fix(api): serialize startup bootstrap ddl

apps/api/src/db/base.py

@@ -157,6 +157,9 @@ async def get_db_context(project_id: str | None = None) -> AsyncGenerator[AsyncS
 # Initialization
 # =============================================================================
 
+_DB_BOOTSTRAP_LOCK_NAME = "awoooi:init_db:ddl"
+
+
 async def init_db() -> None:
     """
     Initialize database tables
@@ -165,6 +168,28 @@ async def init_db() -> None:
     """
     engine = get_engine()
 
+    async with engine.connect() as lock_conn:
+        # 2026-05-24 ogt + Codex: 兩個 API replica 同時啟動時，PostgreSQL 會在
+        # ALTER TABLE ... IF NOT EXISTS 上互相等待並 deadlock。整段 bootstrap
+        # DDL 必須序列化，避免 rollout 因一個 pod CrashLoop 變成 1/2 ready。
+        await lock_conn.execute(
+            text("SELECT pg_advisory_lock(hashtext(:lock_name))"),
+            {"lock_name": _DB_BOOTSTRAP_LOCK_NAME},
+        )
+        try:
+            await _run_init_db_ddl(engine)
+        finally:
+            await lock_conn.execute(
+                text("SELECT pg_advisory_unlock(hashtext(:lock_name))"),
+                {"lock_name": _DB_BOOTSTRAP_LOCK_NAME},
+            )
+
+
+async def _run_init_db_ddl(engine: AsyncEngine) -> None:
+    """
+    Run idempotent DB bootstrap DDL while caller holds the bootstrap advisory lock.
+    """
+
     # 2026-04-15 ogt: 多 replica 並行啟動競爭修復
     # 問題：單一大 transaction 裡兩個 pod 同時建 table → 其中一個 CREATE INDEX 失敗
     #       PostgreSQL 中 transaction 內任何錯誤導致整個 transaction ROLLBACK