Follow-up to the loop guard + artifact cap that addressed the root cause
of issue #2081's runaway captures. The reporter then noted Ctrl+X/Ctrl+C
remaining unresponsive — confirming the secondary symptom: per-keystroke
TUI repaints walked every visible bash row and re-ran `split` /
`replaceTabs` / `truncateToVisualLines` over the stored output. With a
1,000+ message transcript and a 50KB-tail per row, that string work was
what pinned the main thread, not the loop itself.
The eval renderer already caches its computed lines keyed by `(width,
previewLines)` — see `eval-render.ts:709-752`. Mirrored that pattern in
the bash result renderer with a slightly wider key (`width`,
`previewLines`, `expanded`, `rawOutput`, `isPartial`) so the cache is
busted whenever any input that affects the produced lines actually
changes. `invalidate()` continues to clear `CachedOutputBlock` and now
also clears the lines cache, so callers that already drive invalidation
keep working unchanged.
A render() with cache-equivalent inputs is now an array-reference
return; the `CachedOutputBlock` round trip is skipped entirely. New
test in `test/tools/bash-sixel-render.test.ts` pins the contract:
identical inputs → same array reference; width change → cache miss;
invalidate() → fresh array.
Refs #2081
