Allow chat history to be sent to AI engine (#6128)

# Description of Changes
Add an extra parameter to every agent to receive the conversation
history in addition to the current message. This will make it possible
to answer followup questions from the AI without needing to give full
context in your message.

frontend/src/prototypes/components/chat/ChatContext.tsx

@@ -238,6 +238,8 @@ export function ChatProvider({ children }: { children: ReactNode }) {
   const { files: activeFiles, fileStubs: activeFileStubs } = useAllFiles();
   const { actions: fileActions } = useFileActions();
   const abortRef = useRef<AbortController | null>(null);
+  const messagesRef = useRef<ChatMessage[]>(state.messages);
+  messagesRef.current = state.messages;
 
   // Download a File from the Stirling files endpoint.
   const downloadFile = useCallback(
@@ -323,6 +325,8 @@ export function ChatProvider({ children }: { children: ReactNode }) {
       const controller = new AbortController();
       abortRef.current = controller;
 
+      const priorMessages = messagesRef.current;
+
       const userMessage: ChatMessage = {
         id: crypto.randomUUID(),
         role: "user",
@@ -339,6 +343,10 @@ export function ChatProvider({ children }: { children: ReactNode }) {
         activeFiles.forEach((file, i) => {
           formData.append(`fileInputs[${i}].fileInput`, file);
         });
+        priorMessages.forEach((message, i) => {
+          formData.append(`conversationHistory[${i}].role`, message.role);
+          formData.append(`conversationHistory[${i}].content`, message.content);
+        });
 
         const response = await fetch("/api/v1/ai/orchestrate/stream", {
           method: "POST",