fix(mcp): suppress Windows console window on MCP subprocess spawn - #41078
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fix(mcp): suppress Windows console window on MCP subprocess spawn#41078Chameleon-Chaos wants to merge 8 commits into
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fix(logging): best-effort rotation with cooldown for Windows file-lock contention
The file was incorrectly replaced with 'PLACEHOLDER' in commit b3c16f4. Restoring the full 218-line implementation with browser CDP helpers.
On Windows, npx/Node.js MCP servers (and any .cmd wrapper) pop a console window when Hermes spawns them as subprocesses. The MCP SDK already passes CREATE_NO_WINDOW to anyio.open_process, but a broad except Exception in mcp/os/win32/utilities.py falls back to creationflags=0, which lets the window appear. This monkey-patch wraps create_windows_process so that CREATE_NO_WINDOW always survives any exception path — either via anyio.open_process with the flag, or via subprocess.Popen (the fallback) which also carries it. Closes: NousResearch#38101
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Jun 16, 2026
…site Guards against the PR NousResearch#41078 regression where create_windows_process was patched only on mcp.os.win32.utilities, leaving the name imported into mcp.client.stdio (the real call site) unpatched. Windows-only; skips on other platforms. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Closing as superseded by the consolidated Windows console-flash work tracked in #54220. The relevant pieces from this PR/cluster have now landed through the targeted follow-up PRs #54236, #53892, and #54417, or are recorded in the umbrella tracker for any remaining native-Windows verification. Keeping this separate PR open would duplicate the tracker and the merged follow-up work. Thanks for digging into this — the reports and PRs in this cluster helped identify the remaining spawn legs. |
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On Windows, npx/Node.js MCP servers pop a console window when Hermes spawns them as subprocesses. The MCP SDK already passes CREATE_NO_WINDOW to anyio.open_process, but a broad except Exception in mcp/os/win32/utilities.py falls back to creationflags=0.
This monkey-patch wraps create_windows_process so that CREATE_NO_WINDOW always survives any exception path.
Refs: PR #38100 (pythonw.exe)