diff --git a/apps/api/src/services/alert_analyzer_service.py b/apps/api/src/services/alert_analyzer_service.py
index db319fea..8ab2f324 100644
--- a/apps/api/src/services/alert_analyzer_service.py
+++ b/apps/api/src/services/alert_analyzer_service.py
@@ -182,10 +182,14 @@ class AlertAnalyzer:
         """
         生成告警唯一指紋 (SHA256 Hash)
 
-        指紋組成: namespace:deployment:alert_type:target_resource
+        指紋組成: namespace:deployment:alertname:target_resource
 
-        同一個告警模式（相同位置、相同類型）會產生相同指紋，
-        用於識別重複告警並進行聚合。
+        使用 alertname（而非 alert_type）確保不同告警名稱不共用指紋。
+        原本用 alert_type 導致許多不同 alertname 都落入 "custom"，
+        造成同目標上的不同告警互相擋截（ADR-073 修復 2026-04-12 ogt）。
+
+        同一個告警名稱 + 同一目標 → 相同指紋 → 觸發 debounce 去重。
+        不同告警名稱（即使同目標）→ 不同指紋 → 各自建立 Incident。
         """
         # 從 labels 取得 deployment，如果沒有則用 target_resource
         deployment = ""
@@ -194,8 +198,13 @@ class AlertAnalyzer:
         if not deployment:
             deployment = alert.target_resource
 
+        # alertname 優先取 labels，fallback 到 alert_type（非 Alertmanager 來源）
+        alertname = (
+            alert.labels.get("alertname", "") if alert.labels else ""
+        ) or alert.alert_type
+
         # 組合指紋來源
-        fingerprint_source = f"{alert.namespace}:{deployment}:{alert.alert_type}:{alert.target_resource}"
+        fingerprint_source = f"{alert.namespace}:{deployment}:{alertname}:{alert.target_resource}"
 
         # SHA256 Hash
         return hashlib.sha256(fingerprint_source.encode()).hexdigest()[:32]
diff --git a/apps/api/src/services/incident_service.py b/apps/api/src/services/incident_service.py
index 03b12962..e7aa1e58 100644
--- a/apps/api/src/services/incident_service.py
+++ b/apps/api/src/services/incident_service.py
@@ -130,11 +130,14 @@ def classify_alert_early(alertname: str, severity: str, labels: dict | None = No
         return "config_drift", "TYPE-4D"
 
     # 2. 告警鏈路健康（meta-monitoring，優先於 severity 判斷）
+    # 2026-04-12 ogt: 補入 NoAlertsReceived + PrometheusNotConnectedToAlertmanager
     if alertname in (
         "AlertChainBroken_Alertmanager",
         "AlertChainBroken_Sentry",
+        "NoAlertsReceived",
         "NoAlertsReceived2Hours",
         "AlertChainUnhealthy",
+        "PrometheusNotConnectedToAlertmanager",
     ):
         return "alertchain_health", "TYPE-8M"
 
@@ -171,8 +174,10 @@ def classify_alert_early(alertname: str, severity: str, labels: dict | None = No
         "HostBackupFailed", "HostBackupStale", "HostBackupMissing",
         "BackupRestoreTestFailed", "BackupRestoreTestStale",
     }
+    # 2026-04-12 ogt: 補入 DeadMansSwitch（HEARTBEAT_ALERT_NAMES 中但之前漏掉）
     if (
         "watchdog" in alertname_lower
+        or "deadmansswitch" in alertname_lower
         or alertname == "Heartbeat"
         or alertname in _BACKUP_TYPE1_NAMES
         or alertname.startswith("HostBackup")
diff --git a/apps/api/tests/test_classify_alert_early.py b/apps/api/tests/test_classify_alert_early.py
index d1ede5b5..e1008ebe 100644
--- a/apps/api/tests/test_classify_alert_early.py
+++ b/apps/api/tests/test_classify_alert_early.py
@@ -66,6 +66,12 @@ class TestInfoAlerts:
         ac, nt = classify_alert_early("Watchdog", "none", {})
         assert nt == "TYPE-1"
 
+    def test_deadmansswitch_heartbeat(self):
+        # DeadMansSwitch 心跳 → TYPE-1（補入 2026-04-12 ogt）
+        ac, nt = classify_alert_early("DeadMansSwitch", "warning", {})
+        assert ac == "backup"
+        assert nt == "TYPE-1"
+
     def test_backup_critical_not_type1(self):
         # critical backup 告警應走各自 prefix，不是純資訊
         ac, nt = classify_alert_early("BACKUP_MISSING", "critical", {})
@@ -115,6 +121,8 @@ class TestAlertchainHealth:
         "AlertChainBroken_Sentry",
         "NoAlertsReceived2Hours",
         "AlertChainUnhealthy",
+        "NoAlertsReceived",
+        "PrometheusNotConnectedToAlertmanager",
     ])
     def test_alertchain_alerts(self, alertname):
         ac, nt = classify_alert_early(alertname, "critical", {})