Skip to content

Human-in-the-Loop Workflows

FlowDrop can pause a running workflow to ask a user for input — a confirmation, a choice, free-form text, or a structured form. This is called Human-in-the-Loop (HITL) and is useful for approval workflows, interactive data collection, and any process that needs human judgment.

Modules Required

Enable the following modules: 

drush en flowdrop_interrupt flowdrop_stategraph
For the interactive testing interface, also enable: 
drush en flowdrop_playground

How It Works

  1. The workflow reaches an interrupt node (e.g., ConfirmationNode).
  2. The pipeline pauses and creates an interrupt request.
  3. The user responds to the interrupt (via the Playground UI or API).
  4. The pipeline resumes from where it left off, using the user's response as input.

Important

Human-in-the-loop workflows require the StateGraph orchestrator, which supports pausing and resuming. The standard synchronous orchestrator cannot pause.

Interrupt Node Types

Node What It Does User Sees
ConfirmationNode Asks a yes/no question A confirmation prompt with Yes/No buttons
ChoiceNode Presents a list of options A list of choices (single or multi-select)
TextInputNode Requests free-form text A text input field
FormInputNode Requests structured data A form generated from a JSON Schema definition

Step-by-Step: Build an Approval Workflow

This example builds a workflow that asks for confirmation before logging a message.

Step 1: Create the Workflow

  1. Navigate to Administration > FlowDrop > Workflows and create a new workflow.
  2. Open it in the visual editor.

Step 2: Add the Nodes

Add three nodes to the canvas:

  1. Text Input — The data to be approved.
  2. ConfirmationNode — Found in the Human-in-the-Loop category. This will pause the workflow and ask the user to confirm.
  3. Logger — To log the result after approval.

Step 3: Configure the Confirmation Node

  1. Click on the ConfirmationNode to open its configuration panel.
  2. Set the prompt — the question the user will see (e.g., "Do you want to proceed with logging this message?").

Step 4: Connect the Nodes

  1. Connect Text Input output → ConfirmationNode input.
  2. Connect ConfirmationNode output → Logger input.

Step 5: Save the Workflow

Click Save in the editor toolbar.

Step 6: Test in the Playground

The Playground is the easiest way to test interrupt workflows interactively.

  1. From the workflow listing, click the dropdown and select Playground.
  2. Send a message to start the workflow.
  3. When the workflow reaches the ConfirmationNode, the Playground shows the confirmation prompt inline.
  4. Click Yes or No to respond.
  5. The workflow resumes and completes.

Playground Access

The Playground requires the flowdrop_playground module and the execute playground workflow permission.

Using the Playground

The Playground provides a chat-like interface for testing workflows:

Starting a Session

  1. Navigate to Administration > FlowDrop > Workflows.
  2. Click the dropdown on a workflow and select Playground.
  3. Send a message to start the workflow execution.

Responding to Interrupts

When the workflow pauses for user input, the Playground renders the appropriate UI inline:

  • Confirmation — Yes/No buttons
  • Choice — A list of selectable options
  • Text Input — A text field with a submit button
  • Form Input — A generated form with fields based on the JSON Schema

Click or fill in your response and submit. The workflow will resume.

Managing Sessions

  • Each Playground interaction is a session with its own message history.
  • Create multiple sessions to test different scenarios.
  • Reset a session to start over.
  • Delete old sessions to clean up.

Permissions

Permission What It Allows
resolve own flowdrop interrupts Respond to own interrupt requests
resolve any flowdrop interrupts Respond to any interrupt request
view own flowdrop interrupts View own pending interrupts
view any flowdrop interrupts View any pending interrupt
cancel own flowdrop interrupts Cancel own pending interrupts
cancel any flowdrop interrupts Cancel any pending interrupt
execute playground workflow Use the Playground interface

For a complete permissions reference, see the Permissions page.

Tips

  • Use the StateGraph orchestrator — HITL workflows require it. The Playground uses StateGraph automatically.
  • Keep prompts clear — Write confirmation prompts that clearly explain what will happen on Yes vs No.
  • Test in Playground first — Before connecting triggers, validate your interrupt flow in the Playground.
  • Approval Gates — For multi-step approval processes, use the ApprovalGateNode from the flowdrop_stategraph module. It works like a confirmation but is designed for formal approval workflows.

Next Steps