fix: validate complete-day monitoring coverage

tests/test_complete_observation_day_gate.py

@@ -187,6 +187,39 @@ class TestGateNoCompleteDay:
         assert any("full local observation day" in fact
                    for fact in result.contributing_facts)
 
+    def test_day_split_by_deliberate_pause_does_not_open_gate(self, store):
+        """A complete-looking summary cannot span separate monitoring periods."""
+        _insert_baseline(store)
+        _insert_segment(store)
+        for i in range(20):
+            day = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, day, bw=1024 * 1024 * 100)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+
+        store.executemany(
+            "INSERT INTO monitoring_periods (started_at, ended_at, end_cause) "
+            "VALUES (?, ?, ?)",
+            [
+                ("2026-09-29T00:00:00+00:00", "2026-09-29T12:00:00+00:00", "user_disabled"),
+                ("2026-09-29T13:00:00+00:00", "2026-09-30T00:00:00+00:00", "user_disabled"),
+                ("2026-09-30T00:00:00+00:00", None, None),
+            ],
+        )
+        store.commit()
+        _insert_local_day(
+            store,
+            "2026-09-29",
+            utc_start="2026-09-29T00:00:00+00:00",
+            utc_end="2026-09-30T00:00:00+00:00",
+            complete=True,
+        )
+
+        result = compute_projection(store, _clock())
+
+        assert result.confidence_state == ConfidenceState.UNSUPPORTED
+        assert any("full local observation day" in fact
+                   for fact in result.contributing_facts)
+
     def test_partial_but_trusted_local_activity_opens_gate(self, store):
         """Known local intervals can coexist with an incomplete day total."""
         _insert_baseline(store)