Add TypeScript types for handlers

**Description**
Currently helpers lacks proper search support.

**Proposed solution**
Add configurable search with sensible defaults.

**Priority**: Low/Medium

Start by locating the helpers and handler definitions referenced by the issue, then reconcile the title's TypeScript-types request with the description's configurable search proposal. Confirm the intended scope and sensible defaults with the maintainers before implementing; done means the agreed handler types or search behavior is covered and validated by the relevant existing checks.

Written by the indexing model from the issue text.