diff --git a/docs/META.md b/docs/META.md
index 62ae4972..4d0b0dc5 100644
--- a/docs/META.md
+++ b/docs/META.md
@@ -331,7 +331,9 @@ Other equipment: 2 slots; a third replaces the equipped item the player picks in
 equipped on the target ⇒ `BAD_TARGET`, nothing changes) — and the replaced item is destroyed. Equipped items are
 otherwise locked (research 04 §2 / addendum: they leave the operator only on promotion, merge or sale): `g.destroy`
 refuses them (`BAD_TARGET 'equipped items are locked'`). A second copy of an equipped normal item merges into the golden
-item in the hand.
+item in the hand. Every path that hands an item to the player (buy, reward, 机变, grants, equip, the equipment a sale,
+a promotion or `ctx.destroyPiece` returns) ends with the auto-merge (`acquireItem` / `checkItemMerges`: "已拥有2件同一初始
+装备时…自动合并"), so a player never holds two identical mergeable normal items (`test/match/feedback1b-items.test.js`).
 
 Built-ins (builtinMeta.js, overridable): 盟约之币 / 骑士储蓄罐 (random funds), 随身身份牌 (layers of the target's bonds),
 紧急调度券 (take shop chess), 精打细算玩偶 (+funds each round), 简易通讯机 / 拟态物质 (same-bond chess), 见钱眼开玩偶
diff --git a/server/match/PlayerState.js b/server/match/PlayerState.js
index 6a6a433e..73b9d0b8 100644
--- a/server/match/PlayerState.js
+++ b/server/match/PlayerState.js
@@ -477,7 +477,8 @@ export class PlayerState {
    * grows. Otherwise the elite goes to the hand, overflow temp — outside PREP too (a SETTLE merge's elite waits in temp
    * through the next prep, tempDue). The copies' equipment returns to the hand ("干员晋级后已配发装备会回收至整备区";
    * overflow temp; with both full it stays on the elite, up to its equipPerChess (2) slots — any further item is
-   * destroyed with a log warning, as before the official rule); their summons are removed, and an elite on the board
+   * destroyed with a log warning, as before the official rule) and an identical normal pair among it merges like any gain
+   * (checkItemMerges); their summons are removed, and an elite on the board
    * gets its own summon stack (grantTokensFor: its loadout, like any deployment). Returns the elite piece (or null if
    * the elite could not be stored).
    * @param {string} baseId
@@ -515,6 +516,8 @@ export class PlayerState {
       if (where && elite.items.length < this.gd.equipPerChess) { elite.items.push(it); continue; }
       this.m.log.warn?.(`[match ${this.m.roomCode}] ${this.playerId}: returned item ${it.id} destroyed (no space)`);
     }
+    // the returned equipment follows the auto-merge rule like any other gain ("已拥有2件同一初始装备时…自动合并")
+    this.checkItemMerges();
     // deployed like any operator placed by hand: its manually deployable summons join the hand (after the returned
     // equipment, which would be lost in temp — a summon stack removed there comes back at the next round start)
     if (where === 'board') this.grantTokensFor(elite);
diff --git a/server/match/effectsMeta.js b/server/match/effectsMeta.js
index 14ab7369..3a87af63 100644
--- a/server/match/effectsMeta.js
+++ b/server/match/effectsMeta.js
@@ -506,6 +506,7 @@ export function makeCtx(m, ps, source, hook, ev = null) {
         for (const it of l.piece.items || []) ps.stow(it, { allowTemp: true });
         l.piece.items = [];
         ps.returnCopies(l.piece);
+        ps.checkItemMerges(); // the returned equipment auto-merges like any gain
       }
       ps.recompute();
       return true;
diff --git a/test/match/feedback1b-items.test.js b/test/match/feedback1b-items.test.js
new file mode 100644
index 00000000..8ffc2541
--- /dev/null
+++ b/test/match/feedback1b-items.test.js
@@ -0,0 +1,177 @@
+// Player report after the public 0.1.0 release (relayed, untested by the user): "源石溶剂两个白的合成一个金色的之后又多给一个白的"
+// — after two white 源石溶剂 (chess_item_1_05_e_a) merged into the golden one (_b), an extra white appeared.
