🚀 LiteLLM Connector for GitHub Copilot Chat

Bring any LiteLLM-supported model into the Copilot Chat model picker — OpenAI, Anthropic, Google, Mistral, local Llama, and more. If LiteLLM can talk to it, Copilot can use it.

🆕 What's New in 2.5.6

Version 2.5.6 adds Claude Fable 5.1 / Mythos 5.1 compatibility and removes ~2,700 lines of dead code.

• 🤖 Claude Fable 5.1 / Mythos 5.1 compatibility — Forced tool_choice is downgraded to "auto" (these models reject it with a 400), retained thinking_blocks are stripped when front-trimming invalidates their conversation binding, the one-shot continuity retry recognizes the Fable-specific rejection strings, and stop_reason: "refusal" (HTTP 200) is detected and logged on both endpoints.
• 🎚️ Sampling params stripped for Fable 5.1 — temperature, top_p, and top_k are removed for claude-fable-5-1 / claude-mythos-5-1 (non-default values 400), covering proxies whose model cards misreport capabilities. Model-card lists still win.
• 🧭 Unified model-ID matching — The tool_choice downgrade and sampling guard now share one boundary-aware matcher, so aliased IDs (anthropic.claude-fable-5-1-v1:0, claude-fable-5-1@20260801) get both protections together.
• 🗑️ Removed the dead V2 message pipeline — ~2,700 lines of orphaned message-conversion code that no provider called. No behavior change; all four coverage categories improved.

See CHANGELOG.md for previous release notes.

⭐️ Support the Project

• ⭐ Star on GitHub: https://github.com/gethnet/litellm-connector-copilot
• 📝 Leave a review on the VS Code Marketplace
• ☕ Support development: Ko-fi | Buy Me a Coffee

⚡ Quick Start (60 Seconds)

1. Install GitHub Copilot Chat (if not already installed)
2. Install LiteLLM Connector for Copilot
3. Open Command Palette (Ctrl+Shift+P)
4. Run LiteLLM: Manage Configuration
5. Add a provider group:
   • Name (e.g., "Cloud", "Local")
   • Base URL (e.g., http://localhost:4000)
   • API Key (required)
6. Open Copilot Chat → pick a model → start chatting!

✅ Requirements

• 🖥️ VS Code 1.120+
• 🌐 A LiteLLM proxy URL and API key

No Copilot subscription required. BYOK models work without a GitHub login or Copilot plan — including air-gapped scenarios. See Using BYOK Without Copilot to redirect the Copilot-backed utility models to your LiteLLM models.

✨ Features & Differentiators

🐛 Troubleshooting

Models not showing up?

1. Run LiteLLM: Manage Configuration and verify Base URL + API key
2. Run LiteLLM: Reload Models to force refresh
3. If stuck: Remove LiteLLM provider groups via LiteLLM: Manage Configuration → VS Code's Language Models UI, then re-add

🚫 Using BYOK Without Copilot

BYOK models work without signing into a GitHub account or a Copilot plan, including fully air-gapped scenarios. Your LiteLLM Connector models appear in the Chat model picker and work for chat and agent workflows with no Copilot subscription required.

A few Copilot-backed features stop working without a login because their defaults point at Copilot models. You can redirect all of them to your LiteLLM Connector models so the full chat experience keeps working offline.

⚠️ Keep chat.byokUtilityModelDefault set to GitHub Copilot. This setting governs how BYOK models are surfaced. Changing it can prevent your BYOK models from appearing in the picker.

Settings that take a fully qualified model name

A fully qualified model name is litellm-connector/<provider-group>/<model>, matching the identifier shown in the Chat model picker.

Settings that use a model dropdown

These settings present a dropdown of every available model (including your BYOK models). Pick the LiteLLM Connector model you want from the list.

Example settings.json

{
  // Keep this as "GitHub Copilot" so BYOK models are surfaced correctly.
  "chat.byokUtilityModelDefault": "GitHub Copilot",

  // Redirect Copilot-backed features to LiteLLM Connector models.
  "github.copilot.selectedCompletionModel": "litellm-connector/<group>/<model>",
  "github.copilot.chat.workspace.preferredEmbeddingsModel": "litellm-connector/<group>/<embedding-model>",
  "github.copilot.chat.instantApply.shortContextModelName": "litellm-connector/<group>/<model>",

  // Pick these from the model dropdown in Settings UI.
  "chat.utilityModel": "litellm-connector/<group>/<model>",
  "chat.utilitySmallModel": "litellm-connector/<group>/<small-model>"
}

Replace <group> with your provider group name and the model placeholders with models from your LiteLLM proxy. Reload the window (Developer: Reload Window) for changes to take effect.

Copy a fully qualified model name

After configuring a provider, run LiteLLM: Reload Models, then run LiteLLM: Show Available Models. Select a model to copy its fully qualified ID to the clipboard for use in VS Code BYOK settings.

The picker shows a friendly model name but copies the complete model ID, including the provider-group namespace. Use the copied value for settings such as github.copilot.selectedCompletionModel, chat.utilityModel, and chat.utilitySmallModel.

Enterprise note: For Copilot Business or Enterprise, organization administrators can control BYOK availability through Copilot policy settings.

⚙️ Configuration

Base URL + API key are configured through VS Code's Language Models UI (run LiteLLM: Manage Configuration).

Standard Settings

Reasoning model-card overrides are disabled by default. Enable enableModelOverrides when LiteLLM reports incorrect or incomplete reasoning metadata. Overrides replace or add only the explicitly named LiteLLM fields; related fields are not inferred.

🛠️ Help: Applying a Model Override

Model overrides are disabled by default. To correct incomplete LiteLLM /model/info metadata:

1. Open Preferences: Open User Settings (JSON) or Preferences: Open Workspace Settings (JSON).
2. Set litellm-connector.enableModelOverrides to true.
3. Add a matching rule to litellm-connector.modelOverrides.
4. Run LiteLLM: Reload Models.

Use the raw LiteLLM model_name and exact snake_case model-card fields. Only explicitly defined fields are changed; related fields are not inferred.

{
   "litellm-connector.enableModelOverrides": true,
   "litellm-connector.modelOverrides": [
      {
         "match": "^gpt-4\\.8$",
         "supports_reasoning": true,
         "supports_max_reasoning_effort": true
      }
   ]
}

Define each desired effort explicitly, such as supports_xhigh_reasoning_effort: true. Setting one effort field does not enable supports_reasoning or any other effort field automatically.

Advanced (JSON-Only)

These aren't in Settings UI — add to settings.json if needed:

⌨️ Commands

• LiteLLM: Manage Configuration — Add/edit provider groups
• LiteLLM: Reload Models — Refresh model list
• LiteLLM: Show Available Models — View discovered models
• LiteLLM: Generate Commit Message — Generate commit from staged changes
• LiteLLM: Set Log Level — Change logging verbosity

📋 Feedback & Issues

• GitHub Issues: https://github.com/gethnet/litellm-connector-copilot/issues

🧩 Notes

• This extension is a language model provider for VS Code Chat
• Works with or without GitHub Copilot (BYOK models work without a Copilot subscription)
• VS Code Chat (formerly Copilot Chat) is built into VS Code 1.120+

📜 License

Apache-2.0 © GethNet