Update server/chatStream.js

server/chatStream.js

@@ -39,7 +39,7 @@ export async function streamChat(ws, {
 
   const messages = [
     { role: "system", content: SYSTEM_PROMPT },
-    ...history.map(normalizeMessage),
+    ...history.map(normalizeMessage).filter(Boolean),
     { role: "user", content: userMessage },
   ];
 
@@ -119,7 +119,7 @@ export async function streamChat(ws, {
       // Follow-up response after tool calls
       const followUpMessages = [
         { role: "system", content: SYSTEM_PROMPT },
-        ...history.map(normalizeMessage),
+        ...history.map(normalizeMessage).filter(Boolean),
         { role: "user", content: userMessage },
         { role: "assistant", content: assistantText || "", tool_calls: toolCalls },
         ...toolResults,
@@ -138,11 +138,12 @@ export async function streamChat(ws, {
 
       if (followUp.ok) {
         const fuReader = followUp.body.getReader();
+        const fuDecoder = new TextDecoder(); // fresh decoder — reusing the first one corrupts the stream
         let fuBuffer = "";
         while (true) {
           const { done, value } = await fuReader.read();
           if (done) break;
-          fuBuffer += decoder.decode(value, { stream: true });
+          fuBuffer += fuDecoder.decode(value, { stream: true });
           const fuLines = fuBuffer.split("\n");
           fuBuffer = fuLines.pop() || "";
           for (const line of fuLines) {
@@ -171,11 +172,17 @@ export async function streamChat(ws, {
   }
 }
 
+const VALID_ROLES = new Set(["system", "user", "assistant", "tool"]);
+
 function normalizeMessage(msg) {
+  // Drop asset entries (role: "image"/"video"/"audio") — these are UI-only
+  // and sending them to the LLM causes invalid-role rejections / blank responses
+  if (!VALID_ROLES.has(msg.role)) return null;
+
   if (msg.role === "assistant" && msg.tool_calls) {
     return { role: "assistant", content: "", tool_calls: msg.tool_calls };
   }
-  // Flatten multipart content arrays to text-only for history
+  // Flatten multipart content arrays (e.g. image attachments) to text-only for history
   if (Array.isArray(msg.content)) {
     const textOnly = msg.content
       .filter(b => b.type === "text")
@@ -386,4 +393,4 @@ async function processToolCalls(ws, toolCalls, tools, accessToken, clientId, abo
   }
 
   return toolResults;
-}
+}