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/ui/gameLogic.js

@@ -458,7 +458,9 @@ export function priceTone(slot) {
 }
 
 /**
- * Owned copies of a base chess (normal pieces on board/hand/temp) — shop cards show merge progress.
+ * Owned copies of a base chess (normal pieces on board/hand/temp) — shop cards show merge progress. An elite card
+ * never merges (server PlayerState.completesChessMerge refuses isGolden), so it reports 0 copies: no pips, no 可晋升
+ * tag and no mergeTarget tile.
  * @param {any} priv
  * @param {string} chessId
  * @param {(id:string)=>any} [getChess]
@@ -468,12 +470,36 @@ export function mergeProgress(priv, chessId, getChess = () => null) {
   const c = getChess(chessId);
   const base = c?.baseId || chessId;
   const need = Number.isInteger(c?.upgradeNum) && c.upgradeNum > 0 ? c.upgradeNum : 3;
+  if (c?.isGolden) return { copies: 0, need };
   let copies = 0;
   const pieces = [...(Array.isArray(priv?.board) ? priv.board : []), ...(Array.isArray(priv?.hand) ? priv.hand : []), ...(Array.isArray(priv?.temp) ? priv.temp : [])];
   for (const p of pieces) if (p?.kind === 'chess' && !p.golden && (p.id === base || getChess(p.id)?.baseId === base) && !String(p.id).endsWith('_b')) copies += 1;
   return { copies, need };
 }
 
+/**
+ * Where the elite appears when gaining one more normal copy of `chessId` completes a merge now (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"; mirror of server board.js mergeTile / PlayerState._mergeChess): the
+ * board tile of the deployed copy that deploys first (row desc, then col asc) — `{ row, col, dir }` — or null (no
+ * merge — an elite card never merges, see mergeProgress — or no copy is deployed: the elite goes to the hand). The
+ * copies stand on legal tiles, and the elite is the same operator, so the tile needs no legality check here.
+ * @param {any} priv
+ * @param {string} chessId
+ * @param {(id:string)=>any} [getChess]
+ * @returns {{ row: number, col: number, dir: string } | null}
+ */
+export function mergeTarget(priv, chessId, getChess = () => null) {
+  const { copies, need } = mergeProgress(priv, chessId, getChess);
+  if (!(copies > 0 && copies + 1 >= need)) return null;
+  const c = getChess(chessId);
+  const base = c?.baseId || chessId;
+  const board = (Array.isArray(priv?.board) ? priv.board : []).filter((p) => p?.kind === 'chess' && !p.golden && Number.isInteger(p.row) && Number.isInteger(p.col)
+    && !String(p.id).endsWith('_b') && (p.id === base || getChess(p.id)?.baseId === base));
+  if (!board.length) return null;
+  board.sort((a, b) => b.row - a.row || a.col - b.col);
+  return { row: board[0].row, col: board[0].col, dir: board[0].dir || 'RIGHT' };
+}
+
 /** Whether every hand slot is taken (the server refuses a purchase / reward that needs a slot: HAND_FULL). */
 export function handFull(priv) {
   const hand = Array.isArray(priv?.hand) ? priv.hand : [];