<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=590482) </details> <!--IssueSummary end--> ### Release notes Replace the Leaflet raster tile library with MapLibre GL vector tiles for rendering GeoJSON files, removing a patched dependency and improving map rendering quality. ### Problem to solve The GeoJSON blob viewer depends on a patched version of Leaflet (`patches/leaflet+1.9.4.patch`). Maintaining a patched dependency is fragile and the raster tile approach produces blurry maps at high zoom levels with stepped/discrete zoom instead of continuous smooth zooming. After migrating, it would be possible to support also .topojson with maplibre, since it can be tilted to show terrain. ### Proposal Replace Leaflet with [MapLibre GL JS](https://maplibre.org/maplibre-gl-js/docs/) using [OpenFreeMap](https://openfreemap.org/) vector tiles: - Swap `leaflet` for `maplibre-gl` in `package.json` - Rewrite `utils.js` to use MapLibre's source/layer API with native geometry type styling (points, lines, polygons) - Add `https://tiles.openfreemap.org` to CSP `connect_src` - Delete `patches/leaflet+1.9.4.patch` - Update all related specs ### Intended users * [Sasha (Software Developer)](https://handbook.gitlab.com/handbook/product/personas/#sasha-software-developer) ### Feature Usage Metrics No change — this replaces the rendering engine for an existing feature. ### Does this feature require an audit event? No. ### Links / references - [GeoJSON viewer demo — Leaflet raster (GitLab)](https://gitlab.com/birkskyum/geojson-demo/-/blob/main/triangle.geojson?ref_type=heads) - [GeoJSON viewer demo — MapLibre vector (GitHub)](https://github.com/maplibre/maplibre-tile-spec/blob/main/test/synthetic/0x01/polygon.json)