AGENTS.md Generator

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AGENTS.md for Python library

Typed, documented Python package with uv, Ruff and pytest. This AGENTS.md template combines 111 rules from 14 packs and runs to 154 lines.

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What is inside

The generated AGENTS.md

This is the file the generator produces for the Python library preset, before you add your project name and commands.

# AGENTS.md

## Agent behavior

- For changes touching more than three files, outline the plan and wait for confirmation before editing.
- Ask a clarifying question when requirements are ambiguous instead of guessing.
- Keep diffs small and focused on the request; do not refactor unrelated code.
- Run the relevant tests, linter and type checker before reporting a task as done, and report failures honestly.
- Never delete, skip or loosen a failing test to make it pass; fix the cause.
- Do not add new dependencies without explicit approval; prefer the standard library and existing packages.
- Do not edit generated or vendored files; change the source and regenerate.
- Never read, print or commit secrets, .env files or credentials.
- Read the relevant code and tests before proposing a change; do not edit files you have not read.
- Fix the root cause rather than suppressing the symptom with a workaround or silenced warning.
- Do not add lint or type suppressions to get a clean run; fix the underlying issue.
- Report failing tests, skipped steps and unverified claims plainly; never claim success without evidence.
- Verify library APIs in the installed version or its docs before using them; do not invent functions.
- Do not change public behavior, file formats or APIs unless the task asks for it.
- Never hardcode values or special-case inputs to satisfy a test.
- If an approach fails twice, stop and ask instead of trying increasingly invasive workarounds.
- Before editing a directory, read the nearest AGENTS.md and follow it over the root file where they differ.
- Preserve unrelated working tree changes. Never revert or rewrite edits you did not make.

## Testing

- Add or update tests for every behavior change and bug fix.
- For bug fixes, write a failing test that reproduces the bug before fixing it.
- Prefer many fast unit tests, fewer integration tests and a small number of end-to-end tests.
- Mock only external boundaries (network, clock, filesystem); use real collaborators otherwise.
- Keep tests deterministic: no real time, randomness or network without control.
- Keep tests independent; no shared mutable state or required execution order.
- Structure tests as arrange, act, assert with one behavior per test.
- Build test data with small factories instead of large shared fixtures.
- Treat a flaky test as a bug: find the cause instead of adding retries or sleeps.
- Use snapshot tests only for small stable outputs and review snapshot diffs carefully.
- Test public behavior rather than private functions or implementation details.
- Make assertions specific enough that the test fails if the behavior breaks.

## Git and pull requests

- Write commit messages in Conventional Commits format (feat:, fix:, docs:, refactor:, test:, chore:) and mark breaking changes with ! or a BREAKING CHANGE footer.
- Keep pull requests small and focused on one change.
- Write commit subjects in the imperative mood, 72 characters or fewer.
- Never force-push to shared branches and never rewrite published history.
- Run lint, type check and tests before committing.
- Never commit secrets, build output or large binaries.
- Describe motivation, approach and testing in the pull request description.
- Make each commit one logical change that builds and passes tests.
- Do not amend or rebase commits that are already pushed to a shared branch.
- Add build output, local env files and editor files to .gitignore instead of committing them.
- Open pull requests only when CI is green and the diff is self-reviewed.
- Never bypass commit hooks or signing with --no-verify unless explicitly instructed.

## Security

- Load secrets from environment variables or a secret manager; never hardcode them.
- Use parameterized queries and safe APIs; never build SQL, shell commands or HTML by string concatenation with user input.
- Enforce authentication and authorization on the server for every protected operation.
- Pin dependency versions, commit lockfiles and review new packages before adding them.
- Grant the minimum permissions needed for tokens, service accounts and containers.
- Use well-reviewed cryptographic libraries; never invent your own algorithms or store plain passwords.
- Encode output for its context and avoid injecting raw HTML; sanitize rich text with a vetted library.
- Protect state-changing browser requests with CSRF tokens or SameSite cookies.
- Configure CORS with explicit origins; never reflect arbitrary origins with credentials.
- Use HttpOnly, Secure, SameSite cookies and rotate session identifiers on login.
- Validate and allow-list URLs before fetching user-supplied addresses to prevent SSRF.
- Hash passwords with Argon2id, or scrypt or bcrypt where it is unavailable, with a unique salt; never use fast hashes such as SHA-256.
- Run secret scanning in CI and rotate any credential that has been exposed.
- Validate untrusted input against a schema. Never run eval, exec or unpickling on it.

