> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/pingdotgg/t3code/llms.txt
> Use this file to discover all available pages before exploring further.

# Model Contracts

> Model configuration types and schemas for provider AI models

## Overview

The model contracts define TypeScript types and Effect schemas for configuring AI models across different providers. Currently focused on Codex models with support for reasoning effort and performance modes.

## Model Options

### CodexModelOptions

Configuration options specific to Codex models.

<ParamField path="reasoningEffort" type="'xhigh' | 'high' | 'medium' | 'low'" optional>
  Controls the reasoning effort level for the model. Higher values provide more thorough analysis at the cost of increased latency.

  **Available values:**

  * `xhigh` - Extra high reasoning effort
  * `high` - High reasoning effort (default)
  * `medium` - Medium reasoning effort
  * `low` - Low reasoning effort
</ParamField>

<ParamField path="fastMode" type="boolean" optional>
  Enables fast mode for quicker responses with reduced reasoning depth.
</ParamField>

```typescript theme={null}
import { Schema } from "effect";

export const CodexModelOptions = Schema.Struct({
  reasoningEffort: Schema.optional(Schema.Literals(["xhigh", "high", "medium", "low"])),
  fastMode: Schema.optional(Schema.Boolean),
});
export type CodexModelOptions = typeof CodexModelOptions.Type;
```

### ProviderModelOptions

Top-level model options supporting multiple providers.

<ParamField path="codex" type="CodexModelOptions" optional>
  Provider-specific options for Codex models.
</ParamField>

```typescript theme={null}
export const ProviderModelOptions = Schema.Struct({
  codex: Schema.optional(CodexModelOptions),
});
export type ProviderModelOptions = typeof ProviderModelOptions.Type;
```

## Model Slugs

### Available Models

Built-in model options organized by provider:

```typescript theme={null}
export const MODEL_OPTIONS_BY_PROVIDER = {
  codex: [
    { slug: "gpt-5.4", name: "GPT-5.4" },
    { slug: "gpt-5.3-codex", name: "GPT-5.3 Codex" },
    { slug: "gpt-5.3-codex-spark", name: "GPT-5.3 Codex Spark" },
    { slug: "gpt-5.2-codex", name: "GPT-5.2 Codex" },
    { slug: "gpt-5.2", name: "GPT-5.2" },
  ],
} as const;
```

### ModelSlug Type

Flexible type allowing both built-in and custom model slugs:

```typescript theme={null}
type BuiltInModelSlug = ModelOptionsByProvider[ProviderKind][number]["slug"];
export type ModelSlug = BuiltInModelSlug | (string & {});
```

<Info>
  The `ModelSlug` type accepts any string while providing autocomplete for built-in models in TypeScript-aware editors.
</Info>

## Default Configuration

### Default Models

```typescript theme={null}
export const DEFAULT_MODEL_BY_PROVIDER = {
  codex: "gpt-5.4",
} as const;
```

### Model Aliases

Convenience aliases for model slugs:

```typescript theme={null}
export const MODEL_SLUG_ALIASES_BY_PROVIDER = {
  codex: {
    "5.4": "gpt-5.4",
    "5.3": "gpt-5.3-codex",
    "gpt-5.3": "gpt-5.3-codex",
    "5.3-spark": "gpt-5.3-codex-spark",
    "gpt-5.3-spark": "gpt-5.3-codex-spark",
  },
} as const;
```

### Reasoning Effort Options

```typescript theme={null}
export const REASONING_EFFORT_OPTIONS_BY_PROVIDER = {
  codex: ["xhigh", "high", "medium", "low"],
} as const;

export const DEFAULT_REASONING_EFFORT_BY_PROVIDER = {
  codex: "high",
} as const;
```

## Usage Examples

### Basic Model Configuration

```typescript theme={null}
import { CodexModelOptions, ModelSlug } from "@t3tools/contracts";

const modelConfig: CodexModelOptions = {
  reasoningEffort: "high",
  fastMode: false,
};

const modelSlug: ModelSlug = "gpt-5.4";
```

### Provider Model Options

```typescript theme={null}
import { ProviderModelOptions } from "@t3tools/contracts";

const providerOptions: ProviderModelOptions = {
  codex: {
    reasoningEffort: "medium",
    fastMode: true,
  },
};
```

### Using Model Aliases

```typescript theme={null}
import { MODEL_SLUG_ALIASES_BY_PROVIDER } from "@t3tools/contracts";

const alias = "5.3";
const actualSlug = MODEL_SLUG_ALIASES_BY_PROVIDER.codex[alias];
// actualSlug === "gpt-5.3-codex"
```

## Type Definitions

### CodexReasoningEffort

```typescript theme={null}
export const CODEX_REASONING_EFFORT_OPTIONS = ["xhigh", "high", "medium", "low"] as const;
export type CodexReasoningEffort = (typeof CODEX_REASONING_EFFORT_OPTIONS)[number];
```

### ModelOptionsByProvider

```typescript theme={null}
export type ModelOptionsByProvider = typeof MODEL_OPTIONS_BY_PROVIDER;
```

## Related Types

See also:

* [Provider Types](/api/contracts/types#provider-types) - Provider-level configuration
* [Orchestration Schemas](/api/contracts/schemas#thread-commands) - Thread and turn management