feat: add deterministic message interaction stages

frontend/src/components/pages/AssistantPage.tsx

@@ -177,7 +177,11 @@ function blankPromptForm(name: string): AssistantForm {
     knowledgeRetrievalConfig: defaultKnowledgeRetrievalConfig(),
     enableInterrupt: true,
     turnConfig: defaultTurnConfig(),
-    startup: { executionMode: "sequential", actions: [] },
+    startup: {
+      executionMode: "sequential",
+      actions: [],
+      openingMessage: null,
+    },
     visionEnabled: false,
     visionModelResourceId: "",
     toolIds: [],
@@ -466,7 +470,11 @@ export function AssistantPage(props: AssistantPageProps) {
         a.knowledgeRetrievalConfig ?? defaultKnowledgeRetrievalConfig(),
       enableInterrupt: a.enableInterrupt,
       turnConfig: normalizeTurnConfig(a.turnConfig),
-      startup: a.startup ?? { executionMode: "sequential", actions: [] },
+      startup: {
+        executionMode: "sequential",
+        actions: a.startup?.actions ?? [],
+        openingMessage: a.startup?.openingMessage ?? null,
+      },
       visionEnabled: a.visionEnabled,
       visionModelResourceId: a.visionModelResourceId ?? "",
       toolIds: a.toolIds ?? [],
@@ -536,7 +544,11 @@ export function AssistantPage(props: AssistantPageProps) {
       greeting: "",
       enableInterrupt: true,
       turnConfig: defaultTurnConfig(),
-      startup: { executionMode: "sequential", actions: [] },
+      startup: {
+        executionMode: "sequential",
+        actions: [],
+        openingMessage: null,
+      },
       visionEnabled: false,
       visionModelResourceId: null,
       modelResourceIds: {},