tiny-pattern-ts/CONTRIBUTING.md

# Contributing

This document is for maintainers and contributors working on the project itself. End-user documentation is in [README.md](./README.md). The machine entry point for AI coding agents is [AGENTS.md](./AGENTS.md); keep this file as the prose home for the rules below so agents and humans don't diverge.

## Rules the tools don't enforce

CI and review will bounce these even though `npm run check` and the linters don't catch them. They're the high-frequency things a contributor (or an agent) reaches for by default:

- **Source imports use `.ts` extensions, never `.js`.** `node --strip-types` only resolves the `.ts` form at test time; "Pre-fixing" an import to `.js` breaks the inner loop. (rationale: README § Tooling decisions)
- **A new `npm run` script must reuse an existing prefix** (`create:` / `check:` / `fix:` / `test:` / `watch:` / `maintain:` / `publish:` / `setup:`). If none fits, that's a signal the script doesn't belong in the pipeline — not a reason to invent a new prefix. If it genuinely does belong, add the prefix to both lists here in the same commit; an undocumented prefix becomes invisible and quietly accrues members. (see [Script prefix convention](#script-prefix-convention))
- **`oxlint-disable` directives live in source, not `.oxlintrc.json`.** The trade-off must sit next to the code it silences. This is a _human_ last-resort convention; agents must not add these — see [AGENTS.md § Never do](./AGENTS.md#never-do). (rationale: README § Tooling decisions)
- **Don't put slow / network / whole-project scans in `check` or pre-commit.** Advisory scans are not correctness gates; they belong under `maintain:`. (see [Feedback tiers](#feedback-tiers) and [Script prefix convention](#script-prefix-convention))
- **New work starts with `npm run create:branch`, never a hand-written `git switch -c`/`git checkout -b`.** The command carries the branch precondition; branching around it skips the clean-tree, current-`main` and green-baseline checks, and the skip is invisible until a failure can no longer be attributed. (see [Branching model](#branching-model))
- **Work is merged back with `npm run create:finish`, never a hand-written `git merge`.** The command carries the merge-side preconditions (clean tree, current `main`, a `feature/`/`fix/`/`chore/` branch) and runs `npm run verify` after the merge, so a merge cannot land unverified. (see [Branching model](#branching-model))
- **There is no local `npm run publish`, and `publish:publint` / `publish:attw` don't go in `check`.** (see [Publishing workflow](#publishing-workflow))

## Editor configuration

`.editorconfig` is for editor compatibility, not a gate — it is a sane fallback for the files oxfmt does not format (shell scripts, dotfiles, `LICENSE`, the commit-message template, and git's `COMMIT_EDITMSG` buffer). Where both apply, `.oxfmtrc.json` is authoritative: oxfmt is the formatter, and the overlapping `.editorconfig` keys only keep non-oxfmt editors close to the formatted result.

## Commit messages

Gitmoji subject, imperative mood, 50/72 wrapping. The template is `commit-message-template`; run `npm run setup:git-commit-message` once after cloning to register it as git's `commit.template` (or `npm run setup` to run every one-time clone step).

Examples from history: `:sparkles: Add watch tier with watch:test child`, `:recycle: Move type-aware config to .oxlintrc.json; use source-level disable directives`, `:memo: Restore unique maintainer content as CONTRIBUTING.md`. The body explains _what and why_, not _how_; link issues with `Resolves #...`.

## Script prefix convention

Script names in `package.json` use a prefix that signals _when_ the script is intended to run. A `<prefix>:<name>` script is implicitly aggregated by a `<prefix>` script (if one exists) and run by the corresponding lefthook hook or CI step. Picking the right prefix documents the script's intended lifecycle:

- `create:*` — front doors of the repo's own workflow; these mutate git state rather than the source. `create:branch` opens a unit of work (asserts a clean tree, a current `main` and a green baseline before it branches), `create:finish` closes the branch half (merges the current unit of work into `main` and verifies the result), `create:release` closes the release half (maintainer-only). No bare `create` aggregator on purpose — see `publish:*` for the precedent.
- `check:*` — read-only verification; never modifies files. Aggregated by `npm run check`.
- `fix:*` — mutating counterpart of a `check:*` script. Aggregated by `npm run fix`; the diff is the review surface.
- `test:*` — test scripts. `test` is the canonical entry point (`check:tsc` + unit tests); `test:unit` skips the typecheck for fast local iteration; `test:ci` adds c8 coverage.
- `watch:*` — long-running watchers for the manual inner dev loop. Aggregated by `watch`; currently a single child (`watch:test`), and a future `watch:oxlint` / `watch:tsc` would run concurrently under that umbrella.
- `maintain:*` — advisory repo-maintenance scans: read-only, but whole-project and/or network-bound, so never a correctness gate. Aggregated by `npm run maintain`.
- `publish:*` — validates the _publishable artifact_ (e.g. `dist/`) rather than the source, so it needs a fresh build. (see [Rules the tools don't enforce](#rules-the-tools-dont-enforce) and [Publishing workflow](#publishing-workflow))
- `setup:*` — one-time configuration of a fresh clone; mutates the local environment (git config, editor settings) rather than the repo source, so it is never part of a hook or CI step. Aggregated by `npm run setup` (the umbrella), run once after cloning.

