feat: new chat working stateless. Added citation logic.

surfsense_web/lib/chat/new-chat-transport.ts

@@ -0,0 +1,167 @@
+/**
+ * Custom ChatModelAdapter for the new-chat feature using LocalRuntime.
+ * Connects directly to the FastAPI backend using the Vercel AI SDK Data Stream Protocol.
+ */
+
+import type { ChatModelAdapter, ChatModelRunOptions } from "@assistant-ui/react";
+import { getBearerToken } from "@/lib/auth-utils";
+
+interface NewChatAdapterConfig {
+	searchSpaceId: number;
+	chatId: number;
+}
+
+/**
+ * Creates a ChatModelAdapter that connects to the FastAPI new_chat endpoint.
+ *
+ * The backend expects:
+ * - POST /api/v1/new_chat
+ * - Body: { chat_id: number, user_query: string, search_space_id: number }
+ * - Returns: SSE stream with Vercel AI SDK Data Stream Protocol
+ */
+export function createNewChatAdapter(config: NewChatAdapterConfig): ChatModelAdapter {
+	const backendUrl = process.env.NEXT_PUBLIC_FASTAPI_BACKEND_URL || "http://localhost:8000";
+
+	return {
+		async *run({ messages, abortSignal }: ChatModelRunOptions) {
+			// Get the last user message
+			const lastUserMessage = messages.filter((m) => m.role === "user").pop();
+
+			if (!lastUserMessage) {
+				throw new Error("No user message found");
+			}
+
+			// Extract text content from the message
+			let userQuery = "";
+			for (const part of lastUserMessage.content) {
+				if (part.type === "text") {
+					userQuery += part.text;
+				}
+			}
+
+			if (!userQuery.trim()) {
+				throw new Error("User query cannot be empty");
+			}
+
+			const token = getBearerToken();
+			if (!token) {
+				throw new Error("Not authenticated. Please log in again.");
+			}
+
+			const response = await fetch(`${backendUrl}/api/v1/new_chat`, {
+				method: "POST",
+				headers: {
+					"Content-Type": "application/json",
+					Authorization: `Bearer ${token}`,
+				},
+				body: JSON.stringify({
+					chat_id: config.chatId,
+					user_query: userQuery.trim(),
+					search_space_id: config.searchSpaceId,
+				}),
+				signal: abortSignal,
+			});
+
+			if (!response.ok) {
+				const errorText = await response.text().catch(() => "Unknown error");
+				throw new Error(`Backend error (${response.status}): ${errorText}`);
+			}
+
+			if (!response.body) {
+				throw new Error("No response body");
+			}
+
+			// Parse the SSE stream (Vercel AI SDK Data Stream Protocol)
+			const reader = response.body.getReader();
+			const decoder = new TextDecoder();
+			let buffer = "";
+			let accumulatedText = "";
+
+			try {
+				while (true) {
+					const { done, value } = await reader.read();
+					if (done) {
+						break;
+					}
+
+					const chunk = decoder.decode(value, { stream: true });
+					buffer += chunk;
+
+					// Split on double newlines (handle both \n\n and \r\n\r\n)
+					const events = buffer.split(/\r?\n\r?\n/);
+					buffer = events.pop() || "";
+
+					for (const event of events) {
+						// Each event can have multiple lines, find the data line
+						const lines = event.split(/\r?\n/);
+						for (const line of lines) {
+							if (!line.startsWith("data: ")) continue;
+
+							const data = line.slice(6).trim(); // Remove "data: " prefix
+
+							// Handle [DONE] marker
+							if (data === "[DONE]") {
+								continue;
+							}
+
+							if (!data) continue;
+
+							try {
+								const parsed = JSON.parse(data);
+
+								// Handle different message types from the Data Stream Protocol
+								switch (parsed.type) {
+									case "text-delta":
+										accumulatedText += parsed.delta;
+										yield {
+											content: [{ type: "text" as const, text: accumulatedText }],
+										};
+										break;
+
+									case "error":
+										throw new Error(parsed.errorText || "Unknown error from server");
+
+									// Other types like text-start, text-end, tool-*, etc.
+									// are handled implicitly - we just accumulate text deltas
+									default:
+										break;
+								}
+							} catch (e) {
+								// Skip non-JSON lines
+								if (e instanceof SyntaxError) {
+									continue;
+								}
+								throw e;
+							}
+						}
+					}
+				}
+
+				// Handle any remaining buffer
+				if (buffer.trim()) {
+					const lines = buffer.split(/\r?\n/);
+					for (const line of lines) {
+						if (line.startsWith("data: ")) {
+							const data = line.slice(6).trim();
+							if (data && data !== "[DONE]") {
+								try {
+									const parsed = JSON.parse(data);
+									if (parsed.type === "text-delta") {
+										accumulatedText += parsed.delta;
+										yield {
+											content: [{ type: "text" as const, text: accumulatedText }],
+										};
+									}
+								} catch {
+									// Ignore parse errors
+								}
+							}
+						}
+					}
+				}
+			} finally {
+				reader.releaseLock();
+			}
+		},
+	};
+}