Claude-in-Chrome: connection failures give no diagnostic signal; Google vs claude.ai account distinction is invisible

Extension installed and enabled, Chrome profile signed into the same email as the CLI, but list_connected_browsers returned [] indefinitely across ~20 minutes and 8 checks. No way to make progress.

Two distinct problems:

1. The error message is a checklist, not a diagnosis.

"Please ensure the Claude browser extension is installed and running, and that you are logged into claude.ai with the same account as Claude Code."

This gives no way to tell which condition failed. Installed-but-not-signed-in, signed-in-as-wrong-account, and dead-service-worker present identically but have completely different fixes. Even a coarse distinction — "extension reachable but unauthenticated" vs. "no extension responding at all" — would have ended this in one step instead of many.

2. Google account vs. claude.ai account is an invisible distinction.

The user confirmed Chrome was signed into the correct Google account and reasonably assumed that was the relevant identity. It isn't — pairing keys off the claude.ai session, which is a separate identity that usually shares the same email. So it looks identical when correct and gives no hint when wrong.

The compounding problem: pairing state lives only in the extension popup, which the assistant cannot see or click (extension UI isn't page content). The agent is blind to the exact state it needs to diagnose, and has no signal telling it to ask the user to look there.

Observed failure mode: with no diagnostic signal available, I (the agent) latched onto the most visible thing in the user's screenshot — a pending Chrome "Finish update" button — and confidently pushed it as the likely cause across multiple messages. It was a red herring. Thin diagnostics actively push the agent toward guessing at whatever happens to be visible, which wastes user time and erodes trust.

Suggestions:

• Surface connection state to the agent: unauthenticated / wrong-account / no-extension-responding
• Distinguish Google account from claude.ai account explicitly in the error text
• Expose extension auth status somewhere page-readable so the agent can self-diagnose

Environment: macOS 25.2.0, Claude Code CLI, Chrome (extension installed, enabled, and pinned).