fix(core): apply a project descriptor edit in the build it starts

examples/order-flow/server/test/project-visibility.test.ts

@@ -23,11 +23,19 @@
  * holds a single file.
  */
 
-import { AstUtils, DocumentState, type ReferenceInfo } from '@hydranium/langium';
-import { describe, expect, it } from 'vitest';
+import { AstUtils, DocumentState, type ReferenceInfo, URI } from '@hydranium/langium';
+import { readFileSync } from 'node:fs';
+import { describe, expect, it, onTestFinished } from 'vitest';
 import { type DomainModel, type Entity, type Field, isEntity } from '../src/language-server/ast.js';
 import { ORDER_FLOW_STDLIB_URI } from '../src/language-server/order-flow-stdlib.js';
-import { documentFor, makeWorkspaceHarness, type OrderFlowHarness, workspaceUri } from './order-flow-harness.js';
+import {
+   documentFor,
+   makeScratchWorkspaceHarness,
+   makeWorkspaceHarness,
+   type OrderFlowHarness,
+   WORKSPACE_FILES,
+   workspaceUri
+} from './order-flow-harness.js';
 
 function entityNamed(model: DomainModel, name: string): Entity {
    const found = model.declarations.find(declaration => isEntity(declaration) && declaration.name === name);
@@ -211,3 +219,44 @@ describe('order-flow visibility — public declarations cross the project bounda
       expect(candidates).not.toContain('Order');
    });
 });
+
+describe('order-flow projects — a descriptor change', () => {
+   it('takes effect in the build the edit starts', async () => {
+      const { harness, workspace } = await makeScratchWorkspaceHarness();
+      onTestFinished(() => workspace.dispose());
+      const projects = harness.shared.workspace.ProjectManager;
+      const builder = harness.shared.workspace.DocumentBuilder;
+      const ordersPath = workspace.resolve(WORKSPACE_FILES.ordersDomain);
+      const ordersUri = URI.file(ordersPath);
+      const original = readFileSync(ordersPath, 'utf8');
+      const totalTypeName = (): string | undefined => {
+         const model = harness.shared.workspace.LangiumDocuments.getDocument(ordersUri)!.parseResult.value as DomainModel;
+         return fieldNamed(entityNamed(model, 'Order'), 'total').type.declared?.ref?.name;
+      };
+
+      workspace.write(WORKSPACE_FILES.ordersDomain, original.replace('project orders requires commerce-core', 'project orders'));
+      await builder.update([ordersUri], []);
+      expect(projects.getProjectById('orders')?.dependencies).toBeUndefined();
+      expect(totalTypeName()).toBeUndefined();
+
+      workspace.write(WORKSPACE_FILES.ordersDomain, original);
+      await builder.update([ordersUri], []);
+      expect(projects.getProjectById('orders')?.dependencies).toEqual(['commerce-core']);
+      expect(totalTypeName()).toBe('Money');
+   });
+
+   it('registers a descriptor created by an update in that update', async () => {
+      const { harness, workspace } = await makeScratchWorkspaceHarness();
+      onTestFinished(() => workspace.dispose());
+      const projects = harness.shared.workspace.ProjectManager;
+      const refundsUri = URI.file(
+         workspace.write('refunds/refunds.domain', 'project refunds requires commerce-core\n\nentity Refund {\n   amount: Money\n}\n')
+      );
+
+      await harness.shared.workspace.DocumentBuilder.update([refundsUri], []);
+
+      expect(projects.getProjectById('refunds')?.dependencies).toEqual(['commerce-core']);
+      const model = harness.shared.workspace.LangiumDocuments.getDocument(refundsUri)!.parseResult.value as DomainModel;
+      expect(fieldNamed(entityNamed(model, 'Refund'), 'amount').type.declared?.ref?.name).toBe('Money');
+   });
+});

packages/core/src/langium/project/abstract-project-manager.ts

@@ -12,13 +12,14 @@ import {
    type AstNode,
    AstUtils,
    type DocumentBuilder,
+   DocumentState,
    type FileSystemProvider,
    type LangiumDocument,
    type LangiumDocuments,
    type URI,
    UriUtils
 } from '@hydranium/langium';
-import { Disposable } from 'vscode-languageserver';
+import { CancellationToken, Disposable } from 'vscode-languageserver';
 import type { WorkspaceFolder } from 'vscode-languageserver-types';
 import type { LogNameOptions } from '../diagnostics/logger.js';
 import { type ServerSharedServicesMinimal } from '../shared-services.js';
@@ -377,6 +378,13 @@ export abstract class AbstractProjectManager<TProject extends Project = Project>
    protected async loadDescriptor(uri: URI): Promise<TProject | undefined> {
       try {
          const document = await this.langiumDocuments.getOrCreateDocument(uri);
+         if (document.state < DocumentState.Parsed) {
+            // `onUpdate` fires before the build parses, so the AST is still the previous edit's.
+            // The state is restored so the build still runs, and notifies, its own parse phase.
+            const state = document.state;
+            await this.services.workspace.LangiumDocumentFactory.update(document, CancellationToken.None);
+            document.state = state;
+         }
          const project = await this.parseProjectDescriptor(uri, document);
          if (project) {
             this.projects.set(project.id, project);

packages/core/src/langium/project/project-change-event.ts

@@ -28,8 +28,8 @@ import type { URI } from '@hydranium/langium';
  * - {@link affectedDocuments} lists URIs whose reachable scope changed. The
  *   default cascade plumbing in `HydraniumWorkspaceManager` subscribes to
  *   this event and re-runs `DocumentBuilder.resetToState` for each entry,
- *   which the next build cycle picks up. Consumers can subscribe
- *   independently for other reactions.
+ *   which the build of the update that changed the descriptor picks up.
+ *   Consumers can subscribe independently for other reactions.
  */
 export interface ProjectChangeEvent<TProject extends Project = Project> {
    /** Ids of projects newly registered since the last event. */

packages/core/src/langium/workspace/hydranium-workspace-manager.ts

@@ -137,8 +137,8 @@ export interface HydraniumWorkspaceManagerOptions extends LogNameOptions {
  * URIs (its own members plus any transitive dependents per the
  * `getAffectedProjects` hook). This manager re-runs
  * `DocumentBuilder.resetToState(doc, DocumentState.Changed)` on each
- * affected document so the next build cycle re-links them with the new
- * visibility scope.
+ * affected document so the build of the update that changed the descriptor
+ * re-links them with the new visibility scope.
  *
  * Descriptor URIs that triggered the cycle are intentionally excluded
  * from the affected set by `AbstractProjectManager.onBuildUpdate` —
@@ -501,9 +501,9 @@ export class HydraniumWorkspaceManager extends DefaultWorkspaceManager {
 
    /**
     * Default cascade-rebuild handler. Iterates {@link ProjectChangeEvent.affectedDocuments}
-    * and resets each to {@link DocumentState.Changed} so the next build cycle
-    * re-runs the pipeline (parse → link → validate) under the new project
-    * visibility scope.
+    * and resets each to {@link DocumentState.Changed} so the build of the update
+    * that changed the descriptor re-runs the pipeline (parse → link → validate)
+    * under the new project visibility scope.
     *
     * Subclasses can override for additional behaviour (e.g. logging,
     * telemetry, custom rebuild policies); call `super` to preserve the