Battle BGM follows the round: rounds 1–7 无畏者 (bat_kazimierz2_2), rounds 8–13 骑士之日 (bat_kazimierz2_1), as in the official level data (#72)

联防 keeps the escaped stage's corrosion track (#110). Contributed by @Convey123.

data/assets.json

@@ -1 +1 @@
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truncated
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truncated

docs/ASSETS.md

@@ -84,7 +84,7 @@ The research JSONs in `docs/research/` (03, 05, 07) define **which** ids are nee
 | Token Spine | fexli: the default model, or else the first skin variant (`spine/{tokenId}/{variant}/Spine/`) | `spine/token/{tokenId}/{stem}.*` |
 | Enemy Spine (PC build, premultiplied alpha) | isHarryh/Ark-Models `models_enemies/{key}/`, file names from `models_data.json` | `spine/enemy/{enemyId}/{stem}.*` |
 | Enemy Spine that no dump carries (灼热源石虫 / 炽焰源石虫) | the local client only (`tools/local-extract/extract.py ENEMY_SPINES`, optional); never downloaded and never required: an overlay of the web alias (`enemies[id].spineLocal`) | `local/spine/enemy/{enemyId}/{stem}.*` (listed in `data/local-assets.json`) |
-| BGM | AA2 `voice` branch `audio/sound_beta_2/music/**` | `audio/bgm/{file}.mp3` |
+| BGM | AA2 `voice` branch `audio/sound_beta_2/music/**` (大厅/休整期 `act1autochess`, 开战 `act13side/m_bat_kazimierz2_{1,2}` — 骑士之日 / 无畏者; the 开战 track follows the round: `_2` 无畏者 rounds 1–7, `_1` 骑士之日 from round 8) | `audio/bgm/{file}.mp3` |
 | SFX (UI, battle, per unit) | AA2 `voice` `audio/sound_beta_2/**`, mapped from `audio_data.json` banks | `audio/sfx/{same sub-path}.mp3` |
 | Fonts: Bender Regular and Light, Novecento Wide | TimWangZi/The-font-of-Arknights | `public/fonts/*.{otf,ttf,woff2}`, `public/fonts/fonts.css` |
 
@@ -153,11 +153,13 @@ All paths are URL paths relative to the site root, for example `/assets/char/ava
                                     // group + name of the same picture (the client takes the local one first)
   prof:    { icon: {caster…warrior}, large: {…}, battlecard: {…, token}, sub: {[subProfessionId]: url} },
   audio: {
-    bgm:     { lobby, prep, combat, unite?: { intro?, loop }, boss: { intro?, loop } },
-             // intro then crossfade to loop (1 s); `unite` = 联防's own track — the official
-             // escaped_single / escaped_multi levels declare `bgmEvent = corrosion` (卡西米尔 act13d5d0),
-             // so the rescue phase does not reuse the 作战's track (audio.js bgmKeyFor 'unite', falling
-             // back to `bgm.combat` for a manifest that lacks it)
+    bgm:     { lobby, prep, combat, combatAlts?: [{ intro?, loop }, …], unite?: { intro?, loop }, boss: { intro?, loop } },
+             // intro then crossfade to loop (1 s); combatAlts = the 开战 tracks of the mode's own act, chosen by the
+             // round, not drawn: [0] = m_bat_kazimierz2_1 骑士之日 (rounds 8–13), [1] = m_bat_kazimierz2_2 无畏者
+             // (rounds 1–7) — audio.js combatTrackFor / bgmKeyFor 'combat:<i>', the same on every client;
+             // `unite` = 联防's own track — the official escaped_single / escaped_multi levels declare
+             // `bgmEvent = corrosion` (卡西米尔 act13d5d0), so the rescue phase does not reuse the 作战's track
+             // (audio.js bgmKeyFor 'unite', falling back to `bgm.combat` for a manifest that lacks it)
     bossBgm: { [bossId]: { intro?, loop } },                   // per-boss track of its R14/R15 level
     sfx: {
       ui:     { click, back, confirm, tab, pick, drop, error, buy, sell, income, refresh, freeze, levelup,

