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+# Contributing
+
+Thanks for looking. gp-libs is pre-1.0 (`0.0.x`); a minor version bump may
+still carry a breaking change. Bug reports with a reproduction, and notes on
+where the documentation misled you, are the most useful contributions right
+now.
+
+How this project writes prose — README, `CHANGES`, release notes, commit
+messages, docstrings, source comments, and log messages — is set out
+separately in [WRITING.md](WRITING.md). Read that before changing any of it.
+The constraints every change is held to, and the map of what is where, are in
+[AGENTS.md](../AGENTS.md).
+
+## Getting set up
+
+Install [git], [uv], and [just].
+
+```console
+$ git clone https://github.com/git-pull/gp-libs.git
+```
+
+```console
+$ cd gp-libs
+```
+
+```console
+$ uv sync --all-extras --dev
+```
+
+[git]: https://git-scm.com/
+[uv]: https://github.com/astral-sh/uv
+[just]: https://just.systems/
+
+## The gates
+
+Format:
+
+```console
+$ uv run ruff format .
+```
+
+Lint:
+
+```console
+$ uv run ruff check . --fix --show-fixes
+```
+
+Type-check — strict mypy across `src/` and `tests/`:
+
+```console
+$ uv run mypy .
+```
+
+Test:
+
+```console
+$ uv run pytest
+```
+
+**Imports.** Namespace stdlib imports — `import enum`, not
+`from enum import Enum` — so a call site reads `enum.Enum`. Third-party
+packages may use `from X import Y`. For typing, `import typing as t` and
+access via the namespace: `t.NamedTuple`, `t.TYPE_CHECKING`. Every file
+starts with `from __future__ import annotations`; ruff's isort
+`required-imports` (`pyproject.toml`) enforces that one, the rest is
+convention ruff does not check.
+
+Documentation is a gate, not a courtesy. Examples in `src/*.py` docstrings
+and under `docs/` are executed by `uv run pytest`, because `testpaths` in
+`pyproject.toml` lists `tests`, `docs`, and `src`; `README.md` is not in
+`testpaths`, so its three `>>> ` examples do not currently run under CI.
+There is no separate doctest step for the paths that are collected — a
+green `pytest` is the proof. Which blocks qualify, and the one mistake that
+silently removes a test, are in
+[WRITING.md](WRITING.md#documented-examples-that-run).
+
+Before claiming a test or a gate works, show it failing. A gate that has
+never been red is an assumption.
+
+CI (`.github/workflows/tests.yml`) runs the equivalent of the four commands
+above (`ruff check .`, `ruff format . --check`, `mypy .`,
+`py.test --cov=./ --cov-report=xml`) across a matrix of Python 3.10-3.14,
+docutils 0.20 and 0.22.4, and pytest 8 and 9 — gp-libs supports a wider
+version span than most consumers of it, because everything downstream
+depends on this collector staying compatible.
+
+## Tests
+
+Write tests as standalone functions, not classes — no `class TestFoo:`
+groupings. Use descriptive function names and file organization instead.
+
+Prefer fixtures from `tests/conftest.py` over `monkeypatch` and
+`unittest.mock` when one exists; document in the test docstring why a
+standard fixture was not used for an exceptional case. Use `tmp_path`
+(`pathlib.Path`) over `tempfile`, and `monkeypatch` over `unittest.mock`
+when you do need one.
+
+`tests/conftest.py` also provides the Sphinx `app_params`/`make_app_params`
+fixtures (via `pytest_plugins = ["sphinx.testing.fixtures", "pytester"]`)
+for tests that build a throwaway Sphinx app — used by
+`tests/test_linkify_issues.py` and the plugin-suppression tests.
+`tests/regressions/` holds one file per historical bug, named for its
+issue.
+
+Run continuously with [pytest-watcher]:
+
+```console
+$ just start
+```
+
+Or with [entr(1)] when you want a shell-only watcher:
+
+```console
+$ just watch-test
+```
+
+[pytest-watcher]: https://github.com/olzhasar/pytest-watcher
+[entr(1)]: http://eradman.com/entrproject/
+
+## Documentation
+
+Build the docs:
+
+```console
+$ just build-docs
+```
+
+Start the default preview server, which watches for file changes:
+
+```console
+$ just start-docs
+```
+
+From inside `docs/`, the local `docs/justfile` has finer-grained recipes:
+`just html` builds once, `just serve` serves the built output, `just watch`
+rebuilds on change, `just dev` watches and serves together, and
+`just design` disables incremental builds while you edit static assets.
+
+`docs/conf.py` also enables `sphinx.ext.doctest` with a
+`doctest_global_setup` that imports `is_allowed_version` and
+`pytest_ignore_collect`, so the `{doctest}` blocks under `docs/` are valid
+input to Sphinx's own doctest builder as well as to pytest. Run it with
+`just -f docs/justfile doctest`. Neither `tests.yml` nor `docs.yml` invokes
+that recipe — it is a manual, local-only check, not a CI gate. `just
+build-docs` is what CI runs, and it is also the only thing that catches a
+broken `{ref}`/`{doc}` cross-reference; the doctests do not.
+
+## Releasing
+
+gp-libs is pre-1.0: minor version bumps may include breaking changes. [uv]
+handles virtualenv creation, package requirements, versioning, building,
+and publishing — there is no `setup.py` or requirements file.
+
+1. Update `CHANGES` with release notes.
+2. Bump the version in `src/gp_libs.py` and `pyproject.toml`.
+3. Create the release commit:
+
+   ```console
+   $ git commit -m 'Tag v0.1.1'
+   ```
+
+4. Push the branch for review:
+
+   ```console
+   $ git push
+   ```
+
+5. After review, the release owner creates and pushes the tag. Never
+   create tags. Never push tags. The owner handles tagging and tag pushes,
+   because a tag triggers the publish workflow. See
+   [Release commits](WRITING.md#release-commits).
+
+## Pull requests
+
+One subject per pull request. Unrelated cleanup found along the way
+belongs in its own commit, and usually in its own pull request.
+
+Discuss a substantial change via an issue before making it.
+
+Commit format is in [WRITING.md](WRITING.md#commits).
+
+## Decorum
+
+- Participants will be tolerant of opposing views.
+- Participants must ensure that their language and actions are free of
+  personal attacks and disparaging personal remarks.
+- When interpreting the words and actions of others, participants should
+  always assume good intentions.
+- Behaviour which can be reasonably considered harassment will not be
+  tolerated.
+
+Based on [Ruby's Community Conduct Guideline](https://www.ruby-lang.org/en/conduct/).
+
+## Security
+
+Please do not open a public issue for a vulnerability. Report it privately
+through GitHub:
+<https://github.com/git-pull/gp-libs/security/advisories/new>.