Fix GPX export: use API route with direct download link

React Router page actions wrap responses, preventing raw file
downloads. Moved GPX export to GET /api/routes/:id/gpx and
changed the button to a plain <a download> link.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/journal/app/routes.ts

@@ -14,5 +14,6 @@ export default [
   route("routes/:id/edit", "routes/routes.$id.edit.tsx"),
   route("api/routes/:id/callback", "routes/api.routes.$id.callback.ts"),
   route("api/routes/:id/edit-in-planner", "routes/api.routes.$id.edit-in-planner.ts"),
+  route("api/routes/:id/gpx", "routes/api.routes.$id.gpx.ts"),
   route("users/:username", "routes/users.$username.tsx"),
 ] satisfies RouteConfig;

apps/journal/app/routes/api.routes.$id.gpx.ts

@@ -0,0 +1,16 @@
+import type { Route } from "./+types/api.routes.$id.gpx";
+import { getRouteWithVersions } from "~/lib/routes.server";
+
+export async function loader({ params }: Route.LoaderArgs) {
+  const route = await getRouteWithVersions(params.id);
+  if (!route?.gpx) {
+    return new Response("No GPX data", { status: 404 });
+  }
+
+  return new Response(route.gpx, {
+    headers: {
+      "Content-Type": "application/gpx+xml",
+      "Content-Disposition": `attachment; filename="${route.name.replace(/[^a-z0-9]/gi, "_")}.gpx"`,
+    },
+  });
+}

apps/journal/app/routes/routes.$id.tsx

@@ -62,18 +62,6 @@ export async function action({ params, request }: Route.ActionArgs) {
     return redirect(`/routes/${params.id}`);
   }
 
-  if (intent === "export-gpx") {
-    const route = await getRouteWithVersions(params.id);
-    if (!route?.gpx) return data({ error: "No GPX data" }, { status: 400 });
-
-    return new Response(route.gpx, {
-      headers: {
-        "Content-Type": "application/gpx+xml",
-        "Content-Disposition": `attachment; filename="${route.name.replace(/[^a-z0-9]/gi, "_")}.gpx"`,
-      },
-    });
-  }
-
   return data({ error: "Unknown action" }, { status: 400 });
 }
 
@@ -123,16 +111,15 @@ export default function RouteDetailPage({ loaderData }: Route.ComponentProps) {
             >
               Edit
             </a>
-            <form method="post">
-              <input type="hidden" name="intent" value="export-gpx" />
-              <button
-                type="submit"
-                disabled={!route.hasGpx}
-                className="rounded-md border border-gray-300 px-3 py-1.5 text-sm text-gray-700 hover:bg-gray-50 disabled:opacity-50"
+            {route.hasGpx && (
+              <a
+                href={`/api/routes/${route.id}/gpx`}
+                download
+                className="rounded-md border border-gray-300 px-3 py-1.5 text-sm text-gray-700 hover:bg-gray-50"
               >
                 Export GPX
-              </button>
-            </form>
+              </a>
+            )}
           </div>
         )}
       </div>