On a restarted stage, there is a when condition, isRestartedRun() that can be used to run or not a stage.  But there isn't anything that can be used to execute a bit different on a restart than in the original run.  This leads to workarounds like:

    stages {
        stage('Schedule') {
            when

{                 not\{ isRestartedRun() }

            }
            agent any
            steps

{                     myCommand 'isRestartedRun: false'             }

        }
        stage('Restart') {
            when

{                 isRestartedRun()             }

            agent any
            steps

{                     myCommand 'isRestartedRun: true'             }

        }

 

It would be much simpler and clearer to be able to just check for currentBuild.isRestartedRun wherever global variables are accessible