Claude Code CLI cannot connect to Claude-in-Chrome extension on Windows — native host returns unparseable browser list ("JSON Parse error: Unexpected identifier 'Browser'")

Environment

• OS: Windows 11 Home 10.0.26200 (native, not WSL)
• Claude Code: 2.1.179
• Claude extension: 1.0.77 (Chrome Web Store, ID fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Browser: Google Chrome 149.0.0.0 (single profile, Default)
• Plan: direct Anthropic (Max)

Summary

mcp__claude-in-chrome__* tools always return "Browser extension is not connected", despite a fully correct, verified configuration. The extension itself is healthy — its side-panel agent (Sonnet 4.6) opens and works normally — so the fault is isolated to the Claude Code ↔ extension native-messaging bridge.

Key symptom

/chrome reports: Status: Enabled, Extension: Installed, Browser: Browser 1, Enabled by default: Yes.

• Selecting "Select browser…" → Couldn't list connected browsers: JSON Parse error: Unexpected identifier "Browser"
• "Reconnect extension" → no visible effect
• Any tabs_context_mcp call → "not connected"

The literal browser name "Browser 1" plus a JSON parse error on the browser-list response suggests the native host is emitting a non-JSON / wrong-format payload that the CLI can't parse.

Verified correct (ruled out)

• Claude Code 2.1.179 (≥ 2.0.73) and extension 1.0.77 (≥ 1.0.36)
• Native host registered for both Chrome and Edge:

HKCU\Software\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_code_browser_extension
→ C:\Users\dan\AppData\Roaming\Claude Code\ChromeNativeHost\com.anthropic.claude_code_browser_extension.json

• Manifest valid; path → C:\Users\dan\.claude\chrome\chrome-native-host.bat (exists) which launches the current claude.exe (--chrome-native-host)
• allowed_origins = chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/ — matches the installed extension exactly
• Extension signed into the same Anthropic account as the CLI
• Chrome confirmed running throughout

Steps taken (no effect)

• Full Chrome restart (all processes ended, reopened)
• /exit, ended all stale claude.exe in Task Manager (verified down to a single claude.exe), then claude --continue --chrome
• /chrome → Reconnect extension

After a pristine restart (1 claude.exe, Chrome running, all config correct) the failure persists identically — ruling out stale-process / named-pipe conflicts.

Repro

1. Install extension 1.0.77, sign in, confirm Enabled by default: Yes.
2. claude --chrome (CC 2.1.179, Windows native, Chrome 149).
3. /chrome → Select browser… → JSON parse error; any browser tool → "not connected".

Expected

Native host returns a valid JSON browser list; CLI connects.