Greptile Summary

This PR fixes a TypeError breaking the applies plugin-config defaults test in extensions/diffs/index.test.ts by adding the headers property to the localReq() mock helper. The production code's hasProxyForwardingHints() function expects req.headers to exist; the test mock was missing this property entirely.

Changes:

• Added optional headers?: Record<string, string> parameter to localReq() with a default value of {} — identical to the existing pattern in extensions/diffs/src/http.test.ts.
• No production code changes; test mock only.

Impact:

• Unblocks CI for all open PRs that were failing the checks (node, extensions) job due to this TypeError.

Confidence Score: 5/5

• This PR is safe to merge — it only modifies a test mock helper with no production code changes and fixes a CI-blocking TypeError.
• The fix is minimal (6 insertions, 1 deletion), focused solely on test infrastructure, and correctly ensures the mock IncomingMessage matches Node.js contract by always providing a headers property. The implementation exactly mirrors the existing pattern in http.test.ts and directly resolves the root cause of the failing test.
• No files require special attention.

_{Last reviewed commit: eeaa1d6}

Please don't send PRs for CI stuff, it takes far longer to review a PR than to fix while we work.

Superseded and landed directly on main (per maintainer direction to avoid merging CI-only PRs). Thank you @Shennng.

What I did:

• applied the same fix directly in extensions/diffs/index.test.ts (localReq now always provides headers)
• added changelog note under 2026.3.7 fixes referencing fix(tests): add missing headers to diffs index.test.ts localReq mock #39063
• ran full gate before commit: pnpm lint && pnpm build && pnpm test
• pushed direct fix to main

SHA hashes:

• original PR commit: eeaa1d6b161ea41870de030907b401e991924739
• landed direct commit on main: 0f5317797

Thanks for surfacing and patching this quickly.