# SystemMessage

> Represent system instructions as a typed conversation turn.

- Path: `Guides > Inference > Messages > Message Types > SystemMessage`
- Human: https://looprig.com/docs/guides/inference/messages/message-types/system-message
- Machine index: https://looprig.com/llms.txt

`SystemMessage` is the typed system turn. The provider-neutral `Request.System` field is a separate request-level instruction; use `SystemMessage` when the conversation itself needs a system turn.

## API surface

```go
type SystemMessage struct{ Message }
```

```go
system := &content.SystemMessage{Message: content.Message{
	Role: content.RoleSystem,
	Blocks: []content.Block{
		&content.TextBlock{Text: "Use short, factual answers."},
	},
}}
```

The type has no additional fields. A system turn can contain the same block slice as the other message types, although provider codecs may restrict which blocks they accept in a system position.

## Proof

- Source: [`core/content/message.go`](https://github.com/looprig/core/blob/main/content/message.go)
- Tests: [`core/content/message_test.go`](https://github.com/looprig/core/blob/main/content/message_test.go), [`core/content/message_json_test.go`](https://github.com/looprig/core/blob/main/content/message_json_test.go)

Related: [System instructions](/docs/guides/inference/requests/system-instructions.md), [UserMessage](/docs/guides/inference/messages/message-types/user-message.md).