Delay evolution until trainer text ends

src/script/Commands.lua

@@ -265,7 +265,18 @@ function Commands.start_battle(ctx, kind, a, b)
     ctx.lastBattleResult = result
     ctx.lastCheck = result == "win"
     if ctx.overworld then
-      ctx.overworld:afterBattle(result, battle)
+      -- A map script often follows a trainer battle with its own text.
+      -- Keep a level evolution behind that text: otherwise afterBattle
+      -- pushes the evolution screen, then this runner resumes and pushes
+      -- the trainer's text on top of it.
+      if result == "win" then
+        ctx.afterScript = ctx.afterScript or {}
+        table.insert(ctx.afterScript, function()
+          ctx.overworld:afterBattle(result, battle)
+        end)
+      else
+        ctx.overworld:afterBattle(result, battle)
+      end
     end
     runner:resume()
   end

src/script/ScriptRunner.lua

@@ -125,6 +125,10 @@ function ScriptRunner:run(script, extra)
   end
   self.co = coroutine.create(function()
     self:exec(script, ctx)
+    -- Commands can defer a game action until the script's own dialogue is
+    -- done. start_battle uses this for win-path evolutions, which must not
+    -- be covered by post-battle trainer text.
+    for _, callback in ipairs(ctx.afterScript or {}) do callback() end
     if ctx.onDone then ctx.onDone() end
     if Runtime.wants("script.ended") then
       Runtime.emit("script.ended", { ctx = ctx, completed = true })

tests/parity_trainer_evolution_order.lua

@@ -0,0 +1,84 @@
+-- A trainer script's post-battle text must finish before a level evolution.
+-- Its start_battle row resumes the script after OverworldState:afterBattle,
+-- so this covers the same handoff used by trainer and Rocket encounters.
+
+package.path = "./?.lua;./?/init.lua;" .. package.path
+if not _G.love then _G.love = require("tests.love_stub") end
+
+local Data = require("src.core.Data")
+if not Data.maps then Data:load() end
+local S = require("tests.harness").suite("parity trainer evolution order")
+local check = S.check
+
+local Game = require("src.core.Game")
+local SaveData = require("src.core.SaveData")
+local StateStack = require("src.core.StateStack")
+local ScriptRunner = require("src.script.ScriptRunner")
+local OverworldState = require("src.world.OverworldController")
+local Pokemon = require("src.pokemon.Pokemon")
+require("src.render.Font").load(Data)
+
+Game.data = Data
+Game.save = SaveData.newGame()
+Game.stack = StateStack; StateStack:init()
+Game.renderer = { worldViewSize = function() return 160, 144 end }
+
+local caterpie = Pokemon.new(Data, "CATERPIE", 7)
+Game.save.party = { caterpie }
+
+local fakeBattle
+local originalBattleState = package.loaded["src.battle.BattleState"]
+package.loaded["src.battle.BattleState"] = {
+  newTrainer = function()
+    fakeBattle = { leveledUp = { [caterpie] = true } }
+    return fakeBattle
+  end,
+}
+
+local overworld = setmetatable({}, { __index = OverworldState })
+overworld:enter("ROUTE_1", 5, 5, "down")
+local runner = ScriptRunner.new(Game, overworld)
+runner:run({
+  { "start_battle", "trainer", "OPP_YOUNGSTER", 1 },
+  { "show_text", "THE TRAINER TALKS AFTER THE FIGHT" },
+  { "show_text", "THE TRAINER HAS MORE TO SAY" },
+})
+
+check(fakeBattle ~= nil, "trainer battle starts and yields the script")
+Game.stack:pop()
+fakeBattle.onFinish("win")
+
+package.loaded["src.battle.BattleState"] = originalBattleState
+
+local function stateHas(state, text)
+  for _, page in ipairs(state.pages or {}) do
+    for _, line in ipairs(page) do
+      if type(line) == "string" and line:find(text, 1, true) then return true end
+    end
+  end
+  return false
+end
+
+local afterText = Game.stack:top()
+check(stateHas(afterText, "THE TRAINER TALKS"),
+  "the trainer's after-battle text is shown first")
+check(#Game.stack.states == 1,
+  "the evolution screen waits until trainer after-text closes")
+
+Game.stack:pop()
+afterText.onDone()
+
+local moreText = Game.stack:top()
+check(stateHas(moreText, "MORE TO SAY"),
+  "all trainer after-text finishes before evolution")
+check(#Game.stack.states == 1,
+  "the evolution still waits for the last trainer text")
+
+Game.stack:pop()
+moreText.onDone()
+
+local evolutionText = Game.stack:top()
+check(stateHas(evolutionText, "evolving"),
+  "the level evolution starts after trainer after-text closes")
+
+S.finish()

tests/run_tests.lua

@@ -3279,6 +3279,7 @@ runSuites(orderedGlob("tests/parity_*.lua", {
   "tests/parity_hof.lua", "tests/parity_trade_gift.lua",
   "tests/parity_yellow_trades.lua",
   "tests/parity_yellow_bills_pikachu.lua",
+  "tests/parity_trainer_evolution_order.lua",
   "tests/parity_intro.lua", "tests/parity_tilt.lua",
   "tests/parity_gbcfx.lua",
 }))