Integrate battles with the overworld UI and validate browser flows

- Drive wild battles through the real UI in Chromium and WebKit using a
  test-only encounter fixture: victory with level-up, escape, whiteout,
  mid-battle backup restore and unsupported-effect rollback.
- Add keyboard and on-screen D-pad navigation for battle menus.
- Accept pending stat experience in saves (awarded without CalcMonStats).
- Commit whiteout healing, money loss and destination callbacks together;
  aborted scripts restore state and map.
- Give long notices their own status-bar row on narrow screens.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/battle-world.test.ts

@@ -0,0 +1,144 @@
+import { describe, expect, it } from "vitest";
+import { existsSync, readFileSync } from "node:fs";
+import { CrystalAssets } from "../src/game/rom/assets";
+import { battleFixtureWorld, ENCOUNTER_WALK, type BattleScenario } from "./battle-fixture";
+import type { GameWorld } from "../src/game/world/world";
+import { generatePartyMon, calcStats } from "../src/game/party/pokemon";
+
+const romPath = process.env.CRYSTAL_ROM_PATH ?? "Pokemon - Crystal Version (UE) (V1.1) [C][!].gbc";
+const fixture = (scenario: BattleScenario = "win") =>
+  battleFixtureWorld(new CrystalAssets(new Uint8Array(readFileSync(romPath))), scenario);
+
+function encounter(world: GameWorld) {
+  for (const direction of ENCOUNTER_WALK) expect(world.move(direction)).toBe(true);
+  expect(world.battle).toBeDefined();
+}
+
+function finish(world: GameWorld, action: "fight" | "run" = "fight") {
+  const messages = new Set<string>();
+  for (let tick = 0; tick < 10000; tick++) {
+    if (world.battle) {
+      const view = world.battle;
+      if (view.message) messages.add(view.message.text);
+      if (view.prompt?.kind === "action") world.battleAction({ action, move: 0 });
+      else if (view.prompt?.kind === "yesno") world.battleChoose(1);
+      else if (view.prompt?.kind === "forget") world.battleChoose(3);
+      else if (view.prompt?.kind === "stats" || view.message?.prompt) world.interact();
+      else world.tick();
+    } else if (world.dialogue) {
+      messages.add(world.dialogue.pages[world.dialogue.index]);
+      world.advanceDialogue();
+      world.tick();
+    } else if (world.busy) world.tick();
+    else return [...messages].join("\n");
+  }
+  throw new Error(`Battle did not settle: ${world.diagnostic}`);
+}
+
+describe.skipIf(!existsSync(romPath))("world battle integration with the local ROM", () => {
+  it("commits a victory, level-up, move learning and Pokédex sighting", () => {
+    const world = fixture();
+    encounter(world);
+    const before = world.save();
+    expect(before.party[0].level).toBe(5);
+    expect(before.pokedex.seen).toEqual([155]);
+    const messages = finish(world);
+    expect(world.notice, world.diagnostic).toBe("");
+    expect(messages).toContain("SMOKESCREEN");
+    expect(world.state.party[0].level).toBe(6);
+    expect(world.state.party[0].moves).toContain(108);
+    expect(world.state.pokedex.seen.has(16)).toBe(true);
+    expect(world.state.pokedex.caught.has(16)).toBe(false);
+    const saved = world.save();
+    world.restore(saved);
+    expect(world.save()).toEqual(saved);
+  });
+
+  it("escapes without awarding experience and returns to walking", () => {
+    const world = fixture();
+    encounter(world);
+    expect(finish(world, "run")).toMatch(/Got away safely/);
+    expect(world.notice, world.diagnostic).toBe("");
+    expect(world.state.party[0].exp).toBe(178);
+    expect(world.state.pokedex.seen.has(16)).toBe(true);
+    expect(world.move("down")).toBe(true);
+  });
+
+  it("restores earned stat experience before the next stat recalculation", () => {
+    const world = fixture();
+    const mon = generatePartyMon(world.assets.pokemon, {
+      species: 155, level: 100, item: 0, otId: world.playerId,
+      ot: "CHRIS", dvs: 0x823b, caughtData: 0,
+    });
+    mon.moves = [33, 0, 0, 0];
+    mon.pp = [35, 0, 0, 0];
+    world.state.party = [mon];
+    encounter(world);
+    finish(world);
+    expect(world.notice, world.diagnostic).toBe("");
+    const saved = world.save();
+    expect(saved.party[0].statExp.some((value) => value > 0)).toBe(true);
+    expect(saved.party[0].stats).not.toEqual(calcStats(world.assets.pokemon, 155, mon.dvs, 100, saved.party[0].statExp));
+    expect(() => world.restore(saved)).not.toThrow();
+    expect(world.save()).toEqual(saved);
+    const corrupt = structuredClone(saved);
+    corrupt.party[0].stats[1] = 999;
+    expect(() => world.restore(corrupt)).toThrow("Invalid native save");
+  });
+
+  it("whiteout heals the party, halves money and returns home", () => {
+    const world = fixture("loss");
+    encounter(world);
+    const messages = finish(world);
+    expect(world.notice, world.diagnostic).toBe("");
+    expect(messages).toMatch(/whited\s+out/i);
+    expect(world.save()).toMatchObject({ map: "24:7", x: 3, y: 3, money: 1500 });
+    const mon = world.state.party[0];
+    expect(mon.hp).toBe(mon.stats[0]);
+    expect(mon.pp[0]).toBe(35);
+    expect(mon.status).toBe(0);
+  });
+
+  it("a mid-battle save restores the committed party and position", () => {
+    const world = fixture();
+    encounter(world);
+    const committed = world.save();
+    for (let tick = 0; tick < 5000; tick++) {
+      if (world.battle?.prompt?.kind === "action") {
+        world.battleAction({ action: "fight", move: 0 });
+        break;
+      }
+      if (world.battle?.message?.prompt) world.interact();
+      else world.tick();
+    }
+    expect(world.save()).toEqual(committed);
+    world.restore(committed);
+    expect(world.battle).toBeUndefined();
+    expect(world.save()).toEqual(committed);
+    expect(world.move("right")).toBe(true);
+  });
+
+  it("a failed whiteout map callback cannot commit healing or money loss", () => {
+    const world = fixture("loss");
+    encounter(world);
+    const before = world.save();
+    // A malformed callback models a destination whose logic is not supported.
+    world.assets.map("24:7").callbacks.push({ kind: 5, script: world.assets.reader.bytes.length });
+    finish(world);
+    expect(world.notice).toContain("not been ported");
+    expect(world.save().money).toBe(before.money);
+    expect(world.save().party).toEqual(before.party);
+    expect(world.save().pokedex).toEqual(before.pokedex);
+  });
+
+  it("unsupported effects discard all battle party and Pokédex changes", () => {
+    const world = fixture("unsupported");
+    encounter(world);
+    const before = world.save();
+    finish(world);
+    expect(world.notice).toContain("not been ported");
+    expect(world.save().party).toEqual(before.party);
+    expect(world.save().pokedex).toEqual(before.pokedex);
+    expect(world.save().money).toBe(before.money);
+  });
+});