step one

internal/api/middleware/cors.go

@@ -0,0 +1,20 @@
+package middleware
+
+import "net/http"
+
+// CORS wraps next with permissive CORS headers and short-circuits OPTIONS preflight.
+//
+// This service is meant to sit behind an authenticated gateway, so we set
+// "Access-Control-Allow-Origin: *". Tighten this if you deploy elsewhere.
+func CORS(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, DELETE, OPTIONS")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+		if r.Method == http.MethodOptions {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}