fix merge conflicts with dev

src/battle/gen2/Battle.lua

@@ -1619,26 +1619,26 @@ function Battle:useMove(attacker, defender, moveId)
     return
   end
 
-  -- Damage that skips the formula entirely (constantdamage).
-  local fixed = Effects.fixedDamage(def.effect, attacker, defender, self.random, def)
+  -- Damage that skips the formula entirely.  The move's own power goes with
+  -- it: EFFECT_STATIC_DAMAGE's arm of BattleCommand_ConstantDamage reads
+  -- BATTLE_VARS_MOVE_POWER as the damage (effect_commands.asm:3157-3161).
+  local fixed = Effects.fixedDamage(def.effect, attacker, defender, self.random,
+    def.power)
   if fixed then
-    -- StaticDamage's effect script runs resettypematchup after constantdamage
-    -- (data/moves/effects.asm): immunities still miss (Sonic Boom vs Ghost).
-    -- Flat damage is otherwise unscaled — no STAB / effectiveness multiply.
-    if def.effect == "EFFECT_STATIC_DAMAGE" then
-      local defTypes = (self:speciesDef(defender) or {}).types or defender.types
-      local matchups = self.data.type_chart and self.data.type_chart.matchups
-      local mult = Damage.typeMultiplier(def.type, defTypes, matchups)
-      if mult == 0 then
-        self:markMissed()
-        self:emit({ kind = "message",
-          text = "It doesn't affect " .. self:monName(defender) .. "..." })
-        return
-      end
+    -- The constant-damage effect list carries `resettypematchup` instead of
+    -- `stab`, and that command misses the move outright when the matchup byte
+    -- is 0 (effect_commands.asm:1480-1493) -- an immune target is the one
+    -- thing that stops SONIC BOOM, NIGHT SHADE or SUPER FANG.
+    local defenderTypes = (self:speciesDef(defender) or {}).types
+      or defender.types
+    local matchups = self.data.type_chart and self.data.type_chart.matchups
+    if Damage.typeMultiplier(def.type, defenderTypes, matchups) == 0 then
+      self:markMissed()
+      self:emit({ kind = "message",
+        text = "It doesn't affect " .. self:monName(defender) .. "..." })
+      return
     end
-    self:dealDamage(attacker, defender, fixed, {
-      move = def, moveId = moveId, effectiveness = 10,
-    })
+    self:dealDamage(attacker, defender, fixed, { move = def, moveId = moveId })
     return
   end
 

src/battle/gen2/Effects.lua

@@ -179,10 +179,9 @@ end
 
 -- --------------------------------------------------------------- fixed damage
 
--- BattleCommand_ConstantDamage / LevelDamage / SuperFang / Psywave /
--- StaticDamage (Sonic Boom, Dragon Rage): skip the damage formula entirely.
--- `move` is optional; EFFECT_STATIC_DAMAGE reads move.power (20 / 40).
-function Effects.fixedDamage(effect, attacker, defender, random, move)
+-- BattleCommand_ConstantDamage (engine/battle/effect_commands.asm:3131-3205),
+-- one command for the whole SuperFang / Psywave / StaticDamage list.
+function Effects.fixedDamage(effect, attacker, defender, random, power)
   if effect == "EFFECT_LEVEL_DAMAGE" then
     return math.max(1, attacker.level or 1)
   end
@@ -190,12 +189,17 @@ function Effects.fixedDamage(effect, attacker, defender, random, move)
     return math.max(1, math.floor((defender.hp or 1) / 2))
   end
   if effect == "EFFECT_PSYWAVE" then
-    -- 1..(level * 1.5), rerolled until it is in range; one roll is enough here.
-    local ceiling = math.max(1, math.floor((attacker.level or 1) * 3 / 2))
-    return math.max(1, (random and random(ceiling) or 0) + 1)
+    -- .psywave rerolls until the byte is nonzero AND below level * 1.5, so the
+    -- top of the range is that ceiling minus one (effect_commands.asm:3163).
+    local ceiling = math.max(2, math.floor((attacker.level or 1) * 3 / 2))
+    return math.max(1, (random and random(ceiling - 1) or 0) + 1)
   end
+  -- SONIC BOOM and DRAGON RAGE share EFFECT_STATIC_DAMAGE, whose arm reads
+  -- BATTLE_VARS_MOVE_POWER straight into the damage word: their stored power
+  -- (20 and 40) IS the damage, never a formula input
+  -- (effect_commands.asm:3157-3161).
   if effect == "EFFECT_STATIC_DAMAGE" then
-    return math.max(1, (move and move.power) or 1)
+    return math.max(1, math.floor(power or 0))
   end
   return nil
 end

src/core/Checkpoint.lua

@@ -313,6 +313,16 @@ local function equalData(a, b)
   return okA and okB and encodedA == encodedB
 end
 
