Claude in Chrome extension fails to connect / connects then drops intermittently

Environment: Claude desktop app (Cowork), macOS, Chrome browser.

Issue: tabs_context_mcp (and other mcp__claude-in-chrome__* tool calls) consistently return "Browser extension is not connected" throughout a session, with one brief exception.

Timeline:

Initial calls: extension not connected.
After restarting Chrome: one call succeeded partway (extension reported "connected" but tabs_context_mcp timed out waiting on a possible pending permission prompt).
Immediate retry after that: reverted to "not connected."
Disabled VPN, Malwarebytes, and app blockers entirely, retried: still "not connected."
No pending approval prompts or extension badges were visible in Chrome at any point during testing.

Expected: Stable connection to the extension once installed, enabled, and signed into the same claude.ai account as the session.

Actual: Connection is either absent or drops within seconds of connecting, blocking any browser automation task.