Add BRouter proxy, rate limiting, and spec updates (tasks 5.1-5.2) (#11)

apps/planner/app/routes/api.route.ts

@@ -0,0 +1,45 @@
+import { data } from "react-router";
+import type { Route } from "./+types/api.route";
+import { computeRoute } from "~/lib/brouter";
+import { checkRateLimit } from "~/lib/rate-limit";
+
+export async function action({ request }: Route.ActionArgs) {
+  if (request.method !== "POST") {
+    return data({ error: "Method not allowed" }, { status: 405 });
+  }
+
+  const body = await request.json();
+  const { waypoints, profile, sessionId } = body as {
+    waypoints: Array<{ lat: number; lon: number }>;
+    profile?: string;
+    sessionId?: string;
+  };
+
+  if (!waypoints || waypoints.length < 2) {
+    return data({ error: "At least 2 waypoints are required" }, { status: 400 });
+  }
+
+  // Rate limit by session ID or IP
+  const rateLimitKey = sessionId ?? request.headers.get("x-forwarded-for") ?? "unknown";
+  const limit = checkRateLimit(`route:${rateLimitKey}`);
+
+  if (!limit.allowed) {
+    return data(
+      { error: "Rate limit exceeded" },
+      {
+        status: 429,
+        headers: { "Retry-After": String(limit.retryAfterSeconds) },
+      },
+    );
+  }
+
+  try {
+    const route = await computeRoute({ waypoints, profile });
+    return data(route, {
+      headers: { "X-RateLimit-Remaining": String(limit.remaining) },
+    });
+  } catch (e) {
+    const message = e instanceof Error ? e.message : "Route computation failed";
+    return data({ error: message }, { status: 502 });
+  }
+}