diff --git a/backend/tests/auth.test.js b/backend/tests/auth.test.js
index 2677203..36b0998 100644
--- a/backend/tests/auth.test.js
+++ b/backend/tests/auth.test.js
@@ -439,6 +439,36 @@ test('POST /api/auth/storage/create returns probe failures without needsInstall'
   assert.match(res.body.error, /do not reinstall/i);
 });
 
+test('POST /api/auth/storage/create returns REPO_CREATE_FORBIDDEN on Administration 403', async () => {
+  const app = createAuthedApp({
+    user: AUTHED_USER,
+    authService: {
+      clientsFor: async () => ({ githubUserClient: { mock: true } }),
+      getInstallationSetupUrl: async () =>
+        'https://github.com/apps/vizably/installations/new',
+    },
+    storageService: {
+      createGitHubRepository: async () => {
+        const err = new Error(
+          'GitHub App cannot create repositories. Add Repository permissions → Administration: Read and write, accept the permission upgrade on your installation, then sign out and sign in again.',
+        );
+        err.status = 403;
+        err.code = 'REPO_CREATE_FORBIDDEN';
+        throw err;
+      },
+    },
+  });
+  const res = await request(app)
+    .post('/api/auth/storage/create')
+    .send({ name: 'vizably-new' });
+  assert.equal(res.status, 403);
+  assert.equal(res.body.code, 'REPO_CREATE_FORBIDDEN');
+  assert.equal(res.body.needsInstall, undefined);
+  assert.equal(res.body.storageRef, undefined);
+  assert.match(res.body.error, /Administration:\s*Read and write/i);
+  assert.match(res.body.error, /permission upgrade/i);
+});
+
 test('POST /api/auth/storage/validate requires provider and storageRef', async () => {
   const app = createAuthedApp({
     user: AUTHED_USER,
diff --git a/backend/tests/storageService.test.js b/backend/tests/storageService.test.js
index 267bb5a..4d502e5 100644
--- a/backend/tests/storageService.test.js
+++ b/backend/tests/storageService.test.js
@@ -537,6 +537,46 @@ test('createGitHubRepository maps name-taken conflicts', async () => {
   );
 });
 
+test('createGitHubRepository maps Administration permission 403 to REPO_CREATE_FORBIDDEN', async () => {
+  const storageService = new StorageService();
+  const forbidden = new Error('Resource not accessible by integration');
+  forbidden.status = 403;
+  forbidden.response = {
+    data: { message: 'Resource not accessible by integration' },
+  };
+  const client = createMockGitHubClient({ createRepoError: forbidden });
+  await assert.rejects(
+    () => storageService.createGitHubRepository('vizably-new', { githubUserClient: client }),
+    (err) => {
+      assert.equal(err.code, 'REPO_CREATE_FORBIDDEN');
+      assert.equal(err.status, 403);
+      assert.match(err.message, /Administration:\s*Read and write/i);
+      assert.match(err.message, /permission upgrade/i);
+      return true;
+    },
+  );
+});
+
+test('createGitHubRepository maps generic create 403 to REPO_CREATE_FORBIDDEN', async () => {
+  const storageService = new StorageService();
+  const forbidden = new Error('Forbidden');
+  forbidden.status = 403;
+  forbidden.response = {
+    data: { message: 'Although you appear to have the correct authorization credentials, organization policy prevents creating repositories.' },
+  };
+  const client = createMockGitHubClient({ createRepoError: forbidden });
+  await assert.rejects(
+    () => storageService.createGitHubRepository('vizably-new', { githubUserClient: client }),
+    (err) => {
+      assert.equal(err.code, 'REPO_CREATE_FORBIDDEN');
+      assert.equal(err.status, 403);
+      assert.match(err.message, /organization policy prevents creating repositories/i);
+      assert.doesNotMatch(err.message, /Administration/);
+      return true;
+    },
+  );
+});
+
 test('validateStorage returns initializable for empty repo', async () => {
   const storageService = new StorageService();
   const client = createMockGitHubClient();