A new script should pick the prefix that matches its lifecycle, not invent a new one. If no existing prefix fits, that's a signal the script doesn't belong in the standard pipeline. When it genuinely does belong, a new prefix is allowed — but it enters both lists in this file in the same commit as its first member, otherwise the rule "reuse an existing prefix" silently develops an exception (the old `use:` prefix was exactly that; it is now retired into `setup:`).

Separately, some top-level scripts are **bare** (no prefix): the entry points that either run a single tool (`build`, `clean`) or aggregate a `prefix:*` family (`check`, `fix`, `test`, `watch`, `maintain`, `setup`), plus one convenience that composes across tiers: `verify` — composing `check` + `test:unit` into one whole-project correctness gate (it deliberately uses `test:unit` rather than `test` because `check` already runs `check:tsc`, so the type checker runs exactly once). Bare commands are how you invoke a tier; the `prefix:*` scripts are what those tiers are made of.

## Feedback tiers

The tools are organized into a feedback ladder. Each tier catches different things at different costs; the rule of thumb is "earlier tiers fire more often, faster tiers catch less, slower tiers are more thorough":

| Tier                             | When                    | What it runs                                                                                             | Time  |
| -------------------------------- | ----------------------- | -------------------------------------------------------------------------------------------------------- | ----- |
| `npm run watch`                  | manual                  | `watch:test` — re-runs tests on file save                                                                | ~0.1s |
| Pre-commit (auto)                | on stage                | tsc + oxlint + oxfmt + cspell (staged files only)                                                        | ~1.3s |
| Pre-push (auto)                  | on push                 | `npm test` (full tsc + unit tests)                                                                       | ~3.5s |
| `npm run check`                  | manual                  | Correctness gates: tsc + oxlint + oxfmt + cspell (whole project)                                         | ~3s   |
| `npm run verify`                 | manual                  | Definition of done: `npm run check` + unit tests, one shot                                               | ~6s   |
| `npm run fix`                    | manual                  | Auto-resolve fixable issues (lint, format)                                                               | ~3s   |
| `npm run maintain`               | manual / CI (advisory)  | `maintain:knip` + `maintain:outdated` (whole-project + network scans)                                    | ~10s  |
| CI build (auto)                  | on push to `main` / tag | `build` job (build + correctness + packaging) — see [.gitea/workflows/ci.yml](./.gitea/workflows/ci.yml) | ~30s+ |
| CI maintain (auto, non-blocking) | on push to `main`       | `npm run maintain` — reports, never fails the build                                                      | ~10s  |
| CI publish (auto)                | on tag                  | Gitea release page (body from CHANGELOG) + `publish:publint` + `publish:attw`, then `npm publish`        | ~15s  |

### Why these splits?

- **`watch:*` is a manual tier, not a hook.** The developer starts it on demand (it has to be killed with Ctrl-C) and it runs in a dedicated terminal pane. It sits as the earliest tier in the feedback ladder, catching failures the moment a file is saved — before staging, before commit.
- **`check:tsc`, `check:oxlint`, `check:oxfmt`, `check:cspell`** are in pre-commit because they are fast (~0.2–0.5s each), fully offline, and naturally scope to staged files via the `LEFTHOOK_FILES` env var convention. They give instant feedback on what you typed.
- **`test` (and the `tsc` it includes) is in pre-push** because it runs the whole test suite across the whole project. The pre-commit `LEFTHOOK_FILES` convention doesn't apply to the test runner, so pre-commit isn't the right home. Pre-push runs after all commits are made but before the push leaves the machine, catching regressions that span multiple commits.

### Before pushing

Run `npm run verify` — the one-shot correctness gate in the table above. Run `npm run maintain` only on a maintenance / update-deps branch.