+local function normalizeVerificationMetadata(actual, expected)
+  if type(actual) == "table" and type(actual.identity) == "table"
+      and type(expected) == "table" and type(expected.identity) == "table" then
+    -- RFC 0004 treats engineVersion as compatibility metadata, not runtime
+    -- state. A fresh recapture stamps the running engine, so normalize only
+    -- that metadata before differential verification.
+    actual.identity.engineVersion = expected.identity.engineVersion
+  end
+end
+
 local function firstDifference(a, b, path)
   path = path or "$"
   if type(a) ~= type(b) then return path .. " (type)" end
@@ -394,6 +404,7 @@ function Checkpoint.restore(game, checkpoint)
   if ok then
     local restored, verifyCode = Checkpoint.capture(game)
     if restored and validated.rng == nil then restored.rng = nil end
+    normalizeVerificationMetadata(restored, validated)
     if restored and equalData(restored, validated) then
       emitRestored(game, validated)
       return true
@@ -474,6 +485,7 @@ function Checkpoint.resume(game, checkpoint)
   if ok then
     local restored, verifyCode = Checkpoint.capture(game)
     if restored and validated.rng == nil then restored.rng = nil end
+    normalizeVerificationMetadata(restored, validated)
     if restored and equalData(restored, validated) then
       emitRestored(game, validated)
       return true

src/core/HostDisplay.lua

@@ -0,0 +1,41 @@
+-- Optional native-host display lifecycle.
+--
+-- The engine always owns simulation and drawing. A packaged host may install
+-- one backend to observe per-frame updates and prepare/finalize a render target
+-- around an otherwise unchanged draw. With no backend installed every method
+-- is a no-op, which is the normal desktop and mobile path.
+--
+-- Backend methods are optional:
+--   backend:update(dt)
+--   backend:beginFrame(kind, subject)
+--   backend:endFrame(kind, subject)
+--
+-- `kind` is "editor", "touch_editor", "launcher", or "game". `subject` is
+-- the object whose existing draw method runs between beginFrame and endFrame.
+local HostDisplay = {}
+
+local backend
+
+function HostDisplay.setBackend(value)
+  if value ~= nil and type(value) ~= "table" then
+    error("host display backend must be a table or nil", 2)
+  end
+  backend = value
+end
+
+function HostDisplay.update(dt)
+  local fn = backend and backend.update
+  if fn then return fn(backend, dt) end
+end
+
+function HostDisplay.beginFrame(kind, subject)
+  local fn = backend and backend.beginFrame
+  if fn then return fn(backend, kind, subject) end
+end
+
+function HostDisplay.endFrame(kind, subject)
+  local fn = backend and backend.endFrame
+  if fn then return fn(backend, kind, subject) end
+end
+
+return HostDisplay

src/core/SaveData.lua

@@ -335,11 +335,11 @@ function SaveData.defaultOptions()
     -- TouchControls.normalizeConfig folds it into both orientations on load.
     touchControls = { enabled = true },
     -- Haptic feedback level for on-screen pad presses (#806):
-    -- off | light | medium | heavy, mapped to a love.system.vibrate
-    -- duration in src/core/TouchControls.lua.  LIGHT by default, like the
-    -- overlay itself defaulting on, so an options.lua predating this key
-    -- gets the tick without going looking for the row.  Inert wherever the
-    -- overlay never appears (desktop) or LOVE has no vibrator.
+    -- off | light | normal | strong, mapped to a love.system.vibrate duration
+    -- in src/core/TouchControls.lua.  LIGHT by default, so an options.lua
+    -- predating this key gets the tick without going looking for the row.
+    -- Inert wherever the overlay never appears (desktop) or LOVE has no
+    -- vibrator.
     haptics = "light",
     -- Shared UI/mod timestamp presentation. DEVICE follows the process time
     -- locale where the platform exposes one; otherwise DateTime falls back to
@@ -818,9 +818,19 @@ end
 function SaveData.slotSummary(save)
   if type(save) ~= "table" then return nil, nil end
   local name = save.player and save.player.name or nil
+  -- A Gen 2 slot carries no badge items and fills pokedex.caught, so both
+  -- counts come off wJohtoBadges/wPokedexCaught (engine/menus/intro_menu.asm:461).
+  local vinfo = type(save.version) == "string" and GameVersion.info(save.version)
+  local gen2 = save.generation == 2 or (vinfo and vinfo.generation == 2) or false
   local dexCount = 0
-  for _ in pairs((save.pokedex and save.pokedex.owned) or {}) do
-    dexCount = dexCount + 1
+  if gen2 then
+    for _, has in pairs((save.pokedex and save.pokedex.caught) or {}) do
+      if has then dexCount = dexCount + 1 end
+    end
+  else
+    for _ in pairs((save.pokedex and save.pokedex.owned) or {}) do
+      dexCount = dexCount + 1
+    end
   end
   -- playTime is a plain seconds count in a Gen 1 save but a
   -- { hours, minutes, seconds, frames } table in a Gen 2 (Gold) save, matching
@@ -838,8 +848,21 @@ function SaveData.slotSummary(save)
   end
   local timeText = ("%d:%02d"):format(math.floor(t / 3600),
                                       math.floor(t / 60) % 60)
+  local badges
+  if gen2 then
+    -- Continue_DisplayBadgeCount walks TWO bytes, Johto then Kanto
+    -- (engine/menus/intro_menu.asm:461-469).
+    badges = 0
+    local p = save.player or {}
+    for _, has in pairs(p.badges or {}) do if has then badges = badges + 1 end end
+    for _, has in pairs(p.kantoBadges or {}) do
+      if has then badges = badges + 1 end
+    end
+  else
+    badges = Badges.count(nil, save)
+  end
   return name, {
-    badges = Badges.count(nil, save),
+    badges = badges,
     timeText = timeText,
     dexCount = dexCount,
   }

