diff --git a/hooks/session_end.mjs b/hooks/session_end.mjs
index 9704b72..1a9ac15 100644
--- a/hooks/session_end.mjs
+++ b/hooks/session_end.mjs
@@ -12,8 +12,7 @@ const data = pl.loadSession(sessionId);
 const host = data.host;
 
 if (host && pl.personaExists(host)) {
-  const state = pl.decayEmotion(pl.loadEmotion(host));
-  pl.writeJson(pl.emotionPath(host), state);
+  const state = pl.updateEmotion(host, (s) => pl.decayEmotion(s));
   pl.appendJsonl(pl.journalPath(host), {
     ts: pl.nowIso(),
     kind: "session-end",
diff --git a/hooks/turn_end.mjs b/hooks/turn_end.mjs
index 348a136..2d1d681 100644
--- a/hooks/turn_end.mjs
+++ b/hooks/turn_end.mjs
@@ -19,8 +19,7 @@ const host = data.host;
 if (!host || !pl.personaExists(host)) process.exit(0);
 
 pl.heartbeatLock(host, sessionId);
-const state = pl.decayEmotion(pl.loadEmotion(host));
-pl.writeJson(pl.emotionPath(host), state);
+const state = pl.updateEmotion(host, (s) => pl.decayEmotion(s));
 
 const theater = Boolean(data.theater) && (data.rooms || []).length > 0;
 const message = event.last_assistant_message || "";
diff --git a/scripts/persona-gitea.mjs b/scripts/persona-gitea.mjs
index c36811f..6cd7fca 100644
--- a/scripts/persona-gitea.mjs
+++ b/scripts/persona-gitea.mjs
@@ -138,14 +138,31 @@ export const AREA_KEYS = Object.keys(AREAS);
 export const syncDir = (slug, area) => path.join(pl.personaDir(slug), SYNC_DIRNAME, area);
 export const syncStatePath = (slug) => path.join(pl.personaDir(slug), "state", "sync.json");
 
-export function loadSyncState(slug) {
-  const data = pl.readJson(syncStatePath(slug), {}) ?? {};
-  data.areas ??= {};
-  for (const key of AREA_KEYS) data.areas[key] ??= {};
-  return data;
+/** 補上預設欄位。內容格式不變，只是保證 `state.areas[area]` 一定拿得到物件。 */
+function normalizeSyncState(data) {
+  const state = data && typeof data === "object" ? data : {};
+  state.areas ??= {};
+  for (const key of AREA_KEYS) state.areas[key] ??= {};
+  return state;
 }
 
-export const saveSyncState = (slug, data) => pl.writeJson(syncStatePath(slug), data);
+export function loadSyncState(slug) {
+  return normalizeSyncState(pl.readJson(syncStatePath(slug), {}) ?? {});
+}
+
+/**
+ * `sync.json` 的 read-modify-write：整段在檔案鎖裡面做，`mutate(state)` 就地改就好。
+ *
+ * 這個檔會被前景指令與背景 `sync push`（Stop hook 每輪都可能起一個）同時寫。
+ * 以前是各自「讀出來、改幾筆、整份寫回去」，兩邊撞上時後寫的會把前一個的
+ * `pushed_at`／`overwrites` 整段蓋掉——覆蓋紀錄就這樣安靜地消失。
+ */
+export function updateSyncState(slug, mutate) {
+  return pl.updateJson(syncStatePath(slug), (data) => {
+    const state = normalizeSyncState(data);
+    return mutate(state) ?? state;
+  }, {});
+}
 
