fix(canvas): 素材库 - 拒绝空字节数并提供历史数据修复工具

backend/internal/canvas/user_asset_document_test.go

@@ -0,0 +1,32 @@
+package canvas
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestUserAssetBytesRequiresNonNegativeNumber(t *testing.T) {
+	for _, kind := range []string{"image", "video", "audio", "model"} {
+		for _, raw := range []string{"null", " null ", `"12"`, "-1", "true", "{}", "[]", "1e400", "0", "12"} {
+			t.Run(kind+"/"+raw, func(t *testing.T) {
+				data := map[string]json.RawMessage{
+					"dataUrl": json.RawMessage(`"https://example.com/file"`),
+					"url":     json.RawMessage(`"https://example.com/file"`),
+					"width":   json.RawMessage("1"), "height": json.RawMessage("1"),
+					"mimeType": json.RawMessage(`"application/octet-stream"`),
+					"fileName": json.RawMessage(`"file.glb"`),
+					"bytes":    json.RawMessage(raw),
+				}
+				err := validateUserAssetData(kind, data)
+				valid := raw == "0" || raw == "12"
+				if (err == nil) != valid {
+					t.Fatalf("bytes=%s: error=%v, want valid=%v", raw, err, valid)
+				}
+				delete(data, "bytes")
+				if err := validateUserAssetData(kind, data); err == nil {
+					t.Fatal("missing bytes accepted")
+				}
+			})
+		}
+	}
+}