feat(mcp_service): migrate mcp server to gateway

infra/packages/shared/src/gateway_priorities.ts

@@ -15,6 +15,7 @@ export enum GatewayService {
   CONNECTION_GATEWAY = 'CONNECTION_GATEWAY',
   AUTHENTICATION_SERVICE = 'AUTHENTICATION_SERVICE',
   EMAIL_SERVICE = 'EMAIL_SERVICE',
+  MCP_SERVER = 'MCP_SERVER',
   DOCUMENT_COGNITION_SERVICE = 'DOCUMENT_COGNITION_SERVICE',
 }
 
@@ -39,6 +40,7 @@ export const GATEWAY_PRIORITIES: GatewayPriorityMap = {
   [GatewayService.CONNECTION_GATEWAY]: 90,
   [GatewayService.AUTHENTICATION_SERVICE]: 100,
   [GatewayService.EMAIL_SERVICE]: 110,
+  [GatewayService.MCP_SERVER]: 130,
   [GatewayService.DOCUMENT_COGNITION_SERVICE]: 120,
   [GatewayService.CONVERT_SERVICE]: 3000,
 };

infra/packages/shared/src/service_urls.ts

@@ -15,6 +15,7 @@ export enum ServiceUrl {
   LEXICAL_SERVICE_URL = 'LEXICAL_SERVICE_URL',
   UNFURL_SERVICE_URL = 'UNFURL_SERVICE_URL',
   AGENT_HARNESS_SERVICE_URL = 'AGENT_HARNESS_SERVICE_URL',
+  MCP_SERVER_URL = 'MCP_SERVER_URL',
 }
 
 /**
@@ -47,6 +48,7 @@ const DEV_SERVICE_URLS: ServiceUrlMap = {
   [ServiceUrl.UNFURL_SERVICE_URL]: 'https://dev-gateway.macro.com/unfurl',
   [ServiceUrl.AGENT_HARNESS_SERVICE_URL]:
     'https://dev-gateway.macro.com/agent-harness',
+  [ServiceUrl.MCP_SERVER_URL]: 'https://dev-gateway.macro.com/mcp',
 };
 
 /**
@@ -70,6 +72,7 @@ const PROD_SERVICE_URLS: ServiceUrlMap = {
   [ServiceUrl.UNFURL_SERVICE_URL]: 'https://gateway.macro.com/unfurl',
   [ServiceUrl.AGENT_HARNESS_SERVICE_URL]:
     'https://gateway.macro.com/agent-harness',
+  [ServiceUrl.MCP_SERVER_URL]: 'https://gateway.macro.com/mcp',
 };
 
 /**

infra/stacks/fusionauth-instance/index.ts

@@ -303,6 +303,9 @@ const macroApplication = new FusionAuthApplication(
             ]
           : []),
         `https://mcp-server${stack === 'prod' ? '' : `-${stack}`}.macro.com/oauth/callback`,
+        ...(stack === 'dev' || stack === 'prod'
+          ? [`${getServiceUrl(ServiceUrl.MCP_SERVER_URL)}/oauth/callback`]
+          : []),
         ...(stack === 'local' || stack === 'dev'
           ? ['http://localhost:8085/*', 'http://localhost:8085/oauth/*']
           : []),

infra/stacks/mcp-server/mcp-server.ts

@@ -8,16 +8,21 @@ import {
   datadogAgentContainer,
   fargateLogRouterSidecarContainer,
   serviceLoadBalancer,
+  ServiceTargetGroup,
 } from '../../packages/resources';
 import { EcrImage } from '../../packages/service';
 import {
   BASE_DOMAIN,
   CLOUD_TRAIL_SNS_TOPIC_ARN,
   DopplerEcsEnvironment,
+  getGatewayAlb,
   getKafkaClusterPolicy,
+  GatewayService,
   stack,
 } from '../../packages/shared';
 
+const gatewayLoadBalancer = getGatewayAlb();
+
 const BASE_NAME = pulumi.getProject();
 const REPO_ROOT = '../../..';
 
@@ -107,6 +112,22 @@ export class McpServer extends pulumi.ComponentResource {
     this.serviceAlbSg = sg.serviceAlbSg;
     this.serviceSg = sg.serviceSg;
 
+    const gatewayTargetGroup = new ServiceTargetGroup(
+      `${stack}-${BASE_NAME}`,
+      {
+        tags: this.tags,
+        listenerArn: gatewayLoadBalancer.httpsListenerArn,
+        vpcId: vpc.vpcId,
+        containerPort: serviceContainerPort,
+        service: GatewayService.MCP_SERVER,
+        healthCheckPath,
+        pathPatterns: ['/mcp', '/mcp/*'],
+        serviceSecurityGroupId: this.serviceSg.id,
+        albSecurityGroupId: gatewayLoadBalancer.albSecurityGroupId,
+      },
+      { parent: this }
+    );
+
     // lb
     const { targetGroup, lb, listener } = serviceLoadBalancer(this, {
       serviceName: BASE_NAME,
@@ -245,6 +266,18 @@ export class McpServer extends pulumi.ComponentResource {
           enable: true,
           rollback: true,
         },
+        loadBalancers: [
+          {
+            targetGroupArn: targetGroup.arn,
+            containerName: 'service',
+            containerPort: serviceContainerPort,
+          },
+          {
+            targetGroupArn: gatewayTargetGroup.target_group.arn,
+            containerName: 'service',
+            containerPort: serviceContainerPort,
+          },
+        ],
         taskDefinitionArgs: {
           taskRole: {
             roleArn: this.role.arn,
@@ -299,6 +332,10 @@ export class McpServer extends pulumi.ComponentResource {
       },
       {
         parent: this,
+        // ECS refuses a service whose target group is not yet associated with
+        // a load balancer. The dedicated HTTPS listener and the gateway
+        // listener rule each create that association for their target group.
+        dependsOn: [listener, gatewayTargetGroup.listener_rule],
       }
     );
 

services/mcp_auth_proxy/Cargo.toml

@@ -37,4 +37,5 @@ uuid = { workspace = true }
 workspace-hack = { version = "0.1", path = "../../crates/workspace-hack" }
 
