[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Superseded by consolidated postal geocoding PR #124.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

Add approximate postal-code lookup for Japan for return-location distance analysis.

JPN postal code (1234567 or 123-4567)
  → 142,577 full-code records
  → [longitude, latitude] strings, or undefined

Source: GeoNames JP.zip, retrieved 2026-11-04, export dated 2026-11-04, CC BY 4.0. The 146,883 source rows cover 47 prefecture entries. Duplicate coordinate pairs are removed; 16 multi-point codes use an unweighted mean of distinct points. Source, license, checksum, generation steps, and Japan Post assignment checks are in docs/geocode-JPN.md.

This is source coverage, not complete national coverage. GeoNames points are estimates, often shared across locality codes. Four decimals do not establish accuracy. No measured distance-error bound is available. These are not postal-area centroids or scan/building locations.

Evidence

• Before: JPN is unsupported and returns undefined.
  After: coordinates('JPN', '100-0001') returns ['139.7521', '35.6841'].
• Offline tests cover compact/hyphenated formats, leading zero, Tokyo, Rebun, Yonaguni, duplicate-independent averaging, malformed/unknown codes, full dataset shape and finite ranges.
• npm test: 99 pass. npm run lint, npm run format:check, and npm run validate:data: pass. Data validation retains the two existing AUT/BEL warnings.
• Generator assertions pass. No dependencies added. Other countries retain their normalization and data.

Merge Danger

Door: two-way

Blast Radius: JPN

The shared lib/geocode.js allowlist and normalization lines can overlap with concurrent country PRs. Only JPN changes are included. The dataset adds about 12.2 MB of JSON and lookup retains the existing linear scan. No merge, publication, or deployment is included.

[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 2026-11-04T22:04:03.567428Z	56a959e	PR opened

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