public/js/audio.js

@@ -1,7 +1,8 @@
 // Audio manager (Web Audio): BGM per phase, UI SFX, per-unit battle SFX. Never throws.
 //
 // Sources: data/assets.json → audio (docs/ASSETS.md):
-//   bgm { lobby, prep, combat, boss: { intro?, loop } }, bossBgm { [bossId]: { intro?, loop } },
+//   bgm { lobby, prep, combat, combatAlts?: [ {intro?, loop}, … ], boss: { intro?, loop } },
+//   bossBgm { [bossId]: { intro?, loop } },
 //   sfx.ui { click, buy, sell, refresh, freeze, levelup, merge, equip, ready, timer, yourTurn, … },
 //   sfx.battle { deploy, tokenDeploy, charDie, tokenDie?, enemyDie, enemyHit, heal, killCoin, … },
 //   sfx.units { [charId|tokenId|enemyId]: { attack?, hit?, skill?, die?, born?, mix?: { [role]: { p?, vol? } } } }.
@@ -11,6 +12,10 @@
 // - Channels: master → { bgm, sfx } gains; volumes from settings (0..1) + mute. Tab hidden ⇒ suspend.
 // - BGM: `intro` then `loop` (1 s crossfade); switching tracks fades out/in (0.8 s). The same loop URL
 //   keeps playing across phases (prep and combat share a track).
+// - 开战 BGM: `bgm.combatAlts` are the mode's own battle tracks (塞壬唱片 骑士之日 / 无畏者). The track is fixed per
+//   round, not drawn: 无畏者 through rounds 1–7 and 骑士之日 from round 8 on (`combatTrackFor`, the official
+//   schedule), so every client of a match hears the same one, a fight never switches track halfway through and the
+//   联防 that follows a 作战 keeps its round's track.
 // - Battle SFX from `b.ev` tuples (`handleBattleEvents`): at most MAX_VOICES concurrent unit sounds, at most
 //   MAX_PER_URL overlapping copies of one sound (the official banks' maxSoundAllowed 2), a per-unit cooldown and a
 //   per-URL minimum gap (SfxLimiter), so a 60-unit fight stays listenable.
@@ -59,9 +64,11 @@ const SKILL_MODE_FILE = /_(d|h|s)\d*\.mp3$/i;
  * BGM key for a route + match phase.
  * @param {'title'|'lobby'|'room'|'game'|string} route
  * @param {any} pub m.public (may be null)
- * @returns {string|null} 'lobby' | 'prep' | 'combat' | 'unite' | 'boss' | 'boss:<bossId>' | null
+ * @param {0|1|null} [combatTrack] the round's own 开战 track index into `bgm.combatAlts` (combatTrackFor; omitted ⇒
+ *   plain 'combat', i.e. the manifest's default combat track)
+ * @returns {string|null} 'lobby' | 'prep' | 'combat' | 'combat:<i>' | 'unite' | 'boss' | 'boss:<bossId>' | null
  */
-export function bgmKeyFor(route, pub) {
+export function bgmKeyFor(route, pub, combatTrack = null) {
   if (route !== 'game') return route === 'title' || route === 'lobby' || route === 'room' ? 'lobby' : null;
   const phase = pub?.phase;
   if (!phase) return 'lobby';
@@ -74,7 +81,8 @@ export function bgmKeyFor(route, pub) {
       // resolveBgm falls back to `bgm.combat` when a manifest predates it.
       return 'unite';
     case PHASE.COMBAT:
-      return 'combat';
+      // 开战 BGM: the round's own track — 骑士之日 / 无畏者 are fixed per round, not drawn (combatTrackFor)
+      return combatTrack == null ? 'combat' : `combat:${combatTrack ? 1 : 0}`;
     case PHASE.FINAL_ASSAULT:
       return pub.bossId ? `boss:${pub.bossId}` : 'boss';
     case PHASE.HIDDEN_CORE:
@@ -85,8 +93,9 @@ export function bgmKeyFor(route, pub) {
 }
 
 /**
- * Resolve a BGM key to { intro?, loop } URLs from the manifest: `boss:<id>` falls back to the generic boss track and
- * `unite` (联防's own track) to `bgm.combat` when the manifest predates it.
+ * Resolve a BGM key to { intro?, loop } URLs from the manifest: `boss:<id>` falls back to the generic boss track,
+ * `combat:<i>` to the i-th `bgm.combatAlts` entry (and to `bgm.combat` when the manifest has none), and `unite`
+ * (联防's own track) to `bgm.combat` when the manifest predates it.
  * @param {any} manifest
  * @param {string|null} key
  * @returns {{ intro: string|null, loop: string }|null}
@@ -96,12 +105,33 @@ export function resolveBgm(manifest, key) {
   if (!a || !key) return null;
   let t = null;
   if (key.startsWith('boss:')) t = a.bossBgm?.[key.slice(5)] || a.bgm?.boss;
+  else if (key.startsWith('combat:')) t = a.bgm?.combatAlts?.[Number(key.slice('combat:'.length))] || a.bgm?.combat;
   else if (key === 'unite') t = a.bgm?.unite || a.bgm?.combat;
   else t = a.bgm?.[key];
   if (!t || typeof t.loop !== 'string') return null;
   return { intro: typeof t.intro === 'string' ? t.intro : null, loop: t.loop };
 }
 
