feat: expose read-only layer queries to external plugins

apps/geolibre-desktop/src/hooks/usePlugins.ts

@@ -26,6 +26,7 @@ import {
   setEffectsSettings,
   type EffectsSettings,
   maplibreEarthdataGisPlugin,
+  SKETCHES_SOURCE_KIND,
   setEarthdataCogSaver,
   maplibreEnviroAtlasPlugin,
   maplibreEsriWaybackPlugin,
@@ -93,6 +94,7 @@ import type {
   GeoLibreExternalNativeLayerRegistration,
   GeoLibreFileDialogOptions,
   GeoLibreMapControlPosition,
+  GeoLibreSelection,
   GeoLibreTileLayerOptions,
   GeoLibreWmsLayerOptions,
   GeoLibreZarrLayerOptions,
@@ -829,6 +831,19 @@ export function useTimeSliderAutoClose(mapControllerRef: RefObject<MapController
   }, [mapControllerRef]);
 }
 
+function readPluginSelection(): GeoLibreSelection {
+  const state = useAppStore.getState();
+  const layer = state.layers.find((item) => item.id === state.selectedLayerId);
+  if (!layer || state.selectedFeatureIds.length === 0) {
+    return { layerId: state.selectedLayerId, features: [] };
+  }
+  const selected = new Set(state.selectedFeatureIds);
+  const features = (layer.geojson?.features ?? []).filter((feature, index) =>
+    selected.has(String(feature.id ?? index)),
+  );
+  return { layerId: state.selectedLayerId, features };
+}
+
 export function createAppAPI(mapControllerRef?: RefObject<MapController | null>) {
   const store = useAppStore.getState();
   // Captured so methods that delegate to plugin helpers taking the AppAPI
@@ -840,6 +855,36 @@ export function createAppAPI(mapControllerRef?: RefObject<MapController | null>)
       const id = store.addGeoJsonLayer(name, data, sourcePath);
       return id;
     },
+    listLayers: () =>
+      useAppStore.getState().layers.map(({ id, name, type, visible, opacity }) => ({
+        id,
+        name,
+        type,
+        visible,
+        opacity,
+      })),
+    getLayerFeatures: (layerId: string) => {
+      const layer = useAppStore.getState().layers.find((item) => item.id === layerId);
+      if (!layer) throw new Error(`No layer with id "${layerId}"`);
+      return layer.geojson?.features ?? [];
+    },
+    getSelectedFeatures: () => readPluginSelection().features,
+    getSelectedLayerId: () => useAppStore.getState().selectedLayerId,
+    getDrawnFeatures: () =>
+      useAppStore
+        .getState()
+        .layers.flatMap((layer) =>
+          layer.metadata.sourceKind === SKETCHES_SOURCE_KIND ? (layer.geojson?.features ?? []) : [],
+        ),
+    onSelectionChange: (callback: (selection: GeoLibreSelection) => void) =>
+      useAppStore.subscribe((state, previous) => {
+        if (
+          state.selectedLayerId !== previous.selectedLayerId ||
+          state.selectedFeatureIds !== previous.selectedFeatureIds
+        ) {
+          callback(readPluginSelection());
+        }
+      }),
     addTileLayer: (name: string, url: string, options?: GeoLibreTileLayerOptions) =>
       store.addTileLayer(
         name,

