diff --git a/integration-tests/demo/src/main/kotlin/com/squareup/test/demo/DemoService.kt b/integration-tests/demo/src/main/kotlin/com/squareup/test/demo/DemoService.kt
new file mode 100644
index 0000000..eafc02b
--- /dev/null
+++ b/integration-tests/demo/src/main/kotlin/com/squareup/test/demo/DemoService.kt
@@ -0,0 +1,32 @@
+package com.squareup.test.demo
+
+import com.squareup.dagger.AppScope
+import dev.zacsweers.metro.ContributesBinding
+import dev.zacsweers.metro.ContributesTo
+import dev.zacsweers.metro.Inject
+import dev.zacsweers.metro.binding
+
+/**
+ * Reproduces a bug where @ContributesBinding contributions in the same module as a
+ *
+ * @DependencyGraph generated by an external FIR extension (@DevelopmentAppComponent) are not
+ *   discovered during the SUPERTYPES phase.
+ *
+ * The @MetroContribution annotation's scope argument can't be resolved at the SUPERTYPES phase for
+ * same-module classes in real Gradle compilations, causing the contribution to be silently dropped.
+ */
+interface DemoService {
+  val name: String
+}
+
+@Inject
+@ContributesBinding(AppScope::class, binding = binding<DemoService>())
+class DemoServiceImpl : DemoService {
+  override val name: String = "contributed-binding"
+}
+
+/** Exposes [DemoService] on the generated graph. */
+@ContributesTo(AppScope::class)
+interface DemoServiceComponent {
+  val demoService: DemoService
+}
diff --git a/integration-tests/demo/src/test/kotlin/com/squareup/test/demo/DemoAppTest.kt b/integration-tests/demo/src/test/kotlin/com/squareup/test/demo/DemoAppTest.kt
index 8bb73c5..2341cbf 100644
--- a/integration-tests/demo/src/test/kotlin/com/squareup/test/demo/DemoAppTest.kt
+++ b/integration-tests/demo/src/test/kotlin/com/squareup/test/demo/DemoAppTest.kt
@@ -4,6 +4,7 @@ import android.app.Application
 import com.squareup.development.shell.DevelopmentAppComponent
 import dev.zacsweers.metro.createGraphFactory
 import kotlin.test.Test
+import kotlin.test.assertEquals
 import kotlin.test.assertIs
 import kotlin.test.assertNotNull
 
@@ -29,4 +30,16 @@ class DemoAppTest {
     val component = factory.create(Application())
     assertNotNull(component)
   }
+
+  @Test
+  fun `same-module ContributesBinding is discovered for generated DependencyGraph`() {
+    val factory = createGraphFactory<DemoApp.MetroComponent.Factory>()
+    val component = factory.create(Application())
+    // This verifies that DemoServiceImpl's @ContributesBinding(AppScope::class) is properly
+    // merged into the MetroComponent generated by @DevelopmentAppComponent. Without the
+    // name-based fallback in ContributedInterfaceSupertypeGenerator, the scope resolution
+    // fails during the SUPERTYPES phase and DemoService cannot be provided.
+    val service = (component as DemoServiceComponent).demoService
+    assertEquals("contributed-binding", service.name)
+  }
 }