Function sendMessage

sdk/app-builder/src/components/app-builder.tsx:930–992

(event?: FormEvent<HTMLFormElement>)

  }

  async function sendMessage(event?: FormEvent<HTMLFormElement>) {
    event?.preventDefault()

    if (!session || !input.trim() || isRunning) {
      return
    }

    const conversationId = activeConversation.id
    const activeSession = session
    const activeModel = model
    const userText = input.trim()
    const assistantId = crypto.randomUUID()
    lastStreamEventTypeRef.current[conversationId] = null
    setConversationRuntime(conversationId, (current) => ({
      ...current,
      isRunning: true,
    }))
    updateConversation(conversationId, (conversation) => ({
      ...conversation,
      input: "",
      messages: [
        ...conversation.messages,
        { id: crypto.randomUUID(), role: "user", content: userText },
        {
          id: createAssistantSegmentId(assistantId),
          role: "assistant",
          content: "",
        },
      ],
      updatedAt: Date.now(),
    }))

    try {
      const response = await fetch("/api/chat", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          sessionId: activeSession.id,
          message: userText,
          model: activeModel,
        }),
      })

      if (!response.ok || !response.body) {
        const data = await response.json().catch(() => ({}))
        throw new Error(data.error ?? "The agent request failed.")
      }

      await readAgentStream(response.body, conversationId, assistantId)
    } catch (error) {
      const message = getFriendlyErrorMessage(error)
      setConversationMessages(conversationId, (current) => [
        ...current,
        { id: crypto.randomUUID(), role: "system", content: message },
      ])
    } finally {
      setConversationMessages(conversationId, finalizeActiveThinkingMessages)
      setConversationRuntime(conversationId, (current) => ({