# quality-code

Rhys Sullivan's TypeScript coding skill — branded types, discriminated unions, end-to-end types, real tests over mocks, OpenTelemetry observability, and picking the right abstractions instead of premature ones.

**Type:** guideline
**Added:** 2026-05-15
**Author:** [Rhys Sullivan (@RhysSullivan)](https://x.com/RhysSullivan)
**Link:** https://github.com/RhysSullivan/skills/tree/main/skills/quality-code
**Topics:** AI Coding
**Tags:** agents, typescript

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My primary TypeScript coding skill. I reference it from CLAUDE.md/AGENTS.md so it's always in context — agent output ends up measurably better TS across the board.

Covers type safety patterns (branded types, discriminated unions, end-to-end types), why real tests beat mocks, OpenTelemetry as the default observability story, and when to introduce abstractions vs. keep things flat.

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## Links

- Directory entry: https://andrey-markin.com/directory/quality-code
- All directory entries: https://andrey-markin.com/directory
- Contact: https://andrey-markin.com/#contact