fix(ui): hide synthetic helper text in user messages

Avoid rendering tool trace/read output parts on user messages while keeping the primary prompt text visible.

packages/ui/src/components/message-item.tsx

@@ -45,6 +45,15 @@ export default function MessageItem(props: MessageItemProps) {
 
   const messageParts = () => props.parts
 
+  // User messages can temporarily include synthetic helper parts (e.g. tool traces / file reads).
+  // We only want to display the primary prompt text for the user message; other synthetic text
+  // parts should be hidden.
+  const primaryUserTextPartId = () => {
+    if (!isUser()) return null
+    const firstText = messageParts().find((part) => part?.type === "text") as { id?: string } | undefined
+    return typeof firstText?.id === "string" ? firstText.id : null
+  }
+
   const fileAttachments = () =>
     messageParts().filter((part): part is FilePart => part?.type === "file" && typeof (part as FilePart).url === "string")
 
@@ -372,6 +381,7 @@ export default function MessageItem(props: MessageItemProps) {
               messageType={props.record.role}
               instanceId={props.instanceId}
               sessionId={props.sessionId}
+              primaryUserTextPartId={primaryUserTextPartId()}
               onRendered={props.onContentRendered}
             />
           )}

packages/ui/src/components/message-part.tsx

@@ -13,9 +13,12 @@ interface MessagePartProps {
   messageType?: "user" | "assistant"
   instanceId: string
   sessionId: string
+  // For user messages, keep the primary prompt text visible even when synthetic (optimistic).
+  // Other synthetic text parts (tool traces, read outputs, etc.) should be hidden.
+  primaryUserTextPartId?: string | null
   onRendered?: () => void
  }
-  export default function MessagePart(props: MessagePartProps) {
+   export default function MessagePart(props: MessagePartProps) {
 
   const { isDark } = useTheme()
   const { preferences } = useConfig()
@@ -28,8 +31,19 @@ interface MessagePartProps {
   const shouldHideTextPart = () => {
     const part = props.part
     if (!part || part.type !== "text") return false
-    // Keep optimistic user prompts visible; hide synthetic assistant text.
-    return Boolean((part as any).synthetic) && props.messageType !== "user"
+
+    const isSynthetic = Boolean((part as any).synthetic)
+    if (!isSynthetic) return false
+
+    // Keep optimistic user prompts visible; hide other synthetic user helper parts.
+    if (props.messageType === "user") {
+      const primaryId = props.primaryUserTextPartId
+      if (!primaryId) return false
+      return part.id !== primaryId
+    }
+
+    // Hide synthetic assistant text.
+    return true
   }
 
 

packages/ui/src/lib/prompt-placeholders.ts

@@ -1,4 +1,4 @@
-import type { Attachment } from "../types/attachment"
+import type { Attachment, FileSource } from "../types/attachment"
 
 export function resolvePastedPlaceholders(prompt: string, attachments: Attachment[] = []): string {
   if (!prompt) {
@@ -12,7 +12,7 @@ export function resolvePastedPlaceholders(prompt: string, attachments: Attachmen
   // IMPORTANT: avoid rewriting plain `@mentions` or email addresses.
   const fileAttachmentPaths = new Set(
     attachments
-      .filter((a) => a.source.type === "file")
+      .filter((a): a is Attachment & { source: FileSource } => a.source.type === "file")
       .map((a) => a.source.path),
   )