Windows 兼容性修复 + Dify API 适配 + 企微 WS 加载优化 (#2470)

* fix: Windows fsync requires write access to file descriptor

- _fsync_file: os.O_RDONLY -> os.O_RDWR (Windows _commit() requires write access)
- _fsync_directory: tolerate OSError on fsync and os.open (chmod 0o700 blocks access on Windows)

* fix: Dify SSE empty data lines and upload response format mismatch

- Skip malformed/flushed SSE data lines (JSONDecodeError)
- Accept HTTP 200 besides 201 for file upload response
- Unwrap data wrapper in upload response (resp.get('data', resp))

* feat: WeCom WS mode sends empty initial stream frame for loading spinner

Send an empty reply_stream frame immediately after stream session
creation so the WeCom client shows its built-in loading indicator
while the pipeline processes the message (e.g. RAG retrieval).

* fix(compat): harden Windows, Dify, and WeCom changes

* fix(migration): clean interrupted SQLite temp files

---------

Co-authored-by: Hyu <chenhyu@proton.me>

src/langbot/libs/dify_service_api/v1/client.py

@@ -1,13 +1,14 @@
 from __future__ import annotations
 
 import asyncio
-import httpx
-import typing
 import json
+import os
+import typing
+from pathlib import Path
+
+import httpx
 
 from .errors import DifyAPIError
-from pathlib import Path
-import os
 
 _MAX_DIFY_RESPONSE_BYTES = 1024 * 1024
 _MAX_DIFY_SSE_LINE_BYTES = 1024 * 1024
@@ -15,6 +16,32 @@ _MAX_DIFY_STREAM_BYTES = 16 * 1024 * 1024
 _MAX_DIFY_UPLOAD_BYTES = 10 * 1024 * 1024
 
 
+def _decode_sse_data(line: bytes) -> dict[str, typing.Any] | None:
+    data = line[5:].strip()
+    if not data or data == b'[DONE]':
+        return None
+    try:
+        payload = json.loads(data.decode('utf-8'))
+    except (json.JSONDecodeError, UnicodeDecodeError) as exc:
+        raise DifyAPIError('Dify SSE data line is not valid JSON') from exc
+    if not isinstance(payload, dict):
+        raise DifyAPIError('Dify SSE event is not a JSON object')
+    return payload
+
+
+def _decode_upload_response(body: bytes) -> dict[str, typing.Any]:
+    try:
+        response = json.loads(body)
+    except (json.JSONDecodeError, UnicodeDecodeError) as exc:
+        raise DifyAPIError('Dify upload response is not valid JSON') from exc
+    if not isinstance(response, dict):
+        raise DifyAPIError('Dify upload response is not a JSON object')
+    payload = response.get('data', response)
+    if not isinstance(payload, dict) or not isinstance(payload.get('id'), str) or not payload['id']:
+        raise DifyAPIError('Dify upload response does not contain a valid file id')
+    return payload
+
+
 async def _read_limited_response(
     response: httpx.Response,
     *,
@@ -56,16 +83,16 @@ async def _iter_sse_json(
             line = raw_line.rstrip(b'\r').strip()
             if not line or not line.startswith(b'data:'):
                 continue
-            payload = json.loads(line[5:].decode('utf-8', errors='replace'))
-            if isinstance(payload, dict):
+            payload = _decode_sse_data(line)
+            if payload is not None:
                 yield payload
         if len(buffer) > _MAX_DIFY_SSE_LINE_BYTES:
             raise DifyAPIError('Dify SSE event exceeds the runtime limit')
 
     line = bytes(buffer).rstrip(b'\r').strip()
     if line.startswith(b'data:'):
-        payload = json.loads(line[5:].decode('utf-8', errors='replace'))
-        if isinstance(payload, dict):
+        payload = _decode_sse_data(line)
+        if payload is not None:
             yield payload
 
 
@@ -242,7 +269,7 @@ class AsyncDifyServiceClient:
         file: httpx._types.FileTypes,
         user: str,
         timeout: float = 30.0,
-    ) -> str:
+    ) -> dict[str, typing.Any]:
         # 处理 Path 对象
         if isinstance(file, Path):
             if not file.exists():
@@ -271,6 +298,6 @@ class AsyncDifyServiceClient:
             timeout=timeout,
         ) as response:
             body = await _read_limited_response(response)
-            if response.status_code != 201:
+            if response.status_code not in (200, 201):
                 raise DifyAPIError(f'{response.status_code} {body.decode(errors="replace")}')
-        return json.loads(body)
+        return _decode_upload_response(body)

src/langbot/libs/wecom_ai_bot_api/ws_client.py

@@ -936,6 +936,13 @@ class WecomBotWsClient:
                     'chat_type': message_data.get('type', 'single'),
                 }
                 self._prune_stream_state()
+                # Send an initial empty stream frame so the WeCom client
+                # shows its built-in loading spinner while the pipeline
+                # processes the message (e.g. RAG retrieval).
+                try:
+                    await self.reply_stream(req_id, stream_id, '', finish=False)
+                except Exception:
+                    await self.logger.warning(f'Failed to send initial stream frame: {traceback.format_exc()}')
             message_data['stream_id'] = stream_id
             message_data['req_id'] = req_id
 

src/langbot/pkg/persistence/sqlite_migration_backup.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import asyncio
+import contextlib
 import dataclasses
 import datetime
 import json
@@ -82,7 +83,7 @@ def _verify_connection(connection: sqlite3.Connection, expected_revision: str) -
 
 
 def _verify_file(path: pathlib.Path, expected_revision: str) -> None:
-    with _open_read_only(path) as connection:
+    with contextlib.closing(_open_read_only(path)) as connection:
         _verify_connection(connection, expected_revision)
 
