Extension 2.1.129 fails to activate in Cursor 3.1.17 — all commands return "command not found"

Environment

• Editor: Cursor 3.1.17
• Claude Code extension: 2.1.129 (current)
• OS: Windows 11

Symptoms

After auto-update to 2.1.129, the extension fails to activate:

• Extension shows status "Not yet activated" in the Extensions panel
• No Claude icon in activity bar
• Ctrl+Esc shortcut does nothing
• All commands from Command Palette fail with the same pattern:
• Claude Code: Open in Sidebar → command 'claude-vscode.sidebar.open' not found
• Claude Code: Open in New Tab → same pattern
• Claude Code: Open in New Window → same pattern
• Console warning: View container 'claude-sidebar-secondary' does not exist

Reproduction

1. Open Cursor 3.1.17 with Claude Code extension 2.1.129 installed
2. Try to open Claude via Command Palette or Ctrl+Esc
3. Extension never activates, all commands fail

Workaround

Downgrading the extension to 2.1.121 (via Install Another Version) fixes the issue completely. Disabling auto-update keeps it working.

Notes

Worked fine on 2.1.121 the day before auto-update kicked in. Reinstalling 2.1.129 and restarting Cursor did not help — only the version downgrade resolved it.