[A13xB0]

First of six PRs for the Data tab. The plan is at https://claude.ai/artifact/PAJwg4KmQQ7Cp7nSDvyBo9.

This PR lets CoreScope load named areas from a GeoJSON file. They work wherever areas already works today, and later PRs build the Data tab's "origin area" on top of them. No UI changes are in this PR.

What changes

• New package internal/areamap (its own module, with the Dockerfile COPY line added):
  • Parses a GeoJSON FeatureCollection of Polygon and MultiPolygon features.
  • Holes and islands are respected (even-odd rule).
  • Each feature has code (required), label, layer (default region) and an optional iata list.
  • Locate(layer, lat, lon) returns the smallest area that contains the point, so a city inside a country resolves to the city.
  • (0,0) is never treated as a place.
  • Duplicate codes are refused, across layers too.
• New config key areasFile: a path to the GeoJSON file, relative to the config dir unless absolute. It is optional and empty by default.
  • Existing areas entries (bbox or polygon) are merged into the same map.
  • A code that appears in both places is refused at startup with a clear error.
• /api/config/areas lists file areas next to config areas, and each entry gains a layer field.
• The area= filter (nodes, packets, and so on) accepts file area codes through the same cached resolver.
• Docs: docs/examples/areas.example.geojson, a config.example.json entry, and the api-spec.md update.

Tests

• Red before green, two pairs of commits:
  • areamap: 846b0b6, then 1f59c9f.
  • server: 4d72542, then b87f636.
• internal/areamap tests cover:
  • parsing, and lon/lat order;
  • a MultiPolygon with a hole and an island;
  • layers, and smallest-wins;
  • IATA lookup, Has and Contains;
  • bad input and duplicate codes.
• cmd/server tests cover:
  • the config and the file merging;
  • bad files refused (duplicate code, missing file, invalid JSON);
  • /api/config/areas showing layers;
  • area= filtering on a file area;
  • the documented example file loading.
• Repo checks:
  • full server suite passes;
  • scripts/allmod.sh passes 17 of 17;
  • gofmt is clean;
  • check-dockerfile-internal-pkgs.sh passes.
• Manual check: I ran the server against a copy of a real DB with the example file.
  • It logged [areas] 2 areas in layers [region].
  • /api/config/areas returned BAY and MRY.
  • /api/nodes?area=BAY returned only Bay Area nodes.

Benchmark

BenchmarkLocate   2.1 µs/op   0 B/op   0 allocs/op

The benchmark uses a three-area fixture, including a MultiPolygon with a hole. A bounding-box check runs before the ring test.

Gate

• With areasFile unset, the code paths behave as before.
• Config-only areas take the existing PassesFilter route.
• Pre-prod has no areas configured today, so this change is inert there until PR 6 adds ScotMesh's areas.geojson.

🤖 Generated with Claude Code

https://claude.ai/code/session_01KaR4xu8gVykQBkH8yG8m6H

[A13xB0]

Superseded by #16, which carries this as its own commits alongside the rest of the Data tab (one PR, as asked).