How to add a human approval step to an AI agent

import { Mcpd, Worker, when, workflow } from '@mcpd/sdk'

const mcpd = new Mcpd({ project: 'support' })

const refunds = workflow({ id: 'refund_request' })
  // Your agent drafts the action. Its model calls are recorded under this step.
  .agent('draft', async (ctx, input: { ticket: string; amountUsd: number }) => ({
    amountUsd: input.amountUsd,
    reason: 'item arrived damaged',
  }))
  // The run stops here until an event named refund_reviewed arrives with this
  // ticket's key, or a day passes. No process is held open while it waits.
  .waitFor('approval', {
    event: 'refund_reviewed',
    key: '${input.ticket}',
    timeoutMs: 24 * 3_600_000,
    onTimeout: 'continue',
  })
  // Runs only when the reviewer approved. Skipped on a rejection or a timeout.
  .step('issue_refund', async (ctx, input: { amountUsd: number }) => await issueRefund(input.amountUsd), {
    input: { amountUsd: '${steps.draft.output.amountUsd}' },
    when: when('steps.approval.output.approved', 'eq', true),
    effect: 'at_most_once',
  })
  .output({ refund: '${steps.issue_refund.output}', review: '${steps.approval.output}' })

from mcpd import Mcpd, Worker, when, workflow

mcpd = Mcpd(project="support")

refunds = workflow("refund_request")


# Your agent drafts the action. Its model calls are recorded under this step.
@refunds.agent("draft")
def draft(ctx, input, prior):
    return {"amount_usd": input["amount_usd"], "reason": "item arrived damaged"}


# The run stops here until an event named refund_reviewed arrives with this
# ticket's key, or a day passes. No process is held open while it waits.
refunds.wait_for("approval", event="refund_reviewed", key="${input.ticket}",
                 timeout_ms=24 * 3_600_000, on_timeout="continue")


# Runs only when the reviewer approved. Skipped on a rejection or a timeout.
@refunds.step("issue_refund", input={"amount_usd": "${steps.draft.output.amount_usd}"},
              when=when("steps.approval.output.approved", "eq", True),
              effect="at_most_once")
def issue_refund_step(ctx, input, prior):
    return issue_refund(input["amount_usd"])


refunds.output({"refund": "${steps.issue_refund.output}", "review": "${steps.approval.output}"})

const worker = new Worker(mcpd, { concurrency: 8 }).register(refunds)
// Store the definition now, so a run can start before the first claim.
await worker.registerDefinitions()
// Serve the draft and issue_refund steps for as long as the process lives.
void worker.serve()

import threading

worker = Worker(mcpd, concurrency=8).register(refunds)
# Store the definition now, so a run can start before the first claim.
worker.register_definitions()
# Serve the draft and issue_refund steps on a thread of their own.
threading.Thread(target=worker.serve, daemon=True).start()

const run = await mcpd.runs.start({
  definitionId: 'refund_request',
  input: { ticket: 'T-1042', amountUsd: 42 },
})

run = mcpd.runs.start(refunds, input={"ticket": "T-1042", "amount_usd": 42})

# From your review screen: the reviewer approved ticket T-1042.
curl -s -X POST http://localhost:4317/v1/api/events \
  -H 'content-type: application/json' \
  -H "authorization: Bearer $MCPD_EXECUTE_KEY" \
  -d '{"project": "support", "event": "refund_reviewed", "key": "T-1042",
       "payload": {"approved": true, "by": "ops@example.com"},
       "event_id": "review-T-1042"}'
# → {"outcome":"delivered","event_id":"review-T-1042"}

await mcpd.events.publish({
  event: 'refund_reviewed',
  key: 'T-1042',
  payload: { approved: false, by: 'ops@example.com', note: 'outside policy' },
  eventId: 'review-T-1042',
})

mcpd.events.publish("refund_reviewed", "T-1042",
                    payload={"approved": False, "by": "ops@example.com", "note": "outside policy"},
                    event_id="review-T-1042")