skin studio updates, save sync CLOSES #1533

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 x1 = math.floor(math.max(zx, 0))
-    local y1 = math.floor(math.max(zy, 0))
-    local x2 = math.ceil(math.min(zx + (z.w or 160) * sx, w))
-    local y2 = math.ceil(math.min(zy + (z.h or 144) * sy, h))
+    local zx, zy = px + (z.x or 0) * sx, py + (z.y or 0) * sy
+    local x1 = math.floor(math.max(zx, px))
+    local y1 = math.floor(math.max(zy, py))
+    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, 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)
-  if not cfgPath then return nil, "no skin.lua or .cfg in " .. root end
+  local cfgPath, format, prefix = findConfig(root)
+  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]+)$")
+  if not ext or not TouchSkin.ARCHIVE_EXTS[ext:lower()] then return nil end
+  local id = name:sub(1, #name - #ext - 1)
+  if id == "" then return nil end
+  return id, ext:lower()
+end
+
 function TouchSkin.list()
   local out, seen = {}, {}
   local function scan(root, source)
     for _, name in ipairs(listDir(root)) do
-      local id = name:gsub("%.zip$", "")
-      if not seen[id] then
+      local archiveId = TouchSkin.archiveId(name)
+      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("([^/\\]+)$") or ""
-  name = name:gsub("[^%w%._%-]", "_")
-  if not name:lower():match("%.zip$") then return nil, "not a .zip" end
-  local id = name:gsub("%.[Zz][Ii][Pp]$", "")
-  if id == "" then return nil, "bad archive name" end
+  name = name:gsub("[^%w%._%-]", "_"):gsub("^_+", "")
+  local legacy = name:match("%.([%w]+)$")
+  if legacy and TouchSkin.LEGACY_EXTS[legacy:lower()] then
+    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)
-  if not skin then return nil, "no skin" end
-  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("([^/]+)$") or "overlay.cfg", data = cfg }
-    end
-  end
-  local blob = SkinZip.encode(entries)
-  destPath = destPath or (TouchSkin.USER_ROOT .. "/" .. skin.id .. "-export.zip")
+local function writeArchive(entries, destPath)
+  local blob = require("src.core.SkinZip").encode(entries)
   local absolute = destPath:sub(1, 1) == "/" or destPath:match("^%a:[/\\]") ~= nil
+  if not absolute and love and love.filesystem and love.filesystem.createDirectory then
+    local dir = destPath:match("^(.*)/[^/]+$")
+    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 right = halfW * ctl.reachRight * ctl.rangeMod
-  local up = halfH * ctl.reachUp * ctl.rangeMod
-  local down = halfH * ctl.reachDown * ctl.rangeMod
+  local mod = held == false and 1 or ctl.rangeMod
+  local left = halfW * ctl.reachLeft * mod
+  local right = halfW * ctl.reachRight * mod
+  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,
-        imp._modScrollMax or 0)
-    elseif start.dragged and (imp._pageScrollMax or 0) > 0 then
-      local last = start.lastY or start.y
-      imp._pageScroll = (imp._pageScroll or 0) - (y - last)
+      local move = -(y - last)
+      if start.modsList then
+        local listMax = imp._modScrollMax or 0
+        local at, leftover = Kit.scrollHandoff(
+          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
-    rx2, rw = x + m.colW + m.colGap, m.colW
+    local colW = math.floor((w - m.colGap) / 2)
+    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()
-        imp.onOpenSkinStudio(imp.modScope or "red", entry.id)
-      end or nil
+      local configure = function() imp._skinActions = { id = entry.id } end
       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 "$HOME" "*.zip *.deltaskin|Skin archive" 2>/dev/null]])
   end
   return nil
 end
@@ -1349,6 +1349,7 @@ function RomImporter.new(onComplete, opts)
     findLoaded = false, findSources = nil, findIndex = nil,
     findScroll = 0, findNotice = nil, findQuery = "", findCategory = nil,
     _findSearchFocus = false, _findThumbs = nil,
+    skinUrl = "", _skinUrlFocus = false,
     -- Page scroll offset (px) for the column under the tab bar -- panel, updater
     -- banner and footer -- used only while that column is taller than the window
     -- (see draw()).  Clamped against content in draw, reset on a tab change.