 
@@ -119,12 +120,16 @@ def _write_manifest(backup: SQLiteMigrationBackup, status: str, **extra: typing.
 
 
 def _fsync_file(path: pathlib.Path, *, reopen_attempts: int = 20) -> None:
-    """Sync a file, tolerating delayed visibility after replace on bind mounts."""
+    """Sync a file, tolerating delayed visibility after replace on bind mounts.
+
+    Uses O_RDWR so os.fsync works on Windows (where _commit requires write
+    access to the file descriptor).
+    """
 
     descriptor: int | None = None
     for attempt in range(reopen_attempts):
         try:
-            descriptor = os.open(path, os.O_RDONLY)
+            descriptor = os.open(path, os.O_RDWR)
             break
         except FileNotFoundError:
             if attempt + 1 >= reopen_attempts:
@@ -138,13 +143,37 @@ def _fsync_file(path: pathlib.Path, *, reopen_attempts: int = 20) -> None:
 
 
 def _fsync_directory(path: pathlib.Path) -> None:
-    descriptor = os.open(path, os.O_RDONLY)
+    if os.name == 'nt':
+        # Windows cannot fsync directory handles opened through os.open.
+        return
+    descriptor = os.open(path, os.O_RDONLY | getattr(os, 'O_DIRECTORY', 0))
     try:
         os.fsync(descriptor)
     finally:
         os.close(descriptor)
 
 
+def _remove_stale_temporary_files(
+    directory: pathlib.Path,
+    *,
+    prefix: str,
+    suffix: str,
+) -> None:
+    """Remove temporary files left by an interrupted backup or restore."""
+
+    for candidate in directory.iterdir():
+        if candidate.is_dir() or not candidate.name.startswith(prefix) or not candidate.name.endswith(suffix):
+            continue
+        try:
+            candidate.unlink()
+        except FileNotFoundError:
+            continue
+        except PermissionError:
+            # Another process may still own this file. Do not turn harmless
+            # cleanup into a migration failure; its unique name cannot collide.
+            continue
+
+
 def _create_backup(
     database_path: pathlib.Path,
     source_revision: str,
@@ -153,6 +182,11 @@ def _create_backup(
     backup_directory = database_path.parent / 'migration-backups'
     backup_directory.mkdir(mode=0o700, parents=True, exist_ok=True)
     os.chmod(backup_directory, 0o700)
+    _remove_stale_temporary_files(
+        backup_directory,
+        prefix=f'.{database_path.stem}-pre-',
+        suffix='.creating',
+    )
     created_at = datetime.datetime.now(datetime.UTC).strftime('%Y-%m-%dT%H-%M-%S.%fZ')
     stem = (
         f'{database_path.stem}-pre-{_safe_label(target_revision)}-'
@@ -169,11 +203,8 @@ def _create_backup(
     temporary_path = pathlib.Path(temporary_name)
     try:
         with (
-            _open_read_only(database_path) as source,
-            sqlite3.connect(
-                temporary_path,
-                timeout=30,
-            ) as destination,
+            contextlib.closing(_open_read_only(database_path)) as source,
+            contextlib.closing(sqlite3.connect(temporary_path, timeout=30)) as destination,
         ):
             source.execute('PRAGMA busy_timeout = 30000')
             source.backup(destination)
@@ -221,6 +252,11 @@ async def create_verified_backup(
 
 def _restore_backup(backup: SQLiteMigrationBackup) -> None:
     _verify_file(backup.backup_path, backup.source_revision)
+    _remove_stale_temporary_files(
+        backup.database_path.parent,
+        prefix=f'.{backup.database_path.name}.',
+        suffix='.restoring',
+    )
     descriptor, temporary_name = tempfile.mkstemp(
         prefix=f'.{backup.database_path.name}.',
         suffix='.restoring',
@@ -230,11 +266,8 @@ def _restore_backup(backup: SQLiteMigrationBackup) -> None:
     temporary_path = pathlib.Path(temporary_name)
     try:
         with (
-            _open_read_only(backup.backup_path) as source,
-            sqlite3.connect(
-                temporary_path,
-                timeout=30,
-            ) as destination,
+            contextlib.closing(_open_read_only(backup.backup_path)) as source,
+            contextlib.closing(sqlite3.connect(temporary_path, timeout=30)) as destination,
         ):
             source.backup(destination)
             destination.commit()