Two findings from review on #121, plus a third the review prompted.
The cap at three authorities silently dropped the fourth in exactly the case
where the information matters most — a genuinely fragmented place — and
contradicted the stated goal of naming every authority a place sits in. It is
gone. The share rule was always the real limit and already bounds the list at
ten. Measured against the live corpus, one town would have been truncated
today: LONDON, split evenly between Hackney, Lambeth, Westminster and
Lewisham.
parent_authority used mode() while authorities used value_counts(), and on an
exact tie pandas does not guarantee the two pick the same name, so the 301
could have pointed somewhere other than the authority named first on the page.
The parent is now derived from authorities[0]: one computation, one answer.
It also inherits the sentinel filter, so a place can no longer redirect to
/schools/authority/does-not-apply.
Chasing the truncation case surfaced a worse bug. Places were grouped by raw
town value, but the registry is keyed by slug, and GIAS spells the same place
several ways. Five town slugs come from more than one spelling: "London"
(1,819 schools) and "LONDON" (12) both slugify to `london`, so the later group
simply overwrote the earlier one — /schools/london could have shown twelve
schools, silently, depending on row order. Weston-super-Mare was split 14/19
across two spellings and Newcastle-under-Lyme across three. Grouping is now by
slug, and the display name is the most common spelling.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
SW19 is mostly Merton but partly Wandsworth, and the page said only Merton.
The cause was one field doing two jobs: _parent_authority takes the modal
authority, which is right for a 301 target and wrong as a statement about
where a place is.
This is not a corner case. A quarter of viable outcodes (425 of 1,760) and a
third of viable towns (263 of 783) cross an authority boundary — Bedford the
town spans Bedford and Central Bedfordshire.
Place now carries `authorities`, every authority holding at least a tenth of
the schools and at least two of them, largest first. parent_authority stays
single and unchanged, because a redirect still needs one target.
The share threshold exists because GIAS carries postcode errors: EN6 lists two
Shropshire schools among fourteen in Hertfordshire, and a bare "any authority
present" rule would print those as though they were real. A place too small or
too fragmented to clear the threshold still names its largest, so the page
never goes silent about where it is.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
/schools/[place]/[phase] shipped as routes but reached nothing. The sitemap
emitted one URL per registry entry and the registry had no phase dimension, so
~950 pages were absent from every sitemap — and PlaceView did not link them
either, leaving them reachable by nothing at all.
That is the query shape the baseline actually showed: 'primary schools in
beccles', 'secondary schools in brentwood'. Publishing the routes without a
path in meant building for the demand and then hiding from it.
Place now carries phase_urns so the per-phase threshold can be applied without
re-querying, the sitemap emits a variant wherever a phase clears the threshold
on its own, and the API exposes the qualifying phases so the place page links
only variants that exist. Outcodes are excluded: nobody searches 'primary
schools in SW11' and those routes do not exist.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
Sitemap regeneration failed on staging. 'richmond' in the curated locality
list collides with the GIAS town Richmond in North Yorkshire (37 schools), the
registry raised, and the admin endpoint 500d — taking down sitemap generation
for all 25,000 school pages over one bad row of curated data.
The guard now skips the colliding locality and logs an error. Skipping still
achieves what the guard was for — a locality never silently shadows a town —
without letting curated data break the site. That matters beyond this bug:
GIAS town names change with no code change here, so a raise could fire
spontaneously in production later.
Also removes four localities that were London boroughs rather than districts.
Hackney, Islington, Greenwich and Ealing are local authorities with 104, 72,
108 and 115 schools and already have authority pages; a locality defined by
two or three outcodes would have been a partial near-duplicate of one — the
thin-content failure the two-namespace design exists to avoid. A test now
guards the whole borough list.
Validated against the live corpus: 15 localities, no town collisions, no
authority duplicates, all 15 clear the threshold.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
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
Two namespaces because 67 town names collide with an authority name and
neither set contains the other — postal towns cross authority boundaries, so
Bedford the town holds 104 schools against the authority's 86.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj
