fix(ees): read the year from suffixed release slugs (review)

A '2025-26-revised' release read as an unknown year went last, behind the
'2025-26' release, which then owned the year and dropped every revised row.

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

pipeline/tests/test_ees_release_precedence.py

@@ -76,3 +76,25 @@ def test_only_the_ks4_results_stream_opts_in():
     opted_in = [chunk.split('(')[0] for chunk in source.split('\nclass ')[1:]
                 if re.search(r'_newest_release_owns_period\s*=\s*True', chunk)]
     assert opted_in == ['EESKS4PerformanceStream']
+
+
+@pytest.mark.parametrize('slug, period', [
+    ('2024-25', '202425'),
+    ('2024-25-revised', '202425'),
+    ('2025-26-provisional', '202526'),
+    ('latest', None),
+    ('', None),
+])
+def test_a_release_slug_gives_its_year_whatever_its_suffix(precedence, slug, period):
+    # KS2 already publishes "2024-25-revised" and "2025-26-provisional". An
+    # unread suffix sent the release last, behind the provisional one for the
+    # same year, which then owned the year and dropped every revised row.
+    assert precedence.slug_to_time_period(slug) == period
+
+
+def test_within_a_year_the_api_order_is_kept(precedence):
+    # The API lists a year's revised release before its first release.
+    releases = [{'id': 'revised', 'time_period': '202526'},
+                {'id': 'first', 'time_period': '202526'},
+                {'id': 'older', 'time_period': '202425'}]
+    assert [r['id'] for r in precedence.newest_first(releases)] == ['revised', 'first', 'older']