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

# OpenCode

> OpenCode integration guide: use multiple models via LeapX API

## 1. Overview

OpenCode is an open-source AI coding assistant supporting 75+ models and local deployment. With **LeapX API**, you can use mainstream and latest models (e.g. GPT, Claude, Gemini) in OpenCode and configure custom providers and models.

**Download**: [https://opencode.ai/](https://opencode.ai/)

## 2. Quick setup (LeapX API)

### 2.1 Get an API key

Create and copy your API key from the [LeapX API console](https://leapx-hub.com/#/keys).

### 2.2 Configure a custom provider in OpenCode

1. Open OpenCode and go to **Server / Provider** settings.
2. Add a **custom provider** (Configure an OpenAI compatible provider).
3. Fill in:
   * **Provider ID**: e.g. `leapx` (lowercase, digits, hyphens or underscores)
   * **Display name**: e.g. `LeapX API`
   * **Base URL**: `https://api.leapx-hub.com/v1` (must end with `/v1`)
   * **API key**: paste your LeapX API key
4. Under **Models**, add the models you need (e.g. `gpt-4o`, `claude-sonnet-4-20250514`). Model IDs must match the [LeapX model list](https://leapx-hub.com/#/models).
5. After saving, use **providerID/modelID** in the model selector (e.g. `leapx/gpt-4o`).

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code1.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=fdbd182b99b5ff3549d4e470d1e908d8" alt="OpenCode custom provider setup" width="1920" height="1140" data-path="images/open-code1.png" />

**Configuration reference** (matching the screenshots above):

* **Base URL**: `https://api.leapx-hub.com/v1`
* **API key**: from [LeapX console](https://leapx-hub.com/#/keys) (e.g. `sk-xxxxxxxxxxxxx`)
* **Models**: choose from [LeapX model list](https://leapx-hub.com/#/models) and enter the model ID

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code2.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=8c5cb42ac00ca8be61817e7da0abe0a0" alt="OpenCode provider and API config" width="795" height="526" data-path="images/open-code2.png" />

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code3.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=94292cccd9c45d8ba31a8b124bf75700" alt="OpenCode model config" width="784" height="379" data-path="images/open-code3.png" />

### 2.3 Switching models

In the chat or settings, select the configured provider and model (e.g. `leapx/gpt-4o`) to switch.

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code4.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=a44a98c364dac811b660702f9624c586" alt="OpenCode switch model" width="1920" height="1140" data-path="images/open-code4.png" />

<Tip>
  * For self-hosted or backup LeapX, set **Base URL** to that address, e.g. `http://your-server:3003/v1`.
  * Default model can be set in project or global `opencode.json` with `"model": "leapx/modelID"`.
</Tip>

## 3. Some models require the Responses API (important)

Some models use a different API than standard Chat Completions and require the **Responses API**. If you see an error like this when using such a model in OpenCode:

Some Azure / OpenAI models **only support the Responses API** and do not support the traditional Chat Completions endpoint. Example error:

> The chatCompletion operation does not work with the specified model, **gpt-5.1-codex**. Please choose different model and try again.

The screenshot below shows how this error appears in the UI:

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code8.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=b8571e8dc7d0b40a22fe9966c67797aa" alt="Error when using gpt-5.1-codex with Chat Completions" width="829" height="269" data-path="images/open-code8.png" />

This means the request was sent as **Chat Completions** while the model only exposes **Responses API** on the server. You need to configure OpenCode to use the correct API.

### 3.1 Models that require the Responses API (typical)

| Model ID / family        | Notes                                                         |
| ------------------------ | ------------------------------------------------------------- |
| **gpt-5.1-codex**        | GPT 5.1 Codex, coding; Responses API only                     |
| **gpt-5.2-codex**        | GPT 5.2 Codex, same as above                                  |
| **o3** / **o3-pro**      | Reasoning models; some deployments only offer Responses API   |
| **o4-mini** and other o4 | Same; check deployment and vendor docs                        |
| **computer-use-preview** | Experimental model used with Responses API computer-use tools |

For the full and up-to-date list, see **Azure / vendor documentation**, e.g.:

* [Azure OpenAI Responses API](https://learn.microsoft.com/en-us/azure/ai-foundry/openai/how-to/responses)
* Link from the error message: [Which models work with each operation](https://go.microsoft.com/fwlink/?linkid=2197993)

### 3.2 How to configure in OpenCode (recommended: add parameter in config)

You can make OpenCode use the **Responses API** for a given model by **adding the `apiCompatibility` parameter** for that model in the config file. No code changes are required.