 // --------------------------------------------------------------------------- //
 // 環境與 API
@@ -686,9 +703,9 @@ export async function pushArea(slug, area, { message = "", code = null, owner =
   gitOrThrow(["add", "-A"], dir, "git add");
   const dirty = git(["diff", "--cached", "--quiet"], dir);
   if (dirty.ok) {
-    const state = loadSyncState(slug);
-    state.areas[area] = { ...state.areas[area], checked_at: pl.nowIso() };
-    saveSyncState(slug, state);
+    updateSyncState(slug, (state) => {
+      state.areas[area] = { ...state.areas[area], checked_at: pl.nowIso() };
+    });
     return { ok: true, changed: false, files: staged.length, area, code: theCode };
   }
   gitOrThrow(["commit", "-q", "-m", message || `sync(${area}): ${pl.nowIso()}`], dir, "git commit");
@@ -728,16 +745,16 @@ export async function pushArea(slug, area, { message = "", code = null, owner =
     pushed = git(["push", "-q", "-u", "origin", "HEAD"], dir);
   }
   if (!pushed.ok) return { ok: false, area, code: theCode, reason: pushed.stderr || pushed.stdout };
-  const state = loadSyncState(slug);
-  state.code = theCode;
-  state.owner = theOwner;
-  state.areas[area] = { pushed_at: pl.nowIso(), checked_at: pl.nowIso(), files: staged.length };
-  if (overwrote) {
-    // 每輪對話後的 push 是背景執行、輸出丟掉的，所以覆蓋紀錄一定要落地：
-    // 留在 sync.json 裡等人來認領（`sync status` 會列，Stop hook 會提醒一次）。
-    state.overwrites = [...(state.overwrites || []), { at: pl.nowIso(), ...overwrote }].slice(-OVERWRITE_LOG_KEEP);
-  }
-  saveSyncState(slug, state);
+  updateSyncState(slug, (state) => {
+    state.code = theCode;
+    state.owner = theOwner;
+    state.areas[area] = { pushed_at: pl.nowIso(), checked_at: pl.nowIso(), files: staged.length };
+    if (overwrote) {
+      // 每輪對話後的 push 是背景執行、輸出丟掉的，所以覆蓋紀錄一定要落地：
+      // 留在 sync.json 裡等人來認領（`sync status` 會列，Stop hook 會提醒一次）。
+      state.overwrites = [...(state.overwrites || []), { at: pl.nowIso(), ...overwrote }].slice(-OVERWRITE_LOG_KEEP);
+    }
+  });
   return { ok: true, changed: true, files: staged.length, area, code: theCode, overwrote };
 }
 
@@ -748,14 +765,14 @@ export function pendingOverwrites(slug) {
 
 /** 標記為已回報（同一次覆蓋只吵一次）。回傳這次標掉幾筆。 */
 export function markOverwritesReported(slug) {
-  const state = loadSyncState(slug);
   let marked = 0;
-  for (const entry of state.overwrites || []) {
-    if (entry.reported_at) continue;
-    entry.reported_at = pl.nowIso();
-    marked += 1;
-  }
-  if (marked) saveSyncState(slug, state);
+  updateSyncState(slug, (state) => {
+    for (const entry of state.overwrites || []) {
+      if (entry.reported_at) continue;
+      entry.reported_at = pl.nowIso();
+      marked += 1;
+    }
+  });
   return marked;
 }
 
@@ -798,9 +815,9 @@ export async function pullArea(slug, area, { code = null, owner = null, force =
     if (!fs.existsSync(path.join(root, cloneNameToRel(area, dir, name)))) restore.add(name);
   }
   const written = unstageArea(slug, area, dir, restore);
-  const state = loadSyncState(slug);
-  state.areas[area] = { ...state.areas[area], pulled_at: pl.nowIso() };
-  saveSyncState(slug, state);
+  updateSyncState(slug, (state) => {
+    state.areas[area] = { ...state.areas[area], pulled_at: pl.nowIso() };
+  });
   return { ok: true, area, code: theCode, changed: incoming, written };
 }
 
@@ -923,12 +940,12 @@ export async function importFromRemote(code, { owner = null, slug = null, force
   } catch {
     /* 沒有關係圖就算了 */
   }
-  const state = loadSyncState(target);
-  state.code = code;
-  state.owner = theOwner;
-  if (repo?.html_url) state.repo_url = repo.html_url;
-  state.imported_at = pl.nowIso();
-  saveSyncState(target, state);
+  updateSyncState(target, (state) => {
+    state.code = code;
+    state.owner = theOwner;
+    if (repo?.html_url) state.repo_url = repo.html_url;
+    state.imported_at = pl.nowIso();
+  });
   const written = [...new Set(AREA_KEYS.flatMap((key) => results[key]?.written || []))].sort();
   return { persona: target, code, owner: theOwner, repo, results, written, overwrote_local: !fresh };
 }
@@ -954,12 +971,12 @@ export async function initRemote(slug, { code = null, owner = null, private_ = t
       message: `init(${area}): ${AREAS[area].why}`,
     });
   }
-  const state = loadSyncState(slug);
-  state.code = theCode;
-  state.owner = theOwner;
-  state.repo_url = repo.html_url;
-  state.initialized_at = state.initialized_at || pl.nowIso();
-  saveSyncState(slug, state);
+  updateSyncState(slug, (state) => {
+    state.code = theCode;
+    state.owner = theOwner;
+    state.repo_url = repo.html_url;
+    state.initialized_at = state.initialized_at || pl.nowIso();
+  });
   return { code: theCode, owner: theOwner, repo, created, wikiCreated, results };
 }
 
