perf(ui): render read-only todo checkbox without Kobalte

[marius-kilocode]

What Problem This Solves

The todowrite tool card rendered every to-do item with a full Kobalte Checkbox tree (Root + Input + Control + Indicator + Label + ErrorMessage, plus reactive state per item). The card is read-only, so that work buys no interactivity. A 6-item list cost about 8.9 ms of synchronous render in the isolated harness and 4.8 ms in the real webview, making it an outlier versus other non-diff tool cards.

Why This Change Was Made

Replace the read-only Kobalte checkbox with lightweight markup that emits the same DOM slots and accessibility semantics: data-component="checkbox", checkbox-checkbox-input/control/indicator/label, data-readonly, data-checked, a native checkbox with aria-readonly="true" and role="group", and a label tied by for/id. The indicator mounts only when checked. No CSS changes.

User Impact

No visual change. To-do cards render faster. The check icon for completed items, the unchecked box for pending items, in-progress styling, data-completed/data-changed attributes, and compact hidden-count rows are all unchanged.

Evidence

Storybook harness (BENCH_MODE=append BENCH_TOOLS=todowrite BENCH_REPEATS=7, median of 3 runs):

Build	syncMs
Before	8.9
After	3.6

In-app VS Code profiling (isolated Extension Development Host, seeded 6-item todowrite session, collapse and expand remount, 34 iterations):

Build	Median	p95	DOM nodes / inputs / slots
Before	4.8 ms	5.3 ms	42 / 6 / 32
After	3.9 ms	4.7 ms	42 / 6 / 32

bun run typecheck and bun run lint pass in packages/kilo-vscode. Added a Playwright test covering checked states, aria-readonly, label association, indicator count, and that Space does not toggle.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (3 files)

• .changeset/todo-card-render.md
• packages/kilo-ui/src/components/message-part.tsx
• packages/kilo-vscode/tests/accessibility.spec.ts

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