## Testing discipline (type-driven)

For this library the types _are_ the feature — narrowing, `exhaustive()` returns, the `Matcher<T>` contract — so a runtime-only test loop would verify the wrong thing. New behavior follows **type-driven development** (in Edwin Brady's sense): _treat the type as the plan for a program, and use the compiler and type checker as your assistant, guiding you to a complete program that satisfies the type_ ([idris-lang.org](https://www.idris-lang.org/)). Here that plan is the `expectTypeOf` assertion, written first. The loop is **type → red → green → refactor**:

1. **Type** — write the compile-time expectation first (`expectTypeOf(...).toEqualTypeOf<…>()`) and let `npm run check:tsc` fail on the _type_. The type error is the spec you want to hit before the runtime logic exists.
2. **Red** — add the matching runtime assertion (`assert.*`) so `npm run test:unit` now fails on behavior.
3. **Green** — implement in `src/*.ts` until both the type check and the test pass.
4. **Refactor** — with the type system and the tests as the safety net, then `npm run verify` as the definition-of-done gate.

This is why every test in the suite pairs an `expectTypeOf(...)` with an `assert.*` — keep them together. Type-first is also enforced structurally: `npm test` runs `check:tsc` before the test runner, so a wrong type can never be papered over by a passing assertion. Per [AGENTS.md § Never do](./AGENTS.md#never-do), reach green honestly — fix the types so both the type check and the runtime assertion pass, never suppress the ones you can't make pass.

## Branching model

**GitHub Flow (single-developer).** Every change — feature, fix, refactor — branches off `main` and is merged back via a local commit (no PR workflow on Gitea yet). Collaborative review via Gitea UI is not in place — Gitea is the lab; when something is tested and ready for production it will be promoted to GitHub.

- **Base branch:** `main`
- **Branch naming:** `feature/<desc>` / `fix/<desc>` / `chore/<desc>`
- **Starting work:** `npm run create:branch -- <prefix>/<desc>`. It refuses, without changing anything, unless the working tree is clean (untracked files included), no merge/rebase/cherry-pick is in progress, `main` matches its upstream, and `npm run test` is green on `main` — so a later failure is always attributable to your edits. The prefix is still _your_ call, inferred from the task; the script validates it rather than guessing it.
- **Merging:** `npm run create:finish` (on the branch). It asserts the same clean-tree / no-operation / current-`main` preconditions, fast-forwards a stale `main` (a true divergence is refused), merges the branch `--no-ff`, runs `npm run verify`, and deletes the branch only after the merge is green. The push is deliberately left to `create:release`, so the merge stays local and reviewable — read the diff yourself before finishing.
- CI runs `npm run check` + `npm run test:ci` on every push to `main` — this is the authoritative gate. The one exception: a push headed by a release commit (`:rocket: Release x.y.z`) skips the full `build`/`maintain` jobs, because `create:release` pushes the tag for that exact commit right after and the tag run is the authoritative one (see `release-gate` in [.gitea/workflows/ci.yml](./.gitea/workflows/ci.yml)).
- **Releases are NOT triggered by pushes.** Only the maintainer triggers a release (see [Publishing workflow](#publishing-workflow)).

## Publishing workflow

Publishing is CI-only by policy. Local `npm publish` is not supported. The maintainer triggers releases from `main`:

1. All intended changes are merged to `main` and passing CI.
2. The maintainer runs `npm run create:release`. VS Code opens `CHANGELOG.md` to finalize the `[Unreleased]` notes; because pubv refuses a dirty tree, any edit is committed first (then folded into the release commit), and pubv's interactive prompt suggests a version from those notes — the maintainer confirms or edits it.
3. `scripts/release.sh` creates a single release commit (graduated changelog + package.json bump, amended into one commit), tags it, and pushes everything to Gitea.
4. CI fires on both pushes: the `publish` job runs on the tag (`build` + publish-tier checks + release page + `npm publish`), while the branch run's `release-gate` job recognizes the release commit and skips `build`/`maintain` — the tag verifies the identical SHA, so no work is duplicated. The job graph lives in [.gitea/workflows/ci.yml](./.gitea/workflows/ci.yml) — keep that file, not this list, as the source of truth. The publish-tier checks must pass before the artifact is published. The `publish` job also creates the Gitea release page from the matching Keep-a-Changelog section (`scripts/release-notes.sh`); it runs _before_ `npm publish` so a broken page fails CI without consuming a version, and `npm publish` stays the last step.