diff --git a/apps/api/src/db/models.py b/apps/api/src/db/models.py
index a92a606b..3710a736 100644
--- a/apps/api/src/db/models.py
+++ b/apps/api/src/db/models.py
@@ -759,7 +759,7 @@ class IncidentEvidence(Base):
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=generate_uuid)
 
     # 關聯
-    incident_id: Mapped[str] = mapped_column(String(30), nullable=False, index=True)
+    incident_id: Mapped[str] = mapped_column(String(30), nullable=False)  # index via __table_args__
     # Phase 3 填充：matched_playbook_id 目前永久 null，Phase 3 修復
     matched_playbook_id: Mapped[str | None] = mapped_column(String(36), nullable=True)