engine refactor

internal/api/httpjson/httpjson.go

@@ -0,0 +1,27 @@
+// Package httpjson holds the tiny JSON response helpers shared across
+// the admin, v2, and async handlers.
+package httpjson
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// Write writes body as JSON with the given status code.
+func Write(w http.ResponseWriter, status int, body any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(body)
+}
+
+// Error writes a standard error JSON body with the given status code.
+//
+// Shape: {"error": {"type": "...", "description": "..."}}
+func Error(w http.ResponseWriter, status int, description string) {
+	Write(w, status, map[string]any{
+		"error": map[string]string{
+			"type":        http.StatusText(status),
+			"description": description,
+		},
+	})
+}