AskUserQuestion does not fire Notification hook (silent user-input wait)

Summary

When Claude Code awaits user input via AskUserQuestion tool, no hook event fires. Users relying on hooks for async-workflow notifications (terminal bell, system notification, etc.) silently miss these "Claude needs your input" moments.

Steps to Reproduce

1. Configure a Notification hook in ~/.claude/settings.json that produces an audible/visual signal (e.g. writing BEL to tty for a tab-coloring daemon).
2. From an outer agent or model that uses AskUserQuestion, invoke the tool with any question.
3. Switch focus to a different terminal tab or app while the question UI is shown.
4. Observe: no Notification hook fires; no signal reaches the user.
5. Switch back and answer the question → only then does Stop hook fire (after Claude finishes its post-answer response), well after the user would have wanted to know.

Expected Behavior

When Claude Code displays a UI awaiting user input (AskUserQuestion, possibly also permission prompts that already fire Notification), a Notification hook event SHOULD fire so users can be alerted via their hook pipeline.

Actual Behavior

AskUserQuestion is treated as a tool call in flight; Claude is "waiting on tool result" rather than "awaiting user input" at the hook layer, so no event fires until the tool returns.

Why This Matters

Async-workflow users (e.g. multi-tab terminal multiplexing, remote sessions over mosh, BEL-driven tab-coloring daemons) rely on hooks to know when Claude needs attention. Currently:

• "Claude finished responding" → Stop hook ✓ works
• "Claude needs permission for Bash command" → Notification hook ✓ works
• "Claude is asking user to pick from options via AskUserQuestion" → no hook ✗

The third case is just as much "awaiting user input" as the second, but the notification pipeline silently drops it.

Suggested Fix

Fire \Notification\ hook (with appropriate \hook_event_name\ payload distinguishing it from permission prompts) when \AskUserQuestion\ is shown to the user.

Environment

• Claude Code version: 2.1.143
• OS: macOS
• Use case: BEL byte → tmux → mosh → iTerm2 → tab-coloring daemon