diff --git a/apps/api/src/jobs/asset_scanner_job.py b/apps/api/src/jobs/asset_scanner_job.py
index 1ab8282ca..68227b68d 100644
--- a/apps/api/src/jobs/asset_scanner_job.py
+++ b/apps/api/src/jobs/asset_scanner_job.py
@@ -41,6 +41,7 @@ _SCAN_INTERVAL_SEC = 3600       # 每 1 小時
 _FIRST_DELAY_SEC = 60           # 啟動後等 60s 再首掃 (其他 service init)
 _KUBECTL_TIMEOUT_SEC = 30
 _LOOP_BACKOFF_SEC = 300         # 異常時 backoff 5 分鐘
+_PROJECT_ID = "awoooi"
 
 # 7 個自動化覆蓋維度 (ADR-090 §3.5)
 _COVERAGE_DIMENSIONS = (
@@ -522,6 +523,7 @@ async def _collect_prometheus_targets() -> tuple[list[dict[str, Any]], list[dict
     target → host 建 depends_on relationship.
     """
     import httpx
+
     from src.core.config import settings
 
     assets: list[dict[str, Any]] = []
@@ -636,9 +638,10 @@ async def _start_discovery_run(
     """
     try:
         from sqlalchemy import text as _sql
+
         from src.db.base import get_db_context
 
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             row = await db.execute(
                 _sql("""
                     INSERT INTO asset_discovery_run (
@@ -677,9 +680,10 @@ async def _finish_discovery_run(
 ) -> None:
     try:
         from sqlalchemy import text as _sql
+
         from src.db.base import get_db_context
 
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             await db.execute(
                 _sql("""
                     UPDATE asset_discovery_run
@@ -719,13 +723,14 @@ async def _upsert_assets(
         return 0, 0
 
     from sqlalchemy import text as _sql
+
     from src.db.base import get_db_context
 
     new_count = 0
     modified_count = 0
 
     try:
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             for a in assets:
                 # xmax = 0 表示 INSERT (新),否則表示 UPDATE (修改)
                 row = await db.execute(
@@ -781,11 +786,12 @@ async def _upsert_relationships(relationships: list[dict[str, str]]) -> int:
         return 0
 
     from sqlalchemy import text as _sql
+
     from src.db.base import get_db_context
 
     written = 0
     try:
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             for rel in relationships:
                 try:
                     # 用 asset_key → asset_id 解析,同時 UPSERT
@@ -826,9 +832,10 @@ async def _write_coverage_snapshots(run_id: str) -> None:
     """
     try:
         from sqlalchemy import text as _sql
+
         from src.db.base import get_db_context
 
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             # 一次性 INSERT: 取所有 active asset × 7 dimensions
             await db.execute(
                 _sql("""
@@ -871,6 +878,7 @@ async def _log_aol_asset_discovered(
     """寫 automation_operation_log(asset_discovered)。失敗只 log 不阻塞。"""
     try:
         from sqlalchemy import text as _sql
+
         from src.db.base import get_db_context
 
         aol_status = "success" if status == "success" else "failed"
@@ -887,7 +895,7 @@ async def _log_aol_asset_discovered(
             "modified_assets": modified,
         }
 
-        async with get_db_context() as db:
+        async with get_db_context(_PROJECT_ID) as db:
             await db.execute(
                 _sql("""
                     INSERT INTO automation_operation_log (
diff --git a/apps/api/tests/test_asset_scanner_job.py b/apps/api/tests/test_asset_scanner_job.py
new file mode 100644
index 000000000..6106ca412
--- /dev/null
+++ b/apps/api/tests/test_asset_scanner_job.py
@@ -0,0 +1,94 @@
+from __future__ import annotations
+
+import asyncio
+
+from src.jobs import asset_scanner_job
+
+
+class _Result:
+    def scalar(self):
+        return "00000000-0000-0000-0000-000000000001"
+
+    def one(self):
+        return 1, True
+
+
+class _Database:
+    async def execute(self, statement, parameters=None):
+        return _Result()
+
+
+class _Context:
+    async def __aenter__(self):
+        return _Database()
+
+    async def __aexit__(self, exc_type, exc, traceback):
+        return False
+
+
+def test_background_scanner_scopes_every_database_operation(monkeypatch) -> None:
+    requested_projects: list[str | None] = []
+
+    def fake_db_context(project_id: str | None = None):
+        requested_projects.append(project_id)
+        return _Context()
+
+    monkeypatch.setattr("src.db.base.get_db_context", fake_db_context)
+
+    async def exercise_scanner_writes() -> None:
+        run_id = await asset_scanner_job._start_discovery_run(
+            "cron", ["k8s", "prometheus"], "shallow"
+        )
+        assert run_id == "00000000-0000-0000-0000-000000000001"
+
+        await asset_scanner_job._finish_discovery_run(
+            run_id=run_id,
+            status="success",
+            total_assets=1,
+            new_assets=1,
+            modified_assets=0,
+            duration_ms=10,
+            error=None,
+        )
+        inserted, modified = await asset_scanner_job._upsert_assets(
+            [
+                {
+                    "asset_key": "host/test",
+                    "asset_type": "host",
+                    "host": "test",
+                    "namespace": None,
+                    "name": "test",
+                    "metadata": {},
+                    "tags": ["source:test"],
+                }
+            ],
+            run_id,
+        )
+        assert (inserted, modified) == (1, 0)
+
+        written = await asset_scanner_job._upsert_relationships(
+            [
+                {
+                    "from_key": "host/test",
+                    "to_key": "monitoring/test",
+                    "relationship_type": "monitors",
+                }
+            ]
+        )
+        assert written == 1
+
+        await asset_scanner_job._write_coverage_snapshots(run_id)
+        await asset_scanner_job._log_aol_asset_discovered(
+            run_id=run_id,
+            triggered_by="cron",
+            total=1,
+            new=1,
+            modified=0,
+            duration_ms=10,
+            status="success",
+            error=None,
+        )
+
+    asyncio.run(exercise_scanner_writes())
+
+    assert requested_projects == ["awoooi"] * 6