From bb778d44a3e0429bf66a080c08dbc89f691174e0 Mon Sep 17 00:00:00 2001
From: Trish Ta <trish.ta@gmail.com>
Date: Fri, 17 Apr 2026 17:36:55 -0400
Subject: [PATCH] Fix error for running build when there is multiple admin
 links and ui extensions

---
 .../specification.integration.test.ts           | 17 +++++++++++++++++
 .../src/cli/models/extensions/specification.ts  |  9 +++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/packages/app/src/cli/models/extensions/specification.integration.test.ts b/packages/app/src/cli/models/extensions/specification.integration.test.ts
index f49d0712f3a..f446219858f 100644
--- a/packages/app/src/cli/models/extensions/specification.integration.test.ts
+++ b/packages/app/src/cli/models/extensions/specification.integration.test.ts
@@ -109,6 +109,23 @@ describe('createExtensionSpecification', () => {
     // Then
     expect(got.clientSteps).toEqual(testClientSteps)
   })
+
+  test('does not let explicit-undefined spec keys shadow the computed defaults', () => {
+    // When — wrapper-helper style: optional fields are forwarded as `undefined`
+    const got = createExtensionSpecification({
+      identifier: 'test_extension',
+      appModuleFeatures: () => [],
+      experience: undefined,
+      uidStrategy: undefined,
+      buildConfig: undefined,
+      clientSteps: undefined,
+    })
+
+    // Then — defaults apply instead of `undefined` leaking through
+    expect(got.experience).toBe('extension')
+    expect(got.uidStrategy).toBe('uuid')
+    expect(got.buildConfig).toEqual({mode: 'none'})
+  })
 })
 
 describe('createConfigExtensionSpecification', () => {
diff --git a/packages/app/src/cli/models/extensions/specification.ts b/packages/app/src/cli/models/extensions/specification.ts
index 4d9945d408e..149c88faa15 100644
--- a/packages/app/src/cli/models/extensions/specification.ts
+++ b/packages/app/src/cli/models/extensions/specification.ts
@@ -10,7 +10,7 @@ import {ApplicationURLs} from '../../services/dev/urls.js'
 import {Result} from '@shopify/cli-kit/node/result'
 import {capitalize} from '@shopify/cli-kit/common/string'
 import {ParseConfigurationResult, zod} from '@shopify/cli-kit/node/schema'
-import {getPathValue, setPathValue} from '@shopify/cli-kit/common/object'
+import {getPathValue, pickBy, setPathValue} from '@shopify/cli-kit/common/object'
 import {JsonMapType} from '@shopify/cli-kit/node/toml'
 
 export type ExtensionFeature =
@@ -222,7 +222,12 @@ export function createExtensionSpecification<TConfiguration extends BaseConfigTy
     clientSteps: spec.clientSteps,
     buildConfig: spec.buildConfig ?? {mode: 'none'},
   }
-  const merged = {...defaults, ...spec}
+  // Strip undefined keys from `spec` before merging so wrapper helpers that
+  // forward optional fields as explicit `undefined` don't shadow the defaults.
+  const definedSpec = pickBy(spec as unknown as Record<string, unknown>, (value) => value !== undefined) as Partial<
+    CreateExtensionSpecType<TConfiguration>
+  >
+  const merged = {...defaults, ...definedSpec} as typeof defaults & CreateExtensionSpecType<TConfiguration>
 
   return {
     ...merged,