diff --git a/src/utils/appMode.test.ts b/src/utils/appMode.test.ts
new file mode 100644
index 0000000000..21655d2a4c
--- /dev/null
+++ b/src/utils/appMode.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it } from 'vitest'
+
+import { getWorkflowMode, isAppModeValue } from '@/utils/appMode'
+
+describe('getWorkflowMode', () => {
+  it('prefers active mode over initial mode', () => {
+    expect(
+      getWorkflowMode({
+        activeMode: 'builder:arrange',
+        initialMode: 'app'
+      })
+    ).toBe('builder:arrange')
+  })
+
+  it('falls back to initial mode', () => {
+    expect(
+      getWorkflowMode({
+        activeMode: null,
+        initialMode: 'builder:inputs'
+      })
+    ).toBe('builder:inputs')
+  })
+
+  it('defaults to graph mode', () => {
+    expect(getWorkflowMode(null)).toBe('graph')
+    expect(
+      getWorkflowMode({
+        activeMode: null,
+        initialMode: undefined
+      })
+    ).toBe('graph')
+  })
+})
+
+describe('isAppModeValue', () => {
+  it('recognizes app-style modes', () => {
+    expect(isAppModeValue('app')).toBe(true)
+    expect(isAppModeValue('builder:arrange')).toBe(true)
+  })
+
+  it('rejects graph and builder panel modes', () => {
+    expect(isAppModeValue('graph')).toBe(false)
+    expect(isAppModeValue('builder:inputs')).toBe(false)
+    expect(isAppModeValue('builder:outputs')).toBe(false)
+  })
+})