diff --git a/apps/api/tests/integration/setup_test_schema.sql b/apps/api/tests/integration/setup_test_schema.sql
index a4ed6c30..4312ed12 100644
--- a/apps/api/tests/integration/setup_test_schema.sql
+++ b/apps/api/tests/integration/setup_test_schema.sql
@@ -119,11 +119,24 @@ CREATE TABLE IF NOT EXISTS knowledge_entries (
     related_incident_id VARCHAR,
     related_playbook_id VARCHAR,
     symptoms_hash VARCHAR,
+    -- 2026-04-29 ogt + Claude Opus 4.7: M4 KMWriter 反查鏈 + 冪等補欄
+    -- 解 CD #1115-1118 全 failure：column "related_approval_id" does not exist
+    -- 對應 commit c22e5f33 KMWriter ORM 加的欄位
+    related_approval_id VARCHAR(64),
+    path_type VARCHAR(50),
     view_count INTEGER DEFAULT 0,
     created_by VARCHAR,
     created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
     updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
 );
+-- M3 冪等 unique index (incident_id + path_type)
+CREATE UNIQUE INDEX IF NOT EXISTS uix_knowledge_incident_path
+    ON knowledge_entries(related_incident_id, path_type)
+    WHERE related_incident_id IS NOT NULL AND path_type IS NOT NULL;
+-- M4 反查鏈 partial index
+CREATE INDEX IF NOT EXISTS ix_knowledge_related_approval
+    ON knowledge_entries(related_approval_id)
+    WHERE related_approval_id IS NOT NULL;
 
 CREATE TABLE IF NOT EXISTS rag_chunks (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),