Core: Implement component to stories lookup

code/core/src/core-server/change-detection/ChangeDetectionService.ts

@@ -17,6 +17,7 @@ import { CHANGE_DETECTION_STATUS_TYPE_ID } from 'storybook/internal/types';
 
 import type { StoryIndexGenerator } from '../utils/StoryIndexGenerator.ts';
 import type { ChangeDetectionAdapter, FileChangeEvent } from './adapters/index.ts';
+import { setActiveChangeDetectionService } from './active-service-registry.ts';
 import {
   ChangeDetectionResolverFactory,
   DependencyGraphBuilder,
@@ -489,10 +490,48 @@ export class ChangeDetectionService {
     }
   }
 
+  /**
+   * Returns the live reverse-dependency index, or `undefined` if the graph
+   * hasn't finished its cold-start build yet (or change detection is unavailable).
+   *
+   * The returned instance is the same reference patched by `IncrementalPatcher`
+   * on file changes — callers read it lazily at query time, not snapshotted.
+   *
+   * @experimental
+   */
+  getReverseIndex(): ReverseIndexImpl | undefined {
+    return this.reverseIndex;
+  }
+
+  /**
+   * Returns a map from absolute story file path → set of story IDs declared in
+   * that file, derived from the current story index.
+   *
+   * Useful for callers (e.g. addons) that consume {@link getReverseIndex} output:
+   * the reverse-index entries are keyed by absolute file path, but consumers
+   * typically need story IDs.
+   *
+   * @experimental
+   */
+  async getStoryIdsByFile(): Promise<Map<string, Set<string>>> {
+    const generator = await this.options.storyIndexGeneratorPromise;
+    const storyIndex = await generator.getIndex();
+    return getStoryIdsByAbsolutePath(this.storyIdsByFileCache, storyIndex, this.workingDir);
+  }
+
+  /** @experimental Working directory used to resolve relative paths. */
+  getWorkingDir(): string {
+    return this.workingDir;
+  }
+
   async dispose(): Promise<void> {
     this.disposed = true;
     this.rerunAfterCurrentScan = false;
 
+    // Clear the active-service registry so in-process consumers stop seeing
+    // a disposed instance after dev-server shutdown.
+    setActiveChangeDetectionService(undefined);
+
     if (this.debounceTimer) {
       clearTimeout(this.debounceTimer);
       this.debounceTimer = undefined;

code/core/src/core-server/change-detection/active-service-registry.ts

@@ -0,0 +1,27 @@
+import type { ChangeDetectionService } from './ChangeDetectionService.ts';
+
+let activeService: ChangeDetectionService | undefined;
+
+/**
+ * Records the change-detection service started by the current Storybook dev server
+ * so that in-process consumers (addon presets) can reach it without going through a
+ * preset hook. Dev server is single-instance, so only one service is ever active.
+ *
+ * @internal
+ */
+export function setActiveChangeDetectionService(service: ChangeDetectionService | undefined): void {
+  activeService = service;
+}
+
+/**
+ * Returns the change-detection service for the current dev-server process, or
+ * `undefined` when change detection is disabled / not yet started / disposed.
+ *
+ * Read at request time, not at preset load time — the service is constructed
+ * after presets register.
+ *
+ * @experimental
+ */
+export function getActiveChangeDetectionService(): ChangeDetectionService | undefined {
+  return activeService;
+}

code/core/src/core-server/change-detection/index.ts

@@ -6,6 +6,10 @@ export {
   type ChangeDetectionReadiness,
 } from './readiness.ts';
 export { ChangeDetectionService } from './ChangeDetectionService.ts';
+export {
+  getActiveChangeDetectionService,
+  setActiveChangeDetectionService,
+} from './active-service-registry.ts';
 export type {
   ChangeDetectionAdapter,
   FileChangeEvent,

code/core/src/core-server/dev-server.ts

@@ -9,7 +9,10 @@ import polka from 'polka';
 
 import { isTelemetryModuleEnabled, telemetry } from '../telemetry/index.ts';
 import type { ChangeDetectionAdapter } from './change-detection/index.ts';
-import { ChangeDetectionService } from './change-detection/index.ts';
+import {
+  ChangeDetectionService,
+  setActiveChangeDetectionService,
+} from './change-detection/index.ts';
 import { getStatusStoreByTypeId } from './stores/status.ts';
 import type { StoryIndexGenerator } from './utils/StoryIndexGenerator.ts';
 import { doTelemetry } from './utils/doTelemetry.ts';
@@ -54,6 +57,9 @@ export async function storybookDevServer(
     workingDir,
     presets: options.presets,
   });
+  // Expose to in-process consumers (addon presets) via the active-service registry.
+  // Dev server is single-instance, so only one service is ever active.
+  setActiveChangeDetectionService(changeDetectionService);
 
   app.use(compression({ level: 1 }));
 

code/core/src/core-server/index.ts

@@ -67,6 +67,7 @@ export type {
   ParseFileArgs,
 } from './change-detection/index.ts';
 export { ChangeDetectionService } from './change-detection/ChangeDetectionService.ts';
+export { getActiveChangeDetectionService as experimental_getActiveChangeDetectionService } from './change-detection/active-service-registry.ts';
 export {
   getTestProviderStoreById as experimental_getTestProviderStore,
   fullTestProviderStore as internal_fullTestProviderStore,