**1. Locate the config file**

* **Windows**: `C:\Users\<username>\.config\opencode\opencode.jsonc`
* **macOS / Linux**: `~/.config/opencode/opencode.jsonc`\
  You can also use `opencode.json` or `opencode.jsonc` in your project directory.

**2. Add the parameter to the model config under your custom provider**

In your existing provider (e.g. custom provider pointing to LeapX or your own API), add **`"apiCompatibility": "responses"`** for models that need the Responses API (e.g. `gpt-5.1-codex`). Example:

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code5.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=4fbc94a20b123366685c9be77969ca73" alt="Responses API requirement for some models" width="929" height="375" data-path="images/open-code5.png" />

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code6.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=441e5f4636649e2e7e4c7a0a02aad8a3" alt="opencode.jsonc: apiCompatibility responses for gpt-5.1-codex" width="1920" height="1109" data-path="images/open-code6.png" />

```jsonc theme={null}
{
  "$schema": "https://opencode.ai/config.json",
  "disabled_providers": [
    "backup_leapx"
  ],
  "provider": {
    "backup_leapx": {
      "name": "backup_leapx",
      "npm": "@ai-sdk/openai-compatible",
      "models": {
        "gpt-5.2": {
          "name": "gpt-5.2"
        },
        "gpt-5.1-codex": {
          "name": "gpt-5.1-codex",
          "apiCompatibility": "responses"
        },
        "gpt-5.1-chat": {
          "name": "gpt-5.1-chat"
        }
      },
      "options": {
        "baseURL": "xxxxxxxx"
      }
    },
    "backup_v1": {
      "name": "backup_v1",
      "npm": "@ai-sdk/openai-compatible",
      "models": {
        "gpt-5.2": {
          "name": "gpt-5.2"
        },
        "gpt-5.1-codex": {
          "name": "gpt-5.1-codex",
          "apiCompatibility": "responses"
        },
        "gpt-5.1-chat": {
          "name": "gpt-5.1-chat"
        }
      },
      "options": {
        "baseURL": "http://34.87.38.188:3003/v1"
      }
    }
  }
}
```

After saving, when you select that provider’s `gpt-5.1-codex` in OpenCode (e.g. `backup_leapx/gpt-5.1-codex`), requests will be sent to that baseURL in **Responses API** format.

**3. Success example**

The screenshot below shows a normal chat in OpenCode using a correctly configured model (e.g. `backup_v1/gpt-5.1-chat`).

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code7.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=f2a615a8f14b51a974db0de4110053f1" alt="OpenCode chat after successful config" width="1920" height="1140" data-path="images/open-code7.png" />

### 3.3 Summary

| Scenario                                                                       | What to do                                                                                                                                                        |
| ------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Models that only support Responses (e.g. **gpt-5.1-codex**, **gpt-5.2-codex**) | In `opencode.jsonc`, under the custom provider’s **models**, add **`"apiCompatibility": "responses"`** for that model (see config example and screenshots above). |
| Regular models (e.g. **gpt-4o**, **claude-sonnet**)                            | No `apiCompatibility` needed; use LeapX or a custom provider as in “Quick setup” above.                                                                           |

## 4. Recommended models (via LeapX)

| Category               | Model ID examples                               | Notes                                |
| ---------------------- | ----------------------------------------------- | ------------------------------------ |
| Coding / Codex         | `gpt-5.1-codex`                                 | Ensure Responses API (see Section 3) |
| General chat / coding  | `gpt-5.2`, `gpt-5.1-chat`                       | Use as-is; no Responses config       |
| Long context / general | `claude-sonnet-4-20250514`, `claude-sonnet-4-5` | Same                                 |
| Cost-effective         | `gpt-4.1-mini`, `gemini-2.5-flash`              | Same                                 |

See the [LeapX model list](https://leapx-hub.com/#/models) for available models and IDs.

### Success example

The screenshot below shows a normal chat in OpenCode using LeapX API.

<img src="https://mintcdn.com/leapxintelligencetechlimited/X-g5RXsiKme_zara/images/open-code7.png?fit=max&auto=format&n=X-g5RXsiKme_zara&q=85&s=f2a615a8f14b51a974db0de4110053f1" alt="OpenCode success with LeapX API" width="1920" height="1140" data-path="images/open-code7.png" />

## 5. References

* OpenCode site and download: [https://opencode.ai/](https://opencode.ai/)
* OpenCode config and models: [Models](https://opencode.ai/docs/models), [Providers](https://opencode.ai/docs/providers)