fix: harden OpenSim session readiness

docs/grid-agent-session.md

@@ -37,11 +37,14 @@ server failures retry with exponential backoff. `reconnect.maximum_delay_seconds
 is a hard cap. A server retry hint is a minimum up to that cap. Per-instance
 jitter is bounded by `jitter_basis_points`, preventing synchronized reconnects,
 and a connection that remains up for `stable_reset_seconds` resets the failure
-streak.
+streak. A connected generation that does not reach full event-queue readiness
+within `readiness_timeout_seconds` is logged out and retried instead of
+remaining degraded indefinitely.
 
 Backoff defaults are one second initially, 60 seconds maximum, 20 percent
-jitter, and a 120-second stable reset window. All waits use Tokio timers inside
-`select!` with cancellation/control; there are no blocking sleeps.
+jitter, a 30-second readiness deadline, and a 120-second stable reset window.
+All waits use Tokio timers inside `select!` with cancellation/control; there are
+no blocking sleeps.
 
 ## Generation and work safety