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

public/js/render/fx.js

@@ -212,6 +212,9 @@ export const FX_KINDS = Object.freeze({
   thorns: { a: 'counter', c: 0xff9aa6 }, downed: { a: 'down', c: 0xbfeee2 }, stone: { a: 'down', c: 0xc0b8a8, smoke: 0x5a5448 },
   dp: { a: 'dp', c: 0x9fd4ff }, coin: { a: 'coin', c: 0xffc600 }, steal: { a: 'coin', c: 0xffc600 }, crateBreak: { a: 'crate', c: 0xc89a5a },
   lpLoss: { a: 'lp', c: 0xff3b30 },
+  // 限伤 (sim/damage.js leaderHitCancelled): a leader's hit of ≥ 300000 dealt nothing — the official shows no number and
+  // no effect [ASSUMED], so nothing is drawn (`a: 'none'`)
+  hitCap: { a: 'none', c: 0xffffff },
   // beams
   beam: { a: 'beam', c: 0xff7a5a }, link: { a: 'beam', c: 0x9ff0dc }, lightning: { a: 'bolt', c: 0xc9a2ff }, tentacle: { a: 'beam', c: 0x5fe0ff },
   sandChains: { a: 'beam', c: 0xd8c8a0 }, sandChainsCharged: { a: 'beam', c: 0xffd45a },
@@ -1578,6 +1581,29 @@ export class FxSystem {
     this.burst(p.x, p.y, s, 6, col, { speed: 1.6, up: 0.4, life: 0.4, tex: 'dot' });
   }
 
+  /**
+   * Promotion (精锐晋升, a merge) at the elite's spot — the board tile of the consumed copy it replaced (PRTS 卫戍协议/
+   * 帮助 "若消耗已部署至作战区的干员，则发送至作战区对应位置") or its bench slot: a gold pillar with a white core, a shockwave
+   * and a hex ring on the ground, rising motes; `from` = world points of the other consumed copies (gold streaks from
+   * them to the elite). Counted in `promotions` (render/app.js setPrep; tests).
+   * @param {any} view
+   * @param {Array<{ x: number, y: number, z?: number }>} [from]
+   */
+  promote(view, from = []) {
+    if (!view) return;
+    this.promotions = (this.promotions || 0) + 1;
+    const z = view.z || 0;
+    const g = this._proj(view.x, view.y, z, this._g);
+    const gx = g.x, gy = g.y, s = g.s;
+    for (const f of from) if (f && Number.isFinite(f.x) && Number.isFinite(f.y)) this.streak(f.x, f.y, view.x, view.y, Math.max(z, f.z || 0) + 0.3, SKILL_GOLD, 0.45);
+    this.particle('pillar', gx, gy, { tint: SKILL_GOLD, life: 0.8, s0: (s / 64) * 1.1, s1: (s / 64) * 1.4, a0: 0.95, a1: 0, sx: 0.85, ay: 1 });
+    this.particle('pillar', gx, gy, { tint: 0xffffff, life: 0.42, s0: (s / 64) * 0.9, s1: (s / 64) * 1.2, a0: 0.9, a1: 0, sx: 0.3, ay: 1 });
+    this.ring(view.x, view.y, z, 0.15, 1.6, 0xffe7a0, 0.5, 'shock');
+    this.ring(view.x, view.y, z, 0.3, 1.2, SKILL_GOLD, 0.7, 'hex');
+    const c = this._chest(view, this._q);
+    this.burst(c.x, c.y, s, this.rich ? 12 : 5, 0xffe28a, { speed: 1.5, up: 1.8, life: 0.8, tex: 'dot', size: 0.36 });
+  }
+
   death(view) {
     if (!view) return;
     const p = this._chest(view);
@@ -1637,14 +1663,15 @@ export class FxSystem {
   /**
    * b.ev 'fx': every kind the sim / content emits has a visual (FX_KINDS archetypes: blast, shell, zone, telegraph,
    * heal, sp, shield, shatter, summon, vanish, blink, move, wave, mark, reticle, buff, lift, sleep, crit, dodge,
-   * counter, dp, coin, crate, down, beam, bolt, strike, volley, pillar, lp, chill, element, flame); unknown kinds get a
-   * generic sparkle. `extra` keys used: id (anchor unit — or the shooter of a `pt` kind), r | radius, dur | duration,
+   * counter, dp, coin, crate, down, beam, bolt, strike, volley, pillar, lp, chill, element, flame), except kinds whose
+   * archetype is 'none' (hitCap: a leader hit cancelled by 限伤 draws nothing); unknown kinds get a generic sparkle. `extra` keys used: id (anchor unit — or the shooter of a `pt` kind), r | radius, dur | duration,
    * t (shell flight, game s), src / from / to / target / targets (unit ids), fx, fy / fromX, fromY / tx, ty (positions),
    * element, n, scale, kind, tiles.
    */
   simFx(kind, x, y, extra) {
     const ex = extra && typeof extra === 'object' ? extra : {};
     const spec = fxSpec(kind, ex);
+    if (spec.a === 'none') return; // an event the screen does not show (hitCap)
     const at = spec.pt ? this._point(Number(x), Number(y)) : this._where(Number(x), Number(y), ex);
     if (!Number.isFinite(at.x) || !Number.isFinite(at.y)) return;
     // 蕾缪安 S2: the aimed snipe ('crit' on the locked enemy, from her) ends that aim lock
@@ -2174,7 +2201,7 @@ export class FxSystem {
   }
 
   get counts() {
-    return { particles: this.parts.length, projectiles: this.projs.length, numbers: this.nums.length, rings: this.rings.length, auras: this.auras.size, locks: this.locks.length, flames: this.flames.length };
+    return { particles: this.parts.length, projectiles: this.projs.length, numbers: this.nums.length, rings: this.rings.length, auras: this.auras.size, locks: this.locks.length, flames: this.flames.length, promotions: this.promotions || 0 };
   }
 
   destroy() {