---
title: "Anthropic fast mode and deep model testing"
date: "2026-03-21"
---

## Anthropic fast mode

You can now enable Anthropic's fast mode for up to 2.5x faster output from Claude Opus 4.6 by setting `speed: fast` in your workflow stylesheet. This is useful for latency-sensitive stages where throughput matters more than cost.

```dot
graph {
  graph [stylesheet="speed=fast"]
}
```

## `fabro model test --deep`

Model validation now supports a `--deep` flag that runs multi-turn tool-use conversations to verify that a provider handles the full agent loop correctly — not just single-turn completions. Tests run concurrently with a progress bar.

```bash
fabro model test --deep
```

## More

<Accordion title="Fixes">
- Fixed workflow TOML config being lost when running in detach mode
- Fixed edge `thread_id` precedence to match documented fidelity behavior
- Fixed Sonnet 4.5 `reasoning_effort` parameter error by converting to the thinking API format
- Fixed OpenAI reasoning round-trip losing encrypted content by setting `store: false`
- Fixed OpenAI provider incorrectly omitting `store: true` from requests
- Suppressed stderr output noise in detach and create modes
</Accordion>