> ## Documentation Index
> Fetch the complete documentation index at: https://docs.t3planet.de/en/latest/llms.txt
> Use this file to discover all available pages before exploring further.

# Architecture

> Architecture for EXT:ns_t3af (T3AF).

## Overview

<img src="https://mintcdn.com/t3planet/7vzgkyGo0iYgfZc6/en/latest/ExtNsT3AF/DeveloperGuide/Architecture/images/for-developers.webp?fit=max&auto=format&n=7vzgkyGo0iYgfZc6&q=85&s=fba701ef094cbd0518e10455aba03c3a" alt="For Developers tab showing T3AF architecture at a glance" width="1894" height="860" data-path="en/latest/ExtNsT3AF/DeveloperGuide/Architecture/images/for-developers.webp" />

Architecture at a glance — extensions call T3AF, which routes to AI providers and MCP clients.

T3AF is a shared foundation layer:

```
Consuming Extension Code
        |
        v
AiServiceInterface
        |
        v
AdapterRegistry -> Provider adapters
        |
        v
   Provider APIs
```

Parallel support:

```
AiStatisticsService -> OpenAiOrganizationUsageService -> OpenAI Usage API
HttpAuthUtility    -> Protected URL fetching with optional Basic Auth
```

## Main components

* **Request orchestration**: `AiServiceInterface` and `AiService`
* **Provider adapters**: `AdapterRegistry` and `AdapterInterface` implementations
* **Statistics processing**: `AiStatisticsService` and `OpenAiOrganizationUsageService`
* **Engine configuration filtering**: `AiEngineConfiguration`
* **Utility and environment helpers**: `AiUniverseUtilityHelper`
* **HTTP auth helper**: `HttpAuthUtility`

## Configuration model

Runtime AI requests resolve through provider rows in [AI Providers](/en/latest/en/latest/ExtNsT3AF/Configuration/AIProviders/Index). Optional extension settings cover translation helpers, Basic Auth, notifications, and MCP switches. See [Configuration](/en/latest/en/latest/ExtNsT3AF/Configuration/Index).

This includes:

* provider adapters, encrypted API keys, and model IDs
* default provider selection
* optional temperature and capability flags on provider rows
* optional Basic Auth settings for protected URL fetching

## Caching

The extension registers cache `nst3af_statistics` in `ext_localconf.php`.

Statistics service stores processed data in this cache to reduce repeated usage API calls.

## Constraints

* No native frontend plugin and no Fluid frontend output in this package.
* Primary role is reusable service infrastructure.