claude-in-chrome: extension never registers with relay despite correct account and working sidebar

Environment

• Claude Code CLI: 2.1.199
• macOS: 26.5.1 (Darwin 25.5.0)
• Google Chrome: 149.0.7827.201 (stable)

Description

The Claude for Chrome extension never registers with the relay, so all mcp__claude-in-chrome__* tools fail with "Browser extension is not connected", even though everything on the browser side looks correct.

Verified state

• Extension installed and enabled; its settings page (chrome-extension://.../options.html) shows logged in as the same account as Claude Code (verified visually)
• Extension sidebar chat works normally (can converse with Claude in the panel)
• Chrome fully restarted (Cmd+Q) after install — multiple times
• /mcp shows claude-in-chrome ✔ connected · 22 tools (MCP server side is fine)
• Started a brand-new Claude Code session — same result

Failing calls

All of these return "Browser extension is not connected":

• tabs_context_mcp (with createIfEmpty: true)
• list_connected_browsers — implies zero browsers registered account-wide
• switch_browser — broadcast pairing request; no confirmation prompt ever appears in Chrome

Expected

list_connected_browsers should list the browser, or switch_browser should trigger a Connect prompt in the extension.

Notes

• Single Chrome profile in use; extension settings show "No sites have been approved yet" (never got far enough to approve any)