Plan approval popup: pressing Space while typing auto-confirms and dismisses without undo

Summary

When the plan approval modal/popup appears mid-session, pressing the Space (or possibly Enter) key while the user is already composing a follow-up message is treated as confirming the plan. There is no undo, and the in-progress text is discarded. To cancel the approval (if / when noticed) requires clearing the text box and clicking the "stop" square button. However changes may already have been made by this point. The partial text may be recovered by using the up arrow key in the text box then resuming editing before submitting as normal.

Steps to reproduce

1. Be mid-conversation with an active plan in plan mode
2. Start typing a follow-up message in the input box before the plan modal fully renders
3. Press Space (or possibly Enter) as part of normal typing
4. The modal interprets Space (or possibly Enter) as a confirmation keystroke and auto-approves the plan

Expected behaviour

• Keyboard input that lands in the chat input box should NOT propagate to a modal confirmation
• OR: plan approval should require an explicit click or number confirmation on the modal element itself, not a loose keypress

Impact

Plan proceeds when user intended to add further requirements first. Creates frustration and trust issues with the approval flow. May lead to user losing in-progress text, especially if they're unaware of up arrow to recall previous entries.

Environment

Platform: Linux, VS Code extension