## Documentation

- Update README and docs in the same change that alters behavior.
- Document public functions, types and endpoints, including inputs, outputs and errors.
- Keep the README quickstart working: install, run and test in a few commands.
- Document breaking changes and migration steps wherever users will see them.
- Document decisions and trade-offs, not what the code visibly does.

## Workflow and tooling

- Run tools through the project scripts (npm run, make, task) instead of invoking underlying binaries directly, so flags and environments match CI.
- Run the single aggregate check command (for example pre-commit or a lint script) before finishing; fix every failure and re-run until it passes.
- Run the specific test files related to your change first, and run the full suite only before handing off.
- Before editing a directory, read the README and any nested AGENTS.md that applies to it.
- Put throwaway scripts and experiment output in a gitignored scratch directory and delete them when done.
- After switching branches or pulling dependency changes, reinstall and rebuild before running tests.
- When CI fails, find the exact failing job and command, reproduce it locally, then fix the cause instead of re-running blindly.
- Stop any dev servers or watchers you started once you are done.
- Ask before running destructive or irreversible commands such as dropping databases, deleting branches, rm -rf or force operations.
- Prefer existing scripts, generators and templates in the repo over writing new ad hoc tooling.
- When the repository documents skills or runbooks for a task (migrations, releases, dependency bumps), follow them instead of improvising.
- Never start long-running dev servers or watchers in the foreground. Use targeted one-shot commands.

## Verification and CI feedback

- Run the narrowest relevant test first, then widen to the package and workspace checks as confidence grows.
- Run the project formatter and linter on changed files before committing, using the repo scripts or hooks.
- For a bug fix, reproduce the failure first, then show the regression test failing without the fix and passing with it.
- Report a task as done only after running the checks that prove it. If you could not run them, say so.
- Before finishing, re-read the full diff as a reviewer with no knowledge of this session and fix what would confuse them.

## Public API stability

- Treat the public API of a released major version as a compatibility contract. Renames, removals and signature changes need an explicit maintainer decision.
- Prefer additive changes. Add new parameters as optional or keyword-only with safe defaults.
- Deprecate before removing: keep a working shim and mark it deprecated with the replacement and the removal version.
- Define the public surface explicitly, such as __all__ or an exports map. Adding a symbol there is an API decision, not a convenience.

## Releases and migrations

- Follow semantic versioning and bump versions only in release changes.
- Record user-visible changes in CHANGELOG.md under an Unreleased heading.
- Ship database changes in backward compatible steps: add, backfill, switch reads, then remove.
- Make every release reversible and note the rollback path in the pull request.

## Python conventions

- Follow PEP 8 and use Ruff for linting and formatting.
- Add type hints to all function signatures and run mypy or pyright.
- Use pathlib for filesystem paths and context managers for resources.
- Model structured data with dataclasses or Pydantic, not loose dicts.
- Write tests with pytest, using fixtures and parametrize instead of loops.
- Catch specific exceptions, never bare except.
- Never use mutable default arguments.
- Use the logging module with a module-level logger, not print.
- Do not mix blocking calls into async code; use asyncio.to_thread for unavoidable blocking work.

## uv conventions

- Add dependencies with uv add so pyproject.toml and the lockfile stay in sync. Never use pip install in a uv project.
- Run tools with uv run --locked, which fails if the lock is stale. Use --frozen only when the lock must not be checked.
- Upgrade a single package with uv lock --upgrade-package <name> instead of upgrading everything.
- Never use the system python3 or a bare pip for project work. Go through uv and the project environment.

## Ruff conventions

- Use ruff format as the formatter and ruff check --fix for autofixable lint.
- Keep Ruff settings in pyproject.toml or ruff.toml under the lint and format tables.
- Choose rule families with select or extend-select rather than enabling everything.
- Scope exceptions with per-file-ignores for tests, scripts and __init__.py instead of global ignores.

## pytest conventions

- Write tests as plain test_ functions with fixtures. Do not add test classes to new code.
- Use pytest.mark.parametrize with pytest.param(..., id=...) for named cases.
- Share fixtures through conftest.py and keep them small and composable.
- Use tmp_path for files and monkeypatch for environment and attributes.

## Python library packaging conventions

- Define the public API in the package __init__.py with __all__. Adding a symbol there is a deliberate API decision.
- Pass encoding= to text-mode open, read_text and write_text. The default is the locale encoding, not UTF-8.
- Give public APIs docstrings, with a Raises section for exceptions callers should catch.
- Add new parameters as keyword-only with defaults so positional callers keep working.

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