Chrome extension v1.0.63 broken — Claude Code cannot connect (macOS, Desktop app)

Environment

• Claude Code desktop app (not CLI) on macOS Sequoia 25.3.0
• Claude Opus 4.6 (1M context)
• Chrome extension v1.0.63
• Chrome profile: non-default profile
• Claude Desktop also installed and running

The problem

Since approximately 20 March (extension v1.0.63 update), tabs_context_mcp consistently returns "Browser extension is not connected" despite the extension showing as connected in Chrome.

This worked reliably for weeks before the update. We use Chrome MCP daily for email triage, social media management, and form filling across multiple sites.

What we tried

• Clicked Connect in the extension 10+ times
• Verified extension is installed and enabled in chrome://extensions
• Verified same Anthropic account in both extension and Desktop app
• Tried both org options (personal org and team org) — personal org connects silently but Code still cannot reach it; team org gives Authorization failed Redirect URI not supported by client
• Fully quit and restarted Chrome
• Verified native messaging host file exists
• Created com.anthropic.claude_code_browser_extension.json manually (docs say this should exist but it did not)
• Restarted Chrome after creating the file
• Confirmed the native host process runs from Claude.app

Expected behaviour

tabs_context_mcp creates a tab group and returns tab IDs, as it did reliably before 20 March.

Actual behaviour

Every call returns "Claude in Chrome is not connected" and pops a dialog asking the user to check their account. The account is correct.

Impact

Complete loss of browser automation. Cannot open tabs, fill forms, read pages, or interact with any web application. This is a core daily workflow.

Related issues

#36910, #37541, #37684, #36018, #36551, #31971, #24593, #26305