+/**
+ * The last round that plays 无畏者 (1–7); from the next round on it is 骑士之日 (8–13) — the official schedule
+ * (docs/ASSETS.md "BGM"; the two tracks are the 塞壬唱片 act13side battle themes).
+ */
+export const COMBAT_TRACK_SWITCH_ROUND = 7;
+
+/**
+ * The round's own 开战 track index into `bgm.combatAlts` (plan.mjs order: 0 = `m_bat_kazimierz2_1` 骑士之日,
+ * 1 = `m_bat_kazimierz2_2` 无畏者). The mode does not draw these: the official schedule plays one per round, 无畏者
+ * through the early rounds (1–7) and 骑士之日 from round 8 to the last normal round (8–13). Everything after that is
+ * the boss rounds (最终攻势 / 隐秘核心), which have their own tracks and never ask for `combat:<i>`.
+ * @param {number|null|undefined} round m.public.round
+ * @returns {0|1|null} null when the round is unknown ⇒ the manifest's plain `combat` track
+ */
+export function combatTrackFor(round) {
+  const r = Number(round);
+  if (!Number.isFinite(r) || r < 1) return null;
+  return r <= COMBAT_TRACK_SWITCH_ROUND ? 1 : 0;
+}
+
 /**
  * Official sound class of a battle unit (audio_data `battle.ON_UNIT_DEAD|BORN.<class>` defaults):
  * 'enemy' | 'char' (operators: b_char_dead “干员被击倒” / b_char_set) | 'token' (summons: b_char_tokendead /
@@ -718,7 +748,13 @@ export function installAudio(deps) {
     if (deps?.settings) audio.setVolumes(deps.settings);
     if (typeof deps?.subscribe === 'function' && typeof deps?.getState === 'function') {
       const sync = (s) => {
-        try { audio.playBgm(bgmKeyFor(deps.selectRoute(s), s.match?.public)); } catch { /* ignore */ }
+        try {
+          const pub = s.match?.public ?? null;
+          // 开战 BGM: the round's own track out of bgm.combatAlts (骑士之日 / 无畏者 are fixed per round, not drawn),
+          // so every client of a room hears the same one, a mid-fight re-render (or a teammate view) never switches,
+          // and the next round moves on by the table. 联防 shares its round ⇒ same key ⇒ the loop keeps playing.
+          audio.playBgm(bgmKeyFor(deps.selectRoute(s), pub, combatTrackFor(pub?.round)));
+        } catch { /* ignore */ }
       };
       sync(deps.getState());
       return deps.subscribe((s, prev) => {

test/ui/audio.test.js

@@ -6,7 +6,7 @@ import assert from 'node:assert/strict';
 import { readFileSync } from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { bgmKeyFor, resolveBgm, SfxLimiter, AudioManager, normalAttackSfx } from '../../public/js/audio.js';
+import { bgmKeyFor, resolveBgm, SfxLimiter, AudioManager, normalAttackSfx, installAudio, audio, combatTrackFor, COMBAT_TRACK_SWITCH_ROUND } from '../../public/js/audio.js';
 import { mediaUrl } from '../../public/js/media.js';
 import { PHASE } from '../../shared/constants.js';
 
