diff --git a/embrace-android-sdk/src/main/java/io/embrace/android/embracesdk/payload/SessionMessage.kt b/embrace-android-sdk/src/main/java/io/embrace/android/embracesdk/payload/SessionMessage.kt
index be9eda69f6..329faeaefb 100644
--- a/embrace-android-sdk/src/main/java/io/embrace/android/embracesdk/payload/SessionMessage.kt
+++ b/embrace-android-sdk/src/main/java/io/embrace/android/embracesdk/payload/SessionMessage.kt
@@ -3,6 +3,9 @@ package io.embrace.android.embracesdk.payload
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
 import io.embrace.android.embracesdk.comms.api.ApiClient
+import io.embrace.android.embracesdk.internal.payload.EnvelopeMetadata
+import io.embrace.android.embracesdk.internal.payload.EnvelopeResource
+import io.embrace.android.embracesdk.internal.payload.SessionPayload
 import io.embrace.android.embracesdk.internal.spans.EmbraceSpanData
 
 /**
@@ -52,5 +55,32 @@ internal data class SessionMessage @JvmOverloads internal constructor(
     val spans: List<EmbraceSpanData>? = null,
 
     @Json(name = "v")
-    val version: Int = ApiClient.MESSAGE_VERSION
+    val version: Int = ApiClient.MESSAGE_VERSION,
+
+    /*
+     * Values below this point are copied temporarily from [Envelope]. Eventually we will migrate
+     * everything to use [Envelope] and [SessionPayload] and remove this class,
+     * but we'll keep it for now for backwards compat.
+     */
+
+    @Json(name = "resource")
+    val resource: EnvelopeResource? = null,
+
+    @Json(name = "metadata")
+    val metadata: EnvelopeMetadata? = null,
+
+    @Json(name = "version")
+    val newVersion: String? = null,
+
+    @Json(name = "type")
+    val type: String? = null,
+
+    @Json(name = "data")
+    val data: SessionPayload? = null
 )
+
+/**
+ * Returns true if this message is a v2 payload. If so, it should be sent to a different
+ * endpoint & handled differently.
+ */
+internal fun SessionMessage.isV2Payload() = data != null
diff --git a/embrace-android-sdk/src/test/java/io/embrace/android/embracesdk/payload/SessionMessageTest.kt b/embrace-android-sdk/src/test/java/io/embrace/android/embracesdk/payload/SessionMessageTest.kt
index 36ed4eb7a0..9b8c5fd825 100644
--- a/embrace-android-sdk/src/test/java/io/embrace/android/embracesdk/payload/SessionMessageTest.kt
+++ b/embrace-android-sdk/src/test/java/io/embrace/android/embracesdk/payload/SessionMessageTest.kt
@@ -5,10 +5,13 @@ import io.embrace.android.embracesdk.assertJsonMatchesGoldenFile
 import io.embrace.android.embracesdk.deserializeEmptyJsonString
 import io.embrace.android.embracesdk.deserializeJsonFromResource
 import io.embrace.android.embracesdk.fakes.fakeSession
+import io.embrace.android.embracesdk.internal.payload.SessionPayload
 import io.embrace.android.embracesdk.internal.spans.EmbraceSpanData
 import io.opentelemetry.api.trace.StatusCode
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
 import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertTrue
 import org.junit.Test
 
 internal class SessionMessageTest {
@@ -66,4 +69,11 @@ internal class SessionMessageTest {
     fun testEmptyObject() {
         deserializeEmptyJsonString<SessionMessage>()
     }
+
+    @Test
+    fun `is v2 payload`() {
+        assertFalse(info.isV2Payload())
+        val obj = SessionMessage(session = session, data = SessionPayload())
+        assertTrue(obj.isV2Payload())
+    }
 }