* fix(mcp): redirect stdout to stderr during import to protect JSON-RPC channel (#225)
Fixes#225.
Several transitive dependencies (chromadb, onnxruntime, posthog) print
banners and warnings to stdout — sometimes at the C level — during the
mcp_server import chain. Because the MCP protocol multiplexes JSON-RPC
over stdio, any non-JSON output on stdout corrupted the message stream
and broke Claude Desktop's parser with errors like:
MCP mempalace: Unexpected token '*', "**********"... is not valid JSON
MCP mempalace: Unexpected token 'E', "EP Error D"... is not valid JSON
MCP mempalace: Unexpected token 'F', "Falling ba"... is not valid JSON
Reproduced on Windows 11 with mempalace 3.0.0 / Python 3.10 / Claude
Desktop 1.1062.0.
Fix: at module load, redirect stdout to stderr at both the Python level
(sys.stdout = sys.stderr) and the file-descriptor level (os.dup2(2, 1))
to catch C-level prints, while preserving the real stdout for later
restore. main() calls _restore_stdout() right before entering the
protocol loop so JSON-RPC responses still go to the real stdout.
Adds tests/test_mcp_stdio_protection.py with three regression tests:
- module-level redirect is in place after import
- _restore_stdout() restores the original stdout (idempotent)
- 'python -m mempalace.mcp_server' with empty stdin emits no stdout
* style: reformat with ruff 0.4 (CI version) for #225
Arnold Wender