@@ -32,18 +32,53 @@ describe('bgm selection', () => {
     assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT }), 'combat');
     // 联防 has its own track: the official escaped_single / escaped_multi levels declare bgmEvent = corrosion
     assert.equal(bgmKeyFor('game', { phase: PHASE.UNITE }), 'unite');
+    // 开战 BGM: the round's own track (combatTrackFor) indexes the manifest's `bgm.combatAlts`
+    assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT }, 0), 'combat:0');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT }, 1), 'combat:1');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.UNITE }, 1), 'unite', '联防 keeps its own track, not the round index');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.PREP }, 1), 'prep');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.FINAL_ASSAULT, bossId: 'boss_4' }, 1), 'boss:boss_4');
     assert.equal(bgmKeyFor('game', { phase: PHASE.FINAL_ASSAULT, bossId: 'boss_4' }), 'boss:boss_4');
     assert.equal(bgmKeyFor('game', { phase: PHASE.FINAL_ASSAULT }), 'boss');
-    assert.equal(bgmKeyFor('game', { phase: PHASE.HIDDEN_CORE, bossId: 'boss_1', hiddenBossId: 'boss_9' }), 'boss:boss_9');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.HIDDEN_CORE, bossId: 'boss_1', hiddenBossId: 'boss_9' }, 1), 'boss:boss_9');
     assert.equal(bgmKeyFor('game', { phase: PHASE.RESULT }), 'lobby');
     assert.equal(bgmKeyFor('weird', null), null);
   });
+  test('开战 BGM: the track is fixed per round, not drawn (无畏者 1–7, 骑士之日 8–13)', () => {
+    // The mode does not draw its battle theme: the official schedule plays 无畏者 through the early rounds and
+    // 骑士之日 from round 8 on (reviewer note — review had this as a per-match 0.5 draw before).
+    for (const r of [1, 2, 3, 4, 5, 6, 7]) assert.equal(combatTrackFor(r), 1, `round ${r} plays 无畏者`);
+    for (const r of [8, 9, 10, 11, 12, 13]) assert.equal(combatTrackFor(r), 0, `round ${r} plays 骑士之日`);
+    assert.equal(COMBAT_TRACK_SWITCH_ROUND, 7, 'the switch sits between round 7 and 8');
+    // the boss rounds (14 最终攻势 / 15 隐秘核心) have their own tracks and never ask for combat:<i>
+    assert.equal(bgmKeyFor('game', { phase: PHASE.FINAL_ASSAULT, round: 14 }, combatTrackFor(14)), 'boss');
+    // an unknown round falls back to the manifest's plain combat track (older manifest / no round yet)
+    for (const bad of [null, undefined, 0, -1, NaN, 'x']) assert.equal(combatTrackFor(bad), null, `${bad} ⇒ no index`);
+    assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT, round: 3 }, combatTrackFor(null)), 'combat');
+    // both ends of a real run: a solo 标准 match is 9 rounds, so it hears 无畏者 and then 骑士之日
+    assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT, round: 7 }, combatTrackFor(7)), 'combat:1');
+    assert.equal(bgmKeyFor('game', { phase: PHASE.COMBAT, round: 8 }, combatTrackFor(8)), 'combat:0');
+    // the index↔track mapping this table assumes, from docs/ASSETS.md: combatAlts[0] = m_bat_kazimierz2_1 骑士之日,
+    // combatAlts[1] = m_bat_kazimierz2_2 无畏者 (a reordering upstream breaks this test, not the players' ears)
+    const alt = manifest.audio.bgm.combatAlts;
+    assert.ok(alt[0].loop.includes('m_bat_kazimierz2_1'), `combatAlts[0] is 骑士之日: ${alt[0].loop}`);
+    assert.ok(alt[1].loop.includes('m_bat_kazimierz2_2'), `combatAlts[1] is 无畏者: ${alt[1].loop}`);
+  });
   test('resolveBgm uses the manifest (boss fallback, intro optional)', () => {
     const lobby = resolveBgm(manifest, 'lobby');
     assert.ok(lobby && typeof lobby.loop === 'string');
     const b4 = resolveBgm(manifest, 'boss:boss_4');
     assert.equal(b4.loop, manifest.audio.bossBgm.boss_4.loop);
     assert.equal(resolveBgm(manifest, 'boss:nope').loop, manifest.audio.bgm.boss.loop);
+    // 开战 BGM: combat:<i> → bgm.combatAlts[i], and back to the default combat track when the index (or the whole
+    // array, e.g. an older manifest) is missing
+    const alts = manifest.audio.bgm.combatAlts;
+    assert.ok(Array.isArray(alts) && alts.length >= 2, 'manifest carries the mode’s own battle tracks');
+    assert.equal(resolveBgm(manifest, 'combat:0').loop, alts[0].loop);
+    assert.equal(resolveBgm(manifest, 'combat:1').loop, alts[1].loop);
+    assert.notEqual(alts[0].loop, manifest.audio.bgm.combat.loop, 'a real battle track, not the shop loop');
+    assert.equal(resolveBgm(manifest, 'combat:9').loop, manifest.audio.bgm.combat.loop);
+    assert.equal(resolveBgm({ audio: { bgm: { combat: { loop: '/shop.mp3' } } } }, 'combat:0').loop, '/shop.mp3');
     assert.equal(resolveBgm(manifest, 'prep').intro, manifest.audio.bgm.prep.intro ?? null);
     // 联防's own track (bgm.unite = corrosion, the official escaped levels' bgmEvent), and the fallback for an older
     // manifest that has no `unite` entry (the music must not go silent)
@@ -57,6 +92,49 @@ describe('bgm selection', () => {
     assert.equal(resolveBgm(manifest, null), null);
     assert.equal(resolveBgm(manifest, 'nope'), null);
   });
+  test('installAudio: the round\'s own 开战 track, fixed per round and the same on every client', () => {
+    const calls = [];
+    const origPlay = audio.playBgm;
+    audio.playBgm = (k) => { calls.push(k); };
+    try {
+      const pub = (o) => ({ phase: PHASE.PREP, round: 1, stageId: 'st1', players: [{ playerId: 'p1' }], ...o });
+      const state = { route: 'game', match: { public: pub({}) } };
+      let fire = null;
+      /** One client: its own store subscription (the expected keys below are what its own round yields — the point of
+       * the test is that the track follows the round, never moves inside a battle and never differs between clients). */
+      const wire = () => installAudio({
+        getManifest: () => manifest, getState: () => state, selectRoute: (s) => s.route,
+        subscribe: (fn) => { fire = fn; return () => {}; },
+      });
+      wire();
+      assert.equal(calls.at(-1), 'prep', 'the prep keeps the shop track');
+      // round 1 ⇒ 无畏者 (combatAlts[1])
+      state.match.public = pub({ phase: PHASE.COMBAT });
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:1');
+      // a re-render / teammate view inside the same battle never moves
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:1');
+      // 联防 has its OWN track (#110, the official escaped levels' `bgmEvent = corrosion`) — it does not inherit the
+      // round's 开战 track
+      state.match.public = pub({ phase: PHASE.UNITE });
+      fire(state, {}); assert.equal(calls.at(-1), 'unite');
+      // …and back to the round's own track in the 作战
+      state.match.public = pub({ phase: PHASE.COMBAT });
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:1', "back to the round's own track");
+      // a second client of the same room hears the same track (its own installAudio, same round)
+      calls.length = 0; wire();
+      assert.deepEqual(calls, ['combat:1'], 'every client of the match hears the same track');
+      // round 7 is the last on 无畏者, round 8 switches to 骑士之日 (combatAlts[0]) — whoever sits in seat 1
+      state.match.public = pub({ round: 7, phase: PHASE.COMBAT });
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:1');
+      state.match.public = pub({ round: 8, phase: PHASE.COMBAT });
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:0');
+      state.match.public = pub({ round: 8, phase: PHASE.COMBAT, players: [{ playerId: 'p2' }] });
+      fire(state, {}); assert.equal(calls.at(-1), 'combat:0', 'the track does not depend on the seats');
+      // the boss rounds keep their own tracks
+      state.match.public = pub({ phase: PHASE.FINAL_ASSAULT, bossId: 'boss_4' });
+      fire(state, {}); assert.equal(calls.at(-1), 'boss:boss_4');
+    } finally { audio.playBgm = origPlay; }
+  });
 });
 
