Studio.confirm ~= nil, "and a prompt is up")
+Studio.confirmNo()
+eq(ran, 1, "cancelling drops the action")
+check(Studio.confirm == nil, "and closes the prompt")
+
+Studio.guard("lose it?", function() ran = ran + 1 end)
+Studio.confirmYes()
+eq(ran, 2, "confirming runs it")
+check(Studio.confirm == nil, "and closes the prompt")
+
+session()
+Studio.dirty = true
+Studio.openLoadPicker()
+check(Studio.confirm ~= nil, "Load prompts over unsaved work")
+check(Studio.modal == nil, "and does not open the picker yet")
+Studio.confirmYes()
+check(Studio.modal ~= nil and Studio.modal.kind == "open",
+      "confirming opens the picker")
+Studio.closeModal()
+
+eq(Studio.toggleBindPart("nul", "left"), "left",
+   "a bind starts from decoration")
+eq(Studio.toggleBindPart("left", "up"), "left|up",
+   "directions combine in the canonical order")
+eq(Studio.toggleBindPart("up", "left"), "left|up",
+   "and the order does not depend on which was added first")
+eq(Studio.toggleBindPart("left|up", "up"), "left",
+   "toggling a part off removes it")
+eq(Studio.toggleBindPart("left", "left"), "nul",
+   "removing the last part leaves decoration")
+eq(Studio.toggleBindPart("a", "b"), "a|b", "buttons combine as well")
+check(Studio.hasBindPart("left|down", "down"), "hasBindPart finds a part")
+check(not Studio.hasBindPart("left|down", "up"), "and misses one that is absent")
+
+session()
+check(not Studio.openBindPicker(), "the bind picker needs a selected control")
+check(Studio.statusErr, "and says so as an error")
+Studio.addControl()
+check(Studio.openBindPicker(), "with a control selected it opens")
+eq(Studio.modal.kind, "bind", "as the bind modal")
+Studio.setBindSpec("start")
+eq(Studio.selectedControl().spec, "start", "picking a bind writes the spec")
+eq(Studio.selectedControl().buttons[1], "start", "and reparses it")
+Studio.undo()
+eq(Studio.selectedControl().spec, "a", "the bind change is undoable")
+Studio.closeModal()
+
+Studio.toggleSelectedBindPart("b")
+eq(Studio.selectedControl().spec, "a|b", "the combine chips build a pipe bind")
+eq(#Studio.selectedControl().buttons, 2, "which fires both buttons")
+
+local specs = {}
+for _, group in ipairs(Studio.BIND_GROUPS) do
+  check(#group.specs > 0, group.title .. " lists at least one bind")
+  for _, spec in ipairs(group.specs) do specs[spec] = true end
+end
+check(specs["a"] and specs["start"], "the GB buttons are reachable")
+check(specs["overlay_previous"], "overlay_previous is reachable at last")
+check(specs["pause_toggle"] and specs["exit_emulator"],
+      "so are the hotkeys the old cycle could not reach")
+check(specs["key:escape"], "and a keyboard bind can be picked")
+check(specs["nul"], "decoration is still an option")
+
+session()
+Studio.addControl()
+Studio.addControl()
+Studio.selected = 1
+local first = Studio.page().controls[1]
+check(Studio.moveControlOrder(1), "bring forward moves the control up")
+eq(Studio.selected, 2, "and follows it with the selection")
+check(Studio.page().controls[2] == first, "the control really moved")
+check(not Studio.moveControlOrder(1), "the front control cannot go further")
+check(Studio.moveControlOrder(-1), "send back moves it down again")
+eq(Studio.selected, 1, "selection follows back")
+check(not Studio.moveControlOrder(-1), "and the back control stays put")
+
+session()
+Studio.addControl()
+local ctl = Studio.selectedControl()
+local canvas = Studio.canvas()
+local startX, startY = ctl.x, ctl.y
+Studio.nudge(1, 0)
+near(ctl.x, startX + 1 / canvas.w, 1e-9, "an arrow moves one canvas pixel")
+Studio.nudge(0, 1, true)
+near(ctl.y, startY + 10 / canvas.h, 1e-9, "shift moves ten")
+Studio.undo()
+near(Studio.selectedControl().x, startX, 1e-9, "nudging is undoable")
+Studio.selected = nil
+check(not Studio.nudge(1, 0), "nothing selected, nothing nudged")
+
+check(Studio.NUDGES.up[2] == -1 and Studio.NUDGES.down[2] == 1,
+      "up is negative y on the canvas")
+check(Studio.NUDGES.left[1] == -1 and Studio.NUDGES.right[1] == 1,
+      "and left is negative x")
+
+local off, line = Studio.snapOffset({ 100, 150, 200 }, { 152, 400 }, 4)
+near(off, 2, 1e-9, "an edge within tolerance snaps to the guide")
+near(line, 152, 1e-9, "and reports the line it snapped to")
+off, line = Studio.snapOffset({ 100 }, { 400 }, 4)
+eq(off, 0, "a line out of range does not move anything")
+eq(line, nil, "and reports no guide")
+off = Studio.snapOffset({ 100, 200 }, { 203, 101 }, 4)
+near(off, 1, 1e-9, "the nearest candidate wins")
+
+session()
+Studio.addControl()
+local r = { x = 0, y = 0, w = 1000, h = 1000 }
+local xs, ys = Studio.snapLines(Studio.page(), r, nil)
+check(#xs >= 6 and #ys >= 6,
+      "snap lines cover the page box and every other control")
+local skipped = select(1, Studio.snapLines(Studio.page(), r, 1))
+eq(#skipped, 3, "the dragged control is not a guide for itself")
+
+session()
+Studio.addControl()
+Studio.page().controls[1].x = 0.25
+Studio.addControl()
+Studio.selected = 2
+local moving = Studio.selectedControl()
+moving.x = 0.6
+local target = Studio.page().controls[1]
+local bx, by, bw, bh = 0, 0, 0, 0
+local cx, cy, hw, hh = TouchSkin.controlGeometry(Studio.page(), moving,
+  r.w, r.h, r.x, r.y)
+bx, by, bw, bh = cx - hw, cy - hh, hw * 2, hh * 2
+local tcx = select(1, TouchSkin.controlGeometry(Studio.page(), target,
+  r.w, r.h, r.x, r.y))
+Studio.drag = { kind = "control-move", mx = 0, my = 0,
+                bx = bx, by = by, bw = bw, bh = bh }
+Studio.updateDrag((tcx - cx) + 3, 0, r)
+local cx2 = select(1, TouchSkin.controlGeometry(Studio.page(), moving,
+  r.w, r.h, r.x, r.y))
+near(cx2, tcx, 1e-6, "a near miss snaps onto the other control's centre")
+check(Studio.guides ~= nil and Studio.guides.x ~= nil,
+      "and a guide line is recorded for the canvas to draw")
+Studio.drag = nil
+
+session()
+Studio.addPage()
+Studio.addPage()
+eq(#Studio.skin.pages, 3, "three pages")
+check(Studio.setPage(1), "setPage jumps to a page by index")
+eq(Studio.pageIndex, 1, "and lands there")
+check(not Studio.setPage(9), "an index past the end is refused")
+Studio.nextPage()
+eq(Studio.pageIndex, 2, "next page still cycles")
+local name, detail = Studio.pageLabel(2)
+eq(name, "page2", "the page list shows the page name")
+check(detail:find("controls", 1, true) ~= nil, "and what is on it")
+
+check(Studio.renamePage("landscape"), "a page can be renamed")
+eq(Studio.page().name, "landscape", "and keeps the new name")
+check(not Studio.renamePage("  "), "an empty name is refused")
+Studio.undo()
+eq(Studio.page().name, "page2", "renaming is undoable")
+
+Studio.pageIndex = 2
+check(Studio.deletePage(2), "a page can be deleted")
+eq(#Studio.skin.pages, 2, "and the skin loses it")
+Studio.deletePage(1)
+check(not Studio.deletePage(1), "the last page cannot be deleted")
+check(Studio.statusErr, "and the studio says why")
+
+session()
+check(not Studio.openImagePicker("idle"), "art needs a selected control")
+Studio.addControl()
+check(Studio.openImagePicker("idle"), "with one selected the grid opens")
+eq(Studio.modal.kind, "image", "as the image modal")
+eq(Studio.imageTarget, "idle", "aimed at the idle art")
+check(Studio.openImagePicker("bezel"), "the bezel needs no selection")
+eq(Studio.currentImagePath(), nil, "a new page has no bezel yet")
+Studio.imageTarget = "idle"
+Studio.selectedControl().imagePath = "img/a.png"
+eq(Studio.currentImagePath(), "img/a.png", "the picker marks the current art")
+Studio.chooseImage(nil)
+eq(Studio.selectedControl().imagePath, nil, "picking (none) clears the art")
+eq(Studio.modal, nil, "and closes the picker")
+Studio.undo()
+eq(Studio.selectedControl().imagePath, "img/a.png", "clearing art is undoable")
+
+session()
+Studio.setStatus("boom", true)
+check(Studio.statusErr, "an error status is flagged")
+Studio.addControl()
+eq(Studio.status, "boom", "a later edit does not wipe the error off the footer")
+Studio.setStatus("fine")
+Studio.addControl()
+eq(Studio.status, nil, "an ordinary status still clears on the next edit")
+Studio.setStatus("boom", true)
+Studio.statusAt = -1000
+Studio.expireStatus()
+eq(Studio.status, nil, "and an error clears itself after a few seconds")
+
+local ids = {}
+for _, spec in ipairs(Studio.EXPORTS) do ids[spec.id] = spec.label end
+check(ids.native and ids.retroarch and ids.delta,
+      "the export menu offers all three formats")
+
+session()
+Studio.skinIdField = "uxtest"
+local nativePath = Studio.exportAs("native")
+check(nativePath ~= nil and nativePath:match("%.zip$") ~= nil,
+      "the native export writes a .zip")
+local raPath = Studio.exportAs("retroarch")
+check(raPath ~= nil and raPath:match("%.zip$") ~= nil,
+      "the RetroArch export writes a .zip")
+local deltaPath = Studio.exportAs("delta")
+check(deltaPath ~= nil and deltaPath:match("%.deltaskin$") ~= nil,
+      "the Delta export writes a .deltaskin")
+check(love.filesystem.read(deltaPath) ~= nil, "and the archive is on disk")
+eq(Studio.lastExport, deltaPath, "the last export is remembered for Show file")
+
+eq(Studio.skinFormat({ format = "retroarch" }), "RetroArch",
+   "a format badge reads in words")
+eq(Studio.skinFormat({ format = "delta" }), "Delta", "Delta included")
+
+love.graphics.getDimensions = love.graphics.getDimensions
+  or function() return 1280, 720 end
+session()
+Studio.addControl()
+for _, kind in ipairs({ "bind", "image", "open", "page", "export" }) do
+  Studio.openModal(kind)
+  check(pcall(Studio.draw), "the studio draws with the " .. kind .. " modal up")
+end
+Studio.closeModal()
+Studio.ask("sure?", function() end)
+check(pcall(Studio.draw), "and with the confirm prompt up")
+Studio.confirmNo()
+
+Studio.openModal("bind")
+Studio.lastCanvas = { x = 0, y = 0, w = 100, h = 100 }
+Studio.mousepressed(50, 50, 1)
+eq(Studio.drag, nil, "a click under an open modal does not grab a control")
+Studio.closeModal()
+
+T.finish("skin_studio_ux")

tests/engine/skin_viewport_containment.lua

@@ -0,0 +1,214 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+love = love or require("tests.love_stub")
+
+local TouchSkin = require("src.core.TouchSkin")
+local Playfield = require("src.render.Playfield")
+local Renderer = require("src.render.Renderer")
+local Chrome = require("src.ui.gen2.Chrome")
+local Zoom = require("src.render.Zoom")
+
+local EPS = 1e-6
+
+local function setWindow(w, h)
+  love.graphics.getDimensions = function() return w, h end
+  love.graphics.getPixelDimensions = function() return w, h end
+end
+
+local function cfg(viewport, extra)
+  return ([[
+overlays = 1
+overlay0_name = "bezel"
+overlay0_full_screen = true
+overlay0_normalized = true
+overlay0_viewport = "%s"
+%s
+overlay0_descs = 1
+overlay0_desc0 = "nul,0.5,0.5,rect,0.02,0.02"
+]]):format(viewport, extra or "")
+end
+
+local function useSkin(viewport, extra)
+  local skin = assert(TouchSkin.parse(cfg(viewport, extra)))
+  TouchSkin.setActive(skin)
+  TouchSkin.setOverlayLive(false)
+  return skin
+end
+
+local function inside(x, y, w, h, bx, by, bw, bh)
+  return x >= bx - EPS and y >= by - EPS
+    and x + w <= bx + bw + EPS and y + h <= by + bh + EPS
+end
+
+setWindow(640, 576)
+TouchSkin.setActive(nil)
+Renderer:init()
+local plain = Renderer:frameRects()
+eq(plain.cut, false, "no skin: no cutout")
+eq(plain.vux, 0, "no skin: the picture starts at the window origin")
+eq(plain.vuw, 640, "no skin: the picture is the whole window")
+eq(plain.Sp, 4, "no skin: 640x576 fits four whole GB pixels")
+eq(plain.uox, 0, "no skin: the UI letterbox fills the window")
+eq(select(3, Playfield.rect(640, 576)), 640, "no skin: the playfield is the window")
+eq(Chrome.fitScale(640, 576), 4, "no skin: Gold fits the window the same way")
+
+local WINDOWS = {
+  { 640, 576 }, { 1280, 720 }, { 1920, 1080 },
+  { 800, 480 }, { 480, 800 }, { 360, 640 },
+}
+local VIEWPORTS = {
+  "0.2335,0.0855,0.5335,0.830",
+  "0.2,0.15,0.6,0.5",
+  "0.05,0.05,0.9,0.35",
+  "0.3,0.1,0.4,0.8",
+}
+local UI_SIZES = { { 160, 144 }, { 304, 144 } }
+
+local escapes, uncut, cases = 0, 0, 0
+for _, win in ipairs(WINDOWS) do
+  setWindow(win[1], win[2])
+  for _, vp in ipairs(VIEWPORTS) do
+    useSkin(vp)
+    Renderer:init()
+    for _, size in ipairs(UI_SIZES) do
+      Renderer:setUISize(size[1], size[2])
+      for off = -8, 8 do
+        Zoom.offset = off
+        for _, fill in ipairs({ false, true }) do
+          for _, centered in ipairs({ true, false }) do
+            Renderer.uiFill = fill
+            Renderer.uiCentered = centered
+            Renderer.worldActive = true
+            cases = cases + 1
+            local r = Renderer:frameRects()
+            local ux, uy, uw, uh = Renderer.clipToView(r, r.uox, r.uoy,
+              r.uvpw, r.uvph)
+            if not inside(ux, uy, uw, uh, r.vux, r.vuy, r.vuw, r.vuh) then
+              escapes = escapes + 1
+            end
+            if uw < r.uvpw - EPS or uh < r.uvph - EPS then uncut = uncut + 1 end
+            local vw, vh = Renderer:worldViewSize()
+            local sp = Zoom.scale(r.Sp)
+            if vw * sp > r.vuw + 2 * sp + EPS
+              or vh * sp > r.vuh + 2 * sp + EPS then
+              escapes = escapes + 1
+            end
+          end
+        end
+      end
+    end
+  end
+end
+check(cases > 1000, "the sweep covers every window x cutout x zoom x layout")
+eq(escapes, 0, "no zoom, battle surface or UI layout puts a rect past the cutout")
+eq(uncut, 0, "and the UI was sized to fit, so the clip never has to cut it")
+
+setWindow(1280, 720)
+useSkin("0.25,0.1,0.5,0.6")
+Renderer:init()
+Renderer:setUISize(160, 144)
+Renderer.uiFill, Renderer.uiCentered = false, true
+Zoom.offset = 0
+local r = Renderer:frameRects()
+eq(r.cut, true, "the skin's cutout is folded into the frame")
+eq(r.vux, 320, "cutout x")
+eq(r.vuy, 72, "cutout y")
+eq(r.vuw, 640, "cutout width")
+eq(r.vuh, 432, "cutout height")
+eq(r.Sp, 3, "the fit is measured against the cutout, not the window")
+check(inside(r.uox, r.uoy, r.uvpw, r.uvph, r.vux, r.vuy, r.vuw, r.vuh),
+  "the UI letterbox sits inside the cutout")
+check(inside(r.ox, r.oy, r.vpw, r.vph, r.vux, r.vuy, r.vuw, r.vuh),
+  "so does the world letterbox")
+
+local lo, hi = Zoom.offsetRange(r.Sp)
+for off = lo, hi do
+  Zoom.offset = off
+  local z = Renderer:frameRects()
+  check(inside(z.uox, z.uoy, z.uvpw, z.uvph, z.vux, z.vuy, z.vuw, z.vuh),
+    "zoom " .. Zoom.offsetLabel(off) .. " keeps the UI in the cutout")
+  local vw, vh = Renderer:worldViewSize()
+  local sp = Zoom.scale(z.Sp)
+  check(vw * sp <= z.vuw + 2 * sp and vh * sp <= z.vuh + 2 * sp,
+    "zoom " .. Zoom.offsetLabel(off) .. " keeps the world pass capped")
+end
+Zoom.offset = 0
+
+local capped = select(1, Renderer:worldViewSize())
+useSkin("0.25,0.1,0.5,0.6", "overlay0_viewport_expand = true")
+local expanded = select(1, Renderer:worldViewSize())
+check(expanded > capped,
+  "viewport_expand lets the survey world fill the cutout instead of the GB box")
+useSkin("0.25,0.1,0.5,0.6")
+
+setWindow(480, 800)
+useSkin("0.3,0.1,0.4,0.3")
+Renderer:init()
+Renderer:setUISize(304, 144)
+Renderer.uiFill, Renderer.uiCentered = false, true
+local tight = Renderer:frameRects()
+check(tight.vuw < 304, "the cutout cannot hold the WIDE battle at 1x")
+check(inside(tight.uox, tight.uoy, tight.uvpw, tight.uvph,
+  tight.vux, tight.vuy, tight.vuw, tight.vuh),
+  "so the surface is scaled down to the cutout rather than over the bezel")
+Renderer:setUISize(160, 144)
+
+setWindow(1280, 720)
+useSkin("0.25,0.1,0.5,0.6")
+local px, py, pw, ph, active = Playfield.rect(1280, 720)
+eq(active, true, "Gold sees the cutout too")
+eq(pw, 480, "the playfield is a whole multiple of 160")
+eq(ph, 432, "and of 144")
+check(inside(px, py, pw, ph, 320, 72, 640, 432),
