Fix Windows MCP handshake crash under PYTHONUTF8 - #42
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tasklist/netstat emit OEM/GBK on non-English Windows. With UTF-8 mode, subprocess text=True decodes as UTF-8, the reader thread raises UnicodeDecodeError, check_output returns None, and out.strip() kills the stdio server before initialize. Decode console utilities with encoding=oem (UTF-8 elsewhere) and errors=replace. Treat empty/None stdout as no GUI instances. Accept localized LISTENING states. Never let rediscovery exceptions prevent MCP initialize so headless idalib tools still start.
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Problem
On Chinese (and other non-English) Windows, MCP clients such as Grok start Python in UTF-8 mode (
PYTHONUTF8=1).ida-multi-mcpscans for live IDA GUI processes withtasklist /FO CSVandnetstatbefore answering MCPinitialize.Those utilities emit OEM/GBK. With
subprocess.check_output(..., text=True)and noencoding=, CPython decodes as UTF-8. The stdout reader thread raisesUnicodeDecodeError(oftenbyte 0xb1),check_outputreturnsNone, andout.strip()crashes the process. The client reports:handshake failed: connection closed: initialize responseThis happens even when no IDA GUI is running. Headless
idalib_*tools never get a chance to start.Reproduced with Python 3.13 UTF-8 mode:
text=TrueontasklistreturnsNone; the raw bytes decode with GBK/OEM.Fix
encoding="oem"on Windows and UTF-8 elsewhere, alwayserrors="replace".Nonestdout as "no GUI instances" instead of crashing.LISTENING/侦听) and IPv6 local addresses.initialize.Tests
pytest tests/test_health.py: 18 passed, 3 skipped (Unix-only cases on Windows).Live stdio
initializeunderPYTHONUTF8=1now returnsserverInfo.name=ida-multi-mcpwith noUnicodeDecodeError.