Human-in-the-Loop - Rilo Documentation

Human-in-the-Loop (HITL) blocks allow you to pause workflow execution for human review, approval, or modification of data before continuing. Perfect for content moderation, data validation, or any process that needs human oversight.

Overview

HITL blocks:

Pause execution: Workflow stops until human review is complete
Interactive forms: Dynamic UI forms generated from data
Edit and approve: Users can modify data before approval
Resume automatically: Workflow continues after review submission

HITL blocks use the UI Manifest system to generate dynamic review forms based on the data structure from previous blocks.

When to Use HITL

HITL blocks are ideal for:

Content Review: Approve AI-generated content before publishing
Data Validation: Review scraped data before adding to CRM
Quality Gates: Human approval checkpoint before critical actions
Data Enrichment: Review and correct AI-enriched data
Compliance: Ensure content meets compliance requirements

Creating HITL Blocks

Via Natural Language

Simply describe what needs review:

"After scraping leads, add a human review step to approve them before adding to the CRM"

The AI agent automatically creates a HITL block with:

block_type: "hitl"
instruction: Description of what to review
display_format: Optional layout preferences

HITL Block Structure

{
  "name": "Review Leads",
  "slug": "review-leads",
  "block_type": "hitl",
  "instructions": "Review scraped leads. Approve or reject each lead before adding to CRM.",
  "dependent_on": ["scrape-leads"],
  "display_format": "Show name, company, email in a table"
}

Display Formats

HITL blocks support multiple display layouts:

Table

Best for quick scanning and comparing items. Shows data in rows and columns.

Card Grid

Good for items with images or detailed content. Displays items as cards in a grid.

List

For sequential review of complex items. Shows items in a vertical list.

Carousel

For horizontal scrolling through items. Useful for image-heavy content.

Configuring Display Format

Specify display format in instructions:

"Display as cards with 2 columns showing image and title"

Or use the block configuration:

{
  "display_format": "table with name, email, company columns"
}

Review Process

1. Data Generation

Previous block generates data:

{
  "items": [
    {
      "id": "1",
      "name": "John Doe",
      "email": "[email protected]",
      "company": "Acme Corp"
    }
  ]
}

2. Form Generation

UI Manifest Agent generates a review form:

Analyzes data structure
Creates appropriate input fields
Adds approve/reject buttons
Configures layout based on display_format

3. User Review

User sees the review form:

Editable fields: Can modify data before approval
Action buttons: Approve, reject, or skip items
Draft saving: Save progress and return later

4. Submission

After review:

Modified data is captured
Approval status is recorded
Workflow resumes automatically

5. Output

HITL block outputs reviewed data:

{
  "summary": {
    "total_items": 10,
    "approved": 7,
    "rejected": 3
  },
  "items": [
    {
      "id": "1",
      "original_data": {
        "name": "John",
        "email": "[email protected]"
      },
      "final_data": {
        "name": "John Doe",
        "email": "[email protected]",
        "status": "approved"
      }
    }
  ]
}

Block Execution States

HITL blocks have specific execution states:

Status	Description
`pending`	Block not yet started
`running`	Block is executing
`form_generating`	UI Manifest Agent generating the form
`awaiting_input`	Waiting for human review
`processing_response`	Processing submitted response
`completed`	Review completed, workflow continues
`failed`	Block encountered an error

The awaiting_input state is unique to HITL blocks. The workflow pauses here until the user completes the review.

Reminder System

HITL blocks support email reminders for pending reviews:

Configuration

{
  "hitl_reminder_enabled": true,
  "hitl_reminder_intervals": [1, 24, 72],
  "hitl_reminder_modes": ["email", "in_app"]
}

Reminder Intervals

[1, 24, 72]: Reminders at 1 hour, 24 hours, 72 hours
[24]: Single reminder at 24 hours (default)
[]: No reminders

Notification Modes

Mode	Description
`in_app`	Notification in the app UI
`email`	Email to workflow owner
`slack`	Slack message (if configured)
`whatsapp`	WhatsApp message (if configured)

See Email Reminder for more details on the reminder system.

Example Workflows

Example 1: Content Review

Workflow:

Generate quotes (Code block)
Review quotes (HITL block)
Post approved quotes (Code block)

HITL Configuration:

{
  "block_type": "hitl",
  "instructions": "Review generated quotes. Edit if needed, then approve for posting.",
  "display_format": "Display as cards with quote and author"
}

Example 2: Lead Validation

Workflow:

Scrape leads (Code block)
Review leads (HITL block)
Add to CRM (Code block)

HITL Configuration:

{
  "block_type": "hitl",
  "instructions": "Review scraped leads. Verify email addresses and company names.",
  "display_format": "Table with name, email, company columns. Make email editable."
}

Best Practices

Clear Review Instructions

Write clear instructions about what to review. Users should understand what they’re approving.

Appropriate Display Format

Choose the display format that best fits your data. Tables for structured data, cards for rich content.

Enable Reminders

Enable reminders for time-sensitive reviews. Don’t let reviews sit indefinitely.

Limit Review Items

Keep review batches manageable. Too many items can be overwhelming.

Limitations

HITL blocks can only depend on exactly one code block. They cannot depend on other HITL blocks or start blocks.

Single dependency: Must depend on exactly one code block
No chaining: Cannot chain HITL blocks directly (use code blocks between)
Data structure: Input data should be structured (list of items)

Workaround for Multiple Reviews

To create multiple review stages:

code-1 → hitl-1 → code-2 (processes approved items) → hitl-2

Troubleshooting

Form not generating

Check that previous block output is structured correctly
Verify data format matches expected structure
Ensure HITL block depends on a code block

Review not submitting

Check that all required fields are filled
Verify action buttons are configured correctly
Review browser console for errors

Reminders not sending

Verify reminder configuration is correct
Check email settings in account
Ensure reminder intervals are set

Email Reminder - Configure reminders for HITL blocks
Configs - Configure HITL block settings
Graph Mode - Visualize HITL blocks in workflows

HITL blocks are a powerful way to add human oversight to automated workflows. Use them when you need quality control or compliance checks.

​Overview

​When to Use HITL

​Creating HITL Blocks

​Via Natural Language

​HITL Block Structure

​Display Formats

Table

Card Grid

List

Carousel

​Configuring Display Format

​Review Process

​1. Data Generation

​2. Form Generation

​3. User Review

​4. Submission

​5. Output

​Block Execution States

​Reminder System

​Configuration

​Reminder Intervals

​Notification Modes

​Example Workflows

​Example 1: Content Review

​Example 2: Lead Validation

​Best Practices

​Limitations

​Workaround for Multiple Reviews

​Troubleshooting

​Related Features

Overview

When to Use HITL

Creating HITL Blocks

Via Natural Language

HITL Block Structure

Display Formats

Configuring Display Format

Review Process

1. Data Generation

2. Form Generation

3. User Review

4. Submission

5. Output

Block Execution States

Reminder System

Configuration

Reminder Intervals

Notification Modes

Example Workflows

Example 1: Content Review

Example 2: Lead Validation

Best Practices

Limitations

Workaround for Multiple Reviews

Troubleshooting

Related Features