[pratikbuilds]

PromptInput is a fully controlled form. PromptInputTextarea draws @mention and /command tokens on an aria-hidden mirror beneath transparent native text, grows through field-sizing with a measured fallback, and never submits during IME composition. usePromptInput drives PromptInputSuggestions from the keyboard, and PromptInputSubmit turns Send into Stop while a reply is running.

Stacked on #2: review only this commit. Part of corbitsdev#94.

Notes for review

• status lives on PromptInput (root), not PromptInputSubmit: Enter must see the status so it never sends mid-reply; PromptInputSubmit takes only onStop.
• Fixed while building: Stop could also send the draft when the host flipped status to ready inside onStop; the Stop click now cancels that (e2e covers it).
• Sizing fallback is covered by e2e only (happy-dom reports field-sizing as supported and has no layout).
• Not shared with ChatInput/Textarea sizing to keep existing modules untouched; a follow-up could consolidate after the old family is removed.
• canSubmit on PromptInput (default value.trim() !== "") lets a host send attachments with no text, e.g. canSubmit={value.trim() !== "" || files.length > 0}; Enter and Send both honour it; disabled, busy status and IME composition still block.

Verification

• This commit passes bun run typecheck and bun run lint on its own (the stack is checked commit by commit).
• At the top of the stack: bun run check, bun run build, bun run dep-guard, bun run contrast-test and bun run test:e2e (Playwright specs and the Storybook axe sweep in light and dark) pass.

Closes corbitsdev#102

[pratikbuilds]

Moved upstream: corbitsdev#115