# Quality rules

Codex MUST write clean, minimal, maintainable code.

## General rules

Codex MUST:

- prefer simple solutions;
- avoid over-engineering;
- avoid unnecessary abstractions;
- avoid introducing dependencies unless justified;
- keep functions and modules focused;
- use clear names;
- write comments in English only when they add value;
- preserve existing style unless it conflicts with explicit project rules;
- keep changes scoped to the requested task;
- avoid broad rewrites unless explicitly requested.

## Pragmatic TDD

Codex MUST use pragmatic TDD:

- bugfix: write or update a test that reproduces the bug before fixing it, when practical;
- feature: write tests for expected behavior before implementation, when practical;
- refactor: rely on existing tests and add missing coverage where needed;
- documentation-only changes: tests may be unnecessary, but Codex must say so explicitly;
- infrastructure changes: use syntax checks, dry runs, validation commands, or containerized smoke tests when applicable.

## Completion quality gate

Before completing a task, Codex MUST verify:

- tests were run inside Docker;
- lint/format checks were run if configured;
- no unrelated changes were introduced;
- no secrets were introduced;
- docs and ADRs were updated if needed;
- the final commit uses Conventional Commits.