---
title: Overview
description: Server-side TypeScript that runs inside Twenty — triggered by HTTP routes, cron schedules, database events, AI tools, or workflow actions.
icon: "bolt"
---

A Twenty app's **logic layer** is the code that *runs* — server-side TypeScript handlers reacting to HTTP requests, cron schedules, and record changes; AI skills and agents that live inside the workspace; and OAuth connections that let your functions act on a user's behalf in third-party services.

```text
            ┌─ HTTP route      ──┐
            │  Cron schedule     │
            │  Database event    │      ┌────────────────────┐
  triggers ─┤  AI tool call      ├─────▶│ Logic function     │
            │  Workflow action   │      │ (your handler)     │
            │  Manual exec       │      └────────────────────┘
            └────────────────────┘                │
                                                  ▼
                                  ┌────────────────────────────┐
                                  │ Twenty API (records)       │
                                  │ Third-party API            │
                                  │   (via Connection token)   │
                                  └────────────────────────────┘
```

## In this section

<CardGroup cols={2}>
  <Card title="Logic Functions" icon="bolt" href="/developers/extend/apps/logic/logic-functions">
    The core building block — trigger types, payloads, and the typed API client.
  </Card>
  <Card title="Skills & Agents" icon="robot" href="/developers/extend/apps/logic/skills-and-agents">
    Reusable AI agent instructions and assistants with custom system prompts.
  </Card>
  <Card title="Connections" icon="plug" href="/developers/extend/apps/logic/connections">
    OAuth credentials your app holds for third-party services — Linear, GitHub, Slack, and more.
  </Card>
</CardGroup>

## Trigger types at a glance

A logic function picks one or more triggers — every entry below is a separate field on `defineLogicFunction()`:

| Trigger | When it runs | Setting |
|---------|--------------|---------|
| **HTTP route** | A request hits your function's public URL | `httpRouteTriggerSettings` |
| **Cron** | A CRON expression matches | `cronTriggerSettings` |
| **Database event** | A workspace record is created, updated, or deleted | `databaseEventTriggerSettings` |
| **AI tool** | A Twenty AI feature decides to call your function | `toolTriggerSettings` |
| **Workflow action** | A workflow step invokes your function | `workflowActionTriggerSettings` |

Functions run sandboxed in isolated Node.js processes and access the workspace through a typed API client scoped to the role declared on [`defineApplication()`](/developers/extend/apps/config/application).

<Note>
**Install-time hooks** — code that runs before or after the install — share this runtime but use their own define functions and live under [Config → Install Hooks](/developers/extend/apps/config/install-hooks).
</Note>
