The "Attached to shared daemon" line is benign INFO, but it was written to
stderr — and MCP hosts render all server stderr at error level (and append an
`undefined` data field), so on every session start a healthy attach showed up
as `[error] … undefined`. It is now gated behind CODEGRAPH_MCP_LOG_ATTACH=1:
silent by default, opt-in for debugging daemon attach. Both attach sites
(runProxy + connectWithHello) route through one helper. The daemon integration
tests opt the harness into the log so their attach assertions still observe a
successful attach.
Re-applies the approach from #640 by @mturac.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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