docs: two process rules the wave paid for

Both are the reviewers' framings rather than mine, and both are better arguments
than the ones I gave.

AGENTS.md: under merge-as-soon-as-green a review round can finish AFTER its own
merge, and GitHub has deleted the branch by then — so a fix push to the old name
silently succeeds and accomplishes nothing. It re-creates a branch main will
never see, CI runs on it and passes, and the commit is nowhere. The tell is in
git's own output: `* [new branch]` where an `old..new` range was expected.
Happened on #51, four minutes after the merge.

design-principles §6: an argument must not live only in a commit message. I had
justified the context/ rule as "context/ is what readers grep", which is weak.
The real reason is that a commit message is write-once and unauditable — it
cannot be corrected without rewriting merged history, and NO check in this repo
can read one, because the ID audit greps source and docs and a message is in
neither. A reason recorded only there is a reason nothing can ever find wrong.
PR #51's 7d25762 is the worked example: a declined-test reason that was
factually wrong, cited across two rounds, and correctable only by #56 saying so
in context/.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -191,6 +191,17 @@ exact-frame characterization tests that were the PR's only evidence the
 migration changed nothing. Two right findings, different costs. File the
 declined one.
 
+**Under merge-as-soon-as-green, a review round can land after its own merge.**
+GitHub deletes the branch when a PR merges, so a fix push to the old branch name
+**silently succeeds and accomplishes nothing** — it re-creates a branch `main`
+will never see, CI runs on it, and the commit is nowhere. The tell is the push
+printing `* [new branch]` where you expected an `old..new` range. It happened on
+#51: the third review round completed four minutes after the merge, and the
+correction it prompted went to a re-created `wave/b-projection-gaps`. The repair
+is to branch from `gh/main`, cherry-pick, open a follow-up PR, and delete the
+stray re-creation. Check `gh pr view <n> --json state` *before* pushing a fix to
+a PR you have not looked at in a few minutes, rather than after.
+
 Merge only once Copilot passes. Prefer a **merge commit** — `AGENTS.md` says
 merges over rebases, and a wave's commits are individually meaningful.
 

context/design-principles.md

@@ -303,6 +303,16 @@ candidate for the store.
   A ``` fence in a doc comment is a doctest — a running test, not prose — and
   is exempt.
 
+- **And an argument must not live only in a commit message.** A message is
+  write-once and unauditable: it cannot be corrected without rewriting merged
+  history, and no check in this repo can read one — the ID audit greps
+  `context`, `README.md`, `AGENTS.md`, `CLAUDE.md`, `crates`, `src`, `tests`,
+  `examples`, `web`, `harness` and `docs`, and a commit message is in none of
+  them. So a reason recorded only there is a reason nothing can ever find wrong.
+  When one turns out to be wrong, correct `context/` and say in `context/` that
+  the message is superseded; that is the fix rather than a compromise. PR #51's
+  `7d25762` is the worked example, corrected by #56.
+
 ---
 
 ## 7. Testing