The GIAS town field puts 1,819 London schools under the single value
'London', so it cannot answer 'schools in Battersea' — a query that appears in
the baseline. No single field can: parliamentary constituency gives Battersea
but not Canary Wharf, admin_ward gives Canary Wharf but not Battersea, and
neither gives Clapham or Shoreditch. So a locality is curated, defined by the
postcode districts it covers, which needs no new ingestion.
A locality may not shadow a published town: the registry raises rather than
silently costing a page that carries real demand. One below the threshold is
logged rather than raising, because a locality can legitimately be too small.
The pipeline seed mirrors the module, with a test guarding the drift — the
same arrangement gias_codes has, and for the same reason: the backend image
does not contain pipeline/.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
