diff --git a/backend/packages/harness/deerflow/config/database_config.py b/backend/packages/harness/deerflow/config/database_config.py
index 84875a2f2..ee984a5fe 100644
--- a/backend/packages/harness/deerflow/config/database_config.py
+++ b/backend/packages/harness/deerflow/config/database_config.py
@@ -309,6 +309,14 @@ class DatabaseConfig(BaseModel):
             return f"sqlite:///{self.sqlite_path}"
         if self.backend == "postgres":
             url = self.postgres_url
+            if self.postgres_schema:
+                # The synchronous agent stores use psycopg via SQLAlchemy,
+                # so they need the same search_path as the async ORM engine
+                # and LangGraph stores.  Keep the option merge in the shared
+                # PostgreSQL helper so existing libpq options are preserved.
+                from deerflow.persistence.postgres_schema import dsn_with_search_path
+
+                url = dsn_with_search_path(url, self.postgres_schema)
             if url.startswith("postgresql+asyncpg://"):
                 url = url.replace("postgresql+asyncpg://", "postgresql+psycopg://", 1)
             elif url.startswith("postgresql://"):
diff --git a/backend/packages/harness/deerflow/persistence/AGENTS.md b/backend/packages/harness/deerflow/persistence/AGENTS.md
index 74bd638e3..850696418 100644
--- a/backend/packages/harness/deerflow/persistence/AGENTS.md
+++ b/backend/packages/harness/deerflow/persistence/AGENTS.md
@@ -1,3 +1,5 @@
 # Persistence lifecycle
 
 Postgres bootstrap owns its session-scoped advisory lock until `pg_advisory_unlock` completes. Drain that unlock across host cancellation before leaving the SQLAlchemy connection context; repeated cancellation must not return a pooled session while it still holds the bootstrap mutex. Ordinary database errors remain best-effort and are logged.
+
+When `database.postgres_schema` is configured, both async ORM connections and the synchronous SQLAlchemy connections used by DB-backed custom agents and managed subagents must use the same `search_path`; preserve this invariant when adding another persistence entry point.
diff --git a/backend/packages/harness/deerflow/persistence/postgres_schema.py b/backend/packages/harness/deerflow/persistence/postgres_schema.py
index ba8ff5a8c..9d07f81b5 100644
--- a/backend/packages/harness/deerflow/persistence/postgres_schema.py
+++ b/backend/packages/harness/deerflow/persistence/postgres_schema.py
@@ -7,9 +7,9 @@ uses expect different mechanisms:
 - **asyncpg** (app ORM engine): only honours ``server_settings`` passed
   via SQLAlchemy ``connect_args``. It does not understand libpq's
   ``options=-c ...`` syntax.
-- **psycopg** (LangGraph checkpointer/store): uses the libpq
-  ``options=-c search_path=...`` connection parameter, either as a pool
-  kwarg or encoded into the DSN query string.
+- **psycopg** (LangGraph checkpointer/store and synchronous agent stores): uses
+  the libpq ``options=-c search_path=...`` connection parameter, either as a
+  pool kwarg or encoded into the DSN query string.
 
 Schema names are validated upstream by
 :class:`deerflow.config.database_config.DatabaseConfig` to be plain
diff --git a/backend/tests/test_persistence_scaffold.py b/backend/tests/test_persistence_scaffold.py
index 77ebaa466..b415d74d8 100644
--- a/backend/tests/test_persistence_scaffold.py
+++ b/backend/tests/test_persistence_scaffold.py
@@ -115,6 +115,21 @@ class TestDatabaseConfig:
         assert "deerflow" not in url.replace("/db", "")
         assert url.startswith("postgresql+asyncpg://")
 
+    def test_sync_postgres_url_uses_configured_schema(self):
+        c = DatabaseConfig(backend="postgres", postgres_url="postgresql://u:p@h:5432/db", postgres_schema="deerflow")
+        url = c.app_sync_sqlalchemy_url
+        assert url.startswith("postgresql+psycopg://")
+        assert "options=-c%20search_path%3Ddeerflow" in url
+
+    def test_sync_postgres_url_preserves_existing_libpq_options(self):
+        c = DatabaseConfig(
+            backend="postgres",
+            postgres_url="postgresql://u:p@h:5432/db?options=-c%20statement_timeout%3D5000",
+            postgres_schema="deerflow",
+        )
+        url = c.app_sync_sqlalchemy_url
+        assert "options=-c%20statement_timeout%3D5000%20-c%20search_path%3Ddeerflow" in url
+
 
 # -- MemoryRunStore --