+// Official rule (PRTS 卫戍协议/帮助 §装备; activity_table act2autochess trapChessDataDict upgradeNum 2 → _b): "已拥有2件同一初始
+// 装备时，该装备将自动合并为1件进阶品质的同名装备，发送至手牌区"; equipment is removed "在失去该干员（干员出售、销毁、合并等）或
+// 装备合并为进阶品质时". Every real PlayerState path that hands the player a second white is replayed here and must end
+// with exactly one golden and no white (none duplicates — the report did not reproduce); random intents conserve the
+// white-equivalents W + 2·G. The one gap found: equipment a promotion (or an effect that removes an operator) returns
+// to the hand skipped the auto-merge — unreachable from a normal state (a pair never exists), closed anyway.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { DATA, makeMatch, give, giveItem, legalTileFor, checkInvariants } from './harness.js';
+import { tileKey } from '../../server/match/board.js';
+import { applyCard } from '../../server/match/choices.js';
+
+const WHITE = 'chess_item_1_05_e_a';
+const GOLD = 'chess_item_1_05_e_b';
+const OP = 'chess_char_1_17_a';
+
+function prep(seed = 5) {
+  const h = makeMatch({ mode: 'solo', difficulty: 'NORMAL', humans: 1, seed, fake: true }).start();
+  h.toPrep(1);
+  const m = h.m, ps = h.ps('p_0');
+  for (const p of [...ps.board.values(), ...ps.hand.filter(Boolean)]) if (p.kind === 'chess') ps.returnCopies(p);
+  ps.board.clear();
+  ps.hand.fill(null);
+  ps.offers.length = 0;
+  ps.funds = 99;
+  ps.recompute();
+  return { h, m, ps };
+}
+function count(ps) {
+  const c = { white: 0, gold: 0 };
+  const see = (p) => { if (p && p.kind === 'item') { if (p.id === WHITE) c.white++; if (p.id === GOLD) c.gold++; } };
+  for (const p of [...ps.hand, ...ps.temp, ...ps.board.values()]) { see(p); for (const it of (p && p.items) || []) see(it); }
+  return c;
+}
+/** Put item `id` into the shop's first item slot (after the chess slots); returns its slot index. */
+function stockItem(ps, id = WHITE) {
+  const i = ps.shop.layout ? ps.shop.layout.chess : ps.shop.slots.findIndex((s) => s && s.kind === 'item');
+  ps.shop.slots[i] = { kind: 'item', id, basePrice: ps.gd.itemPrice(id), frozen: false, sold: false };
+  return i;
+}
+/** Put chess `id` into shop slot 0. */
+function stockChess(ps, id) {
+  ps.shop.slots[0] = { kind: 'chess', id, basePrice: ps.gd.chessPrice(id), frozen: false, sold: false };
+  return 0;
+}
+function deploy(m, ps, ids) {
+  const used = new Set();
+  return ids.map((id) => { const t = legalTileFor(m, ps, id, used); used.add(tileKey(t[0], t[1])); return give(m, ps, id, 'board', t); });
+}
+
+test('源石溶剂: the data is the official pair (upgradeNum 2 → the golden _b; 40 % / 60 % ATK, −60 HP/s)', () => {
+  const w = DATA.items[WHITE], g = DATA.items[GOLD];
+  assert.equal(w.upgradeNum, 2);
+  assert.equal(w.upgradeChessId, GOLD);
+  assert.equal(w.mergeable, true);
+  assert.equal(g.isGolden, true);
+  assert.deepEqual([w.params.atk, g.params.atk, w.params.damage, g.params.damage], [0.4, 0.6, 60, 60]);
+});
+
+test('源石溶剂: every way to get a second white merges the pair into ONE golden and leaves no white (the player report)', () => {
+  const cases = {
+    'buy with a white in the hand': ({ m, ps }) => { giveItem(m, ps, WHITE); return m.handle('p_0', { t: 'g.buy', slot: stockItem(ps) }); },
