Feature request: Hook event for auto-suggested prompts

Feature Request

Add a hook event that fires when Claude Code generates auto-suggested prompts (the dimmed "ghost text" that appears in the input area after a response).

Context

Claude Code generates contextual follow-up suggestions after responses — e.g., "run the tests", "deploy to production". These appear as dimmed placeholder text in the terminal input. Users can accept them with Tab/Enter or ignore them.

Currently, these suggestions are:

• Generated client-side in the terminal UI
• Completely transient — not persisted to JSONL transcripts
• Not exposed to any hook event
• Invisible to any external observability or monitoring system

Proposed Hook Event

A new hook event type (e.g., SuggestedPrompts or ResponseSuggestions) that fires after a response completes and suggestions are generated.

Stdin payload:

{
  "session_id": "abc123",
  "suggestions": [
    "run the tests",
    "deploy to production"
  ],
  "parent_message_id": "msg_01..."
}

Use Case

I'm building Kuroryuu, an Electron desktop app for Claude Code that includes a real-time observability dashboard tracking all 12 hook events (tool usage swim lanes, event timelines, pulse views, etc.). Being able to track what Claude suggests — and which suggestions users accept — would provide valuable insights into:

• Workflow patterns: Which follow-up actions does Claude most commonly suggest?
• Acceptance rate: How often do users accept suggestions vs. type their own prompts?
• Session flow: Understanding the natural rhythm of human-AI collaboration
• UX research: Which suggestion styles are most useful?

Current Workaround Attempts

| Approach | Result |
|----------|--------|
| Hook stdin (Stop/Notification) | Suggestions not included in any hook event payload |
| JSONL transcript parsing | Suggestions not persisted — only API message exchanges stored |
| Anthropic API response | No suggestion field in the Messages API response |

Environment

• Claude Code v2.1.x on Windows 11
• Hook system: PostToolUse, Stop, UserPromptSubmit, SubagentStop, Notification (working)
• 7 of 12 hook events broken as standalone arrays on Windows (separate known issue)