diff --git a/docs/document-runtime-architecture.md b/docs/document-runtime-architecture.md
index 28ec80e..f4730eb 100644
--- a/docs/document-runtime-architecture.md
+++ b/docs/document-runtime-architecture.md
@@ -146,7 +146,7 @@ pub struct ReadingSessionV2 {
 pub struct ReadingEventV2 {
     pub event_id: String,             // UUID, Rust 生成
     pub client_session_id: String,    // 来自 ReadingSessionV2
-    pub material_id: String,          // 来自 ReadingMaterialRef
+    pub material_id: String,          // 来自 ReadingMaterialRefV2
     pub event_type: ReadingEventTypeV2,
     pub position: Option<ReadingPosition>,
     pub active_seconds_delta: u32,    // 增量，非累计