host: Add indexing drain after restoring cached realm

packages/host/tests/acceptance/ai-assistant-test.gts

@@ -37,6 +37,8 @@ import type MonacoService from '@cardstack/host/services/monaco-service';
 import { AiAssistantMessageDrafts } from '@cardstack/host/utils/local-storage-keys';
 
 import {
+  withCachedRealmSetup,
+  setupRealmCacheTeardown,
   setupLocalIndexing,
   addSkillToAiAssistant,
   setupOnSave,
@@ -142,13 +144,8 @@ function modelNameFor(llmId: string): string {
 
 module('Acceptance | AI Assistant tests', function (hooks) {
   setupApplicationTest(hooks);
-  // Every test in this module builds the same realm fixtures in the beforeEach
-  // below, so the realm is indexed once and that index restored for each
-  // subsequent test. What a test writes afterwards stays with that test — the
-  // snapshot is restored, not carried forward.
-  setupLocalIndexing(hooks, {
-    reuseIndexAcrossTests: 'aiAssistant',
-  });
+  setupLocalIndexing(hooks);
+  setupRealmCacheTeardown(hooks);
   setupOnSave(hooks);
 
   let mockMatrixUtils = setupMockMatrix(hooks, {
@@ -431,13 +428,16 @@ module('Acceptance | AI Assistant tests', function (hooks) {
       modelConfigurations: [deepseekModel, geminiFlashModel, openAiGpt5Model],
     });
 
