refactor(persistence): introduce ThreadMetaStore ABC for backend-agnostic thread metadata

Add ThreadMetaStore abstract base class with create/get/search/update/delete
interface. ThreadMetaRepository (SQL) now inherits from it. New
MemoryThreadMetaStore wraps LangGraph BaseStore for memory-mode deployments.

deps.py now always provides a non-None thread_meta_repo, eliminating all
`if thread_meta_repo is not None` guards in services.py, worker.py, and
routers/threads.py. search_threads no longer needs a Store fallback branch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/packages/harness/deerflow/persistence/repositories/thread_meta_base.py

@@ -0,0 +1,51 @@
+"""Abstract interface for thread metadata storage.
+
+Implementations:
+- ThreadMetaRepository: SQL-backed (sqlite / postgres via SQLAlchemy)
+- MemoryThreadMetaStore: wraps LangGraph BaseStore (memory mode)
+"""
+
+from __future__ import annotations
+
+import abc
+
+
+class ThreadMetaStore(abc.ABC):
+    @abc.abstractmethod
+    async def create(
+        self,
+        thread_id: str,
+        *,
+        assistant_id: str | None = None,
+        owner_id: str | None = None,
+        display_name: str | None = None,
+        metadata: dict | None = None,
+    ) -> dict:
+        pass
+
+    @abc.abstractmethod
+    async def get(self, thread_id: str) -> dict | None:
+        pass
+
+    @abc.abstractmethod
+    async def search(
+        self,
+        *,
+        metadata: dict | None = None,
+        status: str | None = None,
+        limit: int = 100,
+        offset: int = 0,
+    ) -> list[dict]:
+        pass
+
+    @abc.abstractmethod
+    async def update_display_name(self, thread_id: str, display_name: str) -> None:
+        pass
+
+    @abc.abstractmethod
+    async def update_status(self, thread_id: str, status: str) -> None:
+        pass
+
+    @abc.abstractmethod
+    async def delete(self, thread_id: str) -> None:
+        pass

backend/packages/harness/deerflow/persistence/repositories/thread_meta_memory.py

@@ -0,0 +1,108 @@
+"""In-memory ThreadMetaStore backed by LangGraph BaseStore.
+
+Used when database.backend=memory. Delegates to the LangGraph Store's
+``("threads",)`` namespace — the same namespace used by the Gateway
+router for thread records.
+"""
+
+from __future__ import annotations
+
+import time
+from typing import Any
+
+from langgraph.store.base import BaseStore
+
+from deerflow.persistence.repositories.thread_meta_base import ThreadMetaStore
+
+THREADS_NS: tuple[str, ...] = ("threads",)
+
+
+class MemoryThreadMetaStore(ThreadMetaStore):
+    def __init__(self, store: BaseStore) -> None:
+        self._store = store
+
+    async def create(
+        self,
+        thread_id: str,
+        *,
+        assistant_id: str | None = None,
+        owner_id: str | None = None,
+        display_name: str | None = None,
+        metadata: dict | None = None,
+    ) -> dict:
+        now = time.time()
+        record: dict[str, Any] = {
+            "thread_id": thread_id,
+            "assistant_id": assistant_id,
+            "owner_id": owner_id,
+            "display_name": display_name,
+            "status": "idle",
+            "metadata": metadata or {},
+            "values": {},
+            "created_at": now,
+            "updated_at": now,
+        }
+        await self._store.aput(THREADS_NS, thread_id, record)
+        return record
+
+    async def get(self, thread_id: str) -> dict | None:
+        item = await self._store.aget(THREADS_NS, thread_id)
+        return item.value if item is not None else None
+
+    async def search(
+        self,
+        *,
+        metadata: dict | None = None,
+        status: str | None = None,
+        limit: int = 100,
+        offset: int = 0,
+    ) -> list[dict]:
+        filter_dict: dict[str, Any] = {}
+        if metadata:
+            filter_dict.update(metadata)
+        if status:
+            filter_dict["status"] = status
+
+        items = await self._store.asearch(
+            THREADS_NS,
+            filter=filter_dict or None,
+            limit=limit,
+            offset=offset,
+        )
+        return [self._item_to_dict(item) for item in items]
+
+    async def update_display_name(self, thread_id: str, display_name: str) -> None:
+        item = await self._store.aget(THREADS_NS, thread_id)
+        if item is None:
+            return
+        record = dict(item.value)
+        record["display_name"] = display_name
+        record["updated_at"] = time.time()
+        await self._store.aput(THREADS_NS, thread_id, record)
+
+    async def update_status(self, thread_id: str, status: str) -> None:
+        item = await self._store.aget(THREADS_NS, thread_id)
+        if item is None:
+            return
+        record = dict(item.value)
+        record["status"] = status
+        record["updated_at"] = time.time()
+        await self._store.aput(THREADS_NS, thread_id, record)
+
+    async def delete(self, thread_id: str) -> None:
+        await self._store.adelete(THREADS_NS, thread_id)
+
+    @staticmethod
+    def _item_to_dict(item) -> dict[str, Any]:
+        """Convert a Store SearchItem to the dict format expected by callers."""
+        val = item.value
+        return {
+            "thread_id": item.key,
+            "assistant_id": val.get("assistant_id"),
+            "owner_id": val.get("owner_id"),
+            "display_name": val.get("display_name"),
+            "status": val.get("status", "idle"),
+            "metadata": val.get("metadata", {}),
+            "created_at": str(val.get("created_at", "")),
+            "updated_at": str(val.get("updated_at", "")),
+        }

backend/packages/harness/deerflow/persistence/repositories/thread_meta_repo.py

@@ -9,9 +9,10 @@ from sqlalchemy import select, update
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
 
 from deerflow.persistence.models.thread_meta import ThreadMetaRow
+from deerflow.persistence.repositories.thread_meta_base import ThreadMetaStore
 
 
-class ThreadMetaRepository:
+class ThreadMetaRepository(ThreadMetaStore):
     def __init__(self, session_factory: async_sessionmaker[AsyncSession]) -> None:
         self._sf = session_factory
 

backend/packages/harness/deerflow/runtime/runs/worker.py

@@ -285,7 +285,7 @@ async def run_agent(
             await run_manager.update_run_completion(run_id, status=record.status.value, **completion)
 
         # Sync title from checkpoint to threads_meta.display_name
-        if thread_meta_repo is not None and checkpointer is not None:
+        if checkpointer is not None:
             try:
                 ckpt_config = {"configurable": {"thread_id": thread_id, "checkpoint_ns": ""}}
                 ckpt_tuple = await checkpointer.aget_tuple(ckpt_config)
@@ -298,12 +298,11 @@ async def run_agent(
                 logger.debug("Failed to sync title for thread %s (non-fatal)", thread_id)
 
         # Update threads_meta status based on run outcome
-        if thread_meta_repo is not None:
-            try:
-                final_status = "idle" if record.status == RunStatus.success else record.status.value
-                await thread_meta_repo.update_status(thread_id, final_status)
-            except Exception:
-                logger.debug("Failed to update thread_meta status for %s (non-fatal)", thread_id)
+        try:
+            final_status = "idle" if record.status == RunStatus.success else record.status.value
+            await thread_meta_repo.update_status(thread_id, final_status)
+        except Exception:
+            logger.debug("Failed to update thread_meta status for %s (non-fatal)", thread_id)
 
         await bridge.publish_end(run_id)
         asyncio.create_task(bridge.cleanup(run_id, delay=60))