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

# Harnesses and models

> The seven coding-agent harnesses on every sandbox, the models each one runs, and fast mode.

Pick the harness for each prompt with `--provider`. If you omit it, Boat uses the harness you chose on the Agents dashboard.

## Harnesses

| `--provider` | Harness | Models |
| - | - | - |
| `claude` | Claude Code | Anthropic models, or DeepSeek models on a DeepSeek key |
| `codex` | OpenAI Codex | OpenAI models, or DeepSeek models on a DeepSeek key |
| `pi` | pi | Anthropic, OpenAI, Mistral, and OpenRouter or llmgateway-routed models (DeepSeek and Mistral included) |
| `opencode` | OpenCode | same multi-vendor catalog |
| `prime` | Prime Agent | same multi-vendor catalog |
| `kimi` | Kimi Code CLI (Moonshot AI) | Kimi models: K3, Kimi for Coding, K2.7 Code, K2.6 |
| `mistral` | Mistral Vibe (Mistral AI) | Mistral models: Large 4 (default), Medium 3.5, Small 4 |

For the keys each harness needs, read [Keys and subscriptions](/integrated-agents/keys).

## The model catalog

Each model accepts a different set of reasoning levels. The catalog changes often, so Boat serves it live. This page does not list it.

* `boat prompt --help` prints the catalog.
* `GET /provider-models` returns it as JSON.

You can change the model or the thinking level on any prompt. The prompt stays in the same conversation.

```bash theme={null}
boat prompt --provider pi --model claude-sonnet-5 --reasoning-effort high "Refactor the billing module"
boat prompt --model gpt-5.6-terra "Same task, second opinion"        # same conversation, other model
```

## Fast mode

Fast mode runs the same model with faster output. The provider bills it at its higher fast rate.

| Harness | Fast mode is | Speed | Billing |
| - | - | - | - |
| Codex | The "Fast" service tier | About 1.5x to 2x faster | Uses ChatGPT plan limits faster |
| Claude Code | Opus fast mode | Up to 2.5x faster | Billed from Claude usage credits |

* Only models with `"fastMode": true` in `GET /provider-models` accept it. Examples are GPT-6.1 Sol, GPT-6 Sol and Opus.
* A prompt without `fast` uses the choice saved on the Agents dashboard.
* `fast: false` forces standard speed.

<CodeGroup>
  ```bash CLI theme={null}
  boat prompt --provider codex --model gpt-6.1-sol --fast "Fix the failing tests"
  ```

  ```bash curl theme={null}
  curl -sS -X POST "$BOAT_API_BASE/sandboxes/$BOAT_ID/prompt" \
    -H "Authorization: Bearer $BOAT_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{"provider":"codex","model":"gpt-6.1-sol","fast":true,"prompt":"Fix the failing tests"}'
  ```

  ```ts TypeScript theme={null}
  await sandbox.prompt({ sandboxId, provider: "codex", model: "gpt-6.1-sol", fast: true, prompt: "Fix the failing tests" });
  ```

  ```python Python theme={null}
  sandbox.prompt(sandbox_id, PromptRequest(provider="codex", model="gpt-6.1-sol", fast=True, prompt="Fix the failing tests"))
  ```
</CodeGroup>

A model without fast mode refuses `fast: true` with `400 fast_mode_not_supported`. The error message lists the models that have fast mode.


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