[Bug] First schedule action started using triggerImmediately flag does not honor the schedule's overlap policy

[jhecking]

What are you really trying to do?

I'm creating a new schedule and I want to trigger it immediately. I don't want any overlapping schedule runs.

Describe the bug

I'm creating a new schedule using a combination of ScheduleOverlapPolicy.BUFFER_ONE and triggerImmediately: true, i.e.

export async function schedulePeriodicWorkflowExecution(
  action: ScheduleOptionsStartWorkflowAction<Workflow>,
  scheduleId: string,
  cronExpression: string,
) {
  const client = await getScheduleClient()
  const spec = { cronExpressions: [cronExpression] }
  return client.create({
    action,
    spec,
    scheduleId,
    policies: {
      overlap: ScheduleOverlapPolicy.BUFFER_ONE,
    },
    state: {
      triggerImmediately: true,
    },
  })
}

If the initial schedule run, started via triggerImmediately: true takes long enough that the next run gets triggered as per the provided cron schedule, that second schedule run does not get buffered but gets executed immediately.

I believe this is because the initial schedule run always gets executed with a default "AllowAll" overlap policy:

sdk-typescript/packages/client/src/schedule-client.ts

Lines 246 to 249 in 4cf092d

	initialPatch: {
	triggerImmediately: opts.state?.triggerImmediately
	? { overlapPolicy: temporal.api.enums.v1.ScheduleOverlapPolicy.SCHEDULE_OVERLAP_POLICY_ALLOW_ALL }
	: undefined,

A possible work-around is to create the schedule and then immediately trigger it ourselves using the correct overlap policy, i.e.

export async function schedulePeriodicWorkflowExecution(
  action: ScheduleOptionsStartWorkflowAction<Workflow>,
  scheduleId: string,
  cronExpression: string,
) {
  const client = await getScheduleClient()
  const spec = { cronExpressions: [cronExpression] }
  const handle = client.create({
    action,
    spec,
    scheduleId,
    policies: {
      overlap: ScheduleOverlapPolicy.BUFFER_ONE,
    },
  })
  await handle.trigger(ScheduleOverlapPolicy.BUFFER_ONE)
  return handle
}

But I think triggerImmediately: true should honor the schedule's overlap policy instead of defaulting to the "AllowAll" policy.

Minimal Reproduction

https://github.com/jhecking/samples-typescript/tree/schedules-trigger-immediately-overlapping/schedules-trigger-immediately-overlapping

Environment/Versions

• Temporal Version: 1.11.2

Additional context

n/a