TypeScript coding conventions

Apply the active file's repository documentation, AGENTS.md, lint rules, and configuration first. Use this guidance for TypeScript, including embedded TypeScript, and combine available framework, testing, or library skills when needed.
Use Valibot for runtime validation schemas, following the project's schema organization and reusing existing contracts where applicable.

Avoid `return undefined`

Do not use return undefined. When exiting a function without a value, use a bare return.

Before embedding a non-trivial computation in an argument, property value, array element, condition, loop input, spread source, return value, or larger expression, assign it to a named const or let.
Give ordinary nested calls, awaited values, constructors, chained transforms, template-built values, ternaries, and multi-operator expressions meaningful intermediate names before another computation consumes them.
Exception: keep immediately clear elementary expressions inline, including property or element access, optional chaining, ??, unary checks, simple comparisons, and one-step arithmetic. Do not split them solely to satisfy this rule. An initializer that already gives its result a meaningful name may contain a clear calculation.
Arrange dependent statements in execution order: resolve input, transform it, then consume the result.
Keep nested or chained calls in declarative library APIs (embedded DSLs) when their structure expresses a declaration, such as a schema, query, or rule set. Follow the API's established composition style. Extract ordinary data preparation used as input; for example, name the result of parseId(rawId) before using it inside eq(users.id, id). A chain of data transformations follows the ordinary extraction rule.
Preserve behavior and algorithmic complexity; do not add intermediate collections or passes solely for formatting.