@@ -1851,10 +1852,14 @@ end
 function RomImporter:filedropped(file)
   if self.workState == "working" then return end
   -- A dropped .zip is a mod archive: hand it straight to the mods installer
-  -- (which mounts + validates it).  Everything else is treated as a ROM.  The
-  -- dropped file itself is passed through -- installZip opens it the same way
-  -- readDroppedFile does here.
+  -- (which mounts + validates it).  A .deltaskin is only ever a skin, and
+  -- everything else is treated as a ROM.  The dropped file itself is passed
+  -- through -- installZip opens it the same way readDroppedFile does here.
   local name = file:getFilename() or ""
+  if name:lower():match("%.deltaskin$") 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)
-  if sw and sw >= 1 and sh >= 1 then
-    vx, vy = math.floor(sx), math.floor(sy)
-    pw, ph = math.floor(sw), math.floor(sh)
+  local cut, grow = false, false
+  local sx, sy, sw, sh, _, expand = Playfield.cutout(pw, ph)
+  if sx then
+    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
-    local page = TouchSkin.page()
-    if not page.viewportExpand then cap = self:fitScale() end
-  end
+  if not cap and cut and not grow then cap = self:fitScale() 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 padT = math.max(0, math.ceil(oy / TH))
-  local padR = math.max(0, math.ceil((ww - ox - vpw) / TW))
-  local padB = math.max(0, math.ceil((wh - oy - vph) / TH))
+  local padL = math.max(0, math.ceil((ox - wx) / TW))
+  local padT = math.max(0, math.ceil((oy - wy) / TH))
+  local padR = math.max(0, math.ceil((wx + ww - ox - vpw) / TW))
+  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", 0, wh - h, ww, h)
-      love.graphics.rectangle("fill", 0, 0, w, wh)
-      love.graphics.rectangle("fill", ww - w, 0, w, wh)
+      love.graphics.rectangle("fill", wx, wy, ww, h)
+      love.graphics.rectangle("fill", wx, wy + wh - h, ww, h)
+      love.graphics.rectangle("fill", wx, wy, 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", ww / 2 - w, 0, w * 2, wh)
+      love.graphics.rectangle("fill", wx, wy + wh / 2 - h, ww, h * 2)
+      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)
-  GameViewport.setTarget()
-  local ww, wh, pw, ph, dpiX, dpiY, vx, vy = displayMetrics()
-  local vux, vuy = vx / dpiX, vy / dpiY
-  local vuw, vuh = pw / dpiX, ph / dpiY
+function Renderer:frameRects()
+  local ww, wh, pw, ph, dpiX, dpiY, vx, vy, cut = displayMetrics()
+  local r = {
+    ww = ww, wh = wh, pw = pw, ph = ph, dpiX = dpiX, dpiY = 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
-  local oy = (vy + math.floor((ph - uih * Sp) / 2)) / dpiY
+  r.ox = (vx + math.floor((pw - uiw * Sp) / 2)) / dpiX
+  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
-  local uvpw, uvph = uiw * Ux, uih * Uy
-  local uox = (vx + math.floor((pw - uiw * Up) / 2)) / dpiX
-  local uoy = (vy + math.floor((ph - uih * Up) / 2)) / dpiY
+  if uiw * Up > pw or uih * Up > ph then
+    Up = math.min(ph / uih, pw / uiw)
+  end
+  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
+  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", 0, 0, ww, wh)
+  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
-        dy = a.y * Uy
+        dx = vux + vuw - gapR - dw
+        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))
-        dy = math.max(0, math.min(math.max(0, wh - dh), dy))
+        dx = math.max(vux, math.min(math.max(vux, vux + vuw - dw), dx))
+        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),
-    (winH or 0) / (Chrome.SCREEN_H * 8))))
+  local _, _, w, h = playfieldRect(winW, winH)
+  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),
-    math.floor((winH - Chrome.SCREEN_H * 8 * scale) / 2)
+  local x, y, w, h = playfieldRect(winW, winH)
+  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
--- a long list: no scrollbars, no momentum, bounded row count per frame.
+-- never silently truncated.  A long list still PAGES rather than scrolling:
+-- 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)