Attainly/ai/shared.md

# Shared rules

Rules that apply to both backend and frontend work in this repository.
Stack-specific guides (`backend-context.md`, `frontend-context.md`) extend
these rules.

## Project state

- Attainly is in early development.
- Attainly helps users break hierarchical goals into scheduled assignments,
  complete daily work, and track progress toward a target date.
- Schedule recalculation must preserve completed work while redistributing
  unfinished assignments across the remaining dates.
- Planned features in `README.md` are future ideas, not authorized scope.
- The Laravel backend exists under `backend/`.
- The Vue frontend has not been scaffolded yet. Do not create it unless the
  user explicitly asks for that work.
- PostgreSQL is the development and runtime database.
- PHPUnit uses in-memory SQLite for isolated tests.

## Process (TDD)

0. Before editing any file, ensure you are working in a dedicated git
   worktree, not the main checkout (`git status` and `git worktree list`).
   If on `master`/`main` or in the main working directory, create a worktree
   first (see Branching).
1. Write the test first.
2. Run the test to confirm it fails for the expected reason.
3. Commit the failing test. The test commit must precede the implementation
   commit, not merely appear earlier in the implementation diff.
4. Implement the smallest change that makes the test pass.
5. Run the test to confirm it passes.
6. Commit the implementation.
7. Repeat for each new behavior.

Use judgment for changes that cannot meaningfully be test-driven, such as
documentation-only edits or declarative environment configuration. Validate
those changes with the most relevant parser, formatter, dry run, or check.

## Running processes

- The main checkout owns the canonical stack on the default ports. Assume it
  is the user's stack. Do not start, restart, or stop it unless the user asks.
- A worktree owns its own isolated stack. The flake shell hook assigns a
  deterministic port offset and creates worktree-local PostgreSQL state.
- Start a worktree stack from its root with `process-compose up`. For
  non-interactive use, run `process-compose up -D` and stop it with
  `process-compose down`.
- Do not use `process-compose -t=false` for a detached stack. It can leave an
  orphaned PostgreSQL process holding the data directory.
- Non-interactive agent shells do not automatically load direnv. A bare
  `process-compose`, `php artisan`, or database command from a worktree can
  silently use default ports and target the main checkout.
- Prefix worktree stack and database commands with `direnv exec <worktree>`.
  Examples:

  ```sh
  direnv exec <worktree> process-compose up -D
  direnv exec <worktree> process-compose down
  direnv exec <worktree> php artisan migrate:fresh --seed
  ```

- Run backend commands from `backend/`, or explicitly change into it in the
  command.
- When a normally valid check fails because a required service is down,
  surface the environmental failure. Do not skip the check or silently switch
  to a different database or service.
- PHPUnit is self-contained and uses in-memory SQLite. It does not require the
  PostgreSQL stack unless a future test is explicitly designed as a real
  PostgreSQL integration test.

## Code style

- Keep lines at or below 80 columns where practical. Do not split short,
  readable lines unnecessarily.
- Use explicit, descriptive variable names. Do not use single-letter or
  unexplained abbreviated names.
- Explore the codebase and inspect similar files before implementing a new
  pattern.
- Never use em dashes in code, comments, or docblocks. Use hyphens.
- Always use braced control-statement bodies, including early returns:

  ```ts
  if (identifier === null) {
    return null
  }
  ```

## Git commit style

- Use present-tense, imperative subjects: `add`, `create`, `wire`, `fix`,
  `test`.
- Keep subjects lowercase and short, normally three to six words.
- Match patterns in the existing git history.
- Do not add AI or tool coauthor trailers.
- Add a body when the subject cannot explain non-obvious motivation or
  multi-file coordination.
- Wrap bodies at approximately 72 columns and separate them from the subject
  with a blank line.

## Git commits

- Commit tests before implementation.
- Keep one logical change per commit. A logical change may span multiple
  files.
- Commit each meaningful step rather than batching unrelated work.
- Do not include drive-by formatter or linter changes. Restore them or land
  them as a separate formatting commit.
- If a check fails on untouched code, do not bundle an unrelated fix. Report
  the pre-existing failure or handle it as its own explicitly scoped change.

## Branching

- Never implement features directly in the main checkout or on
  `master`/`main`.
- Use a dedicated worktree under
  `<repo-root>/.worktrees/<branch>`.
- Create it with:

  ```sh
  git worktree add \
    "$(git rev-parse --show-toplevel)/.worktrees/<branch>" \
    -b <branch>
  ```

- Use descriptive kebab-case branch names, optionally prefixed with a type
  such as `feature/` or `fix/`.
- Keep worktree names short, preferably no more than about 20 characters.
  PostgreSQL Unix socket paths are limited in length.
- Provision a fresh worktree through direnv:

  ```sh
  direnv allow <worktree>
  direnv exec <worktree> true
  ```

- Never symlink `backend/vendor` or a future frontend's `node_modules` from
  another checkout. Dependency paths and generated autoloaders must remain
  worktree-local.

Do not push anything. Make commits as the TDD workflow requires.

## Before completing a change

Run the smallest relevant checks while iterating, then run every repository
gate affected by the change.

### Backend

- Run tests from `backend/` with `php artisan test`.
- Run the Composer checks defined by `backend/composer.json` when their
  dependencies are available:

  ```sh
  composer lint:check
  composer types:check
  composer test
  ```

- Do not claim a green gate when a command fails. If the failure predates the
  change, report the precise baseline failure.

### Frontend

- The frontend does not exist yet. Once scaffolded, use the scripts defined in
  its `package.json` for formatting, linting, type checking, unit tests, and
  end-to-end tests.
- Update `ai/frontend-context.md` when the actual scaffold, package manager,
  and commands are known.

### Environment and integration

- For Nix or shell-hook changes, run `nix fmt` and `nix flake check`.
- For service configuration changes, run `process-compose --dry-run`.
- When a change affects runtime wiring, start the worktree's stack and verify
  the relevant endpoint or service against that worktree.
- If you started the stack only for validation, stop it before finishing.