Overview

The Problem Without Node Policies

Without a contract, every node is a black box. The platform cannot:

• Route data from upstream nodes to the right fields without per-node custom code
• Know which fields a human reviewer should see or be able to edit
• Apply consistent credential masking rules across all 60+ node types
• Register suspension timers when a node waits for human input
• Evaluate template expressions at the correct lifecycle stage

Node Policies solve this by giving every node a machine-readable manifest that the platform reads to handle all of these concerns automatically.

The Five Policy Types

The Two Layers

Layer 1 — Code Manifest (Compile-time)

Each node executor defines its manifest in a .Config.cs partial by overriding GetNodeExecutorManifest():

// SmtpNodeExecutor.Config.cs
protected override NodeExecutorManifest? GetNodeExecutorManifest()
    => NodeExecutorManifest.From(
        ProcessElementTypeCode,
        new[]
        {
            new NodeFieldDescriptor
            {
                FieldId          = "to",
                Description      = "Recipient email address",
                ExpressionPolicy = new ExpressionPolicy
                {
                    EvaluationStage = EvaluationStage.AtInputReady,
                    EvaluatorKind   = EvaluatorKind.Template
                },
                DataFlowPolicy = new DataFlowPolicy
                {
                    AcceptsUpstreamInput     = true,
                    ExcludeFromOutputMapping = true
                },
                HilPolicy = new HilPolicy
                {
                    SendToHil   = true,
                    DisplayMode = HilDisplayMode.ReadableContext,
                    InputMode   = HilInputMode.EditableOptional,
                    Label       = "To"
                },
                SecurityPolicy = new SecurityPolicy()
            }
        }
    );

Layer 2 — Extension JSON (Runtime Override)

Administrators store additional field descriptors or override existing ones in the database (ProcessNodePolicies table). This JSON is merged with the code manifest at runtime by NodeFieldManifestResolver, allowing customisation without redeployment — for example adjusting HIL labels or enabling masking for a specific tenant.

{
  "nodeTypeName": "email-smtp",
  "fields": [
    {
      "id": "body",
      "hilPolicy": {
        "sendToHil": true,
        "inputMode": "RequiredFromHuman",
        "label": "Email Body",
        "description": "You must confirm this before the email sends."
      }
    }
  ]
}

Runtime Execution Flow

Key Types