src/core/TouchControls.lua

@@ -105,17 +105,21 @@ end
 -- would be dropped on every editor save.
 -- love.system.vibrate takes a duration and nothing else, so "intensity" is a
 -- duration preset: Android runs the platform vibrator for exactly that long,
--- while iOS ignores the duration and fires the fixed system vibration, so
--- there the three levels all read as simply on.
-TouchControls.HAPTICS = { "off", "light", "medium", "heavy" }
+-- while iOS maps each duration to a matching Taptic Engine impact.
+TouchControls.HAPTICS = { "off", "light", "normal", "strong" }
 TouchControls.HAPTIC_DEFAULT = "light"
 
-local HAPTIC_SECONDS = { off = 0, light = 0.012, medium = 0.025, heavy = 0.045 }
+local HAPTIC_SECONDS = {
+  off = 0, light = 0.012, normal = 0.025, strong = 0.045,
+}
 local HAPTIC_LABELS = {
-  off = "OFF", light = "LIGHT", medium = "MEDIUM", heavy = "HEAVY",
+  off = "OFF", light = "LIGHT", normal = "NORMAL", strong = "STRONG",
 }
 
 function TouchControls.normalizeHaptics(level)
+  if level == "physical" then return "light" end
+  if level == "medium" then return "normal" end
+  if level == "heavy" then return "strong" end
   if HAPTIC_SECONDS[level] then return level end
   return TouchControls.HAPTIC_DEFAULT
 end

src/core/Version.lua

@@ -8,6 +8,9 @@ local Version = {
                           -- "-dev" placeholder; CI stamps the real X.Y.Z into
                           -- the packed game.love only, never the working tree.
   shell = 1,              -- native-shell contract this build implements
+  payloadHost = "love",   -- native host family for in-place Lua payloads.
+                          -- A payload must name the same family; this prevents
+                          -- mounting code packaged for a different native host.
   minShell = 1,           -- lowest shell contract that can RUN this payload.
                           -- Bump only when a payload needs a newer native
                           -- binary (e.g. a LOVE version bump); an older shell

src/core/gen2/Save.lua

@@ -764,9 +764,14 @@ end
 function Save.summary(save)
   if type(save) ~= "table" then return nil end
   local badges = 0
+  -- Continue_DisplayBadgeCount counts TWO bytes, wJohtoBadges then wKantoBadges
+  -- (engine/menus/intro_menu.asm:461-469).
   for _, has in pairs(save.player and save.player.badges or {}) do
     if has then badges = badges + 1 end
   end
+  for _, has in pairs(save.player and save.player.kantoBadges or {}) do
+    if has then badges = badges + 1 end
+  end
   local caught = 0
   for _, has in pairs(save.pokedex and save.pokedex.caught or {}) do
     if has then caught = caught + 1 end

