[ztownsend]

Summary

• make gbrain code-def fall back to definition-shaped code chunks when symbol metadata is incomplete
• add a code_symbol_lookup doctor check so healthy brains prove symbol navigation works
• register the new/onboard doctor checks in categories and bump release metadata to v0.42.2.0

Test plan

• bun test test/code-def-refs.test.ts test/doctor-behavioral.test.ts test/doctor-categories.test.ts test/e2e/code-intel-mcp-ops-pglite.test.ts
• bun run typecheck
• gbrain code-def load_router --limit 5 --json
• gbrain code-def RouteRateLimiter --limit 5 --json
• gbrain doctor --json --scope brain
• MCP stdio smoke with MCP_STDIO=1 listed the code/search tools successfully

[garrytan]

Thanks for this contribution — and apologies for the slow triage. We did a full pass over the entire PR backlog. gbrain has moved fast, and the maintainer's larger "cathedral" rewrites have superseded a big share of community PRs: the AI gateway + recipes + user_provided_models system replaced almost all individual provider PRs; #1805 fixed the whole Postgres module-singleton class; #1542 unified the type taxonomy; #1657 the retrieval path; #1802 the doctor; and so on.

We're closing this one in that cleanup — either the fix already landed on master, it duplicates another PR or merged change, or it's outside the current merge bar. Where a closed PR carried a genuinely valuable idea, we've recorded it in docs/designs/COMMUNITY_IDEAS.md so nothing good is lost (a few may graduate into TODOs).

Please don't read the close as a judgment of the work — thank you for contributing. If you believe the underlying issue is still live on the latest master, reopen with a quick note and we'll take another look. 🙏