[Stocist]

Someone who installs the extension from a store and skips the host saw only "Host not running".

• The worker classifies the browser's disconnect message as a missing host or one that refuses this copy of the extension, and clears it once the host answers.
• The popup shows "Host not installed" or "Host needs an update" with an Install the host button that opens the README's install section.
• A host that merely stopped keeps the existing reconnect notice.
• User-visible popup text names the extension Tailtab.

Checked in Edge with a missing host and with a host whose manifest does not list the extension's ID.