AI Toolkit Foundry models show as "Added, Supports Agent Mode" but do not appear in Copilot Chat model picker

Problem

Models added through Microsoft Foundry via AI Toolkit appear correctly in the VS Code Language Models view, but they do not appear in the GitHub Copilot Chat model picker, even though they are marked as:

• Added
• Supports Agent Mode
• Capabilities: Tools
• Capabilities: Vision

Because of this, the models seem to be registered and recognized by VS Code, but they are not selectable from Copilot Chat.

Expected Behavior

Models that are shown in Language Models as Added, Supports Agent Mode should also appear in the GitHub Copilot Chat model picker and be selectable for Agent Mode.

Actual Behavior

The models are visible in the Language Models view under:

Microsoft Foundry via AI Toolkit

Examples:

• DeepSeek-V3.1
• DeepSeek-V4-Flash
• gpt-4.1-mini
• gpt-5.3-codex

They show:

• Context size: 139K
• Capabilities: Tools, Vision
• Status: Added, Supports Agent Mode

However, they do not appear in the Copilot Chat model dropdown/picker.

Steps to Reproduce

1. Install/update VS Code.
2. Install/update GitHub Copilot and GitHub Copilot Chat.
3. Install/update AI Toolkit / Foundry Toolkit.
4. Open the Language Models view.
5. Add models from Microsoft Foundry via AI Toolkit.
6. Confirm the models appear as Added, Supports Agent Mode.
7. Open GitHub Copilot Chat.
8. Switch to Agent Mode.
9. Open the model picker/dropdown.
10. Notice that the added Foundry models are not listed.

Screenshot

The screenshot shows the models correctly listed in the Language Models view with Added, Supports Agent Mode, including Tools and Vision capabilities, but they are not available in the Copilot Chat model picker.

Environment

Please let me know if you need the exact versions. I can provide:

• VS Code version 1.120.0
• GitHub Copilot extension version 0.48.1
• GitHub Copilot Chat extension version 0.48.1
• AI Toolkit / Foundry Toolkit extension version 1.2.1
• Operating system Windows 11
• Copilot plan type (Plus)

Additional Notes

This does not seem to be related to missing Agent Mode support because the models are explicitly shown as Supports Agent Mode and have the Tools capability.

The report names no source files, tests, or entry points. Reproduce the issue by adding a Microsoft Foundry model in the Language Models view, then compare its status with the Agent Mode model picker; done means eligible added models appear and can be selected in Copilot Chat.