src/import/LauncherSettings.lua

@@ -62,6 +62,68 @@ local FILTERS = { "OFF", "1X", "2X", "3X" }
 -- The core rows.  Helper modules are required lazily under pcall: they are
 -- pure label/cycle tables, but the launcher must never die because a render
 -- module grew a dependency on live game data.
+-- TOUCH PAD, VIBRATION and the layout editor, shared by both row sets.
+--
+-- Gold reads these out of its own `gold` block (src/core/gen2/Save.lua:297),
+-- so `opts` is whichever table the gear is editing and the rows never have to
+-- know which game they belong to.  #1100 / #1135: the Gold gear carried none
+-- of them, so a phone player could turn the pad and the buzz off in Red and
+-- had no way to reach either in Gold.
+local function addTouchRows(rows, add, opts, hooks)
+  -- TOUCH PAD only where the overlay can appear, mirroring OptionsMenu's
+  -- gate (mobile, or desktop forced by POKEPORT_TOUCH=1).
+  local env = os.getenv("POKEPORT_TOUCH")
+  local osName = love.system and love.system.getOS and love.system.getOS()
+  local show = env == "1"
+    or (env ~= "0" and (osName == "Android" or osName == "iOS"))
+  if show then
+    add(Strings("TOUCH PAD"),
+      function()
+        local tc = opts.touchControls
+        local on = not (type(tc) == "table" and tc.enabled == false)
+        return on and Strings("ON") or Strings("OFF")
+      end,
+      function()
+        local tc = type(opts.touchControls) == "table" and opts.touchControls or {}
+        tc.enabled = tc.enabled == false
+        opts.touchControls = tc
+        return true
+      end)
+    -- VIBRATION sits with it (#806): same gate, same subsystem.  Stepping
+    -- the row buzzes once at the level being selected.
+    local okTC, TC = pcall(require, "src.core.TouchControls")
+    if okTC then
+      add(Strings("VIBRATION"),
+        function() return Strings(TC.hapticLabel(opts.haptics)) end,
+        function(dir)
+          opts.haptics = TC.cycleHaptics(opts.haptics, dir)
+          TC.buzz(opts.haptics)
+          return true
+        end)
+    end
+  end
+
+  -- TOUCH CONTROLS, the on-screen pad's layout editor.  It used to be a
+  -- button on the game panel, once per game -- but the overlay layout is
+  -- global (options.touchControls.layouts), so three tabs offered three
+  -- buttons that edited the same thing while crowding the column that has to
+  -- hold Play.  It belongs with the other control rows, behind the gear.
+  -- The host owns the editor screen, so the row only fires when a hook was
+  -- supplied (the standalone save editor opens this model with none).
+  if hooks and hooks.editTouchControls then
+    rows[#rows + 1] = {
+      label = Strings("TOUCH CONTROLS"),
+      actionLabel = Strings("Edit"),
+      action = function()
+        hooks.editTouchControls()
+        -- The editor replaces the whole screen: nothing left to persist here
+        -- beyond what the caller already saved on the way out.
+        return false
+      end,
+    }
+  end
+end
+
 local function coreRows(opts, hooks)
   local rows = {}
   local function add(label, value, step)
@@ -236,60 +298,7 @@ local function coreRows(opts, hooks)
       end)
   end
 
-  -- TOUCH PAD only where the overlay can appear, mirroring OptionsMenu's
-  -- gate (mobile, or desktop forced by POKEPORT_TOUCH=1).
-  do
-    local env = os.getenv("POKEPORT_TOUCH")
-    local osName = love.system and love.system.getOS and love.system.getOS()
-    local show = env == "1"
-      or (env ~= "0" and (osName == "Android" or osName == "iOS"))
-    if show then
-      add(Strings("TOUCH PAD"),
-        function()
-          local tc = opts.touchControls
-          local on = not (type(tc) == "table" and tc.enabled == false)
-          return on and Strings("ON") or Strings("OFF")
-        end,
-        function()
-          local tc = type(opts.touchControls) == "table" and opts.touchControls or {}
-          tc.enabled = tc.enabled == false
-          opts.touchControls = tc
-          return true
-        end)
-      -- VIBRATION sits with it (#806): same gate, same subsystem.  Stepping
-      -- the row buzzes once at the level being selected.
-      local okTC, TC = pcall(require, "src.core.TouchControls")
-      if okTC then
-        add(Strings("VIBRATION"),
-          function() return Strings(TC.hapticLabel(opts.haptics)) end,
-          function(dir)
-            opts.haptics = TC.cycleHaptics(opts.haptics, dir)
-            TC.buzz(opts.haptics)
-            return true
-          end)
-      end
-    end
-  end
-
-  -- TOUCH CONTROLS, the on-screen pad's layout editor.  It used to be a
-  -- button on the game panel, once per game -- but the overlay layout is
-  -- global (options.touchControls.layouts), so three tabs offered three
-  -- buttons that edited the same thing while crowding the column that has to
-  -- hold Play.  It belongs with the other control rows, behind the gear.
-  -- The host owns the editor screen, so the row only fires when a hook was
-  -- supplied (the standalone save editor opens this model with none).
-  if hooks and hooks.editTouchControls then
-    rows[#rows + 1] = {
-      label = Strings("TOUCH CONTROLS"),
-      actionLabel = Strings("Edit"),
-      action = function()
-        hooks.editTouchControls()
-        -- The editor replaces the whole screen: nothing left to persist here
-        -- beyond what the caller already saved on the way out.
-        return false
-      end,
-    }
-  end
+  addTouchRows(rows, add, opts, hooks)
 
   -- RESET REBINDS, directly under the touch-pad row.  Rebinds are additive
   -- (src/core/Input.lua:applyBindings layers options.bindings over the
@@ -462,7 +471,7 @@ end
 -- src/ui/gen2/OptionsMenu.lua's ROWS; when editing one, keep the two in sync.
 local GEN2_KEY = "gold"
 
-local function gen2Rows(opts)
+local function gen2Rows(opts, hooks)
   local rows = {}
   local function add(label, value, step)
     rows[#rows + 1] = { label = label, value = value, step = step }
@@ -551,6 +560,8 @@ local function gen2Rows(opts)
       end)
   end
 
