Fixed OAuth error when 401 comes from initialize (instead of connect, as is more common). Also, now we automatically start auth when auth required (instead of just bringing up the auth ux and making the user push a button). This should be at parity with how v1 works.

Author: BobDickinson

core/mcp/remote/node/server.ts

@@ -461,11 +461,11 @@ export function createRemoteApp(
     } catch (err) {
       // transport.start() threw - this is the expected failure path
       const msg = err instanceof Error ? err.message : String(err);
-      // Preserve 401 status if the underlying error is a 401
-      const is401 =
-        (err as { code?: number }).code === 401 ||
-        msg.includes("401") ||
-        msg.includes("Unauthorized");
+      // Preserve 401 only when the transport/SDK reports it (no message guessing)
+      const status =
+        (err as { code?: number; status?: number }).code ??
+        (err as { code?: number; status?: number }).status;
+      const is401 = status === 401;
       return c.json(
         { error: `Failed to start transport: ${msg}` },
         is401 ? 401 : 500,
@@ -509,7 +509,12 @@ export function createRemoteApp(
       return c.json({ ok: true });
     } catch (err) {
       const msg = err instanceof Error ? err.message : String(err);
-      return c.json({ error: msg }, 500);
+      // Preserve 401 only when the transport/SDK reports it (no message guessing)
+      const status =
+        (err as { code?: number; status?: number }).code ??
+        (err as { code?: number; status?: number }).status;
+      const is401 = status === 401;
+      return c.json({ error: msg }, is401 ? 401 : 500);
     }
   });
 

core/mcp/remote/remoteClientTransport.ts

@@ -294,7 +294,9 @@ export class RemoteClientTransport implements Transport {
 
     if (!res.ok) {
       const text = await res.text();
-      throw new Error(`Remote send failed (${res.status}): ${text}`);
+      const error = new Error(`Remote send failed (${res.status}): ${text}`);
+      (error as { status?: number }).status = res.status;
+      throw error;
     }
   }
 

web/src/App.tsx

@@ -547,12 +547,29 @@ const App = () => {
     try {
       await client.connect();
     } catch (error) {
-      const message = error instanceof Error ? error.message : String(error);
-      toast({
-        title: "Connection failed",
-        description: message,
-        variant: "destructive",
-      });
+      const status = (error as { status?: number }).status;
+      if (status === 401) {
+        try {
+          await client.authenticate();
+        } catch (authError) {
+          setIsAuthDebuggerVisible(true);
+          toast({
+            title: "Authentication required",
+            description:
+              authError instanceof Error
+                ? authError.message
+                : String(authError),
+            variant: "destructive",
+          });
+        }
+      } else {
+        const message = error instanceof Error ? error.message : String(error);
+        toast({
+          title: "Connection failed",
+          description: message,
+          variant: "destructive",
+        });
+      }
       if (client.getStatus() === "connecting") {
         await client.disconnect();
       }