change-discipline git:20260803.c459c14A

Immutable. This exact content never changes and is served at /api/v1/blob/90fad5d2e2fa9967.

---
description: Scope a change and land it without a multi-round review loop
globs: **/*
alwaysApply: true
---

# Change discipline

The canonical text is **`AGENTS.md` → "Change discipline"**, and the "Definition
of Done" section beside it. This file exists only because Cursor reads
`.cursor/rules` and not `AGENTS.md` — Claude Code reads AGENTS.md via
`CLAUDE.md`, and it is Codex's source of truth. Keep the two in sync; if they
disagree, AGENTS.md wins.

The short form:

1. **Acceptance criteria in the PR before the first commit**, plus an explicit
   statement of what the change does NOT cover. Skipping this is what turned
   PR #97 into twelve review rounds: with no written finish line every round
   ended at "I fixed what was reported" and the next round moved it, and with no
   stated boundary, findings equally true of `main` arrived as blockers.
2. **Put a shared rule where every path reaches it, then delete the other copy** —
   not at the site the report happened to mention.
3. **Grep for siblings before calling a class closed.** Every single-instance fix
   in #97 had two or three.
4. **Make a test fail before trusting it, and pin the CALL, not just the
   function.** Delete the call site and confirm red.
5. **Never assert wall-clock time.** Assert the observable consequence instead.
6. **Run the gates and READ the output** — build, typecheck, test, lint, the three
   CI smokes, `release:qa` — then wait for CI on the SHA you actually pushed.