Human approval layer for your mission critical AI workflows

A unified typescript SDK for human-in-the-loop

npm i @hitl-sdk/hitl

claude "Follow this guide: https://hitl-sdk.dev/onboard.md"

or Quick start

The Chat Platform Agnostic

The Workflow Engine Agnostic

The Persistence Agnostic

Human-in-the-loop as code

Human oversight as code — easy to integrate into any workflow, easy to build automation people can trust.

One await

Replace polling, queues, and resume logic with a single await.

No polling
No queues
No custom retry logic

Without HITL sdk

const approvalId = crypto.randomUUID();

await db.approvals.insert({
  id: approvalId,
  status: "pending",
  leadEmail: input.email,
  draft: input.draft,
  expiresAt: addHours(new Date(), 72),
});

await slack.postMessage({
  channel: "#sales",
  text: `Inbound lead: ${input.email}`,
  blocks: buildApprovalBlocks(approvalId),
});

await queue.enqueue("approval.poll", { approvalId }, {
  repeat: { every: "15m" },
  attempts: 288,
});

// workflow pauses here — resume via cron/webhook
let row = await db.approvals.findById(approvalId);
while (row.status === "pending") {
  if (row.expiresAt < new Date()) {
    await db.approvals.update(approvalId, { status: "expired" });
    return;
  }
  await sleep(POLL_INTERVAL_MS);
  row = await db.approvals.findById(approvalId);
}

if (row.status !== "approved") return;

const edits = await db.approvalEdits.findByApprovalId(approvalId);
await sendEmail({
  to: input.email,
  subject: edits?.subject ?? input.draft.subject,
  body: edits?.body ?? input.draft.body,
});

const approvalId = crypto.randomUUID();

await db.approvals.insert({
  id: approvalId,
  status: "pending",
  leadEmail: input.email,
  draft: input.draft,
  expiresAt: addHours(new Date(), 72),
});

await slack.postMessage({
  channel: "#sales",
  text: `Inbound lead: ${input.email}`,
  blocks: buildApprovalBlocks(approvalId),
});

await queue.enqueue("approval.poll", { approvalId }, {
  repeat: { every: "15m" },
  attempts: 288,
});

// workflow pauses here — resume via cron/webhook
let row = await db.approvals.findById(approvalId);
while (row.status === "pending") {
  if (row.expiresAt < new Date()) {
    await db.approvals.update(approvalId, { status: "expired" });
    return;
  }
  await sleep(POLL_INTERVAL_MS);
  row = await db.approvals.findById(approvalId);
}

if (row.status !== "approved") return;

const edits = await db.approvalEdits.findByApprovalId(approvalId);
await sendEmail({
  to: input.email,
  subject: edits?.subject ?? input.draft.subject,
  body: edits?.body ?? input.draft.body,
});

With HITL sdk

const approval = await waitForHuman({
  message: `Inbound lead: ${input.email}`,
  actions: actions()
    .approve({ fields: { subject, body } })
    .build(),
  timeout: "72h",
});

if (isResolved(approval, "approve")) {
  await sendEmail({ ...approval.feedbacks });
}

const approval = await waitForHuman({
  message: `Inbound lead: ${input.email}`,
  actions: actions()
    .approve({ fields: { subject, body } })
    .build(),
  timeout: "72h",
});

if (isResolved(approval, "approve")) {
  await sendEmail({ ...approval.feedbacks });
}

One waitForHuman,
tons of patterns

Editable approve, deny with reason, and custom actions — all in one call.

Approve with editable fields
Deny with a reason
Custom actions for any workflow

const approval = await waitForHuman({
  message: `Draft email to ${input.email} ready for your review.`,
  actions: actions()
    .approve({
      label: "Review and send",
      fields: {
        subject: field.textField({ label: "Subject", default: draft.subject }),
        body: field.textArea({ label: "Body", default: draft.body }),
      },
    })
    .deny({ fields: { reason: field.textArea({ label: "Reason" }) } })
    .build(),
});

const approval = await waitForHuman({
  message: `Draft email to ${input.email} ready for your review.`,
  actions: actions()
    .approve({
      label: "Review and send",
      fields: {
        subject: field.textField({ label: "Subject", default: draft.subject }),
        body: field.textArea({ label: "Body", default: draft.body }),
      },
    })
    .deny({ fields: { reason: field.textArea({ label: "Reason" }) } })
    .build(),
});

remind or escalate
at any time

Keep following up in-thread or on another channel — on your schedule.

Remind after an hour
Every weekday morning
Escalate when it's time

import { remind, escalate } from "@hitl-sdk/hitl";

const approval = await waitForHuman({
  message: "Approve expense report?",
  actions,
  timeout: "72h",
  reminders: [
    remind.after("1h", { message: "Still waiting for approval" }),
    remind.weekdaysAt("07:00", { tz: "UTC", message: "Morning reminder" }),
    escalate.to("oncall").after("2d"),
  ],
});

import { remind, escalate } from "@hitl-sdk/hitl";

const approval = await waitForHuman({
  message: "Approve expense report?",
  actions,
  timeout: "72h",
  reminders: [
    remind.after("1h", { message: "Still waiting for approval" }),
    remind.weekdaysAt("07:00", { tz: "UTC", message: "Morning reminder" }),
    escalate.to("oncall").after("2d"),
  ],
});

Keep humans in the loop, wherever they work

AI handles the work. Humans make the calls. Integrates with Vercel's Chat SDK — all within Slack, Microsoft Teams, and Discord.

Slack

Approve without leaving the channels and threads where your team already collaborates.

Microsoft Teams

Sign off inside Teams — right where chats and handoffs already happen.

Discord

Drop AI drafts into your server channels and let your team review in place.

Web UI

Embed approvals into your web app. Inbox API is included in the SDK.

Your durable agent stack.
No lock-in.

HITL sdk plugs into the tools you already use.

npm i @hitl-sdk/hitl

AI Agent layer

Claude, GPT, Kimi, and more. Build your own AI agents.

npm i @workflow/ai ai

Chat layer

Deliver approvals to Slack, Teams, Discord, and every chat platform.

npm i @hitl-sdk/adapter-chat-sdk

Workflow layer

Pick your workflow engine. Make workflows durable.

npm i @hitl-sdk/resolver-workflow-sdk

npm i @hitl-sdk/resolver-inngest

npm i @hitl-sdk/resolver-temporal

Persistent layer

Pick your database. Wait years for approval.

npm i @hitl-sdk/state-pg

npm i @hitl-sdk/state-sqlite

npm i @hitl-sdk/state-ioredis

Try now

Create your first approval flow today.

npm i @hitl-sdk/hitl

claude "Follow this guide: https://hitl-sdk.dev/onboard.md"

or read the docs

Human approval layer for your mission critical AI workflows

Human-in-the-loop as code

One await

One waitForHuman, tons of patterns

remind or escalateat any time

Keep humans in the loop, wherever they work

Slack

Microsoft Teams

Discord

Web UI

Your durable agent stack.No lock-in.

AI Agent layer

Chat layer

Workflow layer

Persistent layer

Create your first approval flow today.

One waitForHuman,
tons of patterns

remind or escalate
at any time

Your durable agent stack.
No lock-in.