diff --git a/src/apps/chat/AppChat.tsx b/src/apps/chat/AppChat.tsx
index 639577a3c..74324bc27 100644
--- a/src/apps/chat/AppChat.tsx
+++ b/src/apps/chat/AppChat.tsx
@@ -268,7 +268,7 @@ export function AppChat() {
     if (!focusedPaneConversationId) return;
     const cHandler = ConversationsManager.getHandler(focusedPaneConversationId);
     if (!cHandler.isValid()) return;
-    const inputHistory = cHandler.historyViewHead('chat-beam-shortcut');
+    const inputHistory = cHandler.historyViewHeadOrThrow('chat-beam-shortcut');
     if (!inputHistory.length) return;
 
     // TODO: replace the Persona and Auto-Cache-hint in the history?
diff --git a/src/apps/chat/components/ChatMessageList.tsx b/src/apps/chat/components/ChatMessageList.tsx
index 12d8b0b7a..3842fa3d5 100644
--- a/src/apps/chat/components/ChatMessageList.tsx
+++ b/src/apps/chat/components/ChatMessageList.tsx
@@ -138,7 +138,7 @@ export function ChatMessageList(props: {
   const handleMessageBeam = React.useCallback(async (messageId: DMessageId) => {
     // Message option menu Beam
     if (!conversationId || !props.conversationHandler || !props.conversationHandler.isValid()) return;
-    const inputHistory = props.conversationHandler.historyViewHead('chat-beam-message');
+    const inputHistory = props.conversationHandler.historyViewHeadOrThrow('chat-beam-message');
     if (!inputHistory.length) return;
 
     // TODO: replace the Persona and Auto-Cache-hint in the history?
diff --git a/src/apps/chat/editors/_handleExecute.ts b/src/apps/chat/editors/_handleExecute.ts
index c94773fe8..79be46f71 100644
--- a/src/apps/chat/editors/_handleExecute.ts
+++ b/src/apps/chat/editors/_handleExecute.ts
@@ -24,7 +24,7 @@ export async function _handleExecute(chatExecuteMode: ChatExecuteMode, conversat
 
   const chatLLMId = getChatLLMId();
   const cHandler = ConversationsManager.getHandler(conversationId);
-  const initialHistory = cHandler.historyViewHead('chat-execute-' + executeCallerNameDebug) as Readonly<DMessage[]>;
+  const initialHistory = cHandler.historyViewHeadOrThrow('handle-execute-' + executeCallerNameDebug) as Readonly<DMessage[]>;
 
   // Update the system message from the active persona to the history
   // NOTE: this does NOT call setMessages anymore (optimization). make sure to:
@@ -72,7 +72,7 @@ export async function _handleExecute(chatExecuteMode: ChatExecuteMode, conversat
       return await runPersonaOnConversationHead(chatLLMId, conversationId);
 
     case 'beam-content':
-      const updatedInputHistory = cHandler.historyViewHead('chat-beam-execute');
+      const updatedInputHistory = cHandler.historyViewHeadOrThrow('chat-beam-execute');
       cHandler.beamInvoke(updatedInputHistory, [], null);
       return true;
 
diff --git a/src/apps/chat/editors/chat-persona.ts b/src/apps/chat/editors/chat-persona.ts
index 571035fc1..411b18e64 100644
--- a/src/apps/chat/editors/chat-persona.ts
+++ b/src/apps/chat/editors/chat-persona.ts
@@ -34,7 +34,7 @@ export async function runPersonaOnConversationHead(
 
   const cHandler = ConversationsManager.getHandler(conversationId);
 
-  const _history = cHandler.historyViewHead('runPersonaOnConversationHead') as Readonly<DMessage[]>;
+  const _history = cHandler.historyViewHeadOrThrow('runPersonaOnConversationHead') as Readonly<DMessage[]>;
   if (_history.length === 0)
     return false;
 
diff --git a/src/common/chat-overlay/ConversationHandler.ts b/src/common/chat-overlay/ConversationHandler.ts
index 971b170da..acbbb1a53 100644
--- a/src/common/chat-overlay/ConversationHandler.ts
+++ b/src/common/chat-overlay/ConversationHandler.ts
@@ -209,7 +209,7 @@ export class ConversationHandler {
     _chatStoreActions.historyTruncateToIncluded(this.conversationId, messageId, offset);
   }
 
-  historyViewHead(scope: string): Readonly<DMessage[]> {
+  historyViewHeadOrThrow(scope: string): Readonly<DMessage[]> {
     const messages = _chatStoreActions.historyView(this.conversationId);
     if (messages === undefined)
       throw new Error(`allMessages: Conversation not found, ${scope}`);
diff --git a/src/modules/aifn/digrams/DiagramsModal.tsx b/src/modules/aifn/digrams/DiagramsModal.tsx
index 10ae9b54c..2ad16848c 100644
--- a/src/modules/aifn/digrams/DiagramsModal.tsx
+++ b/src/modules/aifn/digrams/DiagramsModal.tsx
@@ -95,7 +95,7 @@ export function DiagramsModal(props: { config: DiagramConfig, onClose: () => voi
     setAbortController(stepAbortController);
     // cHandler.setAbortController(stepAbortController);
 
-    const reChatHistory = cHandler.historyViewHead('diagrams-modal');
+    const reChatHistory = cHandler.historyViewHeadOrThrow('diagrams-modal');
     const { chatSystemInstruction } = splitSystemMessageFromHistory(reChatHistory);
     if (!chatSystemInstruction)
       return setErrorMessage('No System instruction in this conversation');