fix(dags): build stg_gias_ukprn monthly, never daily (review)

Rebuilding the view in the daily build dropped the Ofsted views on it
(CASCADE), which dim_school reads: every daily run would have failed. A
selector test now rejects any build that drops views it then reads.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pipeline/tests/test_dag_selectors.py

@@ -96,3 +96,41 @@ def test_selected_models_only_read_models_that_exist(dag_id):
     missing = {model: sorted(PARENTS[model] - available) for model in sorted(selected)
                if PARENTS[model] - available}
     assert missing == {}, f'{dag_id} builds models whose parents it never builds: {missing}'
+
+
+TABLE = re.compile(r"materialized\s*=\s*['\"]table['\"]")
+
+
+def views():
+    """Staging and intermediate models are views unless configured as tables."""
+    out = set()
+    for path in MODELS.rglob('*.sql'):
+        layer = path.relative_to(MODELS).parts[0]
+        if layer in ('staging', 'intermediate') and not TABLE.search(path.read_text()):
+            out.add(path.stem)
+    return out
+
+
+VIEWS = views()
+
+
+@pytest.mark.parametrize('dag_id', sorted(BUILDS))
+def test_rebuilt_relations_do_not_drop_views_the_build_reads(dag_id):
+    """dbt rebuilds a relation by dropping the old one with CASCADE, which drops
+    every view built on it. A view dropped that way and not rebuilt by the same
+    build is gone when that build reads it: the daily GIAS build rebuilt
+    stg_gias_ukprn and dropped the Ofsted views dim_school reads (audit H4)."""
+    selected = selected_models(BUILDS[dag_id], PARENTS)
+    children = defaultdict(set)
+    for model, ps in PARENTS.items():
+        for p in ps:
+            children[p].add(model)
+    dropped, stack = set(), list(selected)
+    while stack:
+        for child in children[stack.pop()]:
+            if child in VIEWS and child not in dropped:
+                dropped.add(child)
+                stack.append(child)
+    dropped -= selected
+    broken = {m: sorted(PARENTS[m] & dropped) for m in sorted(selected) if PARENTS[m] & dropped}
+    assert broken == {}, f'{dag_id} drops views it then reads: {broken}'