+  "centred inside the cutout")
+eq(Chrome.fitScale(1280, 720), 3, "Chrome fits the playfield")
+local cox, coy = Chrome.fitOrigin(1280, 720)
+eq(cox, px, "and centres the panel on it")
+eq(coy, py, "on both axes")
+
+useSkin("0.25,0.1,0.5,0.6", "overlay0_viewport_expand = true")
+local ex, ey, ew, eh = Playfield.rect(1280, 720)
+eq(ew, 640, "expand hands the picture the full cutout width")
+eq(eh, 432, "and its full height")
+eq(ex, 320, "at the cutout origin")
+eq(ey, 72, "on both axes")
+useSkin("0.25,0.1,0.5,0.6")
+
+local ew2, eh2, ex2, ey2, act2 = Playfield.push(1280, 720)
+eq(act2, true, "push reports the frame is contained")
+eq(ex2, px, "push translates to the playfield origin")
+eq(ey2, py, "on both axes")
+eq(ew2, pw, "and hands the scene the playfield size")
+eq(Playfield.cutout(ew2, eh2), nil, "inside the frame there is no cutout left")
+eq(select(3, Playfield.rect(ew2, eh2)), pw, "so the playfield is the surface")
+eq(Chrome.fitScale(ew2, eh2), 3, "and Chrome fits it without re-applying")
+eq(select(1, Chrome.fitOrigin(ew2, eh2)), 0, "at a local origin")
+eq(select(1, Playfield.dimensions()), pw, "screens read the playfield as the display")
+Playfield.pop()
+eq(Playfield.entered, false, "pop leaves the frame")
+eq(select(1, Playfield.cutout(1280, 720)), 320, "and the cutout is visible again")
+
+useSkin("0.4,0.4,0.1,0.1")
+local sx, sy, sw, sh = Playfield.rect(1280, 720)
+check(inside(sx, sy, sw, sh, 512, 288, 128, 72),
+  "a cutout smaller than 160x144 still bounds the playfield")
+check(sw <= 128 and sh <= 72, "the playfield never exceeds the cutout")
+
+TouchSkin.setActive(nil)
+eq(Playfield.cutout(1280, 720), nil, "no skin, no cutout")
+eq(select(3, Playfield.rect(1280, 720)), 1280, "and the playfield is the window")
+local saved = TouchSkin.viewport
+TouchSkin.viewport = function() error("boom") end
+eq(Playfield.cutout(1280, 720), nil, "a throwing viewport is no cutout")
+TouchSkin.viewport = function() return 10, 10, 0, 0 end
+eq(Playfield.cutout(1280, 720), nil, "a zero-sized cutout is no cutout")
+TouchSkin.viewport = function() return -50, -50, 200, 200 end
+eq(select(1, Playfield.cutout(1280, 720)), 0, "a cutout off the surface is clamped")
+eq(select(3, Playfield.cutout(1280, 720)), 150, "to what is left of it")
+TouchSkin.viewport = saved
+TouchSkin.setActive(nil)
+setWindow(640, 576)
+
+T.finish("skin_viewport_containment")

tests/engine/sync_client_test.lua

@@ -0,0 +1,175 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+love = love or require("tests.love_stub")
+
+local Json = require("src.link.Json")
+local SyncClient = require("src.sync.SyncClient")
+
+local function recorder()
+  local t = { sent = {}, replies = {}, released = 0 }
+  function t:begin(req)
+    self.sent[#self.sent + 1] = req
+    return #self.sent
+  end
+  function t:poll(handle)
+    local reply = self.replies[handle]
+    if not reply then return { status = "pending" } end
+    return reply
+  end
+  function t:release() self.released = self.released + 1 end
+  function t:answer(handle, code, body)
+    self.replies[handle] = { status = "ok", code = code, body = body }
+  end
+  function t:fail(handle, err)
+    self.replies[handle] = { status = "error", err = err }
+  end
+  return t
+end
+
+local function client(transport)
+  return SyncClient.new({ baseUrl = "http://sync.test/", transport = transport })
+end
+
+do
+  T.eq(SyncClient.normalizeCode("1234-5678"), "12345678",
+    "a dashed code normalizes to digits")
+  T.eq(SyncClient.normalizeCode(" 1234 5678 "), "12345678",
+    "and so does a spaced one")
+  T.eq(SyncClient.normalizeCode("1234567"), nil, "seven digits is not a code")
+  T.eq(SyncClient.normalizeCode("123456789"), nil, "nor is nine")
+  T.eq(SyncClient.normalizeCode("abcdefgh"), nil, "nor letters")
+  T.eq(SyncClient.formatCode("12345678"), "1234-5678",
+    "codes present as two groups of four")
+  T.eq(SyncClient.formatCode("nope"), nil, "a bad code has no presentation")
+end
+
+do
+  local t = recorder()
+  local c = client(t)
+  T.eq(c:isLinked(), false, "a new client is not linked")
+
+  local handle = c:create("laptop")
+  local req = t.sent[1]
+  T.eq(req.method, "POST", "create posts")
+  T.eq(req.url, "http://sync.test/sync/create", "to /sync/create")
+  T.eq(req.headers["x-sync-account"], nil,
+    "and carries no auth header before there is an account")
+  T.eq(Json.decode(req.body).device, "laptop", "the device label rides along")
+
+  t:answer(handle, 200,
+    '{"account":"aa11","code1":"11112222","code2":"33334444","deviceToken":"tok"}')
+  local res = c:poll(handle)
+  T.eq(res.status, "ok", "a 200 with JSON reads as ok")
+  T.eq(res.data.account, "aa11", "and the account comes back decoded")
+
+  c:setAuth(res.data.account, res.data.deviceToken)
+  T.eq(c:isLinked(), true, "storing the token links the client")
+
+  local stateHandle = c:fetchState()
+  local stateReq = t.sent[2]
+  T.eq(stateReq.method, "GET", "state is a GET")
+  T.eq(stateReq.headers["x-sync-account"], "aa11", "with the account header")
+  T.eq(stateReq.headers["x-sync-token"], "tok", "and the device token header")
+  T.eq(stateReq.body, nil, "and no body")
+  T.eq(c:poll(stateHandle).status, "pending", "an unanswered request is pending")
+
+  local bad, err = c:link("123", "456", "phone")
+  T.eq(bad, nil, "a short code never reaches the network")
+  T.check(tostring(err):find("8 digits", 1, true) ~= nil,
+    "and says what a code looks like")
+  T.eq(#t.sent, 2, "no request was sent for the bad codes")
+end
+
+do
+  local t = recorder()
+  local c = client(t)
+  c:setAuth("aa11", "tok")
+
+  local handle = c:putSave({ version = "red", slot = "slot1",
+    meta = { savedAt = 100, sessionStart = 50 }, blob = "return {}",
+    baseRev = 4 })
+  local req = t.sent[1]
+  T.eq(req.method, "PUT", "a save upload is a PUT")
+  T.eq(req.url, "http://sync.test/sync/save", "to /sync/save")
+  local body = Json.decode(req.body)
+  T.eq(body.version, "red", "the version rides in the body")
+  T.eq(body.baseRev, 4, "with the rev the client last synced")
+  T.eq(body.meta.sessionStart, 50, "and the session start in the meta")
+
+  t:answer(handle, 409,
+    '{"conflict":true,"rev":9,"remoteMeta":{"savedAt":200,"sessionStart":60}}')
+  local res = c:poll(handle)
+  T.eq(res.status, "error", "a 409 is not a success")
+  T.eq(res.code, 409, "the status code is reported")
+  T.eq(res.data.remoteMeta.savedAt, 200,
+    "and the conflict body is still readable")
+
+  local tooBig, why = c:putSave({ version = "red", slot = "slot1",
+    blob = string.rep("x", SyncClient.MAX_BLOB + 1) })
+  T.eq(tooBig, nil, "an oversized save is refused before it is sent")
+  T.check(tostring(why):find("too large", 1, true) ~= nil,
+    "with a reason the UI can show")
+
+  local getHandle = c:getSave("red", "abc def")
+  T.eq(t.sent[2].url, "http://sync.test/sync/save?id=abc%20def&version=red",
+    "a download escapes its query parameters")
+  t:answer(getHandle, 200, '{"meta":{"savedAt":200},"blob":"return {}","rev":9}')
+  T.eq(c:poll(getHandle).data.rev, 9, "the download reports the served rev")
+end
+
+do
+  local t = recorder()
+  local c = client(t)
+  c:setAuth("aa11", "tok")
+
+  local h1 = c:fetchState()
+  t:fail(h1, "no route to host")
+  local res = c:poll(h1)
+  T.eq(res.status, "error", "a transport failure is an error")
+  T.check(res.err:find("no route", 1, true) ~= nil, "and keeps the reason")
+
+  local h2 = c:fetchState()
+  t:answer(h2, 200, "<html>nope</html>")
+  local html = c:poll(h2)
+  T.eq(html.status, "error", "an HTML reply is not a sync reply")
+  T.check(html.err:find("HTML", 1, true) ~= nil, "and says so")
+
+  local h3 = c:fetchState()
+  t:answer(h3, 401, '{"error":"bad_token"}')
+  local denied = c:poll(h3)
+  T.eq(denied.status, "error", "a 401 is an error")
