tracking: chroma-mcp spawn fails with MCP -32000 — uvx version syntax errors and Windows cmd.exe redirection mangling

[thedotmack]

Root Cause

The worker uses pip-style == syntax (chroma-mcp==0.2.6) when invoking uvx, but uvx only accepts @ syntax (chroma-mcp@0.2.6) for version pinning. On Windows, the same invocation is additionally routed through cmd.exe /c, which interprets > and < in dependency specifiers (onnxruntime>=1.20, protobuf<7) as shell redirection operators, killing the child immediately. Both bugs cause MCP error -32000 (Connection closed), force the 10s backoff, and permanently degrade semantic search to FTS5 keyword search. A third variant affects uv versions older than 0.5.31 that reject the bare positional form entirely.

Tracked Items

Issues

• Closes Windows: Chroma spawn routes >/< dependency specifiers through cmd.exe /c, breaking semantic search (Connection closed -> FTS5 fallback) #2954 — Windows: Chroma spawn routes >/< dependency specifiers through cmd.exe /c, breaking semantic search (Connection closed -> FTS5 fallback) #2954
• Closes chroma-mcp== version pinning breaks uvx — use @ instead of == (MCP error -32000) #2939 — chroma-mcp== version pinning breaks uvx — use @ instead of == (MCP error -32000) #2939
• Closes Chroma semantic search never connects with uv < 0.5.31 — bare uvx <pkg>==<ver> positional rejected → MCP -32000 Connection closed (repro: macOS) #2879 — Chroma semantic search never connects with uv < 0.5.31 — bare uvx <pkg>==<ver> positional rejected → MCP -32000 Connection closed (repro: macOS) #2879

PRs

• Related PR fix: use @ instead of == for chroma-mcp version pinning with uvx #2940 — fix: use @ instead of == for chroma-mcp version pinning with uvx #2940
• Related PR fix(chroma): spawn chroma-mcp via --from so uv < 0.5.31 works #2880 — fix(chroma): spawn chroma-mcp via --from so uv < 0.5.31 works #2880

Resolution

This is the canonical tracking issue for this root cause. Individual issues and PRs listed above will be closed in favor of this one.