fix(api): tolerate legacy incident outcomes

apps/api/tests/test_incident_service_resolve_idempotency.py

@@ -23,6 +23,7 @@ from src.services.incident_service import (
     IncidentService,
     normalize_status,
     parse_decision_chain,
+    parse_incident_outcome,
 )
 
 
@@ -107,6 +108,11 @@ def test_parse_decision_chain_skips_legacy_list_payload() -> None:
     assert parse_decision_chain([{"stage": "router"}], "INC-LEGACY-CHAIN") is None
 
 
+def test_parse_incident_outcome_skips_legacy_string_payload() -> None:
+    """舊資料 outcome 可能是字串；不應阻斷 incident hydrate / resolve。"""
+    assert parse_incident_outcome("resolved", "INC-LEGACY-OUTCOME") is None
+
+
 def test_record_to_incident_tolerates_legacy_decision_chain_list() -> None:
     """DB fallback 必須能讀回舊 incident，即使 decision_chain 不是新 schema。"""
     now = datetime.now(UTC)
@@ -134,3 +140,32 @@ def test_record_to_incident_tolerates_legacy_decision_chain_list() -> None:
     assert incident.incident_id == "INC-LEGACY-CHAIN"
     assert incident.status == IncidentStatus.INVESTIGATING
     assert incident.decision_chain is None
+
+
+def test_record_to_incident_tolerates_legacy_outcome_string() -> None:
+    """DB fallback 必須能讀回舊 incident，即使 outcome 不是新 schema。"""
+    now = datetime.now(UTC)
+    record = SimpleNamespace(
+        incident_id="INC-LEGACY-OUTCOME",
+        status="INVESTIGATING",
+        severity="P2",
+        signals=[],
+        affected_services=[],
+        decision_chain=None,
+        proposal_ids=[],
+        outcome="resolved",
+        created_at=now,
+        updated_at=now,
+        resolved_at=None,
+        closed_at=None,
+        ttl_days=7,
+        vectorized=False,
+        notification_type="TYPE-3",
+        alert_category="host_resource",
+    )
+
+    incident = IncidentService()._record_to_incident(record)
+
+    assert incident.incident_id == "INC-LEGACY-OUTCOME"
+    assert incident.status == IncidentStatus.INVESTIGATING
+    assert incident.outcome is None