+  T.eq(denied.err, "bad_token", "carrying the server's own reason")
+
+  local h4 = c:fetchState()
+  t:answer(h4, 200, '{"ok":true,"error":"stale"}')
+  T.eq(c:poll(h4).status, "error",
+    "an error field in a 200 body still fails the call")
+
+  c:clearAuth()
+  local nope, err = c:fetchState()
+  T.eq(nope, nil, "an unlinked client refuses an authenticated call")
+  T.check(tostring(err):find("not linked", 1, true) ~= nil,
+    "and says the device is not linked")
+end
+
+do
+  local t = recorder()
+  local c = client(t)
+  c:setAuth("aa11", "tok")
+
+  local handle = c:fetchShare("ab3d9k")
+  T.eq(t.sent[1].headers["x-sync-token"], nil,
+    "reading a share code needs no auth")
+  T.eq(t.sent[1].url, "http://sync.test/sync/modshare?code=AB3D9K",
+    "and the code is upper-cased in the query")
+  t:answer(handle, 200, '{"manifest":{"rev":1,"mods":[],"indexes":[]}}')
+  T.eq(c:poll(handle).data.manifest.rev, 1, "the shared manifest decodes")
+
+  local bad, err = c:fetchShare("12")
+  T.eq(bad, nil, "a short share code never reaches the network")
+  T.check(tostring(err):find("6 characters", 1, true) ~= nil,
+    "and says how long one is")
+end
+
+T.finish("sync_client")

tests/engine/sync_engine_test.lua

@@ -0,0 +1,459 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+love = love or require("tests.love_stub")
+
+local Json = require("src.link.Json")
+local SyncState = require("src.sync.SyncState")
+local SyncEngine = require("src.sync.SyncEngine")
+
+local function scripted(routes)
+  local t = { sent = {}, routes = routes, handles = {} }
+  function t:begin(req)
+    self.sent[#self.sent + 1] = req
+    local path = req.url:match("^[^?]*"):gsub("^http://sync%.test", "")
+    local route = self.routes[req.method .. " " .. path]
+    local reply
+    if type(route) == "function" then
+      reply = route(req, self)
+    else
+      reply = route
+    end
+    reply = reply or { code = 404, body = '{"error":"no route"}' }
+    self.handles[#self.sent] = {
+      status = "ok", code = reply.code or 200,
+      body = reply.body or Json.encode(reply.data or {}),
+    }
+    return #self.sent
+  end
+  function t:poll(handle) return self.handles[handle] end
+  function t:release() end
+  return t
+end
+
+local function pump(eng, times)
+  for _ = 1, (times or 24) do eng:update(0.05) end
+end
+
+local function linkedState()
+  local state = SyncState.defaults()
+  state.account = "aa11bb22cc33dd44"
+  state.deviceToken = "tok"
+  state.enabled = true
+  return state
+end
+
+local function saveEntry(version, id, savedAt, sessionStart, slot)
+  return {
+    version = version, slot = slot or "slot1", playthroughId = id,
+    blob = "return { player = { name = 'ASH' } }",
+    meta = { savedAt = savedAt, sessionStart = sessionStart,
+             playthroughId = id, summary = { name = "ASH", badges = 2 } },
+  }
+end
+
+local function fakeSaves(entries)
+  local writes = {}
+  return {
+    writes = writes,
+    list = function() return entries end,
+    write = function(version, id, blob, mode)
+      writes[#writes + 1] = { version = version, playthroughId = id,
+                              blob = blob, mode = mode }
+      return mode == "new" and "slot9" or "slot1"
+    end,
+  }
+end
+
+local function engine(routes, entries, state)
+  local saves = fakeSaves(entries or {})
+  local transport = scripted(routes)
+  local eng = SyncEngine.new({
+    baseUrl = "http://sync.test",
+    transport = transport,
+    state = state or linkedState(),
+    saves = saves,
+    persist = false,
+    now = function() return 1700001000 end,
+  })
+  return eng, transport, saves
+end
+
+do
+  T.eq(SyncEngine.overlaps({ sessionStart = 10, savedAt = 20 },
+                           { sessionStart = 15, savedAt = 30 }), true,
+    "two sessions that ran over the same minutes overlap")
+  T.eq(SyncEngine.overlaps({ sessionStart = 10, savedAt = 20 },
+                           { sessionStart = 21, savedAt = 30 }), false,
+    "a session that started after the other ended does not")
+  T.eq(SyncEngine.overlaps({ savedAt = 20 }, { sessionStart = 1, savedAt = 30 }),
+    false, "a save with no session start cannot claim an overlap")
+end
+
+do
+  local eng, transport = engine({
+    ["POST /sync/create"] = { code = 200, body =
+      '{"account":"aa11","code1":"11112222","code2":"33334444","deviceToken":"tok"}' },
+  }, {}, SyncState.defaults())
+
+  T.eq(eng:linked(), false, "a fresh engine is not linked")
+  T.eq(eng.status, "Not set up", "and says so")
+
+  eng:createAccount("laptop")
+  pump(eng, 3)
+  T.eq(eng:linked(), true, "creating an account links this device")
+  T.eq(eng.state.account, "aa11", "and stores the account id")
+  T.eq(eng.codes.code1, "1111-2222", "the first code is shown grouped")
+  T.eq(eng.codes.code2, "3333-4444", "and so is the second")
+  T.eq(eng.state.code1, nil, "codes never enter the persisted state")
+  T.eq(eng.phase, "idle", "and the engine settles")
+  T.eq(#transport.sent, 1, "one request was made")
+end
+
+do
+  local eng, transport = engine({
+    ["POST /sync/link"] = { code = 200,
+      body = '{"account":"aa11","deviceToken":"tok"}' },
+    ["GET /sync/state"] = { code = 200, body = '{"saves":{}}' },
+    ["PUT /sync/save"] = { code = 200, body = '{"ok":true,"rev":1}' },
+  }, { saveEntry("red", "abc", 500, 400) }, SyncState.defaults())
+
+  eng:linkDevice("1111-2222", "3333 4444", "phone")
+  pump(eng)
+  T.eq(eng:linked(), true, "linking with both codes links the device")
+  T.eq(transport.sent[2].url, "http://sync.test/sync/state",
+    "and a sync starts immediately")
+  T.eq(transport.sent[3].method, "PUT",
+    "the local save the server has never seen is uploaded")
+  T.eq(SyncState.rev(eng.state, "red/abc"), 1, "the served rev is remembered")
+  T.eq(SyncState.stamp(eng.state, "red/abc"), 500,
+    "along with the savedAt that was uploaded")
+  T.eq(eng.phase, "idle", "and the engine settles")
+  T.eq(eng.state.lastSyncAt, 1700001000, "the sync time is stamped")
+end
+
+do
+  local eng, transport = engine({}, {}, SyncState.defaults())
+  eng:linkDevice("12", "34", "phone")
+  T.eq(#transport.sent, 0, "a malformed code pair is refused locally")
+  T.eq(eng.phase, "error", "and the engine reports the problem")
+  T.check(eng.status:find("8 digits", 1, true) ~= nil,
+    "with copy that says what a code is")
+end
+
+do
+  local eng, transport, saves = engine({
+    ["GET /sync/state"] = { code = 200,
+      body = '{"saves":{"gold/xyz":{"rev":4,"meta":{"savedAt":900}}}}' },
+    ["GET /sync/save"] = { code = 200,
+      body = '{"rev":4,"meta":{"savedAt":900},"blob":"return { player = {} }"}' },
+  }, {})
+
+  eng:syncNow()
+  pump(eng)
+  T.eq(#saves.writes, 1, "the remote-only save is written locally")
+  T.eq(saves.writes[1].version, "gold", "into the right game")
+  T.eq(saves.writes[1].mode, "replace", "as that playthrough's slot")
+  T.eq(SyncState.rev(eng.state, "gold/xyz"), 4, "and its rev is remembered")
+  T.eq(eng.phase, "idle", "the engine settles")
+  T.eq(transport.sent[2].url, "http://sync.test/sync/save?id=xyz&version=gold",
+    "the download names the playthrough, not the slot")
+end
+
+do
+  local state = linkedState()
+  SyncState.setRev(state, "red/abc", 7, 500)
+  local eng, transport = engine({
+    ["GET /sync/state"] = { code = 200,
+      body = '{"saves":{"red/abc":{"rev":7,"meta":{"savedAt":500}}}}' },
+  }, { saveEntry("red", "abc", 500, 400) }, state)
+
+  eng:syncNow()
+  pump(eng)
+  T.eq(#transport.sent, 1, "an unchanged save is neither uploaded nor downloaded")
+  T.eq(eng.phase, "idle", "and the sync ends idle")
+end
+
+local function conflictEngine()
+  local state = linkedState()
+  SyncState.setRev(state, "red/abc", 7, 500)
+  return engine({
+    ["GET /sync/state"] = { code = 200,
+      body = '{"saves":{"red/abc":{"rev":9,"meta":{"savedAt":760,' ..
+             '"sessionStart":600,"summary":{"name":"BLUE","badges":4}}}}}' },
+    ["PUT /sync/save"] = { code = 200, body = '{"ok":true,"rev":10}' },
+    ["GET /sync/save"] = { code = 200,
+      body = '{"rev":9,"meta":{"savedAt":760},"blob":"return { player = {} }"}' },
+  }, { saveEntry("red", "abc", 700, 650) }, state)
+end
+
+do
+  local eng, transport = conflictEngine()
+  eng:syncNow()
+  pump(eng)
+  T.eq(eng.phase, "conflict", "both sides changing is a conflict")
+  T.eq(#eng.conflicts, 1, "one conflict is raised")
+  T.eq(eng.conflicts[1].overlap, true,
+    "the two sessions ran over the same minutes")
+  T.eq(eng.status, "These saves were played at the same time.",
+    "and the status is the wording the player was promised")
+  T.eq(eng.conflicts[1].remoteMeta.summary.name, "BLUE",
+    "the other device's save is summarized for the prompt")
+  T.eq(#transport.sent, 1, "nothing is uploaded while the player decides")
+  T.eq(#eng.state.pendingConflicts, 1, "the conflict survives in the state")
+end
+
+do
+  local eng, transport = conflictEngine()
+  eng:syncNow()
+  pump(eng)
+  eng:resolveConflict("red/abc", "local")
+  pump(eng)
+  local put = transport.sent[2]
+  T.eq(put.method, "PUT", "keep this device uploads")
+  T.eq(Json.decode(put.body).force, true, "with the force flag")
+  T.eq(SyncState.rev(eng.state, "red/abc"), 10, "and adopts the new rev")
+  T.eq(eng.phase, "idle", "the conflict is cleared")
+  T.eq(#eng.state.pendingConflicts, 0, "and dropped from the state")
+end
+
+do
+  local eng, transport, saves = conflictEngine()
+  eng:syncNow()
+  pump(eng)
+  eng:resolveConflict("red/abc", "remote")
+  pump(eng)
+  T.eq(transport.sent[2].method, "GET", "keep the other device downloads")
+  T.eq(#saves.writes, 1, "and writes it locally")
+  T.eq(saves.writes[1].mode, "replace", "over this playthrough's slot")
+  T.eq(SyncState.rev(eng.state, "red/abc"), 9, "adopting the remote rev")
+  T.eq(eng.phase, "idle", "the conflict is cleared")
+end
+
+do
+  local eng, transport, saves = conflictEngine()
+  eng:syncNow()
+  pump(eng)
+  eng:resolveConflict("red/abc", "both")
+  pump(eng)
+  T.eq(#saves.writes, 1, "keep both imports the other save")
+  T.eq(saves.writes[1].mode, "new", "into a new slot")
+  local put = transport.sent[3]
+  T.eq(put.method, "PUT", "and still uploads this device's save")
+  T.eq(Json.decode(put.body).force, true, "forcing past the stale rev")
+  T.eq(eng.phase, "idle", "the conflict is cleared")
+end
+
+do
+  local eng = engine({
+    ["GET /sync/state"] = { code = 200, body = '{"saves":{}}' },
+    ["PUT /sync/save"] = { code = 409, body =
+      '{"conflict":true,"rev":3,"remoteMeta":{"savedAt":710,"sessionStart":600}}' },
+  }, { saveEntry("red", "abc", 700, 650) })
+
+  eng:syncNow()
+  pump(eng)
+  T.eq(eng.phase, "conflict", "a 409 on upload becomes a conflict, not an error")
+  T.eq(eng.conflicts[1].overlap, true, "with the overlap worked out")
+end
+
+do
+  local eng = engine({
+    ["GET /sync/state"] = function()
+      return { code = 500, body = '{"error":"server on fire"}' }
+    end,
+  }, {})
+  eng:syncNow()
+  pump(eng, 3)
+  T.eq(eng.phase, "error", "a server error stops the sync")
+  T.check(eng.status:find("server on fire", 1, true) ~= nil,
+    "and shows what the server said")
+end
+
+do
+  local eng, transport = engine({
+    ["GET /sync/state"] = { code = 200, body = '{"saves":{}}' },
+    ["PUT /sync/save"] = { code = 200, body = '{"ok":true,"rev":1}' },
+  }, { saveEntry("red", "abc", 500, 400) })
+
+  eng:noteSaveWritten()
+  eng:update(1)
+  T.eq(#transport.sent, 0, "an in-game save does not sync straight away")
+  eng:update(SyncEngine.UPLOAD_DEBOUNCE)
+  T.eq(#transport.sent, 1, "it syncs once the debounce has passed")
+  pump(eng)
+  T.eq(transport.sent[2].method, "PUT", "and the save goes up")
+end
+
+do
+  local eng, transport = engine({}, { saveEntry("red", "abc", 500, 400) })
+  eng:setEnabled(false)
+  eng:noteSaveWritten()
+  eng:update(60)
+  T.eq(#transport.sent, 0, "with sync off an in-game save uploads nothing")
+end
+
+do
+  local eng = engine({
+    ["POST /sync/create"] = { code = 200, body =
+      '{"account":"aa11","code1":"11112222","code2":"33334444",' ..
+      '"deviceToken":"tok","device":"0a1b2c3d"}' },
+  }, {}, SyncState.defaults())
+  eng:createAccount("laptop")
+  pump(eng, 3)
+  T.eq(eng.state.deviceId, "0a1b2c3d",
+    "creating an account records the id the server gave this device")
+  T.eq(SyncState.sanitize(eng.state).deviceId, "0a1b2c3d",
+    "and it survives being persisted")
+end
+
+do
+  local eng = engine({
+    ["POST /sync/link"] = { code = 200,
+      body = '{"account":"aa11","deviceToken":"tok","device":"beefcafe"}' },
+    ["GET /sync/state"] = { code = 200, body = '{"saves":{}}' },
+  }, {}, SyncState.defaults())
+  eng:linkDevice("11112222", "33334444", "phone")
+  pump(eng)
+  T.eq(eng.state.deviceId, "beefcafe", "so does linking a second device")
+end
+
+do
+  local state = linkedState()
+  state.deviceId = "0a1b2c3d"
+  local eng, transport = engine({
+    ["POST /sync/unlink"] = { code = 200, body = '{"ok":true,"devices":1}' },
+  }, {}, state)
+
+  eng:unlink()
+  T.eq(eng:linked(), true, "unlink waits for the server before forgetting")
+  local sent = transport.sent[1]
+  T.eq(sent.url, "http://sync.test/sync/unlink", "it asks the server first")
+  T.eq(Json.decode(sent.body).device, "0a1b2c3d",
+    "naming the device id the server knows, not the platform label")
+  pump(eng, 3)
+  T.eq(eng:linked(), false, "and only then drops the credentials")
+  T.eq(eng.status, "Not set up", "reporting the device as unlinked")
+end
+
+do
+  local state = linkedState()
+  state.deviceId = "0a1b2c3d"
+  local eng = engine({
+    ["POST /sync/unlink"] = { code = 500, body = '{"error":"nope"}' },
+  }, {}, state)
+  eng:unlink()
+  pump(eng, 3)
+  T.eq(eng.phase, "error", "a failed revocation is surfaced")
+  T.eq(eng:linked(), true,
+    "and the device stays linked rather than lying about it")
+end
+
+do
+  local state = linkedState()
+  state.deviceId = "0a1b2c3d"
+  local eng = engine({
+    ["POST /sync/unlink"] = { code = 401, body = '{"error":"unauthorized"}' },
+  }, {}, state)
+  eng:unlink()
+  pump(eng, 3)
+  T.eq(eng:linked(), false,
+    "a token the server already revoked is dropped rather than stuck forever")
+end
+
+do
+  local state = linkedState()
+  state.deviceId = "0a1b2c3d"
+  local eng, transport = engine({
+    ["POST /sync/unlink"] = { code = 200, body = '{"ok":true,"devices":1}' },
+    ["GET /sync/state"] = { code = 200, body = '{"saves":{}}' },
+  }, {}, state)
+  eng:unlinkDevice("99998888")
+  T.eq(Json.decode(transport.sent[1].body).device, "99998888",
+    "another device is revoked by its id")
+  pump(eng, 3)
+  T.eq(eng:linked(), true, "without logging this device out")
+end
+
+do
+  local state = linkedState()
+  state.deviceId = "0a1b2c3d"
+  local eng = engine({
+    ["GET /sync/state"] = { code = 200, body =
+      '{"saves":{},"devices":[{"id":"0a1b2c3d","label":"OS X","current":true},' ..
+      '{"id":"99998888","label":"Android"}]}' },
+  }, {}, state)
+  eng:syncNow()
+  pump(eng)
+  T.eq(#eng.devices, 2, "the linked devices are kept for the modal to show")
+  T.eq(eng.devices[1].current, true, "this device is marked")
+  T.eq(eng.devices[2].label, "Android", "and the others are named")
+end
+
+do
+  local eng = conflictEngine()
+  eng:syncNow()
+  pump(eng)
+  eng:syncNow()
+  pump(eng)
+  eng:syncNow()
+  pump(eng)
+  T.eq(#eng.state.pendingConflicts, 1,
+    "syncing again over the same conflict does not stack up rows")
+  T.eq(#eng.conflicts, 1, "and the prompt still has exactly one to answer")
+end
+
+do
+  local eng = engine({}, {})
+  local order, seen = {}, {}
+  eng.modDeps = {
+    installed = function() return {} end,
+    indexes = function() return {} end,
+    addIndex = function(url) order[#order + 1] = "index" return { feed = url } end,
+    findEntry = function() return nil end,
+    install = function(entry) order[#order + 1] = "install:" .. entry.id return true end,
+    setEnabled = function(id) order[#order + 1] = "enable:" .. id return true end,
+  }
+  eng.modPlan = {
+    indexes = { "https://mods.example/i.json" },
+    toInstall = { { id = "beta", entry = { id = "beta" } } },
+    toEnable = { { id = "beta", version = "red" } },
+    missing = {},
+  }
+  eng:applyModPlan(function(done, total, label, finished)
+    seen[#seen + 1] = ("%d/%d %s"):format(done, total, tostring(finished))
+  end)
+  T.eq(#order, 0, "starting an apply installs nothing on the spot")
+  T.eq(eng:busy(), true, "the launcher can see it is working")
+  eng:update(0.016)
+  T.eq(#order, 1, "one step runs per frame, so the progress line can draw")
+  eng:update(0.016)
+  eng:update(0.016)
+  T.eq(#order, 3, "until the whole plan has run")
+  T.eq(order[3], "enable:beta", "in plan order")
+  T.eq(eng.modApply, nil, "the job is done")
+  T.eq(eng.modPlan, nil, "and the plan is spent")
+  T.eq(eng.status, "Mods applied", "the status says so")
+  T.eq(seen[#seen], "3/3 true", "and the last progress call reports the end")
