fix: serve pages in SPA mode when the route also has an API handler (1.x) (#2355)

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: lxsmnsyc

.changeset/spa-page-api-route.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/start": patch
+---
+
+Serve pages in SPA mode (`ssr: false`) when a route file exports both a page and an API handler, such as a `[...404].tsx` with a `GET`. The server treated those routes as API-only, so a `GET` that returned nothing gave a 404 for every URL the route matched.

packages/start/src/router/routes.spec.ts

@@ -0,0 +1,34 @@
+import { describe, expect, it, vi } from "vitest";
+
+const GET = { import: () => Promise.resolve({}) };
+
+// What the server file router produces for `routes/[...404].tsx` exporting
+// both a page and `GET`, with and without the page component.
+vi.mock("vinxi/routes", () => ({
+  default: [
+    {
+      path: "/*404",
+      page: true,
+      $component: { src: "routes/[...404].tsx", import: () => Promise.resolve({}) },
+      $GET: GET
+    },
+    { path: "/spa/*404", page: true, $GET: GET },
+    { path: "/api/*rest", $GET: GET }
+  ]
+}));
+
+const { matchAPIRoute } = await import("./routes");
+
+describe("matchAPIRoute", () => {
+  it("marks a route with a page and an API handler as a page", () => {
+    expect(matchAPIRoute("/missing", "GET")?.isPage).toBe(true);
+  });
+
+  it("marks it as a page in SPA builds, where the server routes have no page components", () => {
+    expect(matchAPIRoute("/spa/missing", "GET")?.isPage).toBe(true);
+  });
+
+  it("does not mark an API-only route as a page", () => {
+    expect(matchAPIRoute("/api/missing", "GET")?.isPage).toBe(false);
+  });
+});

packages/start/src/router/routes.ts

@@ -69,8 +69,9 @@ export function matchAPIRoute(path: string, method: string) {
 
     if (handler === undefined) return;
 
-    // Check if this is a page route
-    const isPage = route.page === true && route.$component !== undefined;
+    // Check if this is a page route. SPA builds leave page components out of
+    // the server routes, so this can't depend on `$component`.
+    const isPage = route.page === true;
 
     // Return comprehensive route information
     return {

packages/start/test/vinxi-routes.stub.ts

@@ -0,0 +1 @@
+export default [];

packages/start/vitest.config.ts

@@ -1,6 +1,14 @@
+import { fileURLToPath } from "node:url";
 import { defineConfig } from "vitest/config";
 
 export default defineConfig({
+  resolve: {
+    alias: {
+      // vinxi serves its route manifest only inside an app build. Specs that
+      // need it mock this stub with `vi.mock("vinxi/routes")`.
+      "vinxi/routes": fileURLToPath(new URL("./test/vinxi-routes.stub.ts", import.meta.url))
+    }
+  },
   test: {
     globals: true,
     environment: "node",