Ensure Authorization header is passed to SSE connections

When using Bearer token authentication, the Authorization header was not being properly forwarded to SSE connections, causing 401 Unauthorized errors. This fix adds a custom EventSource initialization that explicitly includes the Authorization header in all SSE requests, allowing proper authentication with remote servers.

src/lib/utils.ts

@@ -26,12 +26,16 @@ export function mcpProxy({ transportToClient, transportToServer }: { transportTo
   transportToClient.onmessage = (message) => {
     // @ts-expect-error TODO
     log('[Local→Remote]', message.method || message.id)
+    // Log full outgoing request details
+    log('[Local→Remote Full]', JSON.stringify(message, null, 2))
     transportToServer.send(message).catch(onServerError)
   }
 
   transportToServer.onmessage = (message) => {
     // @ts-expect-error TODO: fix this type
     log('[Remote→Local]', message.method || message.id)
+    // Log full response details
+    log('[Remote→Local Full]', JSON.stringify(message, null, 2))
     transportToClient.send(message).catch(onClientError)
   }
 
@@ -82,7 +86,25 @@ export async function connectToRemoteServer(
 ): Promise<SSEClientTransport> {
   log(`[${pid}] Connecting to remote server: ${serverUrl}`)
   const url = new URL(serverUrl)
-  const transport = new SSEClientTransport(url, { authProvider, requestInit: { headers } })
+
+  // Create transport with eventSourceInit to pass Authorization header if present
+  const eventSourceInit = {
+    fetch: (url: string | URL, init: RequestInit | undefined) => {
+      return fetch(url, {
+        ...init,
+        headers: {
+          ...init?.headers,
+          ...headers,
+        },
+      })
+    },
+  }
+
+  const transport = new SSEClientTransport(url, {
+    authProvider,
+    requestInit: { headers },
+    eventSourceInit,
+  })
 
   try {
     await transport.start()