Id	Rule	In practice
SLICE-1	One change per step, reviewable in one sitting	One pull request per plan step, with clear acceptance. Around a hundred changed lines reads in one sitting.
SLICE-2	Nothing half-done reaches the shared branch	A step merges complete, with tests, docs and, where the repository keeps one, its changelog entry, or waits. Incomplete work stays behind a flag or on its branch.
SLICE-3	Scope discipline	Only what the step requires. Note adjacent cleanups, unused imports, old syntax; leave them for their own step.
SLICE-4	Verify once per change	Run each check after a change that could affect it. A pass on unchanged code is not repeated.
SLICE-5	Stage by path and read the index	`git add <path>`; when another session may have touched a file, re-read `git diff <file>` and stage whole files by path, or the hunks with `git apply --cached <patch>`; read `git diff --cached --stat` before committing. Never `git add -A` (STAGE-1, hook deny).
SLICE-6	A go-ahead per commit, per push, per post	Each waits for its own yes. Approval for one does not extend to the next (ASK-1, ASK-2, ASK-3, hook ask).
SLICE-7	Auto-merge only where allowed	Armed only where the decider allowed it for that repository and branch. A merge to a release branch is a deliberate human act.
SLICE-8	Fresh new files, confirmed deletions	Check the path is absent before writing a new file. Check a file is untracked before deleting it, or get the deletion confirmed.
STAGE-1	Stage by path	Hook: `git add -A`, `--all` or `-u` without a narrowing path, a root pathspec such as `.`, and `git commit -a` are refused. `git add -A src/` passes.
PUSH-1	No force push to a protected branch	Hook: refused. A protected branch moves by merged pull request only.
PUSH-2	Moving a tag is confirmed and explained	Hook: asks, and says that every workflow triggered on tag pushes runs again and release assets may be rebuilt.
SECRET-1	No key-shaped literals	Hook: staged changes are scanned before the commit; CI runs gitleaks. Tests generate keys at runtime; documentation samples use placeholders.
SECRET-2	Never print a secret	Variable name, `file:line`, length or hash. Exclude token-bearing lines before summarising a log. Never trust a masking regex.
PROD-1	Production is read-only	Unless the decider says otherwise for that action. The production targets are the ones `docs/agents/conventions.md` names.
REVIEW-6	Confirm the diff is absent before merging	And re-diff a conflict resolution against the target's current file.
TEST-5	Gate on exit codes	`check && test`, then the commit on its go-ahead, gated on the exit codes.
TRACE-1	An untraceable gated command is confirmed	Hook: a command that mentions a commit, push, bulk add or forge write the parser cannot trace (a variable, an interpreter, an unusual wrapper) asks.

The cycle

Read the glossary and the records that touch the area (decision-records), then implement the smallest complete piece. Ask first what the simplest thing is that could work; three similar lines beat a premature abstraction.
Run the repository's own checks (TEST-5).
Show what changed, what it deliberately leaves out, and what is next, in the change-description form plain-voice owns.
Commit on the go-ahead, with a first line that is short, imperative and standalone, and no tool attribution (ATTR-1).
Next slice. Carry forward; do not restart.

Slicing

Vertical slices by preference: one complete path through the stack per slice. Risk-first when one piece is uncertain: prove it before building on it. Contract-first when two sides develop in parallel: the contract is slice zero. A feature that is not ready for users merges behind a flag with a safe default.

Commit text

Commit and pull request text follows the change-description rules plain-voice owns: a short, imperative, standalone first line; what the change leaves out; no identifiers in code or fixtures and full links for every reference (TICKET-3, TICKET-4). The signer is the operator of record: no tool trailer, no generated-with footer (ATTR-1).

A slice, end to end

Plan step P2.3 says: "the search endpoint rejects a page token with 400". One slice.
Failing test first (test-first), then the smallest handler change that passes it.
just check exits 0. Nothing else in the tree changed (SLICE-3): a stray formatting fix in another file is noted for its own step, not included.
Stage by path: git add src/search.py tests/test_search.py; read git diff --cached --stat.
Say what it does, why, and what it leaves out: "Rejects a page token with 400 and a page_token_unsupported code. Pagination itself is still not implemented; that is P2.4."
On the go-ahead: git commit -m "Reject a page token on search with 400" (-s where the repository requires a sign-off). The hook asks (ASK-1), the decider answers, the commit runs. No trailer names a tool (ATTR-1).
On the next go-ahead: git push, a pull request with the same three sentences, the review from review-change, merge when the checks pass. Then P2.4.

Hooks and secret files

The repository's hooks run on every commit and push. Never pass --no-verify or commit -n, and never point git at another hooks directory or config, on the command line or through git config (GUARD-1); when a hook is wrong, the fix is a change to the hook in its own slice. A file that holds credentials by name (.env, a private key, .netrc, .npmrc, credentials.json, a PEM or keystore file) is not read, copied or sent without a go-ahead (SECRET-3); name the variable or the file's length or hash instead (SECRET-2).

Companion skills

Need	Skill
Tests for the slice	invoke `test-first`
The review before merge	invoke `review-change`
The plan step the slice implements	plan-project
The ticket it closes	cut-tickets

thin-slices

Thin slices

The rules