claude-in-chrome MCP tools broken — tengu_chrome_auto_enable flag is false

Description

The built-in mcp__claude-in-chrome__* browser automation tools in Claude Code are non-functional. The tools are listed as available (deferred tools), but every call returns "Browser extension is not connected."

Root Cause

The GrowthBook feature flag tengu_chrome_auto_enable is set to false in ~/.claude.json under cachedGrowthBookFeatures. This flag is overwritten from the server on every Claude Code startup, so local edits do not persist.

Evidence

The native host bridge is fully healthy:

• Chrome extension is installed and active (shows "Claude (MCP)" tab group)
• Native host process spawns correctly: ~/.claude/chrome/chrome-native-host → /Users/<user>/.local/share/claude/versions/2.1.70 --chrome-native-host
• Unix socket is created and listening at /tmp/claude-mcp-browser-bridge-<user>/<PID>.sock
• Chrome connects to the native host successfully

But Claude Code never connects to the socket. The chrome-native-host.log confirms:

• Jan 12 – Feb 8, 2026: Dozens of successful MCP client connections (Accepted new MCP connection (client N))
• Feb 8, 2026: Last successful MCP client connection
• Feb 8 – present: Native host runs, socket exists, Chrome connects, but zero MCP client connections from Claude Code

Reproduction Steps

1. Open Claude Code (v2.1.70) on macOS
2. Confirm Chrome extension is installed and showing "Claude (MCP)" tab group
3. Call mcp__claude-in-chrome__tabs_context_mcp → returns "Browser extension is not connected"
4. Check ~/.claude.json: cachedGrowthBookFeatures.tengu_chrome_auto_enable = false
5. Manually edit the flag to true, restart Claude Code → flag is back to false
6. Check ~/Library/Logs/Claude/chrome-native-host.log → socket is up, no MCP clients connect

Environment

• Claude Code version: 2.1.70
• macOS Darwin 25.3.0
• Chrome extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
• Native host config: ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json

Expected Behavior

The tengu_chrome_auto_enable flag should be true (or the chrome MCP connection should not be gated by this flag), allowing Claude Code to connect to the native host socket and use the mcp__claude-in-chrome__* tools.