diff --git a/apps/api/src/jobs/ai_slo_watchdog_job.py b/apps/api/src/jobs/ai_slo_watchdog_job.py
index d0c382c1..7c7fbd08 100644
--- a/apps/api/src/jobs/ai_slo_watchdog_job.py
+++ b/apps/api/src/jobs/ai_slo_watchdog_job.py
@@ -183,13 +183,18 @@ async def _check_once() -> None:
         return
 
     # 去重：violations 相同內容 1 小時內不重複發
-    dedup_hash = f"{hash(tuple(sorted(violations))) & 0xFFFFFF:06x}"
+    # 2026-05-04 ogt: 修正 hash() 非確定性 bug — Python hash() 每次 process 重啟值不同
+    # (PYTHONHASHSEED 隨機化)，導致每次 rollout 都繞過 dedup。改用 hashlib.sha256 確保跨 pod/重啟一致。
+    import hashlib
+    _content = "|".join(sorted(violations))
+    dedup_hash = hashlib.sha256(_content.encode()).hexdigest()[:12]
     dedup_key = f"watchdog:alert:{dedup_hash}"
     redis = get_redis()
-    if await redis.exists(dedup_key):
+    # setnx atomic — 同時多個 pod 只有第一個能 set，避免並發多發
+    set_ok = await redis.set(dedup_key, "1", ex=_DEDUP_TTL_SEC, nx=True)
+    if not set_ok:
         logger.debug("ai_slo_watchdog_deduped", key=dedup_key)
         return
-    await redis.setex(dedup_key, _DEDUP_TTL_SEC, "1")
 
     violation_lines = [
         f"{idx + 1}. {item}" for idx, item in enumerate(violations)