crefft Source 2026.10.3

Engineering practice, pinned.

crefft is an engineering standard for people and coding agents, with explicit rules, their reasons, and the tool versions they apply to.

Pin a compatible hook revision

Hook revisions MUST be pinned to a tag that exists in the hook repository and MUST be new enough to parse the project’s target-version.

Recorded Ruff pin v0.16.6

Why

Ruff 0.8.0 rejects this guide’s Ruff configuration outright — unknown variant py314, expected one of py37 ... py313 — and Mypy 1.13.0 cannot parse a t-string, reporting invalid syntax; you likely need to run mypy using Python 3.14 or newer. A stale pin is not a conservative choice; it is a lint stage that never runs.

Do / recorded pin

rev: v0.16.6
hooks:
  - id: ruff-check
    args: [--fix]
  - id: ruff-format

Ruff entry quoted from the guide.

Don't / incompatible pin

rev: v0.8.0
hooks:
  - id: ruff

Illustrative counterexample using the incompatible revision described in the guide.

Both Ruff examples use https://github.com/astral-sh/ruff-pre-commit. The guide records the failure messages; this site build does not rerun Ruff or Mypy.

Complete configuration from the guide 
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.16.6
    hooks:
      - id: ruff-check
        args: [--fix]
      - id: ruff-format

  - repo: https://github.com/pre-commit/mirrors-mypy
    rev: v2.3.1
    hooks:
      - id: mypy
        args: [--strict]

  - repo: https://github.com/semgrep/semgrep
    rev: v1.176.0
    hooks:
      - id: semgrep
        args: [--config=p/python, --config=p/security-audit, --error]

  - repo: https://github.com/jendrikseipp/vulture
    rev: v2.16
    hooks:
      - id: vulture
        args: [src/, --min-confidence=90]

Read the rule and trace its evidence

Source: Python Style Guide, “Pre-commit Configuration.”

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