+  addTouchRows(rows, add, opts, hooks)
+
   return rows
 end
 
@@ -574,7 +585,7 @@ function LauncherSettings.open(hooks, version)
       opts[GEN2_KEY] = block
     end
     sections = {
-      { title = Strings("OPTIONS"), rows = gen2Rows(block) },
+      { title = Strings("OPTIONS"), rows = gen2Rows(block, hooks) },
     }
   else
     sections = {

src/import/RomImporter.lua

@@ -2652,11 +2652,14 @@ function RomImporter:_openSettings()
   -- hook rather than reaching for main.lua's handler itself.  Closing the
   -- settings panel FIRST persists the pending edits (_closeSettings saves)
   -- and leaves no modal behind the editor to return to.
+  -- The tab rides along: the editor persists the layout into that game's own
+  -- option block, and Gold's is not the flat Gen 1 one (#1100).
   local hooks = {}
   if self.onEditTouchControls then
+    local version = self.tab
     hooks.editTouchControls = function()
       self:_closeSettings()
-      self.onEditTouchControls()
+      self.onEditTouchControls(version)
     end
   end
   -- The tab the gear was opened on decides the row set: Gold reads a
@@ -2741,6 +2744,13 @@ function RomImporter:keypressed(key)
   end
   if self._modConfirm or self._modVersions or self._modReleaseNotes
       or self._findDetails then
+    -- Focus navigation belongs to the visible modal as well as the launcher
+    -- beneath it. Route arrows and an already-armed confirm before this guard
+    -- returns; unarmed Enter still falls through to the modal guard. Keep this
+    -- inside the modal branch so text fields retain exclusive keyboard input.
+    if self._flex and require("src.import.LauncherView").keypressed(self, key) then
+      return
+    end
     if key == "escape" then
       if self._findDetails then
         self._findDetails = nil

src/ui/OakSpeech.lua

@@ -266,7 +266,10 @@ function OakSpeech.new(game, onDone)
   -- RedSprite: the walking sprite the pic shrinks into (frame 0 =
   -- standing, facing down)
   local playerSprites = (game.data.field and game.data.field.playerSprites) or {}
-  local red = game.data.sprites and game.data.sprites[playerSprites.walk or "SPRITE_RED"] or game.data.sprites.SPRITE_RED
+  -- The fallback has to read the same guarded table: reaching for
+  -- game.data.sprites.SPRITE_RED after the `and` already found it nil threw.
+  local sprites = game.data.sprites or {}
+  local red = sprites[playerSprites.walk or "SPRITE_RED"] or sprites.SPRITE_RED
   self.walkSheet = tryImage(red and red.image)
   return self
 end

src/ui/OptionsMenu.lua

@@ -501,7 +501,7 @@ local function buildRows(game)
         return true
       end },
     -- Haptic feedback for on-screen pad presses (#806): OFF / LIGHT /
-    -- MEDIUM / HEAVY, where the intensity is a vibration duration --
+    -- NORMAL / STRONG, where the intensity is a vibration duration --
     -- love.system.vibrate takes nothing else.  Hidden with TOUCH PAD below,
     -- since the only thing that buzzes is a virtual button press.
     { id = "haptics", label = Strings("VIBRATION"),
@@ -515,7 +515,7 @@ local function buildRows(game)
         o.haptics = TC.cycleHaptics(o.haptics, dir)
         TC:applyOptions(o)
         -- sample the level being selected: stepping the row is the only way
-        -- to compare LIGHT against HEAVY without leaving the menu
+        -- to compare LIGHT against STRONG without leaving the menu
         TC.buzz(o.haptics)
         return true
       end },

src/ui/gen2/BattleState.lua

@@ -106,6 +106,10 @@ local TEXT_ASK_FORGET_SLOT = Strings.source("Which move should\nbe forgotten?")
 local TEXT_CANT_FORGET_HM = Strings.source("HM moves can't be\nforgotten now.")
 local TEXT_STOP_LEARNING = Strings.source("Stop learning\n%s?")
 
+-- BattleText_EnemyIsAboutToUseWillPlayerChangeMon (data/text/battle.asm:222-231).
+local TEXT_ENEMY_ABOUT_TO_USE = Strings.source(
+  "%s\nis about to use\v%s.\fWill %s\nchange POKéMON?")
+
 -- _AskForgetMoveText, all three paragraphs (data/text/common_3.asm:141-165).
 local TEXT_ASK_FORGET_MOVE = Strings.source(
   "%s is\ntrying to learn\v%s.\fBut %s\ncan't learn more\vthan four moves."
@@ -548,6 +552,14 @@ BattleState.PLAYER_PIC_TILES = 6
 -- box's own bottom centre.
 local PIC_RESIZE_TILES = { [0] = 6, [1] = 4, [2] = 2, [3] = 7, [4] = 5, [5] = 3 }
 
