diff --git a/apps/cloud/src/app-paths.test.ts b/apps/cloud/src/app-paths.test.ts
index dd9ff1af3c..024ec5091a 100644
--- a/apps/cloud/src/app-paths.test.ts
+++ b/apps/cloud/src/app-paths.test.ts
@@ -20,6 +20,7 @@ describe("isAppOwnedPath", () => {
     "/mcp",
     "/mcp/toolkits/deploy-kit",
     "/.well-known/oauth-protected-resource/mcp",
+    "/.well-known/oauth-protected-resource/_v1/mcp",
     "/.well-known/oauth-protected-resource/mcp/toolkits/deploy-kit",
     "/.well-known/oauth-authorization-server",
     // Org-pinned MCP: the org's URL slug (what the install card prints) and
diff --git a/apps/cloud/src/mcp/mount.test.ts b/apps/cloud/src/mcp/mount.test.ts
index dd9c0a3f49..c4d7b0af30 100644
--- a/apps/cloud/src/mcp/mount.test.ts
+++ b/apps/cloud/src/mcp/mount.test.ts
@@ -55,3 +55,48 @@ describe("cloud MCP toolkit route normalization", () => {
     );
   });
 });
+
+// Executor v2 will own `executor.sh/mcp`'s root discovery documents, so plain
+// `/mcp` names a v1-only alias of the bare document in its challenge.
+describe("cloud MCP plain-/mcp resource metadata alias", () => {
+  it("challenges plain /mcp with the v1 alias, and org and toolkit URLs with their own documents", () => {
+    expect(protectedResourceMetadataUrlFor(null)).toBe(
+      "https://executor.sh/.well-known/oauth-protected-resource/_v1/mcp",
+    );
+    expect(protectedResourceMetadataUrlFor("acme")).toBe(
+      "https://executor.sh/.well-known/oauth-protected-resource/acme/mcp",
+    );
+    expect(protectedResourceMetadataUrlFor("org_01ABCDEF")).toBe(
+      "https://executor.sh/.well-known/oauth-protected-resource/org_01ABCDEF/mcp",
+    );
+  });
+
+  it("classifies the alias as the bare document, not an org", () => {
+    expect(classifyMcpPath("/.well-known/oauth-protected-resource/_v1/mcp")).toEqual({
+      kind: "oauth-protected-resource",
+      organizationId: null,
+    });
+    expect(classifyMcpPath("/.well-known/oauth-protected-resource/mcp")).toEqual({
+      kind: "oauth-protected-resource",
+      organizationId: null,
+    });
+    // `_v1` only names the bare document; it is not an org selector.
+    expect(classifyMcpPath("/_v1/mcp")).toBeNull();
+    expect(
+      classifyMcpPath("/.well-known/oauth-protected-resource/_v1/mcp/toolkits/deploy"),
+    ).toBeNull();
+  });
+
+  it("rewrites the alias to the mounted bare document and drops any org header", () => {
+    const request = new Request(
+      "https://executor.sh/.well-known/oauth-protected-resource/_v1/mcp",
+      { headers: { "x-executor-mcp-organization": "spoofed" } },
+    );
+
+    const rewritten = prepareMcpOrgScope(request);
+
+    expect(new URL(rewritten.url).pathname).toBe("/.well-known/oauth-protected-resource/mcp");
+    expect(rewritten.headers.has("x-executor-mcp-organization")).toBe(false);
+    expect(toolkitSlugFromRequest(rewritten)).toBeNull();
+  });
+});
diff --git a/e2e/cloud/mcp-expired-token-rediscovery.test.ts b/e2e/cloud/mcp-expired-token-rediscovery.test.ts
new file mode 100644
index 0000000000..db8d6f9e0d
--- /dev/null
+++ b/e2e/cloud/mcp-expired-token-rediscovery.test.ts
@@ -0,0 +1,171 @@
+// Cloud: an MCP SDK client whose plain-`/mcp` token has expired follows the
+// 401's `resource_metadata` back to this product's authorization server.
+//
+// Executor v2 will serve `executor.sh/mcp`'s root discovery documents
+// (`/.well-known/oauth-protected-resource/mcp`,
+// `/.well-known/oauth-authorization-server`) while v1 still answers plain
+// `/mcp` requests that carry a v1 token. So the challenge must name a v1-only
+// document, and a spec-following client must never consult the root ones on
+// the way to re-authorizing. Driven with the real @modelcontextprotocol/sdk
+// client; the run stops where the SDK would open the browser.