-    await setupAcceptanceTestRealm({
-      mockMatrixUtils,
-      contents: {
-        ...SYSTEM_CARD_FIXTURE_CONTENTS,
-        'person.gts': { Person },
-        'pet.gts': { Pet },
-        'broken-card.gts': `
+    // Every test builds these fixtures identically, so the indexed result is
+    // cached for the module and restored rather than rebuilt.
+    await withCachedRealmSetup(async () => {
+      await setupAcceptanceTestRealm({
+        mockMatrixUtils,
+        contents: {
+          ...SYSTEM_CARD_FIXTURE_CONTENTS,
+          'person.gts': { Person },
+          'pet.gts': { Pet },
+          'broken-card.gts': `
           import { CardDef, field, contains } from '@cardstack/base/card-api';
           import StringField from '@cardstack/base/string';
           import { BrokenField } from './does-not-exist';
@@ -447,133 +447,134 @@ module('Acceptance | AI Assistant tests', function (hooks) {
             @field broken = contains(BrokenField);
           }
         `,
-        'BrokenCard/errored.json': {
-          data: {
-            attributes: {
-              name: 'Errored Instance',
-            },
-            meta: {
-              adoptsFrom: {
-                module: '../broken-card',
-                name: 'BrokenCard',
+          'BrokenCard/errored.json': {
+            data: {
+              attributes: {
+                name: 'Errored Instance',
+              },
+              meta: {
+                adoptsFrom: {
+                  module: '../broken-card',
+                  name: 'BrokenCard',
+                },
               },
             },
           },
-        },
-        'country.gts': countryDefinition,
-        'Country/indonesia.json': {
-          data: {
-            attributes: {
-              name: 'Indonesia',
-            },
-            meta: {
-              adoptsFrom: {
-                module: `${testRealmURL}country`,
-                name: 'Country',
+          'country.gts': countryDefinition,
+          'Country/indonesia.json': {
+            data: {
+              attributes: {
+                name: 'Indonesia',
+              },
+              meta: {
+                adoptsFrom: {
+                  module: `${testRealmURL}country`,
+                  name: 'Country',
+                },
               },
             },
           },
-        },
-        'Pet/ringo.json': new Pet({ name: 'Ringo' }),
-        'Person/hassan.json': new Person({
-          firstName: 'Hassan',
-          lastName: 'Abdel-Rahman',
-          pet: mangoPet,
-          friends: [mangoPet],
-        }),
-        'Pet/mango.json': mangoPet,
-        'Pet/vangogh.json': new Pet({ name: 'Van Gogh' }),
-        'Person/fadhlan.json': new Person({
-          firstName: 'Fadhlan',
-          pet: mangoPet,
-          friends: [mangoPet],
-        }),
-        'plant.gts': `
+          'Pet/ringo.json': new Pet({ name: 'Ringo' }),
+          'Person/hassan.json': new Person({
+            firstName: 'Hassan',
+            lastName: 'Abdel-Rahman',
+            pet: mangoPet,
+            friends: [mangoPet],
+          }),
+          'Pet/mango.json': mangoPet,
+          'Pet/vangogh.json': new Pet({ name: 'Van Gogh' }),
+          'Person/fadhlan.json': new Person({
+            firstName: 'Fadhlan',
+            pet: mangoPet,
+            friends: [mangoPet],
+          }),
+          'plant.gts': `
           import { CardDef, field, contains, StringField } from '@cardstack/base/card-api';
           export class Plant extends CardDef {
             static displayName = "Plant";
             @field commonName = contains(StringField);
           }
         `,
-        'Plant/highbush-blueberry.json': {
-          data: {
-            attributes: {
-              commonName: 'Highbush Blueberry',
-            },
-            meta: {
-              adoptsFrom: {
-                module: `../plant`,
-                name: 'Plant',
+          'Plant/highbush-blueberry.json': {
+            data: {
+              attributes: {
+                commonName: 'Highbush Blueberry',
+              },
+              meta: {
+                adoptsFrom: {
+                  module: `../plant`,
+                  name: 'Plant',
+                },
               },
             },
           },
-        },
-        'Spec/plant-spec.json': {
-          data: {
-            type: 'card',
-            attributes: {
-              ref: {
-                name: 'Plant',
-                module: `${testRealmURL}plant`,
+          'Spec/plant-spec.json': {
+            data: {
+              type: 'card',
+              attributes: {
+                ref: {
+                  name: 'Plant',
+                  module: `${testRealmURL}plant`,
+                },
+                specType: 'card',
+                cardTitle: 'Plant spec',
               },
-              specType: 'card',
-              cardTitle: 'Plant spec',
-            },
-            meta: {
-              adoptsFrom: {
-                module: '@cardstack/base/spec',
-                name: 'Spec',
+              meta: {
+                adoptsFrom: {
+                  module: '@cardstack/base/spec',
+                  name: 'Spec',
+                },
               },
             },
           },
-        },
-        'Skill/example.json': {
-          data: {
-            attributes: {
-              cardTitle: 'Example Skill',
-              cardDescription: 'This skill card is for testing purposes',
-              instructions: 'This is an example skill card',
-              commands: [],
-            },
-            meta: {
-              adoptsFrom: skillCardRef,
+          'Skill/example.json': {
+            data: {
+              attributes: {
+                cardTitle: 'Example Skill',
+                cardDescription: 'This skill card is for testing purposes',
+                instructions: 'This is an example skill card',
+                commands: [],
+              },
+              meta: {
+                adoptsFrom: skillCardRef,
+              },
             },
           },
-        },
-        'Skill/example2.json': {
-          data: {
-            attributes: {
-              cardTitle: 'Example 2 Skill',
-              cardDescription: 'This skill card is also for testing purposes',
-              instructions: 'This is a second example skill card',
-              commands: [],
-            },
-            meta: {
-              adoptsFrom: skillCardRef,
+          'Skill/example2.json': {
+            data: {
+              attributes: {
+                cardTitle: 'Example 2 Skill',
+                cardDescription: 'This skill card is also for testing purposes',
+                instructions: 'This is a second example skill card',
+                commands: [],
+              },
+              meta: {
+                adoptsFrom: skillCardRef,
+              },
             },
           },
+          'ModelConfiguration/gpt-4o-mini.json': openAiGpt4oMiniModel,
+          'ModelConfiguration/gpt-5.json': openAiGpt5Model,
+          'ModelConfiguration/gpt-5-extended.json': openAiGpt5ExtendedModel,
+          'ModelConfiguration/claude-sonnet-4.6.json':
+            anthropicClaudeSonnet46Model,
+          'ModelConfiguration/claude-sonnet-4.5.json':
+            anthropicClaudeSonnet45Model,
+          'ModelConfiguration/claude-sonnet-3.7.json':
+            anthropicClaudeSonnet37Model,
+          'SystemCard/default.json': defaultSystemCard,
+          'ModelConfiguration/deepseek-chat-v3-0324.json': deepseekModel,
+          'ModelConfiguration/gemini-2.5-flash.json': geminiFlashModel,
+          'SystemCard/productivity.json': alternateSystemCard,
+          'index.json': new CardsGrid(),
+          'realm.json': realmConfigCardJSON({
+            name: 'Test Workspace B',
+            backgroundURL:
+              'https://i.postimg.cc/VNvHH93M/pawel-czerwinski-Ly-ZLa-A5jti-Y-unsplash.jpg',
+            iconURL: 'https://i.postimg.cc/L8yXRvws/icon.png',
+          }),
         },
-        'ModelConfiguration/gpt-4o-mini.json': openAiGpt4oMiniModel,
-        'ModelConfiguration/gpt-5.json': openAiGpt5Model,
-        'ModelConfiguration/gpt-5-extended.json': openAiGpt5ExtendedModel,
-        'ModelConfiguration/claude-sonnet-4.6.json':
-          anthropicClaudeSonnet46Model,
-        'ModelConfiguration/claude-sonnet-4.5.json':
-          anthropicClaudeSonnet45Model,
-        'ModelConfiguration/claude-sonnet-3.7.json':
-          anthropicClaudeSonnet37Model,
-        'SystemCard/default.json': defaultSystemCard,
-        'ModelConfiguration/deepseek-chat-v3-0324.json': deepseekModel,
-        'ModelConfiguration/gemini-2.5-flash.json': geminiFlashModel,
-        'SystemCard/productivity.json': alternateSystemCard,
-        'index.json': new CardsGrid(),
-        'realm.json': realmConfigCardJSON({
-          name: 'Test Workspace B',
-          backgroundURL:
-            'https://i.postimg.cc/VNvHH93M/pawel-czerwinski-Ly-ZLa-A5jti-Y-unsplash.jpg',
-          iconURL: 'https://i.postimg.cc/L8yXRvws/icon.png',
-        }),
-      },
+      });
     });
 
