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claude-crystal
claude-crystal
Claude Code skills for the Crystal programming language — written by a Crystal ambassador who uses them daily.
Coverage tells you which lines ran. These skills care about whether your code is well-designed, well-tested, and whether your tests would actually catch a bug.
What's inside
| Skill | What it does |
|---|---|
crystal-tdd |
Drives the Red-Green-Refactor cycle in Crystal: spec structure, matchers, test doubles, spec_helper conventions, debugging specs that pass when they shouldn't. |
crystal-mutation-testing |
Runs and triages mutation testing with crytic: dev-loop incremental runs, CI quality gates, full-project baselines, and a decision tree for surviving mutants. |
crystal-sandi-metz |
Applies Sandi Metz's rules (100-line classes, 5-line methods, no-else discipline, POODR principles) adapted to Crystal's type system — in review mode and in writing mode. |
Install
In Claude Code:
/plugin marketplace add JadeKharats/claude-crystal
/plugin install crystal@claude-crystal
That's it. The skills activate automatically whenever Crystal code, specs, or design questions are in play.
Why skills instead of a long CLAUDE.md?
Skills load on demand: Claude reads the two-line description of each one, and pulls in the full instructions only when the task matches. Your context stays lean, and the guidance is versioned, shareable, and testable (see evals/ in crystal-sandi-metz).
Example: killing mutants
Without the skill, "add tests" tends to produce specs that chase coverage. With crystal-mutation-testing active, asking
mes specs sont vertes mais je ne leur fais pas confiance — aide-moi
gets you: an incremental crytic run on the changed files, a triage of surviving mutants (real gap vs. equivalent mutant), and the missing assertions — not just more executed lines.
License
MIT — see LICENSE.
claude-crystal
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- about 6 hours ago
- July 5, 2026
MIT License
Sun, 05 Jul 2026 19:29:16 GMT