Playtest #6 follow-up (v2.5.1): leader HP review — 直接乘算, one debuff instance, 999 layer cap, 限伤; elite to the board; 假想敌：胄 kit

- co-op leaders died within seconds: leader HP is the official data (40 values pinned); bond / strategy / item /
  机变 / 特质 "+X%" bonuses now add up (PRTS 直接乘算) instead of compounding; a same-named enemy debuff keeps one
  (strongest) instance per target (奥术 across a pair field); leader parts pass damage 1:1; fixed co-op pool (the user's call)
- official limits read from the client: each bond stops at 999 layers (MAX_GARRISON_STACK); a leader hit of 300000+ in
  boss / hidden battles is cancelled (MAX_BATTLE_DAMAGE, 限伤) — shared/constants.js switches, research 11
- a merge that consumes a deployed copy puts the elite on that tile and facing (user-confirmed); gold target highlight,
  promotion effect
- 假想敌：胄 per PRTS: one shell, shells within range, any drone death costs 2 % max HP, 剑/锤 sorties and 瘫痪
- DESIGN §20.10–§20.14; 2842 unit tests, all 28 browser suites green; Chrome = Node on boss fields

test/sim/battle.test.js

@@ -4,7 +4,7 @@ import { test } from 'node:test';
 import assert from 'node:assert/strict';
 import { Battle } from '../../server/sim/Battle.js';
 import { makeBattle, chessRec, enemyRec, flatStage, hashOf, checkInvariants } from '../helpers/battleHarness.js';
-import { UF, ANIM } from '../../shared/constants.js';
+import { UF, ANIM, BOND_LAYER_CAP } from '../../shared/constants.js';
 import { EV } from '../../shared/protocol.js';
 import { getDefaultSource, spawnsFromTemplate, hasGeneratedData } from '../../server/sim/simdata.js';
 import { LocalBossPool } from '../../server/sim/spec.js';
@@ -478,6 +478,19 @@ test('layers & coins: addLayers records gains (normal field) and emits client ev
   assert.equal(h2.b.addLayers('p1', 'yanShip', 3), 0);
 });
 
+test('layers: an IN_BATTLE gain stops at BOND_LAYER_CAP (999, MAX_GARRISON_STACK) — the battle\'s count and the reported gain', () => {
+  assert.equal(BOND_LAYER_CAP, 999);
+  const h = makeBattle({ content: 'none', bonds: { yanShip: { count: 3, active: true, tier: 1, layers: 995 } } });
+  h.step();
+  assert.equal(h.b.addLayers('p1', 'yanShip', 3, 'test'), 3);
+  assert.equal(h.b.addLayers('p1', 'yanShip', 5, 'test'), 1, 'only the room left under the cap');
+  assert.equal(h.b.addLayers('p1', 'yanShip', 5, 'test'), 0, 'at the cap: nothing');
+  assert.equal(h.b.getPlayer('p1').bonds.yanShip.layers, 999);
+  h.b.forceEnd('forced');
+  assert.deepEqual(h.result().perPlayer.p1.layerGains, { yanShip: 4 });
+  assert.deepEqual(h.eventsOf('layer').map((e) => e[3]), [3, 1], 'the client sees what was added');
+});
+
 test('tokens: spawnToken deploys a token next to its owner; manual token pieces deploy from input', () => {
   const ds = getDefaultSource();
   const h = makeBattle({