+end
+
+do
+  local eng = engine({}, {})
+  eng.modDeps = {
+    installed = function() return {} end,
+    indexes = function() return {} end,
+    addIndex = function() return true end,
+    findEntry = function() return nil end,
+    install = function() return nil, "download failed" end,
+    setEnabled = function() return true end,
+  }
+  eng.modPlan = { indexes = {}, toInstall = { { id = "beta", entry = { id = "beta" } } },
+                  toEnable = {}, missing = {} }
+  eng:applyModPlan()
+  eng:update(0.016)
+  T.eq(eng.modApply, nil, "a failing step still ends the job")
+  T.check(eng.status:find("download failed", 1, true) ~= nil,
+    "and the failure reaches the status line")
+end
+
+T.finish("sync_engine")

tests/engine/sync_mods_test.lua

@@ -0,0 +1,148 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+love = love or require("tests.love_stub")
+
+local SyncMods = require("src.sync.SyncMods")
+
+local function row(id, version, enabled, github)
+  return { id = id, version = version, github = github,
+           enabledByVersion = enabled }
+end
+
+local function deps(installed, indexes, catalog)
+  local calls = { installed = {}, enabled = {}, indexes = {} }
+  return calls, {
+    installed = function() return installed end,
+    indexes = function() return indexes or {} end,
+    addIndex = function(url)
+      calls.indexes[#calls.indexes + 1] = url
+      return { feed = url }
+    end,
+    findEntry = function(id) return (catalog or {})[id] end,
+    install = function(entry)
+      calls.installed[#calls.installed + 1] = entry.id
+      return true
+    end,
+    setEnabled = function(id, enabled, version)
+      calls.enabled[#calls.enabled + 1] = id .. ":" .. tostring(version)
+      return true
+    end,
+  }
+end
+
+do
+  local _, d = deps({
+    row("zeta", "1.0.0", { red = true, blue = false, yellow = false, gold = false }),
+    row("alpha", "2.1.0", { red = true, gold = true }, "someone/alpha"),
+  }, { { url = "https://mods.example/index.json",
+        feed = "https://mods.example/index.json" } })
+
+  local manifest = SyncMods.build(d)
+  T.eq(manifest.rev, SyncMods.REV, "the manifest carries its shape revision")
+  T.eq(#manifest.indexes, 1, "the player's index list rides along")
+  T.eq(manifest.indexes[1], "https://mods.example/index.json",
+    "as the url they typed")
+  T.eq(#manifest.mods, 2, "every installed mod is listed")
+  T.eq(manifest.mods[1].id, "alpha", "sorted by id so the manifest is stable")
+  T.eq(manifest.mods[1].source, "github:someone/alpha",
+    "a github mod records where it came from")
+  T.eq(manifest.mods[2].source, "local",
+    "a hand-installed mod is marked local rather than invented")
+  T.eq(#manifest.mods[1].enabledFor, 2, "alpha is on for two games")
+  T.eq(manifest.mods[1].enabledFor[1], "red", "in GameVersion order")
+  T.eq(manifest.mods[1].enabledFor[2], "gold", "red then gold")
+  T.eq(#manifest.mods[2].enabledFor, 1, "zeta is on for one")
+end
+
+do
+  local manifest = {
+    rev = 1,
+    indexes = { "https://mods.example/index.json", "https://other.example/i.json" },
+    mods = {
+      { id = "alpha", version = "2.1.0", enabledFor = { "red", "gold" } },
+      { id = "beta", version = "1.0.0", enabledFor = { "red" } },
+      { id = "ghost", version = "0.1.0", source = "local", enabledFor = { "red" } },
+    },
+  }
+  local _, d = deps(
+    { row("alpha", "2.1.0", { red = true }) },
+    { { url = "https://mods.example/index.json",
+        feed = "https://mods.example/index.json" } },
+    { beta = { id = "beta" } })
+
+  local plan = SyncMods.plan(manifest, d)
+  T.eq(#plan.indexes, 1, "only the index this device is missing is planned")
+  T.eq(plan.indexes[1], "https://other.example/i.json", "the new one")
+  T.eq(#plan.toInstall, 1, "one mod can be fetched from an index")
+  T.eq(plan.toInstall[1].id, "beta", "the one the catalog knows")
+  T.eq(#plan.missing, 1, "the mod nobody publishes is reported, not invented")
+  T.eq(plan.missing[1].id, "ghost", "by id")
+  T.eq(#plan.toEnable, 2, "every game answer that differs is planned")
+  for _, want in ipairs(plan.toEnable) do
+    T.check(want.id ~= "ghost",
+      "a mod that cannot be installed is never enabled")
+  end
+  T.eq(SyncMods.planEmpty(plan), false, "a plan with work is not empty")
+
+  local same = SyncMods.plan({ rev = 1, indexes = {}, mods = {
+    { id = "alpha", version = "2.1.0", enabledFor = { "red" } } } }, d)
+  T.eq(SyncMods.planEmpty(same), true, "a matching device plans nothing")
+end
+
+do
+  local calls, d = deps({}, {}, { beta = { id = "beta" } })
+  local plan = {
+    indexes = { "https://other.example/i.json" },
+    toInstall = { { id = "beta", entry = { id = "beta" } } },
+    toEnable = { { id = "beta", version = "red" } },
+    missing = { { id = "ghost" } },
+  }
+  local seen = {}
+  local ok = SyncMods.apply(plan, function(done, total, label)
+    seen[#seen + 1] = ("%d/%d %s"):format(done, total, label)
+  end, d)
+  T.eq(ok, true, "applying a plan reports success")
+  T.eq(calls.indexes[1], "https://other.example/i.json", "the index is added")
+  T.eq(calls.installed[1], "beta", "the mod is installed through the launcher path")
+  T.eq(calls.enabled[1], "beta:red", "and enabled for the game that wanted it")
+  T.eq(#seen, 3, "progress is reported once per step")
+  T.eq(seen[3], "3/3 beta", "counting up to the total")
+end
+
+do
+  local _, d = deps({}, {}, {})
+  d.install = function() return nil, "download failed" end
+  local ok, err = SyncMods.apply({
+    toInstall = { { id = "beta", entry = { id = "beta" } } } }, nil, d)
+  T.eq(ok, false, "a failed install fails the apply")
+  T.check(tostring(err):find("download failed", 1, true) ~= nil,
+    "naming the mod and the reason")
+end
+
+do
+  local calls, d = deps({}, {}, {})
+  d.install = function() return nil, "download failed" end
+  local ok = SyncMods.apply({
+    toInstall = { { id = "beta", entry = { id = "beta" } } },
+    toEnable = { { id = "beta", version = "red" } },
+  }, nil, d)
+  T.eq(ok, false, "the apply still reports the failure")
+  T.eq(#calls.enabled, 0,
+    "a mod whose install failed is not switched on regardless")
+end
+
+do
+  local calls, d = deps({}, {}, {})
+  local steps = SyncMods.steps({
+    indexes = { "https://other.example/i.json" },
+    toInstall = { { id = "beta", entry = { id = "beta" } } },
+    toEnable = { { id = "beta", version = "red" } },
+  }, d)
+  T.eq(#steps, 3, "a plan splits into one step per unit of work")
+  T.eq(steps[1].run(), true, "steps run one at a time")
+  T.eq(#calls.indexes, 1, "so the caller can draw between them")
+  T.eq(#calls.installed, 0, "without the rest of the plan having run yet")
+end
+
+T.finish("sync_mods")

tests/engine/sync_session_meta_test.lua

@@ -0,0 +1,171 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+love = love or require("tests.love_stub")
+
+local SaveData = require("src.core.SaveData")
+local GameVersion = require("src.core.GameVersion")
+local SyncEngine = require("src.sync.SyncEngine")
+
+local realFS = love.filesystem
+
+local function memfs(files)
+  return {
+    files = files,
+    write = function(path, content) files[path] = content return true end,
+    read = function(path) return files[path] end,
+    remove = function(path) files[path] = nil return true end,
+    getInfo = function(path)
+      if files[path] then return { type = "file" } end
+      return nil
+    end,
+  }
+end
+
+local function fresh()
+  local files = {}
+  love.filesystem = memfs(files)
+  SaveData.resetSlotState()
+  GameVersion.set("red")
+  return files
+end
+
+do
+  local plain = SaveData.buildMeta({})
+  T.check(type(plain.savedAt) == "number", "a save still records when it ended")
+  T.eq(plain.sessionStart, nil,
+    "and records no session start when nobody supplied one")
+
+  local started = os.time() - 600
+  local meta = SaveData.buildMeta({}, nil, started)
+  T.eq(meta.sessionStart, started, "the session start is stamped when given")
+  T.check(meta.savedAt >= meta.sessionStart,
+    "and savedAt is the end of that session")
+
+  local carried = SaveData.buildMeta({}, { sessionStart = started })
+  T.eq(carried.sessionStart, started,
+    "a rewrite with no session keeps the previous start")
+
+  local future = SaveData.buildMeta({}, nil, os.time() + 9999)
+  T.check(future.sessionStart <= future.savedAt,
+    "a clock that ran backwards cannot start a session after it ended")
+
+  local nan = SaveData.buildMeta({}, nil, 0 / 0)
+  T.eq(nan.sessionStart, nil, "a NaN session start is refused")
+
+  local kept = SaveData.buildMeta(nil, { playthroughId = "abc", mods = {},
+                                         sessionStart = 42 })
+  T.eq(kept.playthroughId, "abc", "the playthrough id still rides on the meta")
+  T.eq(kept.sessionStart, 42, "next to the session start")
+end
+
+do
+  local files = fresh()
+  T.eq(SaveData.readSlotSource("red", "slot1"), nil,
+    "an empty slot has no bytes to upload")
+
+  local save = SaveData.newGame()
+  save.player.name = "ASH"
