A teammate's browser on another person's host shows Reconnecting… forever #630

A teammate who opens another person's host in a browser sees "Disconnected from your host. Reconnecting…" forever instead of being told to use their own host.

Where

A browser on Mac A at http://nate16-1:4142/ or http://100.119.196.79:4142/ (Mac B's host), and the reverse.

What was seen

Every address loads Ace's empty shell (HTTP 200): the rail, a plain "A" avatar and the banner "Disconnected from your host. Reconnecting…", which never changes. The console repeats "WebSocket connection to 'ws://…:4142/ws' failed: Error during WebSocket handshake" and "Failed to load resource: the server responded with a status of 400 (Bad Request)". The expected "Open Ace from your own host" (403) never appeared. One tester said it looks exactly like their own expired sign-in. Access itself was refused: no channels or data loaded.

Expected: the page says this is someone else's host and to open Ace from your own (apps/host/src/gateway.ts:1068), and the app shows that instead of reconnecting. Same family as #609 and #625, where an unauthenticated browser only ever sees "Reconnecting…".

Map: ^798.

Found in the 2026-10-22 two-Mac pair study on Canary 0.0.53.88.