Models

A harness runs the agent. A model handles its reasoning and tool calls. Select exactly one claude_code or codex block, and set its model.

{
  "claude_code": {
    "model": "claude-opus-5",
    "prompt": "Find and fix the failing test."
  }
}

Current support

GET /v1/account/models lists available models, their harnesses, capabilities, and token prices.

See Harnesses for feature support and Pricing for the model list and token prices.

A configuration field can exist before that capability is available. Unsupported combinations return unsupported_session_combination before work starts.

Defaults

Claude Code uses the account's default model when the request omits claude_code.model. Codex defaults to gpt-5.6-terra.

Always send exactly one claude_code or codex block. The key selects the harness; no type field is needed.

Provider credentials

Platform-managed routes are available for the listed models.

A connected Claude Code subscription funds Anthropic models, and a connected Codex subscription funds OpenAI models on eligible sessions. Manage both under Models > Subscriptions. Each provider has its own connection, so adding Codex preserves your Claude subscription.

Choose Add subscription, select the provider, and supply its credentials:

• Claude Code: Run claude setup-token and paste the token.
• Codex: Run codex -c cli_auth_credentials_store="file" login, sign in with ChatGPT, and paste the contents of ~/.codex/auth.json into the credential field. Treat this file as a password. Ellipsis stores it on the server and refreshes the login when needed.

Save and verify the connection before using it. Subscription eligibility depends on the session's account and attribution. A failed subscription request does not fall back to paid Ellipsis inference.

Custom Anthropic API keys and Bedrock routes are currently unavailable for session starts. A configured custom provider can prevent a session from starting unless an eligible Claude subscription takes precedence.