fix(dev/typegen): add support for .md and .mdx route file modules

.changeset/cold-bulldogs-help.md

@@ -0,0 +1,5 @@
+---
+"@react-router/dev": patch
+---
+
+fix: add support for `.md` and `.mdx` file modules in type generation

integration/typegen-test.ts

@@ -743,4 +743,36 @@ test.describe("typegen", () => {
     expect(proc.stderr.toString()).toBe("");
     expect(proc.status).toBe(0);
   });
+
+  test("md/mdx route", async () => {
+    const cwd = await createProject({
+      "vite.config.ts": tsx`
+        import mdx from "@mdx-js/rollup";
+        import { reactRouter } from "@react-router/dev/vite";
+
+        export default {
+          plugins: [mdx(), reactRouter()],
+        };
+      `,
+      "app/routes.ts": tsx`
+        import { type RouteConfig, route } from "@react-router/dev/routes";
+
+        export default [
+          route("home", "routes/home.md"),
+          route("changelog", "routes/changelog.mdx"),
+        ] satisfies RouteConfig;
+      `,
+      "app/routes/home.md": tsx`
+        # Lorem ipsum
+      `,
+      "app/routes/changelog.mdx": tsx`
+        # Lorem ipsum
+      `,
+    });
+
+    const proc = typecheck(cwd);
+    expect(proc.stdout.toString()).toBe("");
+    expect(proc.stderr.toString()).toBe("");
+    expect(proc.status).toBe(0);
+  });
 });

packages/react-router-dev/typegen/generate.ts

@@ -50,6 +50,18 @@ export function generateServerBuild(ctx: Context): VirtualFile {
       export const ssr: ServerBuild["ssr"];
       export const unstable_getCriticalCss: ServerBuild["unstable_getCriticalCss"];
     }
+
+    declare module "*.md" {
+      import * as React from "react";
+      const MDComponent: React.FunctionComponent<any>;
+      export default MDComponent;
+    }
+
+    declare module "*.mdx" {
+      import * as React from "react";
+      const MDXComponent: React.FunctionComponent<any>;
+      export default MDXComponent;
+    }
   `;
   return { filename, content };
 }