diff --git a/scripts/persona-lib.mjs b/scripts/persona-lib.mjs
index bb90d47..524d6d6 100644
--- a/scripts/persona-lib.mjs
+++ b/scripts/persona-lib.mjs
@@ -362,16 +362,33 @@ export function defaultEmotionState(baseline = {}) {
   };
 }
 
+/** 0–100 之間的合法數字；不是數字（NaN／字串／null）就退回 `fallback`。 */
+function sanelevel(value, fallback) {
+  const num = Number(value);
+  return Number.isFinite(num) ? clamp(num) : clamp(fallback);
+}
+
+/**
+ * 讀情緒狀態。**檔案是外部輸入**（`import`／`sync pull`／手改都會進到這裡），
+ * 所以不能只補缺、還要驗合法性——以前用 `??=` 只補 undefined，結果：
+ *
+ *   * `baseline.joy = 5000` → 衰減後 joy 破千，mood 卡在 valence/arousal 100
+ *   * `levels.anger = "很生氣"` → 衰減後 anger = NaN，注入的上下文印出 valence NaN
+ *   * `half_life_minutes.joy = 0` 或負數 → factor 恆為 0，那個情緒從此累積不起來
+ *
+ * CLI 的 `--baseline`／`--apply` 本來就有保護，破口純粹在檔案入口，所以擋在這裡。
+ */
 export function loadEmotion(slug) {
   let state = readJson(emotionPath(slug));
   if (!state || typeof state !== "object" || !state.levels) state = defaultEmotionState();
-  state.baseline ??= {};
-  state.levels ??= {};
-  state.half_life_minutes ??= {};
+  if (!state.baseline || typeof state.baseline !== "object") state.baseline = {};
+  if (!state.levels || typeof state.levels !== "object") state.levels = {};
+  if (!state.half_life_minutes || typeof state.half_life_minutes !== "object") state.half_life_minutes = {};
   for (const key of EMOTION_KEYS) {
-    state.baseline[key] ??= DEFAULT_BASELINE[key];
-    state.levels[key] ??= state.baseline[key];
-    state.half_life_minutes[key] ??= EMOTIONS[key].halfLife;
+    state.baseline[key] = sanelevel(state.baseline[key], DEFAULT_BASELINE[key]);
+    state.levels[key] = sanelevel(state.levels[key], state.baseline[key]);
+    const half = Number(state.half_life_minutes[key]);
+    state.half_life_minutes[key] = Number.isFinite(half) && half > 0 ? half : EMOTIONS[key].halfLife;
   }
   return state;
 }
@@ -390,18 +407,31 @@ export function updateEmotion(slug, mutate) {
   });
 }
 
+/**
+ * 把 `minutes` 分鐘的衰減直接套上去（decayEmotion 與 decayEmotionBy 共用）。
+ *
+ * 每個值都重新驗過一次：這兩個函式是 export 的，呼叫端有可能餵進手寫或匯入來的狀態，
+ * 不能假設它一定經過 `loadEmotion()`。半衰期 ≤ 0 會讓 factor 恆為 0（那個情緒從此
+ * 累積不起來），所以一律退回該情緒的預設半衰期。
+ */
+function applyDecay(state, minutes) {
+  for (const key of EMOTION_KEYS) {
+    const rawHalf = Number(state.half_life_minutes?.[key]);
+    const half = Number.isFinite(rawHalf) && rawHalf > 0 ? rawHalf : EMOTIONS[key].halfLife;
+    const base = sanelevel(state.baseline?.[key], DEFAULT_BASELINE[key]);
+    const level = sanelevel(state.levels?.[key], base);
+    const factor = Math.pow(0.5, minutes / half);
+    state.levels[key] = Math.round(clamp(base + (level - base) * factor) * 100) / 100;
+  }
+  return state;
+}
+
 /** 情緒朝 baseline 指數衰減；半衰期依情緒種類不同。 */
 export function decayEmotion(state, now = new Date()) {
   const last = parseIso(state.updated_at) ?? now;
   const minutes = Math.max(0, (now.getTime() - last.getTime()) / 60_000);
   if (minutes <= 0) return state;
-  for (const key of EMOTION_KEYS) {
-    const half = Number(state.half_life_minutes[key] ?? EMOTIONS[key].halfLife);
-    const base = Number(state.baseline[key] ?? DEFAULT_BASELINE[key]);
-    const level = Number(state.levels[key] ?? base);
-    const factor = half > 0 ? Math.pow(0.5, minutes / half) : 0;
-    state.levels[key] = Math.round((base + (level - base) * factor) * 100) / 100;
-  }
+  applyDecay(state, minutes);
   state.updated_at = iso(now);
   return state;
 }
@@ -416,13 +446,7 @@ export function decayEmotion(state, now = new Date()) {
 export function decayEmotionBy(state, minutes = SLEEP_DECAY_MINUTES) {
   const mins = Math.max(0, Number(minutes) || 0);
   if (!mins) return state;
-  for (const key of EMOTION_KEYS) {
-    const half = Number(state.half_life_minutes[key] ?? EMOTIONS[key].halfLife);
-    const base = Number(state.baseline[key] ?? DEFAULT_BASELINE[key]);
-    const level = Number(state.levels[key] ?? base);
-    const factor = half > 0 ? Math.pow(0.5, mins / half) : 0;
-    state.levels[key] = Math.round((base + (level - base) * factor) * 100) / 100;
-  }
+  applyDecay(state, mins);
   state.updated_at = nowIso();
   return state;
 }
diff --git a/scripts/selftest.mjs b/scripts/selftest.mjs
index 6460188..da1a668 100644
--- a/scripts/selftest.mjs
+++ b/scripts/selftest.mjs
@@ -843,6 +843,61 @@ console.log("\n並行寫入：read-modify-rewrite 不能吃掉同時 append 的
       !fs.existsSync(staleLock), pl.fileLockPath(victim));
 }
 
