Skills

Teaches Claude to build spinning 3D globe maps, or turn a flat Leaflet map into one, with MapLibre.

• Globe projection setup: projection, atmosphere, and light in a MapLibre v5 style
• The gotchas: line densification, [lng, lat] order, style.load vs load, CSP worker/connect-src, vendoring, headless WebGL testing
• Data-driven GeoJSON layers: category colors, selection dimming, filters, popups
• A Leaflet-to-MapLibre porting table and a self-contained starter page

Teaches Claude to measure, buffer, and cluster map data in the browser with Turf.js. No server.

• The GeoJSON-in, GeoJSON-out pipeline: Turf computes, the map library draws
• A pick-the-function table across measurement, transformation, joins, grids, and interpolation
• Canonical patterns: buffer + spatial join, hexGrid + collect, Voronoi with bbox
• The gotchas: [lng, lat] order, planar-ish math at planet scale, explicit units, caching heavy ops

Teaches Claude exact earth-curve math for maps: shortest paths, constant-bearing lines, and circles that wrap the planet.

• The discipline: compute as unit vectors, convert to lat/lon at the edge, split at ±180°
• One-liner constructions: great circles as plane normals, midpoints, equidistant loci, antipodes
• Curve sampling: great circles, small circles, loxodromes, isoazimuthals
• The rendering pipeline: antimeridianSplit + polar clipping, plus the numerical edge cases

Teaches Claude to run Leaflet and MapLibre on a locked-down site, including the exact security headers each library needs.

• A per-library directive table: tile hosts, MapLibre's blob: workers, fonts
• The vendoring convention: self-hosted libraries with versioned, licensed READMEs
• Cloudflare Pages _headers patterns: detach-first CSP overrides, forced downloads
• A debugging checklist for blank maps and silently dead workers

Teaches Claude to color regions by a number without lying. Projection, rates instead of raw counts, and honest no-data.

• Projection-first: EPSG:5070 for the US, Equal Earth for the world, and why Mercator lies
• Normalize, never map raw counts — and FIPS/GEOID as strings with zfill
• Classification: quantiles vs Jenks, 5–7 classes, diverging ramps centered on meaning
• MAUP, small-denominator instability, and honest no-data styling

Teaches Claude to pull US Census numbers and shapes the reliable way, then join them without dropping leading zeros.

• API query anatomy: datasets, get/for/in, and decoding B19013_001E-style variable codes
• The geography hierarchy with GEOID digit counts, from state to block group
• TIGER/Line vs cartographic boundary files — and which one maps should use
• Join hygiene: strings with leading zeros, vintage matching, sentinel values, MOEs

Teaches Claude to pull cafes, rail lines, or building footprints out of OpenStreetMap without the query timing out.

• Overpass QL anatomy: area-first bounding, nwr tag filters, out center vs geom
• The route-relation pattern: pulling named train/bus/hiking routes and stitching members
• The timeout escalation path, and when to switch to Geofabrik/osmium/osm2pgsql
• ODbL license rules: attribution, share-alike databases, freely-licensed produced works

Teaches Claude the last mile from a correct map to a picture you can post or print.

• Canvas-first sizing for Instagram, stories, and print, with DPI rules
• The QGIS print-layout workflow and the SVG → Illustrator handoff
• Design rules: visual hierarchy, margins, two-font discipline, dark vs editorial identity
• A pre-publish checklist from legend honesty to thumbnail readability