Implemented shared S3 audio caching for prepare and restore --include-audio

internal/app/restore_plan.go

@@ -257,6 +257,35 @@ func classifyRestoreAction(
 		return action, nil
 	}
 
+	if restoreRelativePathIsAudio(localRelPath) {
+		if object.Size > 0 {
+			if info.Size() == object.Size {
+				action.Kind = RestoreActionSkipSame
+				action.SameLocal = true
+				action.Reason = "local audio size matches remote content"
+				return action, nil
+			}
+			if force {
+				action.Kind = RestoreActionDownload
+				action.Reason = "local audio differs (size mismatch); overwrite with --force"
+				return action, nil
+			}
+			action.Kind = RestoreActionConflict
+			action.Conflict = true
+			action.Reason = "local audio differs (size mismatch)"
+			return action, nil
+		}
+		if force {
+			action.Kind = RestoreActionDownload
+			action.Reason = "local audio exists; remote size unavailable; overwrite with --force"
+			return action, nil
+		}
+		action.Kind = RestoreActionConflict
+		action.Conflict = true
+		action.Reason = "local audio exists; remote size unavailable"
+		return action, nil
+	}
+
 	if object.Size > 0 && info.Size() != object.Size {
 		if force {
 			action.Kind = RestoreActionDownload
@@ -303,6 +332,15 @@ func classifyRestoreAction(
 	return action, nil
 }
 
+func restoreActionIsAudio(action RestoreAction) bool {
+	return restoreRelativePathIsAudio(action.LocalRelativePath)
+}
+
+func restoreRelativePathIsAudio(rel string) bool {
+	cleanRel := path.Clean(strings.TrimSpace(rel))
+	return cleanRel == config.PathAudioDirSegment || strings.HasPrefix(cleanRel, config.PathAudioDirSegment+"/")
+}
+
 func writeRestorePlan(out io.Writer, current *RemoteCurrentState, plan *RestorePlan, opts RestorePlanOptions) error {
 	if out == nil {
 		return fmt.Errorf("output writer is required")