diff --git a/apps/api/src/api/v1/webhooks.py b/apps/api/src/api/v1/webhooks.py
index 9494026b..a3c6ab5e 100644
--- a/apps/api/src/api/v1/webhooks.py
+++ b/apps/api/src/api/v1/webhooks.py
@@ -30,8 +30,8 @@ from fastapi import APIRouter, BackgroundTasks, Header, HTTPException, Request,
 from pydantic import BaseModel, Field
 
 from src.core.config import settings
-from src.constants.alert_types import ALERTNAME_TO_TYPE
 from src.core.constants import is_cicd_alertname, is_heartbeat_alertname
+from src.services.alert_rule_engine import get_incident_type
 from src.core.logging import get_logger
 from src.core.metrics import record_alert_chain_success
 
@@ -1100,9 +1100,8 @@ async def alertmanager_webhook(
                 approval_created=False,
             )
 
-    # M3 重構 2026-04-11: alertname_to_type 抽至 src/constants/alert_types.py
-    # TODO I1: 下 Sprint 整合 ADR-064 Rule Engine 動態推斷
-    alert_type = ALERTNAME_TO_TYPE.get(alertname, "custom")
+    # I1 整合 ADR-064 Rule Engine 2026-04-11: YAML 規則動態推斷，ALERTNAME_TO_TYPE 為 fallback
+    alert_type = get_incident_type(alertname)
 
     severity_map = {"critical": "critical", "warning": "warning", "info": "info"}
     severity = severity_map.get(
diff --git a/apps/api/src/services/alert_rule_engine.py b/apps/api/src/services/alert_rule_engine.py
index 8df2f64f..83b5d299 100644
--- a/apps/api/src/services/alert_rule_engine.py
+++ b/apps/api/src/services/alert_rule_engine.py
@@ -261,6 +261,42 @@ _AUTO_RULE_PROMPT = """\
 """
 
 
+def get_incident_type(alertname: str) -> str:
+    """
+    I1 整合 ADR-064 Rule Engine (2026-04-11):
+    從 YAML 規則動態推斷 incident_type，取代 webhooks.py 靜態 dict。
+
+    優先順序:
+    1. alert_rules.yaml 中 match.alertname 完全匹配 → 使用 rule.incident_type
+    2. ALERTNAME_TO_TYPE 靜態 dict fallback（constants/alert_types.py）
+    3. "custom"（兜底）
+
+    rule.incident_type 可選欄位；若 YAML 規則未設則跳過進 fallback。
+    """
+    from src.constants.alert_types import ALERTNAME_TO_TYPE
+
+    try:
+        rules = _load_rules()
+        for rule in rules:
+            if _is_generic(rule):
+                continue
+            alertnames = rule.get("match", {}).get("alertname", [])
+            if alertname in alertnames:
+                # YAML 有 incident_type 欄位優先用
+                incident_type = rule.get("incident_type")
+                if incident_type:
+                    return incident_type
+                # 無 incident_type 欄位 → 用 rule id 作為 incident_type（語意一致）
+                rule_id = rule.get("id", "")
+                if rule_id:
+                    return rule_id
+                break
+    except Exception:
+        pass
+
+    return ALERTNAME_TO_TYPE.get(alertname, "custom")
+
+
 def _rule_id_exists(alertname: str) -> bool:
     """檢查 alertname 是否已有規則（排除通用兜底）"""
     try: