Contributing

Workflow

Branches flow main ← staging ← feat/<slug>. PRs target staging; main takes only reviewed milestone merges. CI (3.11/3.12/3.13) must pass.

Scaffold: /new-pattern <group>/<slug> "Name" (Claude Code) or copy an existing unit's shape (the template is in CLAUDE.md).
Fill the frontmatter — every key; id must equal <group>/<slug>; pick the verdict (pythonic | use-with-care | prefer-alternative, defined in CLAUDE.md). The catalog loader validates this in CI and fails loudly.
Build the module: pattern/ (the importable code), the three docs/ files, at least one examples/<project>/ mini-project that genuinely imports pattern/ (entry point main.py, never __main__.py), and behavioral tests for both.
make check — ruff, mypy --strict, pytest must all pass. The loader rejects a unit missing any part of the template, and a catalog test rejects an example that never imports its own pattern package.
make readme — regenerate the catalog table (CI rejects a stale one).

Full type hints; import-safe modules (no side effects at import).
Tests assert behavior, not "it runs" — and load-bearing claims get the mutation treatment (mutate the code, prove the suite fails, revert). Reviews are severity-ordered; machines own style, humans argue design.
Mini-projects use realistic domains, no Foo/Bar.
Prose: one page, problem-first, no UML, no history lessons. The classic (GoF) form lives in each unit's docs/fundamentals.md as an annotated listing.