- Removed export leakage by demoting many helper and const symbols to module-local scope.
- Renamed underscore-prefixed internals and cache fields, then updated related references and `satisfies never` checks.
- Deleted obsolete logic branches and helpers, including harmony-stream interruption flow and unused benchmark runtime helpers.
- Updated Biome config and manifests by broadening lint coverage and removing an unused `@napi-rs/cli` dev dependency.
- Adjusted tests and utilities to use renamed test helpers and remove redundant private test-only helpers/locals.
- Added asynchronous Kitty conversion for assistant tool images using `convertToPng`, keyed per tool-call entry with cached and in-flight tracking.
- Updated assistant image rendering to prefer converted PNGs for Kitty terminals while preserving existing behavior for other protocols.
- Added a unit test that verifies WebP tool images are converted and rendered as Kitty image output instead of the raw image/webp fallback.
can1357