Feature: Allow assistant to suggest/set session title

Problem

When using multiple concurrent Claude Code sessions (especially with persona patterns), it's hard to tell sessions apart in the /resume picker. The auto-generated titles are based on conversation content, but they don't capture the role or focus of a session.

Example workflow:

• Session 1: ClaudeClaude working on persona config
• Session 2: ThothClaude drafting documentation
• Session 3: DetectiveClaude investigating a bug

Currently all three might get titles like "Update playbook configuration" which doesn't help identify which persona is active or what mode the session is in.

Proposed Solution

Allow the assistant to suggest or set the session title programmatically. Options:

Option A: New tool SetSessionTitle

SetSessionTitle(title: "ClaudeClaude: Persona config work")

Option B: Hook for title generation

A hook like OnTitleGenerate that can modify or replace the auto-generated title:

{
  "hooks": {
    "OnTitleGenerate": [{
      "type": "command",
      "command": "echo \"${PERSONA:-Claude}: ${AUTO_TITLE}\""
    }]
  }
}

Option C: Title suggestion in assistant response

Allow a special syntax in responses that suggests a title:

<session-title>ClaudeClaude: Building ThothClaude persona</session-title>

Use Cases

1. Persona workflows: Multiple sessions running different personas simultaneously
2. Long-running investigations: Sessions that span days need descriptive names
3. Parallel work: Running tests in one session, coding in another
4. Handoff clarity: When resuming a session, immediately know what it was doing

Current Workarounds

• Manual /rename after every persona activation (easy to forget)
• Terminal tab titles via hooks (doesn't help /resume picker)
• Detailed handoff files (helps context but not identification)

Environment

• Claude Code version: Latest
• Use case: Multi-session persona-based workflows