+-- SUBSTATUS_UNDERGROUND / SUBSTATUS_FLYING, which BattleCommand_Charge sets on
+-- FLY and DIG only (engine/battle/effect_commands.asm:5478-5485); the port
+-- carries both as the volatile `vanished` flag.
+function BattleState.isVanished(mon)
+  local volatiles = mon and mon.volatile
+  return (volatiles and volatiles.vanished) and true or false
+end
+
 function BattleState:drawPic(mon, back)
   -- During the intro slide the player-side pic belongs to presentSlide's
   -- backpic overlay, not to the baked bands (see BattleAnimView).
@@ -571,6 +583,13 @@ function BattleState:drawPic(mon, back)
   -- The box is empty either because the animation running right now has
   -- cleared it, or because the last one ENDED with it cleared (picHidden).
   if (anim and anim.hidden) or self.picHidden[side] then return end
+  -- Mid FLY / DIG the box is empty: DisappearUser ClearBoxes it
+  -- (engine/battle/misc.asm:1-13), AppearUserRaiseSub puts it back on the
+  -- stored attack (engine/battle/effect_commands.asm:2113-2117).
+  if not (trainerBack or enemyTrainer) and BattleState.isVanished(mon)
+     and not (self.vanishAnim and self.vanishAnim == self.anim) then
+    return
+  end
   local G = love.graphics
   local w, h = image:getDimensions()
   local px, py
@@ -582,10 +601,12 @@ function BattleState:drawPic(mon, back)
     py = BattleState.PLAYER_PIC_TILE_Y * 8 + (box - h)
     boxTiles = BattleState.PLAYER_PIC_TILES
   else
-    -- Bottom-aligned and horizontally centred inside the 7x7 box.
+    -- PadFrontpic pads a short pic and never a long one
+    -- (engine/gfx/load_pics.asm:342-386), so an oversized mod pic pins to the
+    -- box's own corner at hlcoord 12, 0 rather than to a negative offset.
     local box = BattleState.ENEMY_PIC_TILES * 8
-    px = BattleState.ENEMY_PIC_TILE_X * 8 + math.floor((box - w) / 2)
-    py = BattleState.ENEMY_PIC_TILE_Y * 8 + (box - h)
+    px = BattleState.ENEMY_PIC_TILE_X * 8 + math.max(0, math.floor((box - w) / 2))
+    py = BattleState.ENEMY_PIC_TILE_Y * 8 + math.max(0, box - h)
     boxTiles = BattleState.ENEMY_PIC_TILES
   end
   -- One tile per two frames to the right, SlideBattlePicOut's own step.
@@ -903,11 +924,12 @@ function BattleState:startAnim(key, opts)
     param = opts.param or 0,
     sfxOrder = audio.sfxOrder,
     ballPalette = opts.ballPalette,
+    -- BGEffect_CheckFlyDigStatus reads wPlayerSubStatus3 / wEnemySubStatus3
+    -- (engine/battle_anims/bg_effects.asm:2838-2851); the port keeps that bit
+    -- on the mon's volatile table, not on the mon itself.
     flying = {
-      player = self.battle and self.battle.player
-        and self.battle.player.vanished or false,
-      enemy = self.battle and self.battle.enemy
-        and self.battle.enemy.vanished or false,
+      player = BattleState.isVanished(self.battle and self.battle.player),
+      enemy = BattleState.isVanished(self.battle and self.battle.enemy),
     },
     hooks = {
       -- anim_sound (engine/battle_anims/anim_commands.asm:1105) calls
@@ -1365,6 +1387,13 @@ function BattleState:advanceQueue()
         end
       end
     end
+    -- BattleCommand_Charge runs LoadMoveAnim BEFORE DisappearUser
+    -- (engine/battle/effect_commands.asm:5459-5470), so FLY / DIG still draw
+    -- the take-off or the burrow on the turn the substatus goes up; the box
+    -- only empties once THIS animation is done with.
+    if BattleState.isVanished(self:activeMon(event.side)) then
+      self.vanishAnim = self.anim
+    end
   elseif event.kind == "damage" and event.side then
     -- ANIM_x_DAMAGE is the MOVE's after-anim (effect_commands.asm:1963-1972),
     -- so only a move hit gets it; `animMove` is HandleWrap's (core.asm:1198-1203).
@@ -1864,6 +1893,20 @@ function BattleState:update(_dt)
     return
   end
 
