The agent's control WS to the relay was purely reactive: it answered the
relay's Ping with a Pong and otherwise never wrote anything for long
stretches. So when the path broke silently — NAT rebinding, a reverse proxy
dropping its state — there were no unacked bytes for the kernel to
retransmit, the socket never errored, and the relay's Close (it gives up
after 120s of quiet) fell into the same hole. stream.next() then parked
forever on a socket to nobody, is_connected() kept answering true, and the
reconnect schedule below it — which works fine, it just never got asked —
was never reached. Only a process restart cleared it.
Relay logs show the cost: three idle-timeout closes of the agent connection
with the agent absent for 2h, 9h and >2h afterwards, while every disconnect
it *did* notice was back in 2-4 seconds. During one of those windows the iOS
client authenticated four times and not a single pipe matched: pipe_invite
rides the E2E channel through the agent's WS, so with the agent gone the web
view had nothing to tunnel through.
Add a per-session liveness probe. Both halves matter: a WS Ping every 20s
keeps unacked bytes on the wire so a dead path finally surfaces as a TCP
error (and the relay's Pong refreshes its own idle timer), and 75s of
inbound silence — two missed relay pings — returns Err, handing the session
to the existing backoff schedule.
Covered by a test against a relay that completes the v2 handshake and then
goes mute, the shape a black-holed path leaves behind. It reads the raw TCP
stream rather than ws.next() because tungstenite auto-answers a Ping with a
Pong on the next read, which would keep last_seen fresh and defeat the
silence being simulated. Without the probe the test hangs instead of
redialing.
The two admin-only console pages become a single "Mobile App" page
visible to every logged-in user: connection status (with the last
connection error for troubleshooting), the device list (admin sees all,
others only their own), a pairing dialog with the QR, and — admin-only —
a settings dialog hosting the plugin config, including a relay picker
(official grayed out, test, custom URL). The generic plugin-detail
config form defers to it via the new Plugin::config_in_detail_page flag.
Pairing is now self-service: any user opens a window and the device
auto-binds to them; revocation is admin-for-anyone, owner-for-self;
(re)binding to another user stays admin-only. Binding-managed plugins
(manages_own_access) now expose their non-admin pages to all users and
self-scope per caller (web_pages_for). The relay client records the
error that ends a WS session and clears it on reconnect.