Fix Foundry Rivet base path and frontend endpoint fallback

foundry/docker/frontend-caddy-entrypoint.sh

@@ -5,9 +5,20 @@ escape_js() {
   printf '%s' "${1:-}" | sed 's/\\/\\\\/g; s/"/\\"/g'
 }
 
+normalize_backend_endpoint() {
+  case "${1:-}" in
+    */api/rivet)
+      printf '%s/v1/rivet' "${1%/api/rivet}"
+      ;;
+    *)
+      printf '%s' "${1:-}"
+      ;;
+  esac
+}
+
 cat > /srv/__foundry_runtime_config.js <<EOF
 window.__FOUNDRY_RUNTIME_CONFIG__ = {
-  backendEndpoint: "$(escape_js "${VITE_HF_BACKEND_ENDPOINT:-}")",
+  backendEndpoint: "$(escape_js "$(normalize_backend_endpoint "${VITE_HF_BACKEND_ENDPOINT:-}")")",
   defaultWorkspaceId: "$(escape_js "${VITE_HF_WORKSPACE:-}")",
   frontendClientMode: "$(escape_js "${FOUNDRY_FRONTEND_CLIENT_MODE:-remote}")"
 };

foundry/packages/backend/src/actors/index.ts

@@ -9,6 +9,9 @@ import { sandboxInstance } from "./sandbox-instance/index.js";
 import { workspace } from "./workspace/index.js";
 
 export const registry = setup({
+  serverless: {
+    basePath: "/v1/rivet",
+  },
   use: {
     workspace,
     project,

foundry/packages/client/src/backend-client.ts

@@ -273,8 +273,16 @@ function stripTrailingSlash(value: string): string {
   return value.replace(/\/$/, "");
 }
 
-function deriveBackendEndpoints(endpoint: string): { appEndpoint: string; rivetEndpoint: string } {
+function normalizeLegacyBackendEndpoint(endpoint: string): string {
   const normalized = stripTrailingSlash(endpoint);
+  if (normalized.endsWith("/api/rivet")) {
+    return `${normalized.slice(0, -"/api/rivet".length)}/v1/rivet`;
+  }
+  return normalized;
+}
+
+function deriveBackendEndpoints(endpoint: string): { appEndpoint: string; rivetEndpoint: string } {
+  const normalized = normalizeLegacyBackendEndpoint(endpoint);
   if (normalized.endsWith("/rivet")) {
     return {
       appEndpoint: normalized.slice(0, -"/rivet".length),