+    'buy twice from the shop': ({ m, ps }) => { m.handle('p_0', { t: 'g.buy', slot: stockItem(ps) }); return m.handle('p_0', { t: 'g.buy', slot: stockItem(ps) }); },
+    'buy with a white equipped': ({ m, ps }) => {
+      const [a] = deploy(m, ps, [OP]);
+      const it = giveItem(m, ps, WHITE);
+      m.handle('p_0', { t: 'g.equip', itemUid: it.uid, targetUid: a.uid });
+      return m.handle('p_0', { t: 'g.buy', slot: stockItem(ps) });
+    },
+    'equip the second on another operator': ({ m, ps }) => {
+      const [a, b] = deploy(m, ps, [OP, 'chess_char_2_10_a']);
+      const it = giveItem(m, ps, WHITE);
+      m.handle('p_0', { t: 'g.equip', itemUid: it.uid, targetUid: a.uid });
+      const it2 = giveItem(m, ps, WHITE);
+      return m.handle('p_0', { t: 'g.equip', itemUid: it2.uid, targetUid: b.uid });
+    },
+    'equip the second on the same full carrier': ({ m, ps }) => {
+      const [a] = deploy(m, ps, [OP]);
+      const it = giveItem(m, ps, WHITE);
+      const other = giveItem(m, ps, 'chess_item_1_01_e_a');
+      m.handle('p_0', { t: 'g.equip', itemUid: it.uid, targetUid: a.uid });
+      m.handle('p_0', { t: 'g.equip', itemUid: other.uid, targetUid: a.uid });
+      // no twin anywhere else: acquire the second white without the auto-merge (the hand) and equip it on the full carrier
+      const it2 = ps.newPiece('item', WHITE);
+      ps.hand[ps.hand.findIndex((x) => x == null)] = it2;
+      return m.handle('p_0', { t: 'g.equip', itemUid: it2.uid, targetUid: a.uid });
+    },
+    'reward offer pick': ({ m, ps }) => { giveItem(m, ps, WHITE); ps.pushItemOffer([WHITE, WHITE, WHITE]); return m.handle('p_0', { t: 'g.reward', idx: 0 }); },
+    '道具补给 card': ({ m, ps }) => { giveItem(m, ps, WHITE); applyCard(m, ps, { kind: 'item', id: WHITE, family: 'supply', name: '源石溶剂' }); return { ok: true }; },
+    '列装 rolling two whites': ({ m, ps }) => {
+      const roll = m.rollPool;
+      m.rollPool = () => ({ kind: 'item', id: WHITE });
+      try { applyCard(m, ps, { kind: 'tactic', id: 'allybuff_select_1', family: 'tactic', team: true }); } finally { m.rollPool = roll; }
+      return { ok: true };
+    },
+    '整备 then a white bought next to a white': ({ m, ps }) => {
+      giveItem(m, ps, WHITE);
+      applyCard(m, ps, { kind: 'tactic', id: 'allybuff_select_5', family: 'tactic' });
+      return m.handle('p_0', { t: 'g.buy', slot: stockItem(ps) });
+    },
+    '画卷 copy of a white carrier': ({ m, ps }) => {
+      const [a] = deploy(m, ps, [OP]);
+      const it = giveItem(m, ps, WHITE);
+      m.handle('p_0', { t: 'g.equip', itemUid: it.uid, targetUid: a.uid });
+      const art = giveItem(m, ps, 'chess_item_6_02_m');
+      const [r, c] = [...ps.board.entries()].find(([, p]) => p === a)[0].split(',').map(Number);
+      return m.handle('p_0', { t: 'g.art', itemUid: art.uid, row: r, col: c, dir: 'RIGHT' });
+    },
+  };
+  for (const [name, run] of Object.entries(cases)) {
+    const s = prep();
+    const res = run(s);
+    assert.equal(res.ok, true, `${name}: ${JSON.stringify(res)}`);
+    assert.deepEqual(count(s.ps), { white: 0, gold: 1 }, name);
+    checkInvariants(s.m);
+    s.m.dispose();
+  }
+});
+
+test('a promotion that returns equipment merges a returned pair (latent: no normal state holds a pair)', () => {
+  const { m, ps } = prep();
