test(observability): cover the missed-run outcome and the listener's guard

MISSED is one of the four outcomes the job metric advertises and had no test,
so nothing would have caught it being dropped or mislabelled. It arrives with no
submission of its own, which is the case worth pinning.

The never-raise guard was only reached through a real scheduler, and a listener
running on the scheduler's own thread is invisible to coverage, so it is now
driven directly as well.

tests/test_litellm/proxy/common_utils/test_scheduled_job_metrics.py

@@ -306,3 +306,34 @@ def test_one_submission_of_several_run_times_pairs_each_completion():
     ]
 
     assert all(d is not None for d in durations), f"every run time must pair, got {durations}"
+
+def test_a_trigger_that_fired_without_running_is_recorded_as_missed():
+    """MISSED is one of the four outcomes the metric advertises. It arrives with
+    no submission of its own, so it must publish a run without a duration rather
+    than be dropped."""
+    from apscheduler.events import EVENT_JOB_MISSED, JobExecutionEvent
+
+    listener = ScheduledJobMetricsListener()
+
+    run = listener._to_run(JobExecutionEvent(EVENT_JOB_MISSED, "update_spend_job", "default", None))
+
+    assert run is not None
+    assert run.result is JobResult.MISSED
+    assert run.job_name == "update_spend_job"
+    assert run.duration_seconds is None
+    assert run.items_processed is None
+
+
+def test_handle_swallows_a_failure_so_the_scheduler_keeps_running():
+    """APScheduler swallows listener exceptions itself, so a throwing listener
+    leaves the scheduler running with no telemetry and nothing to explain it.
+    Driven directly rather than through the scheduler, because a listener that
+    runs on the scheduler's own thread is invisible to coverage."""
+    from apscheduler.events import EVENT_JOB_EXECUTED, JobExecutionEvent
+
+    listener = ScheduledJobMetricsListener()
+    event = JobExecutionEvent(EVENT_JOB_EXECUTED, "job", "default", None, retval=None)
+
+    with patch.object(ScheduledJobMetricsListener, "_publish", side_effect=RuntimeError("metrics down")):
+        listener.handle(event)  # must not raise
+