+import { expect } from "@effect/vitest";
+import { Effect } from "effect";
+
+import { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import {
+  UnauthorizedError,
+  type OAuthClientProvider,
+} from "@modelcontextprotocol/sdk/client/auth.js";
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
+import type {
+  OAuthClientInformationMixed,
+  OAuthTokens,
+} from "@modelcontextprotocol/sdk/shared/auth.js";
+
+import { scenario } from "../src/scenario";
+import { Target } from "../src/services";
+
+const V1_RESOURCE_METADATA_PATH = "/.well-known/oauth-protected-resource/_v1/mcp";
+const ROOT_DISCOVERY_PATHS = [
+  "/.well-known/oauth-protected-resource",
+  "/.well-known/oauth-protected-resource/mcp",
+  "/.well-known/oauth-authorization-server",
+];
+
+const base64url = (value: unknown): string =>
+  Buffer.from(JSON.stringify(value)).toString("base64url");
+
+/** A JWT shaped like an expired access token from `issuer`. The signature is
+ *  junk: the server must reject it either way, and the router only reads `iss`. */
+const expiredAccessToken = (issuer: string): string =>
+  [
+    base64url({ alg: "RS256", typ: "JWT" }),
+    base64url({
+      iss: issuer,
+      sub: "user_e2e_expired",
+      exp: Math.floor(Date.now() / 1000) - 3600,
+    }),
+    base64url("expired"),
+  ].join(".");
+
+type Hop = { readonly method: string; readonly url: string; readonly status: number };
+
+scenario(
+  "MCP protocol · an expired plain-/mcp token re-authorizes through the v1 discovery document",
+  {},
+  Effect.gen(function* () {
+    const target = yield* Target;
+    const mcpUrl = new URL("/mcp", target.baseUrl);
+
+    const bare = (yield* Effect.promise(async () =>
+      (await fetch(new URL("/.well-known/oauth-protected-resource/mcp", target.baseUrl))).json(),
+    )) as { readonly authorization_servers: ReadonlyArray<string> };
+    const authorizationServer = bare.authorization_servers[0] ?? "";
+    expect(authorizationServer, "the product advertises an authorization server").not.toBe("");
+
+    const hops: Array<Hop> = [];
+    const recordingFetch: typeof fetch = async (input, init) => {
+      const request = new Request(input, init);
+      const response = await fetch(request);
+      hops.push({ method: request.method, url: request.url, status: response.status });
+      return response;
+    };
+
+    let tokens: OAuthTokens | undefined = {
+      access_token: expiredAccessToken(authorizationServer),
+      token_type: "Bearer",
+      refresh_token: "refresh_e2e_revoked",
+    };
+    let clientInformation: OAuthClientInformationMixed | undefined;
+    let authorizationUrl: URL | undefined;
+    const provider: OAuthClientProvider = {
+      redirectUrl: "http://127.0.0.1:1/callback",
+      clientMetadata: {
+        client_name: "executor-e2e-expired-token",
+        redirect_uris: ["http://127.0.0.1:1/callback"],
+        grant_types: ["authorization_code", "refresh_token"],
+        response_types: ["code"],
+        token_endpoint_auth_method: "none",
+      },
+      clientInformation: () => clientInformation,
+      saveClientInformation: (info) => {
+        clientInformation = info;
+      },
+      tokens: () => tokens,
+      saveTokens: (next) => {
+        tokens = next;
+      },
+      invalidateCredentials: (scope) => {
+        if (scope === "all" || scope === "tokens") tokens = undefined;
+        if (scope === "all" || scope === "client") clientInformation = undefined;
+      },
+      redirectToAuthorization: (url) => {
+        authorizationUrl = url;
+      },
+      saveCodeVerifier: () => undefined,
+      codeVerifier: () => "",
+    };
+
+    const client = new Client({ name: "executor-e2e-expired-token", version: "0.0.1" });
+    const transport = new StreamableHTTPClientTransport(mcpUrl, {
+      authProvider: provider,
+      fetch: recordingFetch,
+    });
+    const connected = yield* Effect.promise(() =>
+      client.connect(transport).then(
+        () => "connected" as const,
+        (error: unknown) => (error instanceof UnauthorizedError ? "unauthorized" : String(error)),
+      ),
+    );
+    yield* Effect.promise(() => client.close());
+
+    yield* Effect.annotateCurrentSpan({ "e2e.hops": JSON.stringify(hops) });
+    expect(connected, "the expired token cannot connect; the client must re-authorize").toBe(
+      "unauthorized",
+    );
+
+    const first = hops[0];
+    expect(first?.url, "the client first calls plain /mcp with the expired token").toBe(
+      mcpUrl.toString(),
+    );
+    expect(first?.status, "the expired token is challenged").toBe(401);
+
+    const aliasUrl = new URL(V1_RESOURCE_METADATA_PATH, target.baseUrl).toString();
+    expect(
+      hops.some((hop) => hop.url === aliasUrl && hop.status === 200),
