[jkrenge]

Superseded by consolidated postal geocoding PR #124. This PR's head commit is retained in the combined branch. Combined CI passes on Node.js 24/26 and static checks.

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Summary

FIN currently returns no coordinates. Add 3,018 unique five-digit postal-area points from Statistics Finland's 2026 Paavo layer, retrieved 2026-11-04, under CC BY 4.0 with attribution.

coordinates(FIN, postal code)
  -> FIN allowlist entry
  -> geocode/FIN.json
  -> [longitude, latitude] strings

Points are area-weighted geometric centroids in the WGS84 longitude/latitude plane, with holes subtracted and MultiPolygon parts included. This is approximate area-level geocoding, not address or site accuracy. Special recipient and PO box codes without polygons remain unsupported. Åland is included. Large northern/rural areas can have errors of many kilometres; centroids can lie outside the area or in water.

Add a standard-library Python generator with assert checks, country-focused offline tests, and source/licence/method documentation in docs/geocode-FIN.md. Preserve all other countries, existing normalization, string output, and unknown-code behavior. Shared-file overlap with other country PRs is limited to lib/geocode.js's allowlist.

Evidence

• Before: FIN is absent from the geocode allowlist and has no data file; lookup returns undefined.
  After: all 3,018 codes resolve; pinned official-layer examples cover Helsinki, Salla, Utsjoki, Mariehamn and Nauvo.
• npm test: 98 passed.
• npm run lint, npm run format:check, npm run validate:data: passed. Data validation retains two existing AUT/BEL warnings.
• Generator checks source CRS/year/count, unique code format, finite coordinate bounds, square, hole and MultiPolygon centroid examples.
• Source, licence.

Merge Danger

Door: two-way

Static additive data and one allowlist entry; no publish, deployment or merge performed.

Blast Radius: FIN

Callers now receive area coordinates for supported FIN codes. Distance accuracy is limited by postal-area size and the centroid method. No independent address-level accuracy check was performed.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-04T22:03:52.336004Z	18713b9	PR opened

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