feat(opencode): double-escape to clear prompt input

[guarzo]

Issue for this PR

Closes #7319

Type of change

• New feature

What does this PR do?

Adds double-escape to clear the prompt input when idle. First Escape shows a hint (esc again to clear) in the status bar; second Escape within 2 seconds clears the input. No-op when input is empty or when a session is running.

There's already a solid implementation in #7320. This is an alternative approach in case maintainers want to compare:

• Command-based — uses command.register() like all other keybinds; the key is configurable as input_clear_prompt in config (defaults to escape)
• Visual hint — first press shows esc again to clear in the idle status bar, matching the existing session interrupt hint pattern
• 2s window instead of 300ms — more forgiving timing
• Timer cleanup on unmount — clearTimeout in onCleanup to avoid a stale callback firing against a disposed store

Happy to close this if #7320 moves forward.

How did you verify your code works?

bun typecheck passes. Manually tested:

1. Idle + non-empty: first Esc shows hint, second Esc within 2s clears input
2. Hint auto-dismisses after 2s with no second press, input unchanged
3. Idle + empty: Esc is a no-op (command guard prevents it)
4. Session running: Esc fires session_interrupt as before

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Related PR Found

PR #7320: feat: add double-ESC keybind to clear input field
#7320

Why they're related: This is the exact alternative PR mentioned in your PR description. PR #22126 (the current PR) is an alternative implementation approach to #7320 that addresses the same feature request (#7319). Both implement double-escape to clear prompt input, but with different tradeoffs:

• feat: add double-ESC keybind to clear input field #7320: 300ms window, raw useKeyboard handler
• feat(opencode): double-escape to clear prompt input #22126: 2s window, command-based approach with visual hint in status bar

As noted in your PR, you're aware of #7320 and are offering this as a comparison for the maintainers to evaluate.

[github-actions]

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