+      "the client fetches the v1 discovery document the challenge named",
+    ).toBe(true);
+    for (const path of ROOT_DISCOVERY_PATHS) {
+      const rootUrl = new URL(path, target.baseUrl).toString();
+      expect(
+        hops.some((hop) => hop.url === rootUrl),
+        `the client never consults the root discovery document ${path}`,
+      ).toBe(false);
+    }
+
+    const authServerOrigin = new URL(authorizationServer).origin;
+    expect(
+      hops.some(
+        (hop) =>
+          hop.url.startsWith(`${authServerOrigin}/.well-known/oauth-authorization-server`) &&
+          hop.status === 200,
+      ),
+      "the client reads the advertised authorization server's metadata",
+    ).toBe(true);
+    const tokenEndpoint = (yield* Effect.promise(async () =>
+      (await fetch(new URL("/.well-known/oauth-authorization-server", authorizationServer))).json(),
+    )) as { readonly token_endpoint: string };
+    expect(
+      hops.some((hop) => hop.method === "POST" && hop.url === tokenEndpoint.token_endpoint),
+      "the client tries its refresh token at the advertised authorization server",
+    ).toBe(true);
+    expect(
+      authorizationUrl?.origin,
+      "the browser sign-in opens on the advertised authorization server",
+    ).toBe(authServerOrigin);
+    expect(
+      authorizationUrl?.searchParams.get("resource"),
+      "the sign-in asks for the plain MCP resource",
+    ).toBe(mcpUrl.toString());
+  }),
+);
diff --git a/e2e/cloud/mcp-protocol.test.ts b/e2e/cloud/mcp-protocol.test.ts
index c192dd1812..fe19639899 100644
--- a/e2e/cloud/mcp-protocol.test.ts
+++ b/e2e/cloud/mcp-protocol.test.ts
@@ -20,6 +20,10 @@ import { Mcp, Target } from "../src/services";
 import type { Identity } from "../src/target";
 
 const JSON_AND_SSE = "application/json, text/event-stream";
+// Plain `/mcp` challenges name this v1-only alias of the bare discovery
+// document: once Executor v2 serves `executor.sh/mcp`'s root discovery, the
+// path-derived `/.well-known/oauth-protected-resource/mcp` is v2's.
+const V1_RESOURCE_METADATA_PATH = "/.well-known/oauth-protected-resource/_v1/mcp";
 const PROTOCOL_VERSION = "2025-03-26";
 const INITIALIZE_REQUEST = {
   jsonrpc: "2.0" as const,
@@ -201,6 +205,34 @@ scenario(
   }),
 );
 
+scenario(
+  "MCP protocol · the v1 alias serves the same discovery document as the bare path",
+  {},
+  Effect.gen(function* () {
+    const target = yield* Target;
+    const [bare, alias] = yield* Effect.promise(() =>
+      Promise.all([
+        fetch(new URL("/.well-known/oauth-protected-resource/mcp", target.baseUrl)),
+        fetch(new URL(V1_RESOURCE_METADATA_PATH, target.baseUrl), {
+          headers: { origin: "https://claude.ai" },
+        }),
+      ]),
+    );
+    expect(alias.status, "the alias is public").toBe(200);
+    expect(
+      alias.headers.get("access-control-allow-origin"),
+      "the alias is readable cross-origin",
+    ).toBe("*");
+    const aliasBody = (yield* Effect.promise(() => alias.json())) as Record<string, unknown>;
+    expect(aliasBody["resource"], "the alias names the plain MCP resource").toBe(
+      new URL("/mcp", target.baseUrl).toString(),
+    );
+    expect(aliasBody, "the alias is the bare document").toEqual(
+      yield* Effect.promise(() => bare.json()),
+    );
+  }),
+);
+
 scenario(
   "MCP protocol · a request without a bearer is challenged with the resource metadata",
   {},
@@ -212,8 +244,8 @@ scenario(
     expect(response.status, "anonymous requests are rejected").toBe(401);
     const wwwAuth = response.headers.get("www-authenticate") ?? "";
     expect(wwwAuth, "the challenge is a Bearer challenge").toContain('Bearer resource_metadata="');
-    expect(wwwAuth, "the challenge points at the discovery document").toContain(
-      new URL("/.well-known/oauth-protected-resource/mcp", target.baseUrl).toString(),
+    expect(wwwAuth, "the challenge points at v1's alias of the discovery document").toContain(
+      `resource_metadata="${new URL(V1_RESOURCE_METADATA_PATH, target.baseUrl).toString()}"`,
     );
     expect(wwwAuth, "a missing token carries no error code (per RFC 6750)").not.toContain("error=");
     expect(
@@ -241,8 +273,8 @@ scenario(
     expect(wwwAuth, "the challenge names the invalid_token error").toContain(
       'error="invalid_token"',
     );
-    expect(wwwAuth, "the challenge still points at the discovery document").toContain(
-      new URL("/.well-known/oauth-protected-resource/mcp", target.baseUrl).toString(),
+    expect(wwwAuth, "the challenge still points at v1's alias of the discovery document").toContain(
+      `resource_metadata="${new URL(V1_RESOURCE_METADATA_PATH, target.baseUrl).toString()}"`,
     );
     expect(yield* Effect.promise(() => response.json()), "the body is a JSON-RPC error").toEqual({
       jsonrpc: "2.0",