+  -- The prompt's earlier pages: PlaceYesNoBox only follows the LAST one
+  -- (engine/battle/core.asm:3302-3305), so the mon is named and read first.
+  if self.phase == "shift-intro" then
+    if self.messageTimer > 0 then
+      if input:wasPressed("a") or input:wasPressed("b") then
+        self.messageTimer = 0
+      end
+      return
+    end
+    self:nextPage()
+    if not self.messagePages then self.phase = "ask-shift" end
+    return
+  end
+
   -- OfferSwitch's YesNoBox: YES opens PickSwitchMonInBattle, NO (and B) falls
   -- straight through to the enemy's send-out (engine/battle/core.asm:3305-3310).
   if self.phase == "ask-shift" then
@@ -2464,13 +2507,13 @@ end
 -- (engine/battle/core.asm:3298-3304, data/text/battle.asm:222-231).
 function BattleState:offerShiftSwitch(mon)
   self.shiftIndex = 1
-  self.phase = "ask-shift"
   local trainer = (self.battle.trainer and self.battle.trainer.name) or "Foe"
   local player = (self.save and self.save.player and self.save.player.name)
     or "GOLD"
-  self.message = trainer .. " is about to use " .. self:name(mon)
-    .. ". Will " .. player .. " change POKéMON?"
-  self.messageTimer = MESSAGE_FRAMES
+  -- The `para` splits this in two (data/text/battle.asm:222-231): the incoming
+  -- mon is NAMED on its own page, and only the second carries the yes/no box.
+  self:showPages(Strings(TEXT_ENEMY_ABOUT_TO_USE, trainer, self:name(mon), player))
+  self.phase = self.messagePages and "shift-intro" or "ask-shift"
 end
 
 function BattleState:answerUseNextMon(yes)

src/update/Boot.lua

@@ -80,7 +80,8 @@ local function purgeBundledModules()
   end
 end
 
--- Boot.probePayload(rel) -> { engine = string, minShell = number } | nil, err
+-- Boot.probePayload(rel)
+--   -> { engine = string, minShell = number, payloadHost = string } | nil, err
 --
 -- Mount the archive at rel (a save-directory-relative path) on an isolated
 -- mountpoint, read its src/core/Version.lua by executing the source with
@@ -104,24 +105,50 @@ function Boot.probePayload(rel)
   if type(v) ~= "table" or type(v.engine) ~= "string" then
     return nil, "payload has no usable Version table"
   end
-  return { engine = v.engine, minShell = tonumber(v.minShell) or 1 }
+  return {
+    engine = v.engine,
+    minShell = tonumber(v.minShell) or 1,
+    payloadHost = type(v.payloadHost) == "string" and v.payloadHost or "love",
+  }
 end
 
--- Boot.select(candidates, bundledEngine, bundledShell) -> chosen | nil, toDelete
+-- Pure host gate shared by boot selection and the download worker. Missing
+-- payloadHost fields mean "love" so payloads made before this contract remain
+-- compatible with ordinary LOVE packages.
+function Boot.canHost(info, bundledShell, bundledPayloadHost)
+  if type(info) ~= "table" then return false end
+  local payloadHost = type(info.payloadHost) == "string"
+    and info.payloadHost or "love"
+  local host = type(bundledPayloadHost) == "string"
+    and bundledPayloadHost or "love"
+  return payloadHost == host and (tonumber(info.minShell) or 1)
+    <= (tonumber(bundledShell) or 1)
+end
+
+local function samePayloadHost(info, bundledPayloadHost)
+  local payloadHost = type(info.payloadHost) == "string"
+    and info.payloadHost or "love"
+  local host = type(bundledPayloadHost) == "string"
+    and bundledPayloadHost or "love"
+  return payloadHost == host
+end
+
+-- Boot.select(candidates, bundledEngine, bundledShell, bundledPayloadHost)
+--   -> chosen | nil, toDelete
 --
 -- Pure (no love.*): decide which payload to run and which to delete.
--- candidates is a list of { name = , engine = , minShell = }.
+-- candidates is a list of { name = , engine = , minShell = , payloadHost = }.
 --   * chosen: the highest engine that is STRICTLY newer than bundledEngine and
---     whose minShell <= bundledShell (a payload the running shell can host).
+--     whose payloadHost matches and minShell <= bundledShell.
 --   * toDelete: stale payloads -- engine <= bundled (old or the same as what we
 --     already ship), or superseded by the chosen one (not newer than chosen).
---     A payload newer than the chosen one but unrunnable here (minShell too
---     high) is kept: a future shell upgrade may be able to run it.
-function Boot.select(candidates, bundledEngine, bundledShell)
+--     A newer incompatible payload is kept: a matching host or future shell
+--     may be able to run it.
+function Boot.select(candidates, bundledEngine, bundledShell, bundledPayloadHost)
   local chosen
   for _, c in ipairs(candidates) do
     local newer = Semver.compare(c.engine, bundledEngine) > 0
-    local runnable = (c.minShell or 1) <= bundledShell
+    local runnable = Boot.canHost(c, bundledShell, bundledPayloadHost)
     if newer and runnable then
       if not chosen or Semver.compare(c.engine, chosen.engine) > 0 then
         chosen = c
@@ -132,9 +159,15 @@ function Boot.select(candidates, bundledEngine, bundledShell)
   local toDelete = {}
   for _, c in ipairs(candidates) do
     if not (chosen and c.name == chosen.name) then
-      local stale = Semver.compare(c.engine, bundledEngine) <= 0
-      if chosen and Semver.compare(c.engine, chosen.engine) <= 0 then
-        stale = true
+      local stale = false
+      -- Never clean up another host family's payloads. A shared save directory
+      -- may be opened by multiple native packages, and only the matching host
+      -- can decide whether one of its own archives is stale.
+      if samePayloadHost(c, bundledPayloadHost) then
+        stale = Semver.compare(c.engine, bundledEngine) <= 0
+        if chosen and Semver.compare(c.engine, chosen.engine) <= 0 then
+          stale = true
+        end
       end
       if stale then toDelete[#toDelete + 1] = c.name end
     end
@@ -223,6 +256,7 @@ local function runInner(args)
             name = entry,
             engine = info.engine,
             minShell = info.minShell,
+            payloadHost = info.payloadHost,
           }
         end
       end
@@ -230,7 +264,8 @@ local function runInner(args)
   end
 