docs/plugin-api.md

@@ -3,7 +3,7 @@
 ## Interface
 
 ```typescript
-import type { FeatureCollection } from "geojson";
+import type { Feature, FeatureCollection } from "geojson";
 import type { IControl } from "maplibre-gl";
 
 export type GeoLibreMapControlPosition =
@@ -55,13 +55,34 @@ export interface GeoLibreDeckGL {
   mapbox: typeof import("@deck.gl/mapbox");
 }
 
+export interface GeoLibreLayerSummary {
+  id: string;
+  name: string;
+  type: string;
+  visible: boolean;
+  opacity: number;
+}
+
+export interface GeoLibreSelection {
+  layerId: string | null;
+  features: Feature[];
+}
+
 export interface GeoLibreAppAPI {
   setBasemap: (styleUrl: string) => void;
   addGeoJsonLayer: (
     name: string,
     data: FeatureCollection,
     sourcePath?: string,
   ) => string;
+  listLayers?: () => GeoLibreLayerSummary[];
+  getLayerFeatures?: (layerId: string) => Feature[];
+  getSelectedFeatures?: () => Feature[];
+  getSelectedLayerId?: () => string | null;
+  getDrawnFeatures?: () => Feature[];
+  onSelectionChange?: (
+    callback: (selection: GeoLibreSelection) => void,
+  ) => () => void;
   // Native raster/tile layers (see "Raster and tile layers" below). Each
   // returns the new layer's id and the layer appears in the Layers panel and
   // persists with the project, like addGeoJsonLayer does for vector data.
@@ -416,6 +437,48 @@ https://web.geolibre.app/?url=https://example.com/project.geolibre.json&exampleG
 
 A URL parameter activates only an already-registered (installed) plugin that owns it; it never loads a plugin from the URL. For external plugins, include the plugin manifest URL in the project `plugins` state (so the plugin is registered) before relying on its URL handler — the matching parameter then activates and dispatches it even if it is not in the active set.
 
+## Read-only layer and feature queries
+
+External plugins can inspect the current layer list, a layer's GeoJSON features,
+the current feature selection, and features in GeoEditor's Sketches layers. The
+methods are optional so the same plugin remains compatible with older hosts.
+
+```typescript
+const layers = app.listLayers?.() ?? [];
+const selectedLayerId = app.getSelectedLayerId?.() ?? null;
+const selectedFeatures = app.getSelectedFeatures?.() ?? [];
+
+if (selectedLayerId && app.getLayerFeatures) {
+  const layerFeatures = app.getLayerFeatures(selectedLayerId);
+  console.log(layers, layerFeatures, selectedFeatures);
+}
+
+const drawnFeatures = app.getDrawnFeatures?.() ?? [];
+```
+
+`getSelectedFeatures` returns every selected feature in the selected layer, not
+only the most recently selected feature. Features without a GeoJSON `id` are
+matched using their zero-based array index converted to a string. An empty
+selection returns an empty array. `getLayerFeatures` throws when the layer id is
+unknown and returns an empty array for a layer that has no GeoJSON features.
+
+Selection subscriptions fire after the selected layer or selected feature-id
+array changes. Keep and call the returned unsubscribe function during plugin
+deactivation:
+
+```typescript
+const unsubscribe = app.onSelectionChange?.(({ layerId, features }) => {
+  console.log(layerId, features);
+});
+
+// In deactivate or another cleanup path:
+unsubscribe?.();
+```
+
+These methods are a read-only query surface: calling them does not change the
+GeoLibre store. Plugins must also treat returned GeoJSON features as read-only
+and use host APIs such as `addGeoJsonLayer` when they need to add data.
+
 ## Raster and tile layers
 
 `addGeoJsonLayer` registers vector data as a native layer. For raster and tile data there are three matching helpers — `addTileLayer` (XYZ), `addWmtsLayer` (WMTS), and `addWmsLayer` (WMS). Each returns the new layer's id, and the layer appears in the Layers panel with full opacity, reorder, and styling support and persists with the project, so a plugin no longer has to call `getMap().addSource()/addLayer()` directly (which leaves the layer invisible to GeoLibre's layer store).

packages/plugins/src/types.ts

@@ -10,7 +10,7 @@ import type {
   QueryResult as ZarrQueryResult,
   Selector as ZarrSelector,
 } from "@carbonplan/zarr-layer";
-import type { FeatureCollection, Geometry } from "geojson";
+import type { Feature, FeatureCollection, Geometry } from "geojson";
 import type { IControl, Map as MapLibreMap } from "maplibre-gl";
 import type { OvertureTheme } from "maplibre-gl-overture-maps";
 import type { TemporalLayerAdapter } from "./plugins/temporal-layers";
@@ -331,9 +331,28 @@ export interface GeoLibrePickedVectorFile {
   nativeData?: FeatureCollection;
 }
 
+export interface GeoLibreLayerSummary {
+  id: string;
+  name: string;
+  type: string;
+  visible: boolean;
+  opacity: number;
+}
+
+export interface GeoLibreSelection {
+  layerId: string | null;
+  features: Feature[];
+}
+
 export interface GeoLibreAppAPI {
   setBasemap: (styleUrl: string) => void;
   addGeoJsonLayer: (name: string, data: FeatureCollection, sourcePath?: string) => string;
+  listLayers?: () => GeoLibreLayerSummary[];
+  getLayerFeatures?: (layerId: string) => Feature[];
+  getSelectedFeatures?: () => Feature[];
+  getSelectedLayerId?: () => string | null;
+  getDrawnFeatures?: () => Feature[];
+  onSelectionChange?: (callback: (selection: GeoLibreSelection) => void) => () => void;
   /**
    * Add a native XYZ raster tile layer from a tile URL template (with
    * `{x}`/`{y}`/`{z}` placeholders) and return its layer id. Unlike calling