sketch: Introduce versions for sketch state
diff --git a/webui/src/web-components/sketch-app-shell.ts b/webui/src/web-components/sketch-app-shell.ts
index c9553b4..0b58a10 100644
--- a/webui/src/web-components/sketch-app-shell.ts
+++ b/webui/src/web-components/sketch-app-shell.ts
@@ -331,6 +331,7 @@
 
   @property({ attribute: false })
   containerState: State = {
+    state_version: 2,
     title: "",
     os: "",
     message_count: 0,