feat: new ui (#1455)

internal/fetcher/fetcher.go

@@ -21,8 +21,9 @@ type Fetcher interface {
 	Pause() error
 	Close() error
 
-	// Stats refreshes health statistics and returns the latest information
-	Stats() any
+	// Stats returns both the durable protocol snapshot and transient runtime
+	// telemetry. Downloader persists Snapshot and keeps Runtime in memory only.
+	Stats() *Stats
 	// Meta returns the meta information of the download.
 	Meta() *FetcherMeta
 	// Progress returns the progress of the download.
@@ -31,6 +32,14 @@ type Fetcher interface {
 	Wait() error
 }
 
+// Stats separates protocol information that remains meaningful after a task
+// stops from telemetry that is valid only while the fetcher is active.
+// Protocols own both payload schemas; Downloader treats them as opaque values.
+type Stats struct {
+	Snapshot any `json:"snapshot"`
+	Runtime  any `json:"runtime"`
+}
+
 type Uploader interface {
 	Upload() error
 	UploadedBytes() int64