Update app/db_sync.py

app/db_sync.py

@@ -294,6 +294,44 @@ def is_ready() -> bool:
     return _initialized and _db_path is not None
 
 
+# =============================================================================
+# SECTION 6 — PostgreSQL Bridge (Guardian-injected, optional)
+# =============================================================================
+_psql_writer = None
+
+
+def set_psql_writer(writer_fn) -> None:
+    """
+    Receives execute_secured_query callable from Guardian via app.py.
+    Called once in start_application() if db_service is available.
+    app/* never imports postgresql.py directly — this is the only bridge.
+    """
+    global _psql_writer
+    _psql_writer = writer_fn
+    logger.info("PostgreSQL writer registered.")
+
+
+async def persist(table: str, data: dict) -> None:
+    """
+    Write data from app/* to PostgreSQL via Guardian-injected writer.
+    Called by tools.py for provider_type = 'persist'.
+    Graceful degradation: raises RuntimeError if no DB configured.
+
+    Args:
+        table: Target PostgreSQL table name.
+        data:  Dict to persist — stored as JSONB column 'payload'.
+    """
+    if not _psql_writer:
+        raise RuntimeError("No PostgreSQL writer — DATABASE_URL not configured.")
+
+    from datetime import datetime, timezone
+    now = datetime.now(timezone.utc).isoformat()
+
+    sql = f"INSERT INTO {table} (payload, created_at) VALUES ($1::jsonb, $2)"
+    await _psql_writer(sql, json.dumps(data), now, fetch_method="execute")
+    logger.info(f"Persisted to PostgreSQL table '{table}'.")
+
+
 # =============================================================================
 # Direct execution guard
 # =============================================================================