+  save.meta = SaveData.buildMeta({}, { playthroughId = "abc" }, os.time() - 60)
+  T.check(SaveData.writeSlot("red", "slot1", save), "a slot write lands")
+
+  local source = SaveData.readSlotSource("red", "slot1")
+  T.check(type(source) == "string" and #source > 0, "the raw bytes read back")
+  local decoded = SaveData.decode(source)
+  T.eq(decoded.player.name, "ASH", "and decode to the same save")
+  T.eq(decoded.meta.playthroughId, "abc", "carrying the playthrough id")
+
+  files["saves/red/slot1.lua"] = "this is not a save"
+  T.eq(SaveData.readSlotSource("red", "slot1"), nil,
+    "a corrupt slot never hands undecodable bytes to the uploader")
+
+  files["saves/red/slot1.lua.bak"] = source
+  T.eq(SaveData.readSlotSource("red", "slot1"), source,
+    "and the backup copy is used instead")
+
+  T.eq(SaveData.readSlotSource("nosuchgame", "slot1"), nil,
+    "an unknown version has no slots to read")
+end
+
+do
+  fresh()
+  local provider = SyncEngine.defaultSaves()
+  T.eq(#provider.list(), 0, "a fresh install has nothing to sync")
+
+  local slotId = SaveData.createSlot("red")
+  local save = SaveData.newGame()
+  save.player.name = "ASH"
+  save.meta = SaveData.buildMeta({}, { playthroughId = "abc" }, os.time() - 120)
+  SaveData.writeSlot("red", slotId, save)
+
+  local entries = provider.list()
+  T.eq(#entries, 1, "a written slot becomes one sync entry")
+  T.eq(entries[1].version, "red", "keyed by its game")
+  T.eq(entries[1].playthroughId, "abc", "and its playthrough id")
+  T.eq(entries[1].slot, slotId, "remembering which slot it came from")
+  T.eq(entries[1].meta.summary.name, "ASH",
+    "with the launcher summary the conflict prompt shows")
+  T.check(entries[1].meta.sessionStart ~= nil, "and the session start")
+  T.check(entries[1].blob:find("ASH", 1, true) ~= nil,
+    "the blob is the encoded save itself")
+
+  local other = SaveData.newGame()
+  other.player.name = "BLUE"
+  other.meta = SaveData.buildMeta({}, { playthroughId = "xyz" }, os.time() - 30)
+  local newSlot = provider.write("red", "xyz", SaveData.encode(other), "new")
+  T.check(newSlot ~= nil and newSlot ~= slotId,
+    "keep both imports the other device's save into a new slot")
+  local after = provider.list()
+  T.eq(#after, 2, "and both playthroughs are now local")
+  local ids = {}
+  for _, entry in ipairs(after) do ids[entry.playthroughId] = true end
+  T.eq(ids["abc"], true, "this device's playthrough is untouched")
+  T.eq(ids["xyz"], nil,
+    "and the imported copy gets its own identity so the two never merge")
+end
+
+do
+  local source = assert(io.open("src/core/Game.lua")):read("*a")
+  T.check(source:find("self.sessionStartedAt = os.time()", 1, true) ~= nil,
+    "Game stamps when a play session began")
+  T.check(source:find("self.sessionStartedAt)", 1, true) ~= nil,
+    "and hands it to buildMeta when the save is written")
+  local _, stamps = source:gsub("self%.sessionStartedAt = os%.time%(%)", "")
+  T.eq(stamps, 3,
+    "boot, NEW GAME and CONTINUE each start a session")
+end
+
+do
+  fresh()
+  local Game = require("src.core.Game")
+  local notes, pumped = 0, 0
+  SyncEngine._shared = {
+    state = { enabled = true },
+    linked = function() return true end,
+    busy = function() return false end,
+    noteSaveWritten = function() notes = notes + 1 end,
+    update = function(_, dt) pumped = pumped + dt end,
+  }
+  local game = setmetatable({ save = SaveData.newGame(),
+    sessionStartedAt = os.time() - 60 }, { __index = Game })
+  T.eq(Game.writeSave(game), true, "an in-game save still writes")
+  T.eq(notes, 1, "and tells the sync engine, so the 5s debounce can start")
+  Game.updateSync(game, 0.5)
+  T.eq(pumped, 0.5, "the running game pumps the engine, not only the launcher")
+
+  SyncEngine._shared = {
+    state = { enabled = false },
+    linked = function() return false end,
+    busy = function() return false end,
+    noteSaveWritten = function() notes = notes + 1 end,
+    update = function() pumped = pumped + 1 end,
+  }
+  game._syncOff, game._syncEngineRef = nil, nil
+  Game.updateSync(game, 0.5)
+  T.eq(pumped, 0.5, "with sync off the engine is left alone")
+  SyncEngine.forgetShared()
+end
+
+love.filesystem = realFS
+
+T.finish("sync_session_meta")

tests/engine/sync_state_test.lua

@@ -0,0 +1,120 @@
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.harness")
+love = love or require("tests.love_stub")
+
+local SaveData = require("src.core.SaveData")
+local SyncState = require("src.sync.SyncState")
+
+local realFS = love.filesystem
+
+local function memfs(files)
+  return {
+    files = files,
+    write = function(path, content) files[path] = content return true end,
+    read = function(path) return files[path] end,
+    remove = function(path) files[path] = nil return true end,
+    getInfo = function(path)
+      if files[path] then return { type = "file" } end
+      return nil
+    end,
+  }
+end
+
+local function fresh()
+  local files = {}
+  love.filesystem = memfs(files)
+  SaveData.resetSlotState()
+  return files
+end
+
+do
+  local opts = SaveData.defaultOptions()
+  T.check(type(opts.saveSync) == "table", "defaultOptions carries saveSync")
+  T.eq(opts.saveSync.enabled, false, "sync is off until the player sets it up")
+  T.check(type(opts.saveSync.revs) == "table", "and starts with no synced revs")
+  T.eq(opts.saveSync.account, nil, "and no account")
+
+  local state = SyncState.defaults()
+  T.eq(SyncState.linked(state), false, "a default state is not linked")
+  T.eq(state.lastSyncAt, 0, "and has never synced")
+end
+
+do
+  local dirty = SyncState.sanitize({
+    enabled = "yes",
+    account = "aa11bb22cc33dd44",
+    deviceToken = "tok",
+    deviceLabel = "",
+    lastSyncAt = 0 / 0,
+    code1 = "12345678",
+    code2 = "87654321",
+    revs = { ["red/aaa"] = 4, [7] = 9, ["red/bad"] = "no" },
+    stamps = { ["red/aaa"] = 1700 },
+    pendingConflicts = { { key = "red/aaa", version = "red", overlap = true },
+                         { nope = true } },
+  })
+  T.eq(dirty.enabled, false, "a non-boolean enabled reads as off")
+  T.eq(dirty.account, "aa11bb22cc33dd44", "the account id survives")
+  T.eq(dirty.deviceLabel, nil, "an empty device label is dropped")
+  T.eq(dirty.lastSyncAt, 0, "a NaN lastSyncAt is refused")
+  T.eq(dirty.code1, nil, "the first account code is never kept")
+  T.eq(dirty.code2, nil, "nor the second")
+  T.eq(dirty.revs["red/aaa"], 4, "numeric revs survive")
+  T.eq(dirty.revs["red/bad"], nil, "a non-numeric rev is dropped")
+  T.eq(dirty.revs[7], nil, "a non-string rev key is dropped")
+  T.eq(dirty.stamps["red/aaa"], 1700, "the savedAt stamp survives")
+  T.eq(#dirty.pendingConflicts, 1, "only well-formed conflicts are kept")
+  T.eq(dirty.pendingConflicts[1].overlap, true, "with their overlap flag")
+end
+
+do
+  local files = fresh()
+  local state = SyncState.load()
+  T.eq(SyncState.linked(state), false, "a first boot has no linked account")
+
+  state.account = "aa11bb22cc33dd44"
+  state.deviceToken = "feedface"
+  state.deviceId = "0a1b2c3d"
+  state.deviceLabel = "laptop"
+  state.enabled = true
+  state.code1 = "12345678"
+  SyncState.setRev(state, SyncState.key("red", "abc"), 3, 1700000000)
+  SyncState.save(state)
+
+  T.check(files["options.lua"] ~= nil, "the state lands in options.lua")
+  T.eq(files["options.lua"]:find("12345678", 1, true), nil,
+    "the account codes are never written to disk")
+
+  local back = SyncState.load()
+  T.eq(SyncState.linked(back), true, "the linked account survives a reload")
+  T.eq(back.deviceLabel, "laptop", "and the device label")
+  T.eq(back.deviceId, "0a1b2c3d",
+    "and the device id the server revokes tokens by")
+  T.eq(SyncState.rev(back, "red/abc"), 3, "and the last synced rev")
+  T.eq(SyncState.stamp(back, "red/abc"), 1700000000, "and the savedAt stamp")
+  T.eq(back.code1, nil, "the code is gone from the reloaded state")
+
+  local opts = SaveData.loadOptions()
+  T.eq(opts.textSpeed, 3, "writing sync state leaves other options alone")
+
+  SyncState.forget(back, "red/abc")
+  T.eq(SyncState.rev(back, "red/abc"), nil, "forget drops the rev")
+  T.eq(SyncState.stamp(back, "red/abc"), nil, "and the stamp")
+
+  SyncState.clear()
+  T.eq(SyncState.linked(SyncState.load()), false, "clear unlinks the device")
+end
+
+do
+  T.eq(SyncState.key("red", "abc"), "red/abc", "keys join version and id")
+  T.eq(SyncState.key("red", ""), nil, "an empty playthrough id has no key")
+  T.eq(SyncState.key(nil, "abc"), nil, "and neither does a missing version")
+  local version, id = SyncState.splitKey("gold/deadbeef")
+  T.eq(version, "gold", "splitKey reads the version back")
+  T.eq(id, "deadbeef", "and the playthrough id")
+end
+
+love.filesystem = realFS
+
+T.finish("sync_state")

tests/engine/touch_skin_dpad_area.lua

@@ -0,0 +1,199 @@
+-- RetroArch dpad_area / abxy_area descs (#1533): one hitbox whose fired
+-- input is resolved by the angle of the touch from the area centre, and
+-- range_mod growing a hitbox only while it is held.  The cfg below is the
+-- reporter's GBA skin, trimmed to the d-pad and face buttons.
