nats nak w/ shared retry_backoff, exhausted log; no 'will retry' lie

crates/domain/tests/events/events_test.rs

@@ -53,3 +53,13 @@ fn follow_requested_with_handle() {
         }
     ));
 }
+
+#[test]
+fn retry_backoff_doubles_from_ten_seconds_and_caps_at_five_minutes() {
+    use domain::events::retry_backoff;
+    use std::time::Duration;
+    let secs: Vec<u64> = (1..=8).map(|n| retry_backoff(n).as_secs()).collect();
+    assert_eq!(secs, [10, 20, 40, 80, 160, 300, 300, 300]);
+    assert_eq!(retry_backoff(0), Duration::from_secs(5));
+    assert_eq!(retry_backoff(u32::MAX), Duration::from_secs(300));
+}