Chrome extension leaves orphaned tab groups when a session ends without closing its tabs

Description
The Claude in Chrome extension creates a new Chrome tab group per MCP session (via tabs_context_mcp with createIfEmpty). When a session properly closes its tabs with tabs_close_mcp, Chrome correctly auto-removes the now-empty group. However, when a session ends without closing its tabs first (conversation interrupted, session terminated abruptly, or multiple tabs left open in the group), the tab group is left orphaned in the browser — there's no mechanism to detect or clean these up afterward, and they accumulate over time.

Steps to reproduce

1. Start a session that uses tabs_context_mcp(createIfEmpty: true), creating a new tab group.
2. Interact with a tab or two in that group.
3. End the conversation/session without the assistant calling tabs_close_mcp on all tabs in the group (e.g. conversation is closed/interrupted by the user before cleanup).
4. Observe that the Chrome tab group remains open indefinitely.

Expected behavior
Either the extension cleans up its own orphaned tab groups on next launch/reconnect, or provides a way (UI action or tool) to enumerate and close stray groups from past sessions.

Actual behavior
Orphaned tab groups accumulate with no way to clean them up other than manually closing each one in Chrome.

Environment

• Claude Code CLI + Claude in Chrome extension
• macOS (Darwin 25.6.0)