   local Version = require("src.core.Version")
-  local chosen, toDelete = Boot.select(candidates, Version.engine, Version.shell)
+  local chosen, toDelete = Boot.select(candidates, Version.engine,
+    Version.shell, Version.payloadHost)
 
   for _, victim in ipairs(toDelete) do
     love.filesystem.remove(PAYLOAD_DIR .. "/" .. victim)

src/update/check_worker.lua

@@ -153,8 +153,9 @@ local function gatePasses(rel)
   local info = Boot.probePayload(rel)
   if not info then return true end
   local shell = (Version and Version.shell) or 1
-  if info.minShell and info.minShell > shell then return false end
-  return true
+  local payloadHost = (Version and Version.payloadHost) or "love"
+  if Boot.canHost then return Boot.canHost(info, shell, payloadHost) end
+  return not (info.minShell and info.minShell > shell)
 end
 
 -- ---------------------------------------------------------------------------

src/world/OverworldController.lua

@@ -1397,14 +1397,16 @@ function OverworldState:checkLedgeHop(dir)
           return false
         end
         require("src.core.Sound").play(Game.data, "Ledge")
-        p.hopFrames, p.hopTotal = 32, 32 -- jump arc (cosmetic)
+        local hop = (p.stepFramesCur or p.stepFrames or 16) * 2
+        p.hopFrames, p.hopTotal = hop, hop -- jump arc (cosmetic)
         self:scriptMove(p, dir, 1, function() self:checkEdgeExit(dir) end)
         return true
       end
       if not Collision.occupied(self.entities, lx, ly, p)
          and self.map:isWalkableCell(lx, ly) then
         require("src.core.Sound").play(Game.data, "Ledge")
-        p.hopFrames, p.hopTotal = 32, 32 -- jump arc (cosmetic)
+        local hop = (p.stepFramesCur or p.stepFrames or 16) * 2
+        p.hopFrames, p.hopTotal = hop, hop -- jump arc (cosmetic)
         self:scriptMove(p, dir, 2)
         return true
       end
@@ -3515,10 +3517,21 @@ end
 
 function OverworldState:onStepComplete()
   local p = self.player
-  local suppressWildEncounter = self.wildEncounterGraceSteps > 0
-  if suppressWildEncounter then
-    self.wildEncounterGraceSteps = self.wildEncounterGraceSteps - 1
+  -- Defaulted: a state built without the constructor (a mod harness, a test
+  -- fixture) reaches this before :234 ever ran, and nil > 0 threw the step.
+  local grace = self.wildEncounterGraceSteps or 0
+  if grace > 0 then
+    self.wildEncounterGraceSteps = grace - 1
   end
+  -- TryDoWildEncounter's first guard is `ld a, [wNPCMovementScriptPointerTable
+  -- Num] / and a / ret nz` (engine/battle/wild_encounters.asm:3-9): a step the
+  -- player did not take never rolls, which is why Oak's escort walks to the lab
+  -- through Pallet's grass without being jumped.
+  local runner = self.runner
+  local scripted = (runner and runner.isRunning and runner:isRunning())
+    or #(self.scriptMoves or {}) > 0
+    or self.engaging or self.emote or self.teleportOut
+  local suppressWildEncounter = grace > 0 or scripted and true or false
   self.todSteps = (self.todSteps or 0) + 1
   -- UpdatePikachuHappinessAndMood rides the step counter (poison.asm)
   require("src.world.PikachuFollower").onStep(Game.save)

src/world/gen2/World.lua

@@ -3946,7 +3946,8 @@ function World:rollEncounter(kind, terrain, tables, vanilla)
   local ctx = {
     mapId = map and map.id,
     terrain = terrain,
-    rng = love.math.random,
+    -- Same guard World:rockRandom uses: a headless suite has no love global.
+    rng = (love and love.math and love.math.random) or math.random,
     kind = kind,
     daytime = self.daytime,
     environment = map and map.def and map.def.environment,