> ## Documentation Index
> Fetch the complete documentation index at: https://cognitio-agent.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Interface: SessionUsage

> Generated from the public TypeScript API.

Live cost/usage snapshot exposed by `session.usage`. Shapes match
`ResultMessage` so the two read the same way.

Semantics: values accumulate from assistant messages observed on THIS
session handle (attached/resumed handles start at zero) and are reconciled
against each turn's authoritative `session.result` — so subagent
child-session cost appears once the turn completes, without double
counting. Monotonic: rewinds do not subtract.

## Properties

### modelUsage

```ts theme={null}
modelUsage: Record<string, ModelUsageSummary>;
```

***

### totalCostUsd

```ts theme={null}
totalCostUsd: number;
```

***

### turns

```ts theme={null}
turns: number;
```

***

### usage

```ts theme={null}
usage: UsageSummary;
```


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