0.2.4-dev: round-29 community fixes and the official shared card pool

- Shared card pool and item stock as in the official mode (the owner's request, from the 路标档案馆 video and public notes): solo low-tier exceptions, co-op operators x2, shared item stock with special-item exceptions, normal / advanced occupancy 1 / 2, re-check on buy, 机变 exhaustion, release on consume / destroy / elimination; 整备 never exceeds stock; invariant held <= cap.
- 突袭: one taunt-first reselect right after a revive (the owner's rule); ordinary polls and redeploys keep the 0.2.3 rule; a revive on an enemy's tile stays. #475: online boss / hidden-boss Raid may land on the empty half (owner-limited scope).
- 浊心斯卡蒂 S1 x 坚守 no longer bounce redirected damage, and the two shares conserve the hit (idea of PR #464 by @HappyTanuki).
- Operator fixes adapted from PRs by @Xinglan233 (#459 哈洛德 S2 elemental trigger, #460 涤火杰西卡 shield on the four adjacent tiles, #461 家族徽章 first hit after stealth, #462 松果 S2 regrow per deploy); 克莱门莎 S2 splash 1.1 / 100% ATK and air auto-trigger (#467); 白面 copying 歌蕾蒂娅 / 余 skips the three-member condition (#473, the owner's video).
- 香槟炸弹 is not chosen by friendly auras / heals (PR #468 / #476 by @Siornya); 琳琅诗怀雅 coin balance (PR #450 by @IceCodeNew); Touch prep display (PR #451 by @YinqiMargatroid); lobby header (PR #471 by @YuriRestia); Japanese UI terms (PR #448 by @scutkane).
- AI-only boss countdown grace, render-failure cache / recovery without restarting a battle, device units kept on a same-field re-entry, DIY detail / skill previews, large-text result buttons.
- golden: battle families equal 0.2.3 except diy-135 / diy-136 (克莱门莎); all 18 release matches move through the shared pool, every flip named in docs/history/0.2.4.md §29.12; two coverage scenarios added.

test/render/hud-readouts.test.js

@@ -30,6 +30,35 @@ const tuple = (id, hp = 1000, extra = {}) => [id, 5, 10, hp, 1000, extra.sp ?? 0
 const view = (info = {}, extra = {}) => new UnitView(fakeViewCtx(fake.P, { cam, ...extra }),
   { id: 1, side: 'ally', kind: 'op', defId: 'char_x', tier: 3, x: 5, y: 10, maxHp: 1000, dir: 'RIGHT', ...info });
 const sample = (o = {}) => ({ x: 5, y: 10, hp: 1000, maxHp: 1000, sp: 0, spMax: 0, flags: 0, anim: 0, vx: 0, vy: 0, ...o });
+
+test('Swire purse snapshots include zero and the selected skill cap; death removes the readout', () => {
+  for (const skillIndex of [0, 1, 2]) {
+    const h = makeBattle({ autoFinish: false, units: [{ uid: 1, chessId: 'chess_char_3_04_a', row: 10, col: 4, skillIndex }] });
+    h.b.start(); const u = h.unit(1); const cap = u.skill.bb.sp;
+    assert.deepEqual(h.b.snapshot().coins, [[u.id, u.mem.coins, cap]]);
+    u.mem.coins = 0; assert.deepEqual(h.b.snapshot().coins, [[u.id, 0, cap]]);
+    h.b.retreat(u, { reason: 'test' }); assert.equal(h.b.snapshot().coins, undefined);
+  }
+});
+
+test('coin balance is snapshot-owned: preserves zero, rejects malformed entries and clears when absent', () => {
+  const first = normalizeSnapshot({ t: 0, units: [tuple(1)], coins: [[1, 0, 10], [2, 3, 10], [1, -1, 10], [1, 3.5, 10]] });
+  assert.deepEqual([...first.coins], [[1, [0, 10]]]);
+  const b = new SnapshotBuffer();
+  b.push({ t: 0, units: [tuple(1)], coins: [[1, 3, 10]] });
+  b.push({ t: 1, units: [tuple(1)] });
+  assert.deepEqual(b.sample(0).get(1).coins, [3, 10]);
+  assert.equal(b.sample(1).get(1).coins, null);
+});
+
+test('the coin HUD shows balance/cap and does not leave a stale label when its snapshot entry disappears', () => {
+  const v = view();
+  try {
+    v.sync(sample({ coins: [0, 10] }), 0); v.update(0.02, cam(), 0);
+    assert.equal(v.coinHud?.text.text, '0/10'); assert.equal(v.coinHud.root.visible, true);
+    v.sync(sample(), 1); v.update(0.02, cam(), 1); assert.equal(v.coinHud.root.visible, false);
+  } finally { v.destroy(); }
+});
 const frames = (v, n = 2) => { for (let i = 0; i < n; i++) v.update(1 / 60, cam(), i / 60); };
 const barWidth = (v) => v.hpBg.width - 2;