 [dev-dependencies]
+macro_auth = { path = "../../crates/macro_auth", features = ["testing"] }
 tokio = { workspace = true }

services/mcp_auth_proxy/src/domain/service.rs

@@ -81,6 +81,20 @@ pub trait InflightAuthStore: Send + Sync {
     fn cleanup_expired(&self) -> impl Future<Output = anyhow::Result<()>> + Send;
 }
 
+/// Streamable HTTP resource URL advertised in protected-resource metadata.
+///
+/// MCP clients require a `resource` field. When `MCP_PUBLIC_URL` is an origin
+/// (the current Doppler value), append `/mcp`. When it already ends in `/mcp`
+/// (a later gateway cutover), do not append again.
+fn mcp_resource_url(public_url: &str) -> String {
+    let base = public_url.trim_end_matches('/');
+    if base.ends_with("/mcp") {
+        base.to_owned()
+    } else {
+        format!("{base}/mcp")
+    }
+}
+
 /// Domain service backing the MCP OAuth broker.
 pub struct McpAuthProxyServiceImpl<I> {
     inflight_auth: Arc<I>,
@@ -205,6 +219,7 @@ where
         tracing::debug!("oauth-protected-resource metadata requested");
         let base = &self.public_url;
         serde_json::json!({
+            "resource": mcp_resource_url(base),
             "authorization_server": base,
             "authorization_servers": [base],
         })

services/mcp_auth_proxy/src/domain/service/test.rs

@@ -114,6 +114,38 @@ fn service(store: FakeInflightAuth) -> McpAuthProxyServiceImpl<FakeInflightAuth>
     )
 }
 
+#[test]
+fn protected_resource_metadata_includes_required_resource_url() {
+    let json = service(FakeInflightAuth::default()).protected_resource_metadata();
+    assert_eq!(
+        json,
+        serde_json::json!({
+            "resource": "https://mcp.example.com/mcp",
+            "authorization_server": "https://mcp.example.com",
+            "authorization_servers": ["https://mcp.example.com"],
+        })
+    );
+}
+
+#[test]
+fn protected_resource_metadata_does_not_double_the_mcp_path() {
+    let service = McpAuthProxyServiceImpl::new(
+        "https://gateway.macro.com/mcp".to_owned(),
+        Arc::new(FakeInflightAuth::default()),
+        Arc::new(FakeOAuthProvider {
+            expires_in: UPSTREAM_EXPIRES_IN,
+        }),
+    );
+    assert_eq!(
+        service.protected_resource_metadata(),
+        serde_json::json!({
+            "resource": "https://gateway.macro.com/mcp",
+            "authorization_server": "https://gateway.macro.com/mcp",
+            "authorization_servers": ["https://gateway.macro.com/mcp"],
+        })
+    );
+}
+
 fn issued_code(access_token_expires_at: Option<SystemTime>) -> IssuedAuthorizationCode {
     IssuedAuthorizationCode {
         access_token: AccessToken::from("upstream-access"),

services/mcp_auth_proxy/src/inbound.rs

@@ -1,5 +1,8 @@
 //! Inbound adapters for the MCP OAuth broker.
 
+/// Path the shared gateway forwards without stripping.
+pub(crate) const GATEWAY_PATH_PREFIX: &str = "/mcp";
+
 /// Axum router for the MCP OAuth broker.
 pub mod axum_router;
 /// Bearer token middleware for the protected MCP endpoint.

services/mcp_auth_proxy/src/inbound/axum_router.rs

@@ -1,5 +1,8 @@
 //! Axum router for the MCP OAuth broker.
 
+#[cfg(test)]
+mod test;
+
 use std::time::Duration;
 
 use axum::{
@@ -217,10 +220,6 @@ where
             "/.well-known/oauth-protected-resource/mcp",
             routing::get(protected_resource_metadata),
         )
-        .route(
-            "/mcp/.well-known/oauth-protected-resource",
-            routing::get(protected_resource_metadata),
-        )
         .route(
             "/.well-known/oauth-authorization-server",
             routing::get(authorization_server_metadata),
@@ -229,10 +228,6 @@ where
             "/.well-known/oauth-authorization-server/mcp",
             routing::get(authorization_server_metadata),
         )
-        .route(
-            "/mcp/.well-known/oauth-authorization-server",
-            routing::get(authorization_server_metadata),
-        )
         .route("/authorize", routing::get(authorize))
         .route("/register", routing::post(register))
         .route("/oauth/callback", routing::get(oauth_callback))
@@ -247,7 +242,13 @@ where
                 super::middleware::validate_bearer,
             ));
 
-    oauth_routes.merge(mcp_route).layer(mcp_cors_layer())
+    mount_at_root_and_prefix(oauth_routes.merge(mcp_route)).layer(mcp_cors_layer())
+}
+
+fn mount_at_root_and_prefix(inner: Router) -> Router {
+    Router::new()
+        .merge(inner.clone())
+        .nest(super::GATEWAY_PATH_PREFIX, inner)
 }
 
 /// CORS layer for the MCP router.