> ## Documentation Index
> Fetch the complete documentation index at: https://docs.splox.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Node Lifecycle

> Understand node execution states and behavior during workflow runs

## Overview

Nodes go through various execution states as workflows run. Understanding these states helps you monitor and debug workflow execution.

***

## Execution States

<Steps>
  <Step title="Pending">
    Node is queued for execution but hasn't started yet

    **Visual:** Gray background

    **When it happens:**

    * Workflow just started
    * Waiting for previous nodes to complete
    * Queued in execution pipeline
  </Step>

  <Step title="In Progress">
    Node is currently executing

    **Visual:** Blue pulsing animation

    **When it happens:**

    * Node actively processing
    * LLM generating response
    * Tool executing action
    * Template rendering
  </Step>

  <Step title="Completed">
    Node executed successfully

    **Visual:** Green background with checkmark

    **When it happens:**

    * Execution finished without errors
    * Output data available
    * Ready to trigger next nodes
  </Step>

  <Step title="Failed">
    Node execution encountered an error

    **Visual:** Red background with error icon

    **When it happens:**

    * API errors or timeouts
    * Invalid configuration
    * Tool execution failures
    * Template syntax errors
  </Step>

  <Step title="Waiting">
    Node is waiting for dependencies (parallel execution)

    **Visual:** Yellow background

    **When it happens:**

    * Waiting for parallel branches to complete
    * Merge node waiting for all inputs
    * Dependencies not yet satisfied
  </Step>

  <Step title="Blocked">
    Node cannot execute due to missing dependencies

    **Visual:** Orange background

    **When it happens:**

    * Required input node didn't execute
    * Conditional branch not taken
    * Invalid workflow configuration
  </Step>

  <Step title="Skipped">
    Node was skipped (conditional branching)

    **Visual:** Gray background with skip icon

    **When it happens:**

    * Switch node condition not met
    * Unselected conditional branch
    * Workflow path not taken
  </Step>

  <Step title="Stopped">
    Workflow was stopped before reaching this node

    **Visual:** Dark gray background

    **When it happens:**

    * Manual workflow stop
    * Stop node triggered in subflow
    * Error in previous critical node
  </Step>
</Steps>

***

## State Transitions

<div className="block dark:hidden">
  ```mermaid theme={null}
  %%{init: {'theme':'base', 'themeVariables': {'primaryColor':'#f5f5f5','primaryTextColor':'#171717','primaryBorderColor':'#171717','lineColor':'#171717','secondaryColor':'#ffffff','tertiaryColor':'#f5f5f5','background':'#ffffff','mainBkg':'#f5f5f5','secondBkg':'#ffffff','textColor':'#171717','nodeTextColor':'#171717','nodeBorder':'#171717','edgeLabelBackground':'#ffffff'}}}%%
  stateDiagram-v2
      [*] --> Pending: Workflow starts
      Pending --> InProgress: Execution begins
      Pending --> Blocked: Dependencies failed
      Pending --> Stopped: Workflow stopped
      
      InProgress --> Completed: Success
      InProgress --> Failed: Error occurred
      InProgress --> Stopped: Force stop
      
      Waiting --> InProgress: Dependencies ready
      Waiting --> Blocked: Dependencies failed
      Waiting --> Stopped: Workflow stopped
      
      Completed --> [*]: Continue workflow
      Failed --> [*]: Error path
      Skipped --> [*]: Branch not taken
      Blocked --> [*]: Cannot execute
      Stopped --> [*]: Terminated
  ```
</div>

<div className="hidden dark:block">
  ```mermaid theme={null}
  %%{init: {'theme':'base', 'themeVariables': {'primaryColor':'#252526','primaryTextColor':'#fafafa','primaryBorderColor':'#fafafa','lineColor':'#fafafa','secondaryColor':'#1e1e1e','tertiaryColor':'#252526','background':'#1e1e1e','mainBkg':'#252526','secondBkg':'#1e1e1e','textColor':'#fafafa','nodeTextColor':'#fafafa','nodeBorder':'#fafafa','edgeLabelBackground':'#252526'}}}%%
  stateDiagram-v2
      [*] --> Pending: Workflow starts
      Pending --> InProgress: Execution begins
      Pending --> Blocked: Dependencies failed
      Pending --> Stopped: Workflow stopped
      
      InProgress --> Completed: Success
      InProgress --> Failed: Error occurred
      InProgress --> Stopped: Force stop
      
      Waiting --> InProgress: Dependencies ready
      Waiting --> Blocked: Dependencies failed
      Waiting --> Stopped: Workflow stopped
      
      Completed --> [*]: Continue workflow
      Failed --> [*]: Error path
      Skipped --> [*]: Branch not taken
      Blocked --> [*]: Cannot execute
      Stopped --> [*]: Terminated
  ```
</div>

***

## Debugging Tips

<CardGroup cols={2}>
  <Card title="Check Failed Nodes" icon="bug">
    Look for red nodes to identify where execution failed

    View error messages in node outputs
  </Card>

  <Card title="Review Blocked Nodes" icon="ban">
    Orange nodes indicate dependency issues

    Check if required previous nodes executed
  </Card>

  <Card title="Trace Skipped Paths" icon="route">
    Gray skipped nodes show unused branches

    Verify Switch node conditions are correct
  </Card>

  <Card title="Monitor In Progress" icon="spinner">
    Blue pulsing nodes show active execution

    Long execution times may indicate timeouts
  </Card>
</CardGroup>

***

## What's Next?

<CardGroup cols={2}>
  <Card title="Testing Workflows" icon="flask" href="/guides/testing-workflows">
    Learn how to test and debug workflows
  </Card>

  <Card title="Error Handling" icon="triangle-exclamation" href="/concepts/edges">
    Use ERROR handles for graceful error recovery
  </Card>

  <Card title="Execution Nodes" icon="play" href="/concepts/nodes/execution-nodes">
    Control workflow flow with Start, End, Stop
  </Card>

  <Card title="Back to Overview" icon="cube" href="/concepts/nodes">
    Return to nodes overview
  </Card>
</CardGroup>