diff --git a/scripts/persona.mjs b/scripts/persona.mjs
index 0a3ec6a..975f0b8 100644
--- a/scripts/persona.mjs
+++ b/scripts/persona.mjs
@@ -541,8 +541,7 @@ commands.sleep = async ({ flags }) => {
     await run("prune-short-term", () => pl.pruneShortTermDetail(slug));
     await run("archive-threads", () => pl.archiveStaleThreads(slug));
     await run("emotion-decay", () => {
-      const state = pl.decayEmotionBy(pl.loadEmotion(slug), pl.SLEEP_DECAY_MINUTES);
-      pl.writeJson(pl.emotionPath(slug), state);
+      pl.updateEmotion(slug, (s) => pl.decayEmotionBy(s, pl.SLEEP_DECAY_MINUTES));
     });
     await run("reindex", () => pl.rebuildIndex(slug));
     await run("trim-said", () => pl.trimSaid(slug));
@@ -744,8 +743,7 @@ commands.remember = ({ flags }) => {
   pl.rememberShort(slug, entry);
   const kept = pl.pruneShortTerm(slug);
   if (Object.keys(entry.emotion_deltas).length) {
-    const state = pl.applyEmotion(pl.loadEmotion(slug), entry.emotion_deltas, text.slice(0, 80));
-    pl.writeJson(pl.emotionPath(slug), state);
+    const state = pl.updateEmotion(slug, (s) => pl.applyEmotion(s, entry.emotion_deltas, text.slice(0, 80)));
     pl.appendJsonl(pl.journalPath(slug), {
       ts: pl.nowIso(), kind: "emotion", trigger: text.slice(0, 120),
       deltas: entry.emotion_deltas, levels: state.levels, mood: pl.mood(state),
diff --git a/scripts/selftest.mjs b/scripts/selftest.mjs
index cdffc07..15a2e87 100644
--- a/scripts/selftest.mjs
+++ b/scripts/selftest.mjs
@@ -870,6 +870,23 @@ console.log("\n並行寫入：read-modify-rewrite 不能吃掉同時 append 的
   const parallel = joyOf();
   check("並行 8 次 `emotion --apply` 跟循序 8 次結果一樣（情緒更新不遺失）",
     Math.abs(parallel - sequential) < 0.01, `循序 ${sequential} / 並行 ${parallel}`);
+
+  // ②-b `remember --emotion` 是每一輪對話都會走的熱路徑，它的情緒寫入也必須在鎖裡
+  const sayArgs = ["remember", "--session", "sess-race-9999", "--role", "user",
+    "--text", "熱路徑", "--salience", "10", "--emotion", "joy=+5"];
+  resetJoy();
+  for (let i = 0; i < 8; i += 1) cli(sayArgs);
+  const saySequential = joyOf();
+  resetJoy();
+  startAt = Date.now() + 900;
+  await Promise.all(Array.from({ length: 8 }, () => child(`${BARRIER}
+    const { spawnSync } = await import("node:child_process");
+    waitUntil(${startAt});
+    spawnSync(process.execPath, [${JSON.stringify(CLI)}, ...${JSON.stringify(sayArgs)}], { stdio: "ignore" });`)));
+  const sayParallel = joyOf();
+  check("並行 8 次 `remember --emotion`（對話熱路徑）跟循序結果一樣",
+    Math.abs(sayParallel - saySequential) < 0.01, `循序 ${saySequential} / 並行 ${sayParallel}`);
+
   cli(["release", "--session", "sess-race-9999"]);
 
   // ③ withFileLock 本身：N 個程序各做一次 read-increment-write，一次都不能掉