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

# system

> Contract, placement, related fields and source examples for this Nika YAML field.

[Language reference](/reference/language/overview) / `system`

## Meaning and placement

### infer

System prompt · the standing instruction, sent ahead of `prompt:` and unchanged by it.

| Property        | Declaration                      |
| --------------- | -------------------------------- |
| Requirement     | Optional in this object          |
| Schema location | `/$defs/infer/properties/system` |
| type            | "string"                         |

**In the same object:** [max\_tokens](/reference/language/words/max_tokens) · [model](/reference/language/words/model) · [prompt](/reference/language/words/prompt) · [schema](/reference/language/words/schema) · [temperature](/reference/language/words/temperature) · [thinking](/reference/language/words/thinking) · [vision](/reference/language/words/vision)

[Schema source (use the pointer above)](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/schemas/workflow.schema.json)

### agent

System prompt · the standing instruction, sent ahead of `prompt:` and unchanged by any turn of the loop.

| Property        | Declaration                      |
| --------------- | -------------------------------- |
| Requirement     | Optional in this object          |
| Schema location | `/$defs/agent/properties/system` |
| type            | "string"                         |

**In the same object:** [max\_tokens\_total](/reference/language/words/max_tokens_total) · [max\_turns](/reference/language/words/max_turns) · [model](/reference/language/words/model) · [prompt](/reference/language/words/prompt) · [schema](/reference/language/words/schema) · [skills](/reference/language/words/skills) · [temperature](/reference/language/words/temperature) · [tools](/reference/language/words/tools)

[Schema source (use the pointer above)](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/schemas/workflow.schema.json)

## In a source template

Excerpt from `templates/agent-loop.nika.yaml`, source lines 92–101. This is a fragment, not a runnable workflow.

```yaml illustration theme={"system"}
      # either engine, hand-instructing "reply with the object, then call
      # nika:done" only makes that miss more likely (measured twice on that
      # exact instruction). Let the engine own the shape.
      system: "You are a careful analyst. Work the plan step by step and report what you actually found."   # SLOT
      prompt: |
        Goal · ${{ with.goal }}
        Plan · ${{ with.steps }}
      tools:                        # SLOT: the MINIMUM grant for the job
        # Pure compute — this pair needs no filesystem, so the skeleton runs
        # anywhere. Granting the agent a tool here is only HALF a grant: every
```

### Templates containing this field

| Template                         | Source                                                                                                                                 |
| -------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
| `templates/agent-loop.nika.yaml` | [Line 95](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/templates/agent-loop.nika.yaml#L95) |

These are literal key occurrences in the source files, not an execution or conformance claim. [How to instantiate a template](/guides/templates).

## Contract and implementation

This page projects the named specification revision. Check [released engine status](/reference/status) and [the validation workflow](/guides/agent-authoring) before running a file. An optional field is not evidence that every engine supports every value.

Canonical identity: `language:word:system`. Spec revision: [`c5ebbb7b862b`](https://github.com/supernovae-st/nika-spec/tree/c5ebbb7b862b68bc6cf7235efba61173b844afc6).

[How documentation stays connected](/reference/knowledge-system).