fix(pipeline): read the latest Ofsted visit from the dates

int_ofsted_latest treated any report card as the latest visit, relying on report cards postdating legacy inspections. That holds today (0 of 2,451 report-card schools in the 31 Aug 2026 MI) but is now not assumed: the latest visit is the newest of the three dates. A report card still leaves no legacy grade in force, which is the spec's rule rather than an inference. New unit test newer_legacy_visit_after_a_report_card failed RED on the old logic. Review on #183.

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

pipeline/transform/models/intermediate/int_ofsted_latest.sql

@@ -7,12 +7,11 @@
 with inspections as (
     select
         *,
-        -- Report cards began in Nov 2025, after the last legacy inspections,
-        -- so a school's report card is always its latest visit.
-        coalesce(
-            rc_inspection_date,
-            greatest(graded_inspection_date, ungraded_inspection_date)
-        ) as latest_visit_date
+        -- The newest of the three inspections, read from the dates. (Report
+        -- cards began in Nov 2025, after the last legacy inspections, so today
+        -- a report card is always the latest; nothing below relies on that.)
+        greatest(rc_inspection_date, graded_inspection_date, ungraded_inspection_date)
+            as latest_visit_date
     from {{ ref('stg_ofsted_inspections') }}
 ),
 
@@ -34,8 +33,9 @@ ranked as (
 latest as (
     select
         *,
+        -- Same-day ties resolve report card, then graded, then ungraded.
         case
-            when rc_inspection_date is not null then 'report_card'
+            when rc_inspection_date = latest_visit_date then 'report_card'
             when graded_inspection_date = latest_visit_date then 'graded'
             else 'ungraded'
         end as latest_visit_kind
@@ -46,11 +46,14 @@ latest as (
 graded as (
     select
         *,
-        -- The grade still in force. A graded inspection's own overall grade
+        -- The grade still in force. A report card replaced overall grades, so
+        -- none survives it. Otherwise: a graded inspection's own overall grade
         -- (1-4; "Not judged" and the sentinel 9 are no grade); else an
         -- ungraded visit's "School remains X"; else, after an ungraded visit
         -- that names no grade, the graded inspection's grade.
         case
+            when rc_inspection_date is not null
+                then null
             when latest_visit_kind = 'graded' and overall_effectiveness between 1 and 4
                 then 'graded_latest'
             when latest_visit_kind = 'ungraded' and ungraded_grade is not null

pipeline/transform/models/intermediate/int_ofsted_latest.yml

@@ -97,3 +97,17 @@ unit_tests:
     expect:
       rows:
         - {urn: 3, latest_visit_kind: graded, current_grade: null}
+
+  - name: newer_legacy_visit_after_a_report_card
+    description: >
+      Not in Ofsted's data today (0 of 2,451 report-card schools in the 31 Aug
+      2026 MI), but the latest visit is read from the dates, not assumed. The
+      report card still leaves no legacy grade in force.
+    model: int_ofsted_latest
+    given:
+      - input: ref('stg_ofsted_inspections')
+        rows:
+          - {urn: 4, ungraded_inspection_date: '2026-03-02', ungraded_grade: 2, ungraded_outcome: 'School remains Good', rc_inspection_date: '2025-12-01', rc_inclusion: 3}
+    expect:
+      rows:
+        - {urn: 4, latest_visit_date: '2026-03-02', latest_visit_kind: ungraded, latest_visit_outcome: 'School remains Good', current_grade: null, current_grade_date: null, current_grade_basis: null}

pipeline/transform/tests/assert_ofsted_current_grade_consistent.sql

@@ -7,4 +7,4 @@ from {{ ref('fact_ofsted_latest') }}
 where current_grade_date > latest_visit_date
    or (current_grade is null) <> (current_grade_date is null)
    or (current_grade is null) <> (current_grade_basis is null)
-   or (latest_visit_kind = 'report_card' and current_grade is not null)
+   or (rc_inspection_date is not null and current_grade is not null)