* fix(mcp): persist MCP sessions across tool calls for stateful servers
MCP tools loaded via langchain-mcp-adapters created a new session on
every call, causing stateful servers like Playwright to lose browser
state (pages, forms) between consecutive tool invocations within the
same thread.
Add MCPSessionPool that maintains persistent sessions scoped by
(server_name, thread_id). Tool calls within the same thread now reuse
the same MCP session, preserving server-side state. Sessions are evicted
in LRU order (max 256) and cleaned up on cache invalidation.
Fixes#3054
* fix(sandbox): add group/other read permissions to uploaded files for Docker sandbox (#3127)
When using AIO sandbox with LocalContainerBackend, uploaded files are
created with 0o600 (owner-only) permissions by the gateway process
running as root. The sandbox process inside the Docker container runs
as a non-root user and cannot read these bind-mounted files, causing
a "Permission denied" error on read_file.
Add `needs_upload_permission_adjustment` attribute to SandboxProvider
(default True) to indicate that uploaded files need chmod adjustment.
LocalSandboxProvider opts out (same user). A new `_make_file_sandbox_readable`
function adds S_IRGRP | S_IROTH bits after files are written, changing
permissions from 0o600 to 0o644 so the sandbox can read the uploads.
* fix(mcp): address review comments on session pool and tools
- _extract_thread_id: return "default" instead of stringifying None
when get_config() returns no thread_id
- call_with_persistent_session: fix **arguments annotation from
dict[str,Any] to Any
- Replace private _convert_call_tool_result import with a local
implementation that handles all MCP content block types
- _make_session_pool_tool: accept tool_interceptors and apply the
configured interceptor chain on every call (preserving OAuth and
custom interceptors)
- MCPSessionPool: replace asyncio.Lock with threading.Lock; restructure
get/close methods to never await while holding the lock; add
close_all_sync() that closes sessions on their owning event loops
- reset_mcp_tools_cache: use pool.close_all_sync() instead of
asyncio.run-in-thread to close sessions deterministically
- test: add test_session_pool_tool_sync_wrapper_path_is_safe covering
tool invocation via the sync wrapper (tool.func) path
Agent-Logs-Url: https://github.com/bytedance/deer-flow/sessions/9e7f9e7f-1d2b-464a-b3b7-7f1649b74122
Co-authored-by: WillemJiang <219644+WillemJiang@users.noreply.github.com>
* fix(mcp): extract SESSION_CLOSE_TIMEOUT to class constant
Agent-Logs-Url: https://github.com/bytedance/deer-flow/sessions/9e7f9e7f-1d2b-464a-b3b7-7f1649b74122
Co-authored-by: WillemJiang <219644+WillemJiang@users.noreply.github.com>
* Potential fix for pull request finding 'Empty except'
Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>
Willem Jiang
c881d95898