TASK.md — Cross-Drive Backup Validation Fix (v0.12.5)

controller/internal/backup/crossdrive.go

@@ -158,14 +158,19 @@ func (r *CrossDriveRunner) IsRunning(stackName string) bool {
 	return r.running[stackName]
 }
 
-// ValidateDestination checks that the destination path is a mount point, writable,
+// ValidateDestination checks that the destination path exists, is writable,
 // and has sufficient free space (at least 100MB).
+// A non-mount-point destination (e.g. a folder on the system drive) is allowed
+// with a logged warning — consistent with the web UI's CheckBackupDestination.
 func (r *CrossDriveRunner) ValidateDestination(path string) error {
 	if path == "" {
 		return fmt.Errorf("destination path is empty")
 	}
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return fmt.Errorf("destination %s does not exist", path)
+	}
 	if !system.IsMountPoint(path) {
-		return fmt.Errorf("destination %s is not a mount point", path)
+		r.logger.Printf("[WARN] Destination %s is not a separate mount point (system drive) — backup will proceed but data is not protected against drive failure", path)
 	}
 	if !system.IsWritable(path) {
 		return fmt.Errorf("destination %s is not writable", path)