diff --git a/apps/api/src/services/decision_manager.py b/apps/api/src/services/decision_manager.py
index 322e9242..3deb040f 100644
--- a/apps/api/src/services/decision_manager.py
+++ b/apps/api/src/services/decision_manager.py
@@ -263,41 +263,16 @@ async def _push_decision_to_telegram(
         _notification_type = getattr(incident, "notification_type", "") or (_notif_type.value if _notif_type else "")
         _alertname = incident.signals[0].labels.get("alertname", "MetaSystemAlert") if incident.signals else "MetaSystemAlert"
 
-        # 2026-04-16 ogt + Claude Sonnet 4.6: blocked_reason 感知層
-        # ① INVALID_TARGET → TYPE-4：系統無法識別告警目標，SRE 需人工調查
-        # ② NO_ACTION + critical → TYPE-4：critical 事件不能靜默，即便 AI 無法自動修復
-        # ③ NO_ACTION + non-critical → TYPE-1：一般資訊告警，純資訊卡即可
+        # blocked_reason 由上游「決策路由閘門」統一設定（decide() 第 4c 步）
+        # 此處只做狀態轉譯，通知層禁止查詢業務邏輯（架構師鐵律 2026-04-17）
+        # ① INVALID_TARGET → TYPE-4：目標無法解析，SRE 需人工調查
+        # ② NO_ACTION + critical → TYPE-4：critical 事件不可靜默
+        # ③ NO_ACTION + non-critical → TYPE-1：純資訊卡
         _blocked_reason = proposal_data.get("blocked_reason", "")
-
-        # 2026-04-17 ogt + Claude Sonnet 4.6: Inline YAML NO_ACTION 補查
-        # 根因：Phase 2 路徑（agent debate → auto_approve 拒絕 → 直接推 TG）不經過
-        #       auto_execute() 的 YAML check（lines 1427-1439），Coordinator 不設 blocked_reason。
-        # 修復：在 _push_decision_to_telegram 內做一次 alertname 查詢，任何路徑都能偵測 NO_ACTION。
-        if not _blocked_reason and incident.signals:
-            try:
-                from src.services.alert_rule_engine import match_rule as _notif_match
-                _notif_alertname = incident.signals[0].labels.get("alertname", "")
-                if _notif_alertname:
-                    _notif_rule = _notif_match({
-                        "labels": incident.signals[0].labels,
-                        "alert_type": _notif_alertname,
-                        "message": "",
-                        "target_resource": target,
-                        "namespace": "awoooi-prod",
-                    })
-                    if _notif_rule:
-                        if _notif_rule.get("blocked_reason", "").startswith("INVALID_TARGET"):
-                            _blocked_reason = _notif_rule["blocked_reason"]
-                        elif _notif_rule.get("suggested_action") == "NO_ACTION":
-                            _blocked_reason = f"YAML: NO_ACTION for {_notif_alertname}"
-            except Exception:
-                pass  # 查詢失敗不影響主流程
-
         if "INVALID_TARGET" in _blocked_reason:
             _notif_type = NotificationType.TYPE_4
         elif "NO_ACTION" in _blocked_reason:
             if risk_level == "critical":
-                # critical + NO_ACTION: SRE 必須知道（TYPE-4 AI 無法判斷），不可靜默為 TYPE-1
                 _notif_type = NotificationType.TYPE_4
             else:
                 _notif_type = NotificationType.TYPE_1
@@ -1389,6 +1364,57 @@ class DecisionManager:
                 self._persist_decision_to_db(incident.incident_id, token.proposal_data)
             )
 
+        # 4c. YAML NO_ACTION 閘門 — 決策路由中樞（2026-04-17 ogt + Claude Sonnet 4.6）
+        # 架構原則：通知層（_push_decision_to_telegram）只做狀態轉譯，不查業務邏輯。
+        # 因此 NO_ACTION / INVALID_TARGET 判斷必須在此閘門統一完成，任何路徑都必須通過。
+        #
+        # 根因（先前盲點）：Phase 2 路徑拒絕後直接推 TG，不經 auto_execute() 的 YAML check，
+        #   Coordinator 不設 blocked_reason → TG 收到空 blocked_reason → 無法正確分類通知類型。
+        # 修復：在 auto_approve 之前，統一查詢 YAML 規則：
+        #   NO_ACTION → 標記 blocked_reason + is_informational_only → 短路跳過 auto_approve
+        #   INVALID_TARGET → 標記 blocked_reason → 短路，TYPE-4 由 TG 層轉譯
+        if token.state == DecisionState.READY and token.proposal_data and incident.signals:
+            _gate_alertname = incident.signals[0].labels.get("alertname", "")
+            if _gate_alertname and not token.proposal_data.get("blocked_reason", ""):
+                try:
+                    from src.services.alert_rule_engine import match_rule as _gate_match
+                    _gate_r = _gate_match({
+                        "labels": incident.signals[0].labels,
+                        "alert_type": _gate_alertname,
+                        "message": "",
+                        "target_resource": (
+                            incident.affected_services[0]
+                            if incident.affected_services else "unknown"
+                        ),
+                        "namespace": "awoooi-prod",
+                    })
+                    if _gate_r:
+                        _gate_blocked = _gate_r.get("blocked_reason", "")
+                        _gate_action = _gate_r.get("suggested_action", "")
+                        if "INVALID_TARGET" in _gate_blocked or _gate_action == "NO_ACTION":
+                            # 標記 blocked_reason，讓 TG 層正確轉譯通知類型
+                            if "INVALID_TARGET" in _gate_blocked:
+                                token.proposal_data["blocked_reason"] = _gate_blocked
+                            else:
+                                token.proposal_data["blocked_reason"] = f"YAML: NO_ACTION for {_gate_alertname}"
+                                token.proposal_data["is_informational_only"] = True
+                            token.proposal_data["auto_executed"] = False
+                            token.proposal_data["decision_state"] = token.state.value
+                            await self._save_token(token)
+                            _fire_and_forget(
+                                _push_decision_to_telegram(incident, token.proposal_data)
+                            )
+                            logger.info(
+                                "yaml_gate_short_circuit",
+                                incident_id=incident.incident_id,
+                                alertname=_gate_alertname,
+                                blocked_reason=token.proposal_data["blocked_reason"],
+                            )
+                            return token  # 短路 — 跳過 auto_approve + Blast Radius 評估
+                except Exception as _gate_err:
+                    logger.debug("yaml_gate_error", error=str(_gate_err))
+                    # 閘門查詢失敗 → 降級繼續正常流程（不阻塞）
+
         # 5. ADR-030 Phase 4: 自動執行判斷
         if token.state == DecisionState.READY and token.proposal_data:
             # 評估是否可以自動執行