Chrome MCP server never auto-initializes without --chrome flag (macOS, v2.1.76)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The Chrome MCP server (claude-in-chrome) never initializes unless --chrome is explicitly passed on the CLI. Despite having chrome: true and claudeInChromeDefaultEnabled: true in ~/.claude.json, the Chrome module silently fails to load.

Debug log proof:

With claude -p (no --chrome): zero chrome-related entries in --debug output. All other MCP servers connect (perplexity, codex, blitz-iphone, context7, openai-docs, n8n-mcp). Chrome is completely absent. ToolSearch returns 0 matches for chrome tools.

With claude --chrome -p: Chrome MCP loads immediately:

Bridge URL: none (using native socket)
MCP server "claude-in-chrome": In-process Chrome MCP server started
MCP server "claude-in-chrome": Successfully connected to stdio server in 2ms
MCP server "claude-in-chrome": Connection established with capabilities: {"hasTools":true...}

Additionally, even when Chrome MCP loads with --chrome, the bridge to the actual Chrome extension never connects — all tool calls return "Browser extension is not connected." The MCP client never opens a connection to the native host socket at /tmp/claude-mcp-browser-bridge-{user}/{pid}.sock. Confirmed via lsof showing zero connections from the Claude Code process to the socket.

Two Distinct Issues

1. Auto-initialization broken: chrome: true in settings and claudeInChromeDefaultEnabled: true in .claude.json do not cause the Chrome MCP server to load. The --chrome flag is required every session.

1. Bridge connection broken: Even with --chrome, the MCP client never connects to the native host socket. The native host runs correctly (socket created, accepts connections), but Claude Code never attempts to connect. This matches the exact behavior reported in #25058 and #20298.

Contributing Factors

• tengu_copper_bridge is set to true by GrowthBook on every startup, overriding any local fix to false. A SessionStart hook that sets it to false loses the race against GrowthBook's async refresh.
• tengu_chrome_auto_enable is periodically removed entirely from cachedGrowthBookFeatures by GrowthBook sync, which may cause the Chrome module to default to disabled.

What Should Happen?

1. chrome: true in settings should auto-initialize the Chrome MCP server without requiring --chrome on every invocation.
2. The MCP client should connect to the native host socket when tengu_copper_bridge is false.
3. GrowthBook should not override user-set feature flags that are required for Chrome to function.

Environment

• Claude Code: 2.1.76
• macOS: Darwin 25.0.0 (Apple Silicon)
• Chrome: 145.0.7632.160
• Chrome Extension: 1.0.61 (ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Node: v24.11.0
• Plan: Max subscription

Steps to Reproduce

1. Set chrome: true in ~/.claude/settings.json
2. Verify claudeInChromeDefaultEnabled: true in ~/.claude.json
3. Start claude (without --chrome flag)
4. Run --debug --debug-file /tmp/debug.log
5. Observe: zero chrome entries in debug log, chrome tools not available
6. Start claude --chrome
7. Observe: Chrome MCP loads, tools available, but bridge to extension never connects

Related Issues

• #25058 — MCP client never connects to native host socket (same lsof evidence)
• #20298 — Browser extension not connecting (43 comments, oncall label)
• #24593 — Persistent connection failure, tengu_copper_bridge workaround
• #33072 — tengu_chrome_auto_enable forced to false by server

Error Messages/Logs

Browser extension is not connected. Please ensure the Claude browser extension is installed
and running (https://claude.ai/chrome), and that you are logged into claude.ai with the same
account as Claude Code.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Chrome tools were last working around February 25, 2026

Claude Code Version

2.1.76 (Claude Code)

Platform

Anthropic (Max subscription)

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)