     getService('matrix-service').fetchMatrixHostedFile = async (_url) => {

packages/host/tests/helpers/index.gts

@@ -247,13 +247,37 @@ export async function withCachedRealmSetup<T>(
   let dbAdapter = await getDbAdapter();
   if (dbAdapter.hasSnapshot(snapshotName)) {
     await dbAdapter.importSnapshot(snapshotName);
-    return setup();
+    let result = await setup();
+    // A restored index does not stop the realm indexing. Every fixture carries
+    // the mtime the *current* adapter stamped it with, while the restored rows
+    // carry the first test's, and `discover-invalidations` compares those for
+    // equality — so `realm.start()` invalidates the lot and re-indexes. The work
+    // is cheap, because the snapshot also restored the transpile and prerender
+    // caches, but it is asynchronous: without draining it here, a test that
+    // reads index-derived state races indexing still in flight. That is not
+    // hypothetical — it is how `ai-assistant`'s code-mode test lost the cursor
+    // position it clicks a definition to reach.
+    //
+    // Deliberately not solved by making the mtimes match. The mtime comparison
+    // is what rebuilds the index when a module's fixtures diverge from the
+    // snapshot under an unchanged cache key, which is this helper's only
+    // protection against silently serving the wrong fixtures.
+    await drainRealmIndexing();
+    return result;
   }
   let result = await setup();
   await dbAdapter.exportSnapshot(snapshotName);
   return result;
 }
 
+// Settle any indexing the realms have in flight. Mirrors what
+// `setupLocalIndexing`'s afterEach does between tests.
+async function drainRealmIndexing(): Promise<void> {
+  for (let { realm } of getTestRealmRegistry().values()) {
+    await realm.incrementalIndexing();
+  }
+}
+
 function getCurrentModuleCacheKey(): string {
   let config = QUnit.config as QUnit['config'] & {
     currentModule?: { name?: string };