+  const op = Object.values(DATA.chess).find((c) => c.visible && !c.isGolden && c.tier === 1 && m.pool.has(c.chessId) && !m.bannedChess.includes(c.chessId)
+    && m.gd.mergeCount(c.chessId) === 3 && !m.gd.placeableTokens(c.chessId).length).chessId;
+  const [a, b] = deploy(m, ps, [op, op]);
+  // the copies' equipment built directly: a pair never exists in play — every entry path merges it at once
+  a.items = [ps.newPiece('item', WHITE)];
+  b.items = [ps.newPiece('item', WHITE)];
+  ps.recompute();
+  assert.deepEqual(m.handle('p_0', { t: 'g.buy', slot: stockChess(ps, op) }), { ok: true });
+  assert.ok([...ps.board.values()].some((p) => p.id === DATA.chess[op].goldenId), 'the elite formed');
+  assert.deepEqual(count(ps), { white: 0, gold: 1 }, '"干员晋级后已配发装备会回收至整备区" + the auto-merge');
+  checkInvariants(m);
+});
+
+test('random intents around 源石溶剂 (buy, equip / replace, sell, move, destroy) conserve W + 2·G and never leave a pair', () => {
+  let seed = 11;
+  const rnd = () => { seed = (seed * 1103515245 + 12345) >>> 0; return seed / 4294967296; };
+  const pick = (arr) => arr[Math.floor(rnd() * arr.length)];
+  const worth = (ps) => { const c = count(ps); return { ...c, e: c.white + 2 * c.gold }; };
+  let checked = 0;
+  for (let run = 0; run < 4; run++) {
+    const { m, ps } = prep(run + 3);
+    const ops = Object.values(DATA.chess).filter((c) => c.visible && !c.isGolden && c.tier === 1 && m.pool.has(c.chessId) && !m.bannedChess.includes(c.chessId)).slice(0, 2).map((c) => c.chessId);
+    for (let step = 0; step < 150; step++) {
+      ps.funds = 50;
+      const before = worth(ps);
+      const loose = [...ps.hand, ...ps.temp].filter(Boolean);
+      const chess = [...loose, ...ps.board.values()].filter((p) => p.kind === 'chess');
+      const items = loose.filter((p) => p.kind === 'item');
+      const r = rnd();
+      let msg = null, expect = 0, rep = null;
+      if (r < 0.35) { msg = { t: 'g.buy', slot: stockItem(ps) }; expect = 1; }
+      else if (r < 0.5) msg = { t: 'g.buy', slot: stockChess(ps, pick(ops)) };
+      else if (r < 0.8 && items.length && chess.length) {
+        const it = pick(items), tg = pick(chess);
+        rep = (tg.items || []).length >= 2 ? pick(tg.items) : null;
+        msg = { t: 'g.equip', itemUid: it.uid, targetUid: tg.uid, ...(rep ? { replaceUid: rep.uid } : {}) };
+      }
+      else if (r < 0.9 && chess.length) msg = { t: 'g.sell', uid: pick(chess).uid };
+      else if (items.length) { const it = pick(items); msg = { t: 'g.destroy', uid: it.uid }; expect = it.id === WHITE ? -1 : it.id === GOLD ? -2 : 0; }
+      if (!msg) continue;
+      const res = m.handle('p_0', msg);
+      if (!res.ok) continue;
+      // a replacement destroys the replaced item unless the equip merged instead (the replaced one is still owned)
+      if (rep && !ps.find(rep.uid)) expect = rep.id === WHITE ? -1 : rep.id === GOLD ? -2 : 0;
+      const after = worth(ps);
+      assert.equal(after.e - before.e, expect, `run ${run} step ${step} ${JSON.stringify(msg)}: ${JSON.stringify(before)} → ${JSON.stringify(after)}`);
+      assert.ok(after.white <= 1, `run ${run} step ${step}: an unmerged pair`);
+      checked++;
+    }
+    checkInvariants(m);
+    m.dispose();
+  }
+  assert.ok(checked > 150, `${checked} accepted intents`);
+});