diff --git a/src/lib/maintainer/detect.test.ts b/src/lib/maintainer/detect.test.ts
index 31c64a58..977f1e3c 100644
--- a/src/lib/maintainer/detect.test.ts
+++ b/src/lib/maintainer/detect.test.ts
@@ -50,6 +50,19 @@ describe('isUserMaintainer', () => {
     expect(cacheSet).toHaveBeenCalledWith('maint:status:user1', true, 3600);
   });
 
+  it('returns true when github_installations is returned as an array (inner join ambiguity)', async () => {
+    vi.mocked(cacheGet).mockResolvedValue(null);
+    vi.mocked(getServiceSupabase).mockReturnValue(
+      mockSupabase({
+        github_installation_users: [{ github_installations: [{ uninstalled_at: null }] }],
+      }) as unknown as ReturnType<typeof getServiceSupabase>,
+    );
+
+    const result = await isUserMaintainer('user1');
+    expect(result).toBe(true);
+    expect(cacheSet).toHaveBeenCalledWith('maint:status:user1', true, 3600);
+  });
+
   it('returns false when all installation rows have uninstalled_at set', async () => {
     vi.mocked(cacheGet).mockResolvedValue(null);
     vi.mocked(getServiceSupabase).mockReturnValue(
@@ -143,6 +156,36 @@ describe('listMaintainerInstalls', () => {
     ]);
   });
 
+  it('handles github_installations returned as an array (inner join ambiguity)', async () => {
+    vi.mocked(getServiceSupabase).mockReturnValue(
+      mockSupabase({
+        github_installation_users: [
+          {
+            installation_id: 1,
+            permission_level: 'org_admin',
+            github_installations: [
+              {
+                account_login: 'org1',
+                account_type: 'Organization',
+                uninstalled_at: null,
+              },
+            ],
+          },
+        ],
+      }) as unknown as ReturnType<typeof getServiceSupabase>,
+    );
+
+    const result = await listMaintainerInstalls('user1');
+    expect(result).toEqual([
+      {
+        installationId: 1,
+        accountLogin: 'org1',
+        accountType: 'Organization',
+        permissionLevel: 'org_admin',
+      },
+    ]);
+  });
+
   it('filters out installs where uninstalled_at is not null', async () => {
     vi.mocked(getServiceSupabase).mockReturnValue(
       mockSupabase({
diff --git a/src/lib/maintainer/detect.ts b/src/lib/maintainer/detect.ts
index 0f2c9240..eaa55884 100644
--- a/src/lib/maintainer/detect.ts
+++ b/src/lib/maintainer/detect.ts
@@ -1,5 +1,6 @@
 import { getServiceSupabase } from '@/lib/supabase/service';
 import { cacheGet, cacheSet } from '@/lib/cache';
+import { unwrapJoin } from '@/lib/supabase/inner-join';
 
 /**
  * "Is this user a maintainer?" — true if they have at least one active
@@ -30,8 +31,8 @@ export async function isUserMaintainer(userId: string): Promise<boolean> {
     .limit(20);
 
   const has = (data ?? []).some((row) => {
-    const i = (row as unknown as { github_installations: { uninstalled_at: string | null } | null })
-      .github_installations;
+    const r = row as unknown as { github_installations: unknown };
+    const i = unwrapJoin<{ uninstalled_at: string | null }>(r.github_installations);
     return i && i.uninstalled_at === null;
   });
 
@@ -64,15 +65,23 @@ export async function listMaintainerInstalls(userId: string): Promise<Maintainer
   type Row = {
     installation_id: number;
     permission_level: MaintainerInstall['permissionLevel'];
-    github_installations: {
-      account_login: string;
-      account_type: 'User' | 'Organization';
-      uninstalled_at: string | null;
-    } | null;
+    github_installations: unknown;
+  };
+
+  type JoinedInstall = {
+    account_login: string;
+    account_type: 'User' | 'Organization';
+    uninstalled_at: string | null;
   };
 
   return (data ?? [])
-    .map((row) => row as unknown as Row)
+    .map((row) => {
+      const r = row as unknown as Row;
+      return {
+        ...r,
+        github_installations: unwrapJoin<JoinedInstall>(r.github_installations),
+      };
+    })
     .filter((r) => r.github_installations && r.github_installations.uninstalled_at === null)
     .map((r) => ({
       installationId: r.installation_id,