feat(api): publish traversed spec to gosling api

src/compiler/compile.ts

@@ -8,6 +8,7 @@ import type { UrlToFetchOptions } from 'src/core/gosling-component';
 import { renderHiGlass as createHiGlassModels } from './create-higlass-models';
 import { manageResponsiveSpecs } from './responsive';
 import type { IdTable } from '../api/track-and-view-ids';
+import { publish } from '../api/pubsub';
 
 /** The callback function called everytime after the spec has been compiled */
 export type CompileCallback = (
@@ -69,6 +70,13 @@ export function compile(
         trackInfos = getRelativeTrackInfo(specCopy, theme).trackInfos;
     }
 
+    // publish the fixed spec
+    // used for alt-gosling
+    publish('specProcessed', {
+        id: specCopy.id,
+        spec: specCopy
+    });
+
     // Make HiGlass models for individual tracks
     createHiGlassModels(specCopy, trackInfos, callback, theme, urlToFetchOptions);
 }

src/gosling-schema/gosling.schema.ts

@@ -284,6 +284,13 @@ interface CommonEventData {
     data: Datum[];
 }
 
+interface SpecEventData {
+    /** Source visualization ID, i.e., `track.id` */
+    id: string;
+    /** Gosling spec */
+    spec: GoslingSpec;
+}
+
 export interface GenomicPosition {
     chromosome: string;
     position: number;
@@ -372,6 +379,7 @@ export type _EventMap = {
     click: PointMouseEventData;
     rangeSelect: RangeMouseEventData;
     rawData: CommonEventData;
+    specProcessed: SpecEventData;
     trackMouseOver: TrackApiData;
     trackClick: TrackApiData; // TODO (Jul-25-2022): with https://github.com/higlass/higlass/pull/1098, we can support circular layouts
     onNewTrack: OnNewTrackEventData;