react-map-gl

name	react-map-gl
description	react-map-gl/maplibre patterns for FMC geo apps: declarative Source/Layer (never addSource/addLayer), MapProvider + useMap(), interactiveLayerIds, flat Source/Layer, map-loaded guard, window.__mainMap debug exposure, Map event handlers (not useEffect), URL map state, initialViewState, cursor, feature state, missing images. Use when building or reviewing Map components, layers, click/hover handlers, setFeatureState, map URL sync, or agent/test map inspection in TanStack Start / Vite apps. Reference implementation: tilda-geo/app.
disable-model-invocation	true

react-map-gl (MapLibre)

Conventions for react-map-gl/maplibre in FixMyBerlin / FMC projects. Import from react-map-gl/maplibre (not react-map-gl alone). Always import maplibre-gl/dist/maplibre-gl.css.

When to apply

• Adding or changing <Map>, <Source>, <Layer>, controls, markers
• Click/hover/feature inspection wired to map events
• Syncing viewport to URL (map=zoom/lat/lng)
• Child components that need the map instance (feature state, fitBounds, queryRenderedFeatures)
• Debugging “map half loaded” errors, missing style images, or wrong click targets
• Highlighting selected/hovered features (setFeatureState vs layer filter)
• Reviewing code that uses useEffect to sync map camera, clicks, or hover
• Code calling map.addSource, map.addLayer, or effect-driven layer lifecycle
• Agent or E2E inspection of layer order, zoom, or rendered features (window.__mainMap)

Reference reading order

1. declarative-source-layer.md — <Source> / <Layer> only; never map.addSource / map.addLayer
2. map-event-handlers.md — which <Map> handler for which use case; not useEffect
3. map-provider-wrapper.md — MapProvider parent; useMap(); never manual refs
4. interactive-layer-ids.md — interactiveLayerIds + event.features (not raw MapLibre)
5. map-loaded-hook.md — guard map API calls until onLoad / useMapLoaded()
6. map-debug-exposure.md — window.__mainMap in dev/Playwright; exposeMainMapForDebugging in onLoad
7. feature-state.md — setFeatureState vs React filter; reset/diff; inspector sync
8. flat-source-layer.md — sibling <Source> + <Layer>, required props
9. layer-visibility-vs-unmount.md — layout.visibility vs conditional render
10. map-props-attribution-locale.md — attributionControl={false}, locale, RTLTextPlugin
11. cursor-handling.md — cursor prop from hover state
12. initial-view-state.md — uncontrolled initialViewState vs URL-driven vs bounds
13. map-url-state.md — map=zoom/lat/lng hook, rounding, nuqs
14. map-images-missing.md — styleimagemissing + dynamic icons
15. map-images-proactive.md — proactive addImage for known sprites (vzk-bw)

Pair with: skill nuqs (URL parsers), skill zustand-state-management (map UI store like useMapLoaded), skill playwright-skill (E2E map helpers, getMapLayerIds).

Non-negotiable rules

Topic	Rule
Sources / layers	<Source> + <Layer> in JSX only. Never map.addSource / map.addLayer (or remove*) for app data. Show/hide via layout.visibility or conditional render — see declarative-source-layer.md.
Map events	Camera, pointer, load, and tile lifecycle → <Map> callback props. Not useEffect + map.on(…) for the same behavior.
Map access	Wrap app map UI in <MapProvider>. Use useMap() keyed by <Map id="…">. Never pass ref to <Map> for child access.
Map ready	Guard getStyle, queryRenderedFeatures, setFeatureState, etc. with useMapLoaded() (set in onLoad).
Debug exposure	In onLoad, call exposeMainMapForDebugging(event.target) (dev + Playwright only). Agents/tests read window.__mainMap — see map-debug-exposure.md.
Layers	Flat siblings: one <Source> per source id, then <Layer> siblings (not nested layers under Source for refactorability).
Clicks	Put layer ids in interactiveLayerIds; read event.features in handlers — do not call queryRenderedFeatures for primary click picking unless syncing URL features.
Feature highlight	Inspector/form truth in React; map tint via setFeatureState (paint) or React filter layer — see feature-state.md. Clear old state before applying new.
Attribution	attributionControl={false} on <Map>; add <AttributionControl> as child with desired position.
Viewport URL	Serialize zoom/lat/lng with zoom-aware lat/lng rounding; write on onMoveEnd with history: 'replace'.
View state	Prefer uncontrolled initialViewState seeded from URL; do not mirror full viewState in React state unless you need programmatic camera control.

Quick import

import 'maplibre-gl/dist/maplibre-gl.css'
import { MapProvider, Map, Source, Layer, useMap } from 'react-map-gl/maplibre'