From 4f24b8bc6faaea456d92f8296fbc84a560c3c8c6 Mon Sep 17 00:00:00 2001
From: Henry Mao <1828968+calclavia@users.noreply.github.com>
Date: Tue, 24 Jun 2025 04:36:54 +0800
Subject: [PATCH 1/4] Fix `/.well-known/oauth-authorization-server` dropping
 path

---
 src/client/auth.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/client/auth.ts b/src/client/auth.ts
index d953e1f0a..35105daa4 100644
--- a/src/client/auth.ts
+++ b/src/client/auth.ts
@@ -297,7 +297,9 @@ export async function discoverOAuthMetadata(
   authorizationServerUrl: string | URL,
   opts?: { protocolVersion?: string },
 ): Promise<OAuthMetadata | undefined> {
-  const url = new URL("/.well-known/oauth-authorization-server", authorizationServerUrl);
+  const wellKnownPath = `/.well-known/oauth-authorization-server${issuer.pathname}`;
+  const url = new URL(wellKnownPath, authorizationServerUrl);
+
   let response: Response;
   try {
     response = await fetch(url, {

From da6ac79c1e2bcc1979f03ccaaf61094b5c9d4adf Mon Sep 17 00:00:00 2001
From: Henry Mao <1828968+calclavia@users.noreply.github.com>
Date: Tue, 24 Jun 2025 04:41:26 +0800
Subject: [PATCH 2/4] Fix missing issuer

---
 src/client/auth.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/client/auth.ts b/src/client/auth.ts
index 35105daa4..33a9a6b9b 100644
--- a/src/client/auth.ts
+++ b/src/client/auth.ts
@@ -297,6 +297,8 @@ export async function discoverOAuthMetadata(
   authorizationServerUrl: string | URL,
   opts?: { protocolVersion?: string },
 ): Promise<OAuthMetadata | undefined> {
+  const issuer = new URL(authorizationServerUrl);
+
   const wellKnownPath = `/.well-known/oauth-authorization-server${issuer.pathname}`;
   const url = new URL(wellKnownPath, authorizationServerUrl);
 

From 622070135242f9276b87de59b47a301fa7062cdc Mon Sep 17 00:00:00 2001
From: Henry Mao <1828968+calclavia@users.noreply.github.com>
Date: Mon, 23 Jun 2025 17:13:13 -0400
Subject: [PATCH 3/4] Fix trailing slash

---
 src/client/auth.ts | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/client/auth.ts b/src/client/auth.ts
index 33a9a6b9b..cba14a9c5 100644
--- a/src/client/auth.ts
+++ b/src/client/auth.ts
@@ -299,8 +299,12 @@ export async function discoverOAuthMetadata(
 ): Promise<OAuthMetadata | undefined> {
   const issuer = new URL(authorizationServerUrl);
 
-  const wellKnownPath = `/.well-known/oauth-authorization-server${issuer.pathname}`;
-  const url = new URL(wellKnownPath, authorizationServerUrl);
+  let wellKnownPath = `/.well-known/oauth-authorization-server${issuer.pathname}`;
+  if (issuer.pathname.endsWith('/')) {
+    // Strip trailing slash from pathname
+    wellKnownPath = wellKnownPath.slice(0, -1);
+  }
+  const url = new URL(wellKnownPath, issuer);
 
   let response: Response;
   try {

From 1ff08e41d7088a63f208034a0f3bf3acfe5bf03e Mon Sep 17 00:00:00 2001
From: Henry Mao <1828968+calclavia@users.noreply.github.com>
Date: Mon, 23 Jun 2025 17:32:08 -0400
Subject: [PATCH 4/4] Add path test

---
 src/client/auth.test.ts | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/client/auth.test.ts b/src/client/auth.test.ts
index f95cb2ca8..511b351fb 100644
--- a/src/client/auth.test.ts
+++ b/src/client/auth.test.ts
@@ -207,6 +207,24 @@ describe("OAuth Authorization", () => {
       });
     });
 
+    it("returns metadata when discovery succeeds with path", async () => {
+      mockFetch.mockResolvedValueOnce({
+        ok: true,
+        status: 200,
+        json: async () => validMetadata,
+      });
+
+      const metadata = await discoverOAuthMetadata("https://auth.example.com/path/name");
+      expect(metadata).toEqual(validMetadata);
+      const calls = mockFetch.mock.calls;
+      expect(calls.length).toBe(1);
+      const [url, options] = calls[0];
+      expect(url.toString()).toBe("https://auth.example.com/.well-known/oauth-authorization-server/path/name");
+      expect(options.headers).toEqual({
+        "MCP-Protocol-Version": LATEST_PROTOCOL_VERSION
+      });
+    });
+
     it("returns metadata when first fetch fails but second without MCP header succeeds", async () => {
       // Set up a counter to control behavior
       let callCount = 0;