Fix Claude Desktop loading: lazy NAS connection on first tool call

Previously the server blocked at startup waiting for query_api_info()
and login() before starting the MCP protocol. Claude Desktop has a short
initialization timeout and dropped the server before the handshake started.

Changes:
- DsmClient: add _ensure_initialized() with asyncio.Lock for thread-safe
  lazy init; called automatically at the start of request(), upload_text(),
  and download_text() on the first use.
- cli.py serve: remove upfront query_api_info() and auth.login() calls;
  the server now starts immediately ("MCP server ready" on stderr) and
  connects to the NAS on the first tool invocation.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp_synology_container/cli.py

@@ -300,7 +300,7 @@ async def _run_serve(config_path: str | None) -> None:
     # instead of silently killing the process.
     from mcp_synology_container.auth import AuthManager
     from mcp_synology_container.config import load_config
-    from mcp_synology_container.dsm_client import DsmClient, SynologyError
+    from mcp_synology_container.dsm_client import DsmClient
     from mcp_synology_container.server import create_server
 
     logger.debug("Loading config from: %s", config_path or "default path")
@@ -311,29 +311,19 @@ async def _run_serve(config_path: str | None) -> None:
         sys.stderr.flush()
         return
 
-    logger.debug("Connecting to %s", config.base_url)
+    # Open the HTTP client and register auth — but do NOT connect to the NAS yet.
-    try:
+    # Lazy init (_ensure_initialized) runs on the first tool call, so Claude Desktop
-        async with DsmClient(config.base_url, config.connection.verify_ssl) as client:
+    # sees the server as ready immediately without waiting for NAS connectivity.
-            await client.query_api_info()
+    async with DsmClient(config.base_url, config.connection.verify_ssl) as client:
-            auth = AuthManager(config)
+        auth = AuthManager(config)
-            client.set_auth_manager(auth)
+        client.set_auth_manager(auth)
 
-            try:
+        mcp_server = create_server(config, client)
-                client.sid = await auth.login(client)
+        sys.stderr.write("MCP server ready\n")
-            except Exception as e:
+        sys.stderr.flush()
-                sys.stderr.write(f"Login failed: {e}\n")
+        try:
-                sys.stderr.flush()
-                return
-
-            logger.debug("Login OK, creating MCP server")
-            mcp_server = create_server(config, client)
-            sys.stderr.write("MCP server ready\n")
-            sys.stderr.flush()
             await mcp_server.run_stdio_async()
-    except SynologyError as e:
+        except Exception as e:
-        sys.stderr.write(f"DSM error during startup: {e}\n")
+            sys.stderr.write(f"MCP server error: {e}\n")
-        sys.stderr.flush()
+            sys.stderr.flush()
-    except Exception as e:
+            raise
-        sys.stderr.write(f"Fatal error: {e}\n")
-        sys.stderr.flush()
-        raise

src/mcp_synology_container/dsm_client.py

@@ -98,6 +98,8 @@ class DsmClient:
         self._sid: str | None = None
         self._auth_manager: AuthManager | None = None
         self._reauth_lock = asyncio.Lock()
+        self._init_lock = asyncio.Lock()
+        self._initialized = False
         logger.debug(
             "DsmClient: base_url=%s verify_ssl=%s timeout=%d",
             self._base_url,
@@ -118,6 +120,24 @@ class DsmClient:
         """Register the AuthManager for automatic re-login on session errors."""
         self._auth_manager = auth_manager
 
+    async def _ensure_initialized(self) -> None:
+        """Connect to NAS and authenticate on first use (lazy init).
+
+        Subsequent calls are no-ops. Thread-safe via asyncio.Lock.
+        """
+        if self._initialized:
+            return
+        async with self._init_lock:
+            if self._initialized:  # re-check inside lock
+                return
+            logger.debug("Lazy init: querying API info from %s", self._base_url)
+            await self.query_api_info()
+            if self._auth_manager:
+                logger.debug("Lazy init: authenticating")
+                self._sid = await self._auth_manager.login(self)
+            self._initialized = True
+            logger.debug("Lazy init complete")
+
     async def __aenter__(self) -> DsmClient:
         logging.getLogger("httpx").setLevel(logging.WARNING)
         logging.getLogger("httpcore").setLevel(logging.WARNING)
@@ -204,6 +224,7 @@ class DsmClient:
         Raises:
             SynologyError: On API errors.
         """
+        await self._ensure_initialized()
         http = self._get_http()
 
         if api not in self._api_cache:
@@ -278,6 +299,7 @@ class DsmClient:
             Response data dict.
         """
         api = "SYNO.FileStation.Upload"
+        await self._ensure_initialized()
         http = self._get_http()
 
         if api not in self._api_cache:
@@ -328,6 +350,7 @@ class DsmClient:
             File content as string.
         """
         api = "SYNO.FileStation.Download"
+        await self._ensure_initialized()
         http = self._get_http()
 
         if api not in self._api_cache: