diff --git a/src/features/authFiles/AuthFilesPage.tsx b/src/features/authFiles/AuthFilesPage.tsx
index 972eb40e..c7e1bd7c 100644
--- a/src/features/authFiles/AuthFilesPage.tsx
+++ b/src/features/authFiles/AuthFilesPage.tsx
@@ -29,6 +29,7 @@ import { OAuthModelAliasCard } from '@/features/authFiles/components/OAuthModelA
 import { ProviderTabs } from '@/features/authFiles/components/ProviderTabs';
 import { VaultHeader } from '@/features/authFiles/components/VaultHeader';
 import { VaultPulse } from '@/features/authFiles/components/VaultPulse';
+import { invalidateAuthFileDerivedCaches } from '@/features/authFiles/cacheInvalidation';
 import { useAuthFilesData } from '@/features/authFiles/hooks/useAuthFilesData';
 import { useAuthFilesModels } from '@/features/authFiles/hooks/useAuthFilesModels';
 import { useAuthFilesOauth } from '@/features/authFiles/hooks/useAuthFilesOauth';
@@ -110,6 +111,11 @@ export function AuthFilesPage() {
     invalidateModels,
   } = useAuthFilesModels();
 
+  const invalidateDerivedCaches = useCallback(
+    (names?: string[]) => invalidateAuthFileDerivedCaches(invalidateModels, names),
+    [invalidateModels]
+  );
+
   const {
     files,
     selectedFiles,
@@ -139,7 +145,7 @@ export function AuthFilesPage() {
     batchDownload,
     batchSetStatus,
     batchDelete,
-  } = useAuthFilesData({ onFilesMutated: invalidateModels });
+  } = useAuthFilesData({ onFilesMutated: invalidateDerivedCaches });
 
   const statusBarCache = useAuthFilesStatusBarCache(files);
 
diff --git a/src/features/authFiles/cacheInvalidation.ts b/src/features/authFiles/cacheInvalidation.ts
new file mode 100644
index 00000000..56304398
--- /dev/null
+++ b/src/features/authFiles/cacheInvalidation.ts
@@ -0,0 +1,12 @@
+import { useQuotaStore } from '@/stores/useQuotaStore';
+
+type ModelsInvalidator = (names?: string[]) => void;
+
+/** Invalidate every cache whose contents depend on an auth file's credentials. */
+export const invalidateAuthFileDerivedCaches = (
+  invalidateModels: ModelsInvalidator,
+  names?: string[]
+): void => {
+  invalidateModels(names);
+  useQuotaStore.getState().clearQuotaCache();
+};
diff --git a/tests/quotaSessionIsolation.test.ts b/tests/quotaSessionIsolation.test.ts
index 4a56102a..64770a24 100644
--- a/tests/quotaSessionIsolation.test.ts
+++ b/tests/quotaSessionIsolation.test.ts
@@ -1,4 +1,5 @@
 import { beforeEach, describe, expect, test } from 'bun:test';
+import { invalidateAuthFileDerivedCaches } from '../src/features/authFiles/cacheInvalidation';
 import {
   captureQuotaCacheGeneration,
   commitIfQuotaCacheCurrent,
@@ -35,4 +36,35 @@ describe('quota cache session isolation', () => {
     ).toBe(true);
     expect(committed).toBe(true);
   });
+
+  test('clears same-name quota and rejects an in-flight commit after auth mutation', () => {
+    const fileName = 'shared-codex.json';
+    useQuotaStore.getState().setCodexQuota({
+      [fileName]: {
+        status: 'success',
+        windows: [],
+        planType: 'account-a',
+      },
+    });
+    const accountARequest = captureQuotaCacheGeneration();
+    let invalidatedNames: string[] | undefined;
+
+    invalidateAuthFileDerivedCaches(
+      (names) => {
+        invalidatedNames = names;
+      },
+      [fileName]
+    );
+
+    expect(invalidatedNames).toEqual([fileName]);
+    expect(useQuotaStore.getState().codexQuota[fileName]).toBeUndefined();
+
+    let committed = false;
+    expect(
+      commitIfQuotaCacheCurrent(accountARequest, () => {
+        committed = true;
+      })
+    ).toBe(false);
+    expect(committed).toBe(false);
+  });
 });