VS Code (Chat) - Hostlinku Docs

The built-in chat in VS Code (Chat panel, Agent mode, and inline chat) can use external models via the Custom Endpoint provider. This provider supports three API formats—Chat Completions, Responses, and Anthropic Messages—and all three are served by Hostlinku. BYOK models like this do not require a GitHub login or the Copilot package. Prerequisites: The latest version of VS Code (Custom Endpoint replaces the deprecated OpenAI Compatible provider) and the GitHub Copilot Chat extension.

Other API Formats

Each model can use a different format via the apiType per model:

`apiType`	`url`	Notes
`chat-completions`	`https://api.hostlinku.com/v1/chat/completions`	Recommended default — all catalog models.
`messages`	`https://api.hostlinku.com/v1/messages`	Anthropic format; VS Code sends the key as `x-api-key` (accepted by the gateway).
`responses`	`https://api.hostlinku.com/v1/responses`	Required: Add `"statefulResponses": false` — see below.

{
  "id": "gpt-5-5",
  "name": "GPT-5.5 (Responses)",
  "url": "https://api.hostlinku.com/v1/responses",
  "apiType": "responses",
  "statefulResponses": false,
  "toolCalling": true,
  "vision": true,
  "contextWindow": 1000000,
  "maxOutputTokens": 64000
}

What You Need to Know

Inline suggestions (autocomplete) will continue to use Copilot. BYOK applies only to chat and utility task; semantic search, embeddings, and code completions require a GitHub account.
Without logging into GitHub, VS Code asks you to choose a utility model (session title, commit message, etc.). Set chat.utilityModel and chat.utilitySmallModel to the Hostlinku model—claude-haiku-4-5 is suitable for the small model.
Copilot Business/Enterprise: The organization’s administrator must enable the Bring Your Own policy “Language Model Key in VS Code*” in the GitHub Copilot settings.
Untrusted workspace (Restricted Mode) displays only Auto models; trust workspace so that my Hostlink model appears.

Troubleshooting

Symptoms	Solutions
The model does not appear in Agent mode	Set `"toolCalling": true` and use the model via tool calling from the catalog.
`401`	Invalid or revoked API key — update it via the provider’s gear icon in the Language Models editor.
`404 model_not_found`	`id` must be the exact slug from `GET /v1/models`.
`400` refers to `previous_response_id`	A model with `apiType: "responses"` without `"statefulResponses": false`.
The new model isn’t showing up	Restart VS Code after saving `chatLanguageModels.json`.

​Other API Formats

​What You Need to Know

​Troubleshooting

Other API Formats

What You Need to Know

Troubleshooting