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

# Architecture

> System architecture and design references

This section documents system architecture, service workflows, and RFCs. Content is maintained separately from service-level runbooks and configuration guides.

## Service map

```mermaid theme={"theme":"kanagawa-wave"}
flowchart LR
  Frontline[Frontline]
  Sentinel[Sentinel]
  API[API]
  Vault[Vault]
  ControlAPI[Control plane API]
  ControlWorker[Control plane worker]
  Krane[Krane]
  Preflight[Preflight]

  Frontline -->|A| Sentinel
  Sentinel -->|A| API
  API -->|B| Vault
  Frontline -->|B| Vault

  ControlAPI -->|C| ControlWorker
  ControlWorker -->|C| Krane
  ControlWorker -->|B| Vault

  Preflight -->|A| Krane
```

### Legend

* **A**: HTTP or HTTPS request.
* **B**: RPC or service call.
* **C**: Asynchronous workflow trigger.

## Sections

* [Services](/architecture/services)
* [RFCs](/architecture/rfcs)