 describe('SfxLimiter', () => {

tools/assets/plan.mjs

@@ -505,11 +505,19 @@ export function buildPlan({ assets07, ops03, enemies05, maps05, audio, modelsDat
   // bank is missing (the client then falls back to `bgm.combat`; public/js/audio.js resolveBgm), so the manifest stays
   // valid for an older audio_data.
   const unite = flatBgm(bgmLeaf('battle.ON_GAME_READY.corrosion'));
+  // 开战 BGM: the two official battle tracks of the mode's own 卡西米尔 act (music_act13side_1 骑士之日 /
+  // music_act13side_2 无畏者, 塞壬唱片). The client does not draw them: the round decides (audio.js combatTrackFor —
+  // 无畏者 for rounds 1–7, 骑士之日 from round 8 on), so index 0 must stay `bat_kazimierz2_1` and index 1
+  // `bat_kazimierz2_2` (test/ui/audio.test.js pins both the order and the round table).
+  // Kept out of `bgm` below when the index has neither bank, so the manifest stays valid for an older audio_data.
+  const combatAlts = ['battle.ON_GAME_READY.bat_kazimierz2_1', 'battle.ON_GAME_READY.bat_kazimierz2_2']
+    .map((n) => flatBgm(bgmLeaf(n))).filter(Boolean);
   const bgm = {
     lobby: flatBgm(bgmLeaf('sys.ON_ACTIVITY_LOADED.act2autochess')),
     prep: flatBgm(bgmLeaf('battle.ON_GAME_READY.act1autochess_shop')),
     combat: flatBgm(bgmLeaf('battle.ON_GAME_READY.act1autochess_shop')),
     boss: flatBgm(bgmLeaf('battle.ON_GAME_READY.rglk1phantomcastle')),
+    ...(combatAlts.length ? { combatAlts } : {}),
     ...(unite ? { unite } : {}),
   };
   const bossBgm = {};