+// --------------------------------------------------------------------------- //
+// 情緒的檔案入口要驗證：emotion.json 是外部輸入（import／sync pull／手改都會進來），
+// CLI 的 --baseline／--apply 有保護，破口在檔案這一側。
+console.log("\n情緒：不合法的 emotion.json 不能污染整個狀態");
+{
+  cli(["create", "--persona", "badstate", "--session", "sess-bad-8888", "--name", "Bad",
+    "--creature", "壞掉的溫度計", "--vibe", "亂跳", "--emoji", "🌡"]);
+  const anHourAgo = pl.iso(new Date(Date.now() - 3_600_000));
+  const write = (patch) => {
+    const st = pl.defaultEmotionState();
+    st.updated_at = anHourAgo;
+    patch(st);
+    pl.writeJson(pl.emotionPath("badstate"), st);
+  };
+
+  // ① 超出範圍的 baseline：以前 decay 後 joy = 4378，mood 卡在 valence 100 / arousal 100
+  write((st) => { st.baseline.joy = 5000; });
+  const over = pl.decayEmotion(pl.loadEmotion("badstate"));
+  check("baseline 超出 0–100 會被 clamp（不會把 mood 頂到滿）",
+    over.baseline.joy === 100 && over.levels.joy <= 100 && pl.mood(over).valence < 100,
+    `baseline=${over.baseline.joy} joy=${over.levels.joy} valence=${pl.mood(over).valence}`);
+
+  // ② 非數字的 levels：以前 decay 後 anger = NaN，注入的上下文直接印出 valence NaN
+  write((st) => { st.levels.anger = "很生氣"; st.levels.joy = null; });
+  const nan = pl.decayEmotion(pl.loadEmotion("badstate"));
+  check("非數字的情緒值退回預設，不會變成 NaN",
+    Number.isFinite(nan.levels.anger) && Number.isFinite(nan.levels.joy), JSON.stringify(nan.levels));
+  check("注入的上下文不會印出 NaN",
+    !pl.emotionBrief("badstate", nan).includes("NaN") && Number.isFinite(pl.mood(nan).valence),
+    pl.emotionBrief("badstate", nan));
+
+  // ③ 半衰期 ≤ 0：以前 factor 恆為 0，那個情緒從此累積不起來（連三次 +30 結果都一樣）
+  for (const bad of [-10, 0, "很久", null]) {
+    write((st) => { st.half_life_minutes.joy = bad; });
+    check(`half_life=${JSON.stringify(bad)} 會退回預設半衰期`,
+      pl.loadEmotion("badstate").half_life_minutes.joy === pl.EMOTIONS.joy.halfLife);
+  }
+  write((st) => { st.half_life_minutes.joy = -10; });
+  const grow = [];
+  for (let i = 0; i < 3; i += 1) {
+    cli(["emotion", "--session", "sess-bad-8888", "--apply", "joy=+30"]);
+    grow.push(pl.readJson(pl.emotionPath("badstate")).levels.joy);
+  }
+  check("半衰期壞掉時情緒仍然累積得起來（以前三次 +30 一動也不動）",
+    grow[1] > grow[0] && grow[2] > grow[1], grow.join(" → "));
+
+  // ④ 睡眠的固定衰減走同一條路
+  write((st) => { st.half_life_minutes.sadness = 0; st.levels.sadness = 90; });
+  const slept = pl.decayEmotionBy(pl.loadEmotion("badstate"), pl.SLEEP_DECAY_MINUTES);
+  check("decayEmotionBy 也擋得住壞掉的半衰期（不會一覺把情緒歸零）",
+    slept.levels.sadness > pl.DEFAULT_BASELINE.sadness && slept.levels.sadness < 90,
+    `sadness=${slept.levels.sadness}`);
+  cli(["release", "--session", "sess-bad-8888"]);
+}
+
 console.log("\n情緒：飽和、單輪預算、走向、偏差稽核");
 let sat = pl.defaultEmotionState();
 for (let i = 0; i < 10; i += 1) sat = pl.applyEmotion(sat, { joy: +20 }, "連灌");