Import the app handler lazily in start.ts (#1710)

Author: RhysSullivan

apps/cloud/src/start.ts

@@ -1,7 +1,6 @@
 import { createMiddleware, createStart } from "@tanstack/react-start";
 import { decodeOAuthCallbackState } from "@executor-js/sdk/shared";
 
-import { cloudApiHandler } from "./app";
 import { isAppOwnedPath } from "./app-paths";
 import { authGateMiddleware } from "./auth/ssr-gate";
 import { parseCookie } from "./auth/cookies";
@@ -35,8 +34,18 @@ import {
 // (a workerd-only virtual module) into the browser build, breaking it. Keeping
 // the call inside the server callback mirrors how every other server concern
 // here stays server-only.
-let app: ReturnType<typeof cloudApiHandler> | undefined;
-const getApp = () => (app ??= cloudApiHandler());
+//
+// The IMPORT is dynamic for a second, server-side reason: `server.ts` now
+// dispatches `/api/*` at the Worker entry, so the only paths that still reach
+// this middleware are the two Start's own chain claims first (the Sentry tunnel
+// and the OAuth callback's signed-out redirect) plus `/mcp`. A static import
+// would still put the entire Effect app in the graph every SSR page load
+// evaluates — 3.06 MB of the 12.94 MB page closure, for code a page never runs.
+// Deferring it takes the page closure to 9.88 MB; `scripts/start-closure.mjs`
+// reports both planes and will show it coming back if this becomes static.
+let app: ReturnType<typeof import("./app").cloudApiHandler> | undefined;
+const getApp = async (): Promise<NonNullable<typeof app>> =>
+  (app ??= (await import("./app")).cloudApiHandler());
 
 const SESSION_COOKIE = "wos-session";
 const OAUTH_CALLBACK_PATH = "/api/oauth/callback";
@@ -78,11 +87,11 @@ const oauthCallbackSignInMiddleware = createMiddleware({ type: "request" }).serv
 // envelope routes, pinning the org in an internal header (a no-op for everything
 // else, including `/api/*`).
 const appRequestMiddleware = createMiddleware({ type: "request" }).server(
-  ({ pathname, request, next }) => {
+  async ({ pathname, request, next }) => {
     if (isAppOwnedPath(pathname)) {
       const scopedRequest =
         pathname === OAUTH_CALLBACK_PATH ? oauthCallbackOrgScopedRequest(request) : request;
-      return getApp().handler(prepareMcpOrgScope(scopedRequest));
+      return (await getApp()).handler(prepareMcpOrgScope(scopedRequest));
     }
     return next();
   },