docs(agents): record merge, contributor, and verification discipline

Every rule here is something that actually went wrong on the 2026-08-29 night
shift, written down so the next agent does not rediscover it.

Landing other people's work:
- A contributor's branch goes stale because WE land things. #5686 was
  CONFLICTING purely from Route Contract Phase 1 plus that same contributor's
  own earlier PRs merging into the same files. A maintainer resolves that.
- Conflicts that split mid-function do not resolve by keeping both sides — the
  markers landed inside two function bodies and the naive resolution failed to
  compile with 'unclosed delimiter'. Take one side whole, re-insert the other's
  additions at their anchor.
- maintainerCanModify did not grant push access to the fork (403), so the
  resolved merge went to integration/moonshot-kimi-5686-20260829 instead. That
  integration-branch path is now the documented default for conflicted work.
- whp233's #5714 and #5716 each had SEVEN workflows parked at action_required
  because the author was not on .github/APPROVED_CONTRIBUTORS. The PRs looked
  stalled; nobody had looked. Five contributors have since been added.
- Credit is mechanical: AUTHOR_MAP and .mailmap are project conventions and
  GitHub reads neither for the contribution graph.

Merging under a gate:
- #5698 merged while ACCEPTANCE_MATRIX.md still said FAIL and 37 minutes after
  a review confirming five findings were unchanged. Five real bugs reached
  main. A gate is its artifact, and check rollups are not the review thread.

Claiming a test passed:
- cargo test with a non-matching filter exits 0 having run ZERO tests; that was
  briefly mistaken for a pass here.
- A harness scored 72 PASS of which 12 were never evaluated: 'ok = ok and X or
  True' parses as '(ok and X) or True'.

CLAUDE.md already imports this file, so no second entrypoint was created.

No-Issue: process documentation from the night shift
Signed-off-by: CodeWhale Bot <bot@codewhale.net>

Author: CodeWhale Bot

AGENTS.md

@@ -33,6 +33,57 @@ instructions or memory. The nearest scoped `AGENTS.md` adds path-specific rules.
 - Never rewrite published history, retag a release, force-push a shared ref, or
   publish without explicit authorization. Preserve human contributor credit.
 
+## Landing other people's work
+
+An external contributor's branch goes stale because *we* land things, not
+because they did anything wrong. Treat their time as more expensive than ours.
+
+- **Never make a contributor rebase around our churn.** If their PR conflicts
+  only because main moved, a maintainer resolves it. Read their diff against
+  the merge base first so you know exactly what they added, and re-apply that,
+  rather than hand-merging two large sides and hoping.
+- **Conflicts that split mid-function do not resolve by keeping both sides.**
+  Git's markers can land inside a body, so a both-sides resolution produces
+  unbalanced braces that look plausible and do not compile. Take one side
+  whole, then re-insert the other side's additions at their original anchor.
+- **`maintainerCanModify` does not guarantee push access to the fork.** When
+  the push is refused, land the resolved merge on
+  `integration/<topic>-<pr>-<date>` in this repo and land from there. An
+  integration branch is the normal path for anything with conflicts or several
+  moving PRs — it is cheaper than repeatedly rebasing onto a main that keeps
+  moving, and it keeps the contributor's branch untouched.
+- **Check the contribution gate before assuming a PR is stalled.** An unlisted
+  author's workflow runs sit at `action_required` and never start, so the PR
+  looks abandoned when nobody has actually looked at it. Approve the runs, then
+  fix the cause: add them to `.github/APPROVED_CONTRIBUTORS` (`all:username`),
+  or comment `/lgtm` (PR scope) / `/lgtmi` (issue scope) on their thread.
+- **Preserve credit in the mechanical sense, not just the polite one.** Commit
+  authorship and `Co-authored-by` trailers must use the contributor's own
+  GitHub-linked address. `AUTHOR_MAP` and `.mailmap` are project conventions —
+  GitHub reads neither for the contribution graph.
+
+## Merging under a gate
+
+- **A gate is its artifact.** When a rail says a PR merges only on a passing
+  acceptance record, the record must literally say PASS at merge time. "I
+  re-ran it and the failures are rows this PR does not own" is a judgement to
+  write into the artifact first, not a reason to merge past it.
+- **Read the review thread, not the check rollup.** Green checks and an unread
+  review with confirmed findings are a merge that ships known bugs.
+- **When the artifact is ambiguous, resolve the ambiguity — never the merge.**
+
+## Claiming a test passed
+
+- Quote the real `test result: N passed; M failed` line, and confirm `N > 0`
+  for the tests that cover the change. `cargo test <filter>` exits 0 having run
+  zero tests when the filter matches nothing, and an exit code alone has
+  already been mistaken for a pass here.
+- Prefer proving a regression test fails without the fix. A test that passes
+  either way pins the implementation, not the defect.
+- Audit any harness before trusting its score. `ok = ok and X or True` parses
+  as `(ok and X) or True` and silently reported twelve unevaluated rows as
+  passing.
+
 ## Current contracts
 
 - The model-facing subagent tool is `agent`. Do not revive removed