Files
2026-07-13 12:58:18 +08:00

69 lines
3.4 KiB
C#

using Microsoft.Agents.AI;
using Microsoft.Extensions.AI;
using OpenAI;
// ============================================================================
// Multimodal Agent
// ============================================================================
//
// Vision-capable .NET agent for the Multimodal Attachments demo cell.
//
// Design mirrors the LangGraph reference
// (showcase/integrations/langgraph-python/src/agents/multimodal_agent.py):
// - Use a vision-capable chat model (gpt-4o / gpt-4o-mini) so images are
// consumed natively by the model via OpenAI's image content parts.
// - No tools are registered — the model handles image/PDF analysis directly.
// - PDF handling: Microsoft.Extensions.AI passes document/data content parts
// through as DataContent, and modern OpenAI chat models accept PDF input
// directly. We therefore avoid bundling a PDF extractor (like pypdf on the
// Python side) and defer to the model's native document handling. If a PDF
// cannot be read, the model will tell the user — matching the "[Attached
// document: PDF could not be read.]" graceful degradation in Python.
//
// Wire format: `MultimodalEndpoint` parses the modern
// `{ type: "image" | "document", source: {...} }` content parts CopilotChat
// emits and forwards them as DataContent parts the chat client can pass to
// the OpenAI image/file adapters unchanged. The dedicated endpoint exists
// because the current Microsoft AG-UI ASP.NET adapter rejects content arrays
// before an AIAgent can see them.
//
// Mount point: `/multimodal` (see Program.cs). The Next.js runtime's
// `src/app/api/copilotkit-multimodal/route.ts` proxies to this endpoint via
// AG-UI over HTTP.
//
// NOTE (harness): unlike the MapAGUI feature agents, this path is wired as a
// raw `MapPost("/multimodal", ...)` -> MultimodalEndpoint.HandleAsync over a
// shared IChatClient (SalesAgentFactory.CreateMultimodalChatClient). Because
// the endpoint consumes a chat client directly (not an AIAgent), there is no
// AsHarnessAgent transformation here — the harness construction delta does
// not apply. This factory's `Create` is retained for parity/testing and the
// `SystemPrompt` const is what MultimodalEndpoint applies as ChatOptions.
// ============================================================================
internal static class MultimodalAgentFactory
{
internal const string SystemPrompt =
"You are a helpful assistant. The user may attach images or documents " +
"(PDFs). When they do, analyze the attachment carefully and answer the " +
"user's question. If no attachment is present, answer the text question " +
"normally. Keep responses concise (1-3 sentences) unless asked to go deep.";
public static AIAgent Create(OpenAIClient openAiClient)
{
ArgumentNullException.ThrowIfNull(openAiClient);
// gpt-4o-mini supports vision natively. Matches the rest of the
// dotnet showcase (which uses gpt-4o-mini for every cell) so we don't
// introduce a new model id just for this cell. The LangGraph
// reference uses gpt-4o for slightly higher image-reasoning quality;
// gpt-4o-mini is cheaper and still vision-capable.
var chatClient = openAiClient.GetChatClient("gpt-4o-mini").AsIChatClient();
return new ChatClientAgent(
chatClient,
name: "MultimodalAgent",
description: SystemPrompt,
tools: []);
}
}