Claude-in-Chrome: extension signed in with correct account, but MCP always reports "Browser extension is not connected"

Summary

Claude-in-Chrome never connects. Every mcp__claude-in-chrome__* call returns "Browser extension is not connected", even though the extension is installed, enabled, and signed into the same account as Claude Code, on a plan that supports the feature.

Environment

• OS: macOS (Darwin 25.5.0), Apple Silicon
• Chrome: 149.0.7827.201
• Claude extension: fcoeoabgfenejglbffodgkkbkcdhcgfn v1.0.79 — installed, enabled, disable_reasons: []
• Claude Code auth: OAuth login (no ANTHROPIC_API_KEY/ANTHROPIC_AUTH_TOKEN set)
• Plan: claude_max (20x tier), org admin
• Extension account: confirmed signed into the same claude.ai account as Claude Code

Behavior

Every browser tool call fails identically:

• tabs_context_mcp → "Browser extension is not connected"
• list_connected_browsers → "Browser extension is not connected" (i.e. the account-level relay sees zero connected browsers, not just the local tab group)
• switch_browser → fails instantly instead of broadcasting a Connect prompt and waiting, which suggests the relay has no channel to any extension on the account

Things ruled out (verified from the shell)

• ✅ Chrome running (main process + extension render process present)
• ✅ Claude extension installed, enabled, no disable reasons (v1.0.79)
• ✅ Correct claude.ai account on both sides (extension shows the same account as Claude Code)
• ✅ OAuth auth, not an API key (no proxy/key env vars set)
• ✅ Plan supports the feature (claude_max, 20x)
• ✅ Claude Code CLI restarted — tried both --resume and a brand-new conversation (Test A); no change
• ✅ Chrome restarted multiple times; extension toggled
• ✅ No proxy / VPN / firewall — scutil --proxies empty, no active tunnel interfaces, claude.ai and api.anthropic.com both reachable in ~80ms

Expected

tabs_context_mcp returns the current tab group / tab info and browser automation proceeds.

Actual

Persistent "Browser extension is not connected" across every retry, restart, resume, and fresh session.

Notes

Because list_connected_browsers and switch_browser both report nothing at the account/relay level — not just the local tab group — the break appears to be in the pairing/registration between the extension and the account's relay, rather than anything local to the machine. Happy to provide extension logs or run diagnostics if it helps.