Typescript Best Practices

TypeScript best practices

Follow the repository's TypeScript conventions and compiler settings. Strengthen types where they prevent a concrete invalid state or unsafe operation; avoid adding type machinery without a caller that needs it.

• Use discriminated unions for mutually exclusive states and exhaustive handling for closed variants.
• Parse external data from unknown at trust boundaries. Use established schemas and derive types from their authoritative definitions.
• Prefer narrowing or satisfies to assertions that hide a mismatch. When an assertion is unavoidable, keep it local to a verified invariant. as const is not an unsafe cast.
• Use branded primitives when confusing identifiers is a real risk, and non-empty collections only where an operation requires one.
• Preserve established function signatures, logging conventions, and test patterns unless the requested change requires otherwise.

Read patterns when a concrete example is needed. This skill does not require loading a second principle skill or running unrelated runtime tests.