Every response already funnels through runtimeFetch, so a classifier there
spots 401s, confirms them against /auth/session (a proxied provider 401
must not read as a logout), and flips a small auth-session store. The web
and hosted surfaces show a frosted banner under the header whose Log in
button hands off to the session gate's existing unlock flow; sends are
paused while expired, the session-load error screen explains the auth case
and retries itself after login, and returning to a long-idle window
revalidates once via visibility/focus. Native mobile feeds the same signal
into its connection re-probe instead of showing the banner; VS Code is
exempt.