fix(sp41): test has_overridden_visits + clarify pipeline_b forward-compat helper

backend/tests/test_rebill_pipeline_b.py

@@ -38,4 +38,38 @@ def test_override_relaxes_timely_filing():
     out_default = build_pipeline_b_batches(visits, as_of=date(2026, 7, 7), override=False)
     out_overridden = build_pipeline_b_batches(visits, as_of=date(2026, 7, 7), override=True)
     assert out_default == []
-    assert len(out_overridden) == 1
+    assert len(out_overridden) == 1
+
+
+def test_override_flag_set_on_past_window_visit_batch():
+    # Same member "OLD" with one past-window visit (187 days old, ISO
+    # week 1) and one within-window visit (10 days old, ISO week 26).
+    # With override=True the past-window visit survives and the batch
+    # for week 1 must be flagged has_overridden_visits=True because the
+    # override saved an otherwise-excluded visit.
+    visits = [
+        _v(date(2026, 1, 1), "OLD", "T1019", "2.32"),  # 187 days old (past window, W01)
+        _v(date(2026, 6, 27), "OLD", "T1019", "2.32"),  # 10 days old (within window, W26)
+    ]
+    out_overridden = build_pipeline_b_batches(
+        visits, as_of=date(2026, 7, 7), override=True,
+    )
+    # Two batches: one per (member, ISO-week) — the past-window visit and
+    # the within-window visit land in different weeks.
+    assert len(out_overridden) == 2
+    by_week = {b.iso_week: b for b in out_overridden}
+    assert by_week[1].member_id == "OLD"
+    assert by_week[1].has_overridden_visits is True  # the override saved this batch
+    assert by_week[26].member_id == "OLD"
+    assert by_week[26].has_overridden_visits is False  # no override needed here
+
+    # With override=False the past-window visit is dropped. The surviving
+    # within-window batch (W26) must NOT carry the override flag, and the
+    # past-window batch (W01) is absent.
+    out_default = build_pipeline_b_batches(
+        visits, as_of=date(2026, 7, 7), override=False,
+    )
+    assert len(out_default) == 1
+    assert out_default[0].member_id == "OLD"
+    assert out_default[0].iso_week == 26
+    assert out_default[0].has_overridden_visits is False