fix(broker): cap outage backoff overflow and expand worker matrix coverage

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

tests/application/test_balance_health.py

@@ -23,6 +23,28 @@ def test_long_outage_backoff_is_capped_and_status_stays_valid():
     assert state["failure_code"] == "http_5xx"
 
 
+def test_long_outage_over_1100_failures_never_overflows_and_stays_capped():
+    now = {"t": datetime(2026, 9, 12, tzinfo=UTC)}
+    tracker = BalanceHealthTracker(clock=lambda: now["t"], base_backoff_sec=15, max_backoff_sec=300)
+
+    last_lifecycle = None
+    for i in range(1_100):
+        lifecycle, backoff = tracker.record_failure("execution", code="http_5xx")
+        last_lifecycle = lifecycle
+        if i >= 5:
+            assert backoff == 300.0
+        else:
+            assert backoff <= 300.0
+        now["t"] += timedelta(seconds=301)
+
+    state = tracker.status("execution", stale_after_sec=600)
+    assert state["state"] == "unavailable"
+    assert state["consecutive_failures"] == 1_100
+    assert state["failure_code"] == "http_5xx"
+    assert state["next_retry_at"] is not None
+    assert last_lifecycle in {None, "ongoing"}
+
+
 def test_restart_resets_process_local_health_and_re_emits_detected():
     now = {"t": datetime(2026, 9, 12, tzinfo=UTC)}
     before_restart = BalanceHealthTracker(clock=lambda: now["t"])