Broker sessions rest while nothing needs them

A firm's client used to stay logged in around the clock, renewing on a fixed
timer overnight and at weekends. Now, once a firm has nothing open, nothing
pending and nothing left to trade before its next session for a random
15–45 minutes, its client disconnects and the dashboard shows it Resting.
It logs back in a random 20–50 minutes before the next session opens, at a
check-in every 3–7 Central daytime hours, or at once when trading starts, a
manual leg, copy trade, manual order or AutoBuyer run needs it. Token
renewals fall at random points (Tradovate 15–45 min before expiry, TopstepX
every 45–150 min). Settings → Trading → Rest idle broker sessions
(session_rest) turns it off.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -184,8 +184,9 @@ It is read-only unless `DX_CONFIRM=yes DX_ACCOUNT=<code>` are set too, which
 adds one minimum-size live round trip.
 
 `npm run check` runs the pure-logic checks (fees, stops, sizing, trading
-hours, the DXtrade selector, the futures draw and instrument lists), plus local
-HTTP/WebSocket checks against a temporary database.
+hours, session rest times, the DXtrade selector, the futures draw and
+instrument lists), plus local HTTP/WebSocket checks against a temporary
+database.
 
 ### Outbound user agent
 
@@ -203,6 +204,22 @@ Use `brokerWebSocket` or `signalrWebSocket` from `lib/outbound-proxy.ts` for bro
 sockets, and `directWebSocket` for control sockets. All share the same user agent;
 the broker proxy still applies only to broker traffic.
 
+### Broker session rest
+
+A firm's broker session is logged out while nothing needs it, rather than kept
+up around the clock (`lib/clients.ts`, session rest). Once a firm has nothing
+open, nothing pending and nothing left to trade before its next session (the
+weekend, the daily break, or a trade date whose accounts are all done) for a
+random 15–45 minutes, its client disconnects. The dashboard shows it as
+*Resting* with its accounts as last synced. A fresh login comes a random 20–50
+minutes before the firm's next session opens, and a long rest is broken by a
+check-in every 3–7 hours of the Central daytime. Starting trading, a manual leg,
+a copy trade, a manual order or an AutoBuyer run logs a resting firm back in at
+once. While logged in, tokens are renewed at random points (Tradovate 15–45
+minutes before expiry, TopstepX every 45–150 minutes) rather than on a fixed
+timer. Settings → Trading → *Rest idle broker sessions* (`session_rest`) turns
+it off; `/api/health` lists each resting firm and when it is back.
+
 ---
 
 ## The master dashboard