chore: import upstream snapshot with attribution

docs-website/api/mcp.ts

@@ -0,0 +1,72 @@
+// Files under `api/` become HTTP endpoints automatically — this is `/api/mcp`.
+import { VercelRequest, VercelResponse } from "@vercel/node";
+
+export default async function handler(req: VercelRequest, res: VercelResponse) {
+  res.setHeader("Access-Control-Allow-Origin", "*");
+  res.setHeader("Access-Control-Allow-Methods", "POST, OPTIONS");
+  res.setHeader(
+    "Access-Control-Allow-Headers",
+    "Content-Type, Accept, Mcp-Session-Id, Mcp-Protocol-Version"
+  );
+  res.setHeader("Access-Control-Expose-Headers", "Mcp-Session-Id");
+
+  if (req.method === "OPTIONS") {
+    return res.status(204).end();
+  }
+
+  if (req.method !== "POST") {
+    res.setHeader("Allow", "POST, OPTIONS");
+    return res.status(405).end("Method Not Allowed");
+  }
+
+  // Get environment variables
+  const { MCP_WORKSPACE_ID, SEARCH_API_TOKEN } = process.env;
+
+  if (!MCP_WORKSPACE_ID || !SEARCH_API_TOKEN) {
+    return res.status(500).json({ error: "MCP service is not configured." });
+  }
+
+  try {
+    // Forward the JSON-RPC body unchanged with the API key injected, so we
+    // don't need to know any MCP methods — new upstream tools just work.
+    const apiResponse = await fetch(
+      `https://api.cloud.deepset.ai/api/v2/workspaces/${MCP_WORKSPACE_ID}/mcp`,
+      {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          Accept:
+            (req.headers.accept as string) ||
+            "application/json, text/event-stream",
+          "X-Client-Source": "haystack-docs",
+          Authorization: `Bearer ${SEARCH_API_TOKEN}`,
+          // Forward MCP session id so upstream can correlate requests.
+          ...(req.headers["mcp-session-id"] && {
+            "Mcp-Session-Id": req.headers["mcp-session-id"] as string,
+          }),
+          // Forward the protocol version the client negotiated.
+          ...(req.headers["mcp-protocol-version"] && {
+            "Mcp-Protocol-Version": req.headers[
+              "mcp-protocol-version"
+            ] as string,
+          }),
+        },
+        body: JSON.stringify(req.body),
+      }
+    );
+
+    // Pass the response through as-is (status, content-type, raw body).
+    const text = await apiResponse.text();
+    res.status(apiResponse.status);
+    const contentType = apiResponse.headers.get("content-type");
+    if (contentType) res.setHeader("Content-Type", contentType);
+    // Surface the session id back to the client (browsers can read it because
+    // it's in Access-Control-Expose-Headers above).
+    const sessionId = apiResponse.headers.get("mcp-session-id");
+    if (sessionId) res.setHeader("Mcp-Session-Id", sessionId);
+    return res.send(text);
+  } catch (error) {
+    console.error("MCP proxy error:", error);
+    return res.status(502).json({ error: "Failed to reach MCP upstream." });
+  }
+}