+--   luajit tests/engine/touch_skin_dpad_area.lua
+
+package.path = "./?.lua;./?/init.lua;" .. package.path
+if not _G.love then _G.love = require("tests.love_stub") end
+
+local T = require("tests.harness")
+local check, eq = T.check, T.eq
+
+local TouchSkin = require("src.core.TouchSkin")
+local TouchControls = require("src.core.TouchControls")
+local Input = require("src.core.Input")
+
+local CFG = [[
+overlays = 2
+
+overlay0_name = "portrait"
+overlay0_full_screen = true
+overlay0_normalized = true
+overlay0_range_mod = 1.5
+overlay0_alpha_mod = 1
+overlay0_aspect_ratio = 0.45
+overlay0_descs = 13
+overlay0_desc0 = "select,0.41944,0.58793,radial,0.06667,0.03"
+overlay0_desc0_overlay = p-btn-select.png
+overlay0_desc0_reach_x = 1.25
+overlay0_desc0_reach_y = 1.25
+overlay0_desc1 = "start,0.58056,0.58793,radial,0.06667,0.03"
+overlay0_desc1_overlay = p-btn-start.png
+overlay0_desc1_reach_x = 1.25
+overlay0_desc1_reach_y = 1.25
+overlay0_desc2 = "up,0.25,0.6625,radial,0.07778,0.035"
+overlay0_desc2_overlay = p-btn-dpad-up.png
+overlay0_desc2_reach_x = 0
+overlay0_desc3 = "left,0.12222,0.72,radial,0.07778,0.035"
+overlay0_desc3_overlay = p-btn-dpad-left.png
+overlay0_desc3_reach_x = 0
+overlay0_desc4 = "right,0.37778,0.72,radial,0.07778,0.035"
+overlay0_desc4_overlay = p-btn-dpad-right.png
+overlay0_desc4_reach_x = 0
+overlay0_desc5 = "down,0.25,0.7775,radial,0.07778,0.035"
+overlay0_desc5_overlay = p-btn-dpad-down.png
+overlay0_desc5_reach_x = 0
+overlay0_desc6 = "up|left,0.11644,0.6599,radial,0.01667,0.0075"
+overlay0_desc6_overlay = p-btn-corner.png
+overlay0_desc6_reach_x = 0
+overlay0_desc7 = "up|right,0.38356,0.6599,radial,0.01667,0.0075"
+overlay0_desc7_overlay = p-btn-corner.png
+overlay0_desc7_reach_x = 0
+overlay0_desc8 = "down|left,0.11644,0.7801,radial,0.01667,0.0075"
+overlay0_desc8_overlay = p-btn-corner.png
+overlay0_desc8_reach_x = 0
+overlay0_desc9 = "down|right,0.38356,0.7801,radial,0.01667,0.0075"
+overlay0_desc9_overlay = p-btn-corner.png
+overlay0_desc9_reach_x = 0
+overlay0_desc10 = "dpad_area,0.25,0.72,radial,0.22778,0.1025"
+overlay0_desc10_overlay = p-area-dpad.png
+overlay0_desc10_reach_x = 1.25
+overlay0_desc10_reach_y = 1.25
+overlay0_desc11 = "a,0.84382,0.69563,radial,0.09722,0.04375"
+overlay0_desc11_overlay = p-btn-act2-a.png
+overlay0_desc11_reach_x = 1.25
+overlay0_desc11_reach_y = 1.25
+overlay0_desc12 = "b,0.65618,0.74438,radial,0.09722,0.04375"
+overlay0_desc12_overlay = p-btn-act2-b.png
+overlay0_desc12_reach_x = 1.25
+overlay0_desc12_reach_y = 1.25
+
+overlay1_name = "areas"
+overlay1_full_screen = true
+overlay1_normalized = true
+overlay1_descs = 2
+overlay1_desc0 = "dpad_area,0.25,0.5,rect,0.2,0.2"
+overlay1_desc0_up = "start"
+overlay1_desc0_down = "select"
+overlay1_desc0_left = "nul"
+overlay1_desc1 = "abxy_area,0.75,0.5,rect,0.2,0.2"
+]]
+
+local skin = assert(TouchSkin.parse(CFG))
+local page = skin.pages[1]
+
+eq(#page.controls, 12 + 1 + 8, "the dpad_area expands into eight sector controls")
+local sectors = {}
+for _, ctl in ipairs(page.controls) do
+  if ctl.sector then sectors[ctl.sector] = ctl end
+end
+eq(#sectors, 8, "eight sectors, one per direction")
+eq(sectors[1].spec, "right", "sector 1 is right")
+eq(sectors[2].spec, "right|down", "sector 2 is the down-right diagonal")
+eq(sectors[3].spec, "down", "sector 3 is down, y growing downwards")
+eq(sectors[7].spec, "up", "sector 7 is up")
+eq(sectors[1].x, 0.25, "every sector keeps the area centre")
+eq(sectors[5].y, 0.72, "on both axes")
+eq(sectors[3].rangeX, 0.22778, "and the whole area range")
+eq(sectors[3].shape, "radial", "and the declared hitbox shape")
+
+local art = page.controls[11]
+eq(art.imagePath, "p-area-dpad.png", "the area art rides a decorative desc")
+check(art.decorative, "which presses nothing")
+
+TouchControls:init()
+TouchControls.active = true
+TouchControls.enabled = true
+TouchSkin.setOverlayLive(true)
+TouchSkin.setActive(skin)
+Input:init()
+
+local W, H = 720, 1600
+TouchSkin.setSurface(0, 0, W, H)
+eq(TouchSkin.page().name, "portrait", "the portrait page is live at 720x1600")
+
+local BUTTONS = { "up", "down", "left", "right", "a", "b", "start", "select" }
+local function heldNow()
+  local out = {}
+  for _, btn in ipairs(BUTTONS) do
+    if Input:isDown(btn) then out[#out + 1] = btn end
+  end
+  return table.concat(out, "+")
+end
+
+local function press(nx, ny)
+  TouchControls:touchpressed("f1", nx * W, ny * H)
+  local got = heldNow()
+  TouchControls:touchreleased("f1", nx * W, ny * H)
+  return got
+end
+
+local function fires(nx, ny, want, why)
+  eq(press(nx, ny), want, why)
+end
+
+fires(0.25, 0.6625, "up", "the d-pad up arrow fires up alone")
+fires(0.12222, 0.72, "left", "the left arrow fires left alone")
+fires(0.37778, 0.72, "right", "the right arrow fires right alone")
+fires(0.25, 0.7775, "down", "the down arrow fires down alone")
+fires(0.11644, 0.6599, "up+left", "the up-left corner fires both, and only both")
+fires(0.38356, 0.7801, "down+right", "as does the down-right corner")
+
+fires(0.32, 0.77, "down+right",
+      "a spot inside the area but off every arrow resolves by angle: "
+      .. "(50.4, 80) pixels out is 57.8 degrees, the down-right sector")
+
+fires(0.84382, 0.69563, "a", "A fires alone")
+fires(0.65618, 0.74438, "b", "B fires alone: the 1.5x range_mod does not grow the resting d-pad area over it")
+fires(0.58056, 0.58793, "start", "START fires alone")
+fires(0.41944, 0.58793, "select", "SELECT fires alone, with no phantom direction")
+fires(0.5, 0.3, "", "the screen area presses nothing")
+
+TouchControls:touchpressed("f2", 0.25 * W, 0.6625 * H)
+eq(heldNow(), "up", "slide starts on up")
+TouchControls:touchmoved("f2", 0.37778 * W, 0.72 * H)
+eq(heldNow(), "right", "sliding across the area swaps direction")
+TouchControls:touchmoved("f2", 0.38356 * W, 0.7801 * H)
+eq(heldNow(), "down+right", "and picks up the diagonal")
+TouchControls:touchmoved("f2", 0.5 * W, 0.3 * H)
+eq(heldNow(), "", "sliding out of the area releases it")
+TouchControls:touchreleased("f2", 0.5 * W, 0.3 * H)
+
+local area = sectors[1]
+local bx = 0.65618 * W
+local by = 0.74438 * H
+check(not TouchSkin.hits(page, area, W, H, bx, by, 0, 0, false),
+      "at rest the area hitbox stops short of B")
+check(TouchSkin.hits(page, area, W, H, bx, by, 0, 0, true),
+      "a held area grows over B so the finger keeps its direction")
+TouchControls:touchpressed("f3", 0.37778 * W, 0.72 * H)
+TouchControls:touchmoved("f3", bx, by)
+eq(heldNow(), "right+b", "sliding from the held area onto B keeps right held")
+TouchControls:touchreleased("f3", bx, by)
+eq(heldNow(), "", "and lifting clears both")
+
+TouchSkin.autoOrient = false
+TouchSkin.setPage("areas")
+eq(TouchSkin.page().name, "areas", "second page is live")
+
+W, H = 1000, 1000
+TouchSkin.setSurface(0, 0, W, H)
+
+fires(0.25, 0.35, "start", "_up rebinds the up sector of a dpad_area")
+fires(0.25, 0.65, "select", "_down rebinds the down sector")
+fires(0.12, 0.5, "", "_left = nul makes that sector inert")
+fires(0.38, 0.5, "right", "an unset side keeps the d-pad default")
+
+fires(0.88, 0.5, "a", "abxy_area right is GB A")
+fires(0.75, 0.62, "b", "abxy_area down is GB B")
+fires(0.88, 0.62, "a+b", "the down-right sector fires both")
+fires(0.75, 0.38, "", "RetroPad X has no GB button, so up is inert")
+fires(0.94, 0.68, "a+b", "a rect area still hits inside its corner")
+fires(0.75, 0.75, "", "and nothing past its edge")
+
+TouchSkin.setSurface(nil)
+TouchSkin.setActive(nil)
+TouchSkin.autoOrient = true
+
+T.finish("touch_skin_dpad_area")