cursor/typescript-best-practices
pstack/skills/typescript-best-practices/SKILL.md
TypeScript best practices. Use when reading or editing any .ts or .tsx file.
$ install --global
skillsauthnpx skillsauth add cursor/plugins typescript-best-practicesInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
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Last scanned: May 24, 2026, 2:40 AM183.6s2 files scanned
SKILL.md
- name:
- typescript-best-practices
- description:
- TypeScript best practices. Use when reading or editing any .ts or .tsx file.
TypeScript best practices
Apply the type-system-discipline principle skill first; this skill grounds it in TypeScript syntax.
| Rule | Summary |
|------|---------|
| Discriminated unions | Model variants with a kind literal discriminant so impossible states can't be represented. No optional-field bags. |
| Branded types | Brand primitives with & { readonly __brand: "X" } so they can't be mixed up. Validate once at creation. |
| unknown over any | External data is unknown. any disables type checking everywhere it touches. |
| No as casts | Every as is a runtime crash waiting. Cast only after validation. |
| Narrowing hierarchy | Discriminant switch > in operator > typeof/instanceof > user-defined type guard > as. |
| Type guards | Must verify the claim. A lying guard is worse than as because the bug hides behind a name that says it's safe. Name them isX or hasX. |
| Exhaustiveness | Inline const _exhaustive: never = x; in default arms so the compiler errors when a new variant is added. |
| satisfies over as | Validates the value without widening literal types. |
| Boundary validation | Validate where data crosses in; trust types inside. See the boundary-discipline principle skill. |
| Schema-derived types | Reach for Pick/Omit/Parameters/ReturnType/Awaited/typeof before declaring a new interface. |
| Object args | Pass objects, not positional, so argument order is self-documenting. Skip on hot paths (per-frame render, tokenizers, parsers). |
Examples: references/patterns.md.
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