Agents Window: support extension development workflow (extensionDevelopmentPath + debugger)

[lauthieb]

Hello VS Code team 👋, and thank you for the incredible work on the Agents Window — it's already a game-changer for agent-first development!

Problem

Currently, developing and testing a VS Code extension inside the Agents Window is not possible with the standard extension development workflow. The two core pain points are:

1. --agents flag is ignored by the extensionHost debug type

When adding --agents to the args of an extensionHost launch configuration, VS Code opens a regular editor window instead of the Agents Window. The flag is handled by the code CLI wrapper, not by the Electron binary that the debug adapter spawns directly.

Expected: launching with --agents + --extensionDevelopmentPath opens an Agents Window with the extension under development loaded, and the debugger attached.

2. Agents Window loads installed extensions, not the development one

Even when an extension is correctly loaded via --extensionDevelopmentPath in a regular Extension Development Host, opening the Agents Window from that host loads extensions from the default installed profile — not from --extensionDevelopmentPath. This means the production version of the extension is loaded instead of the one being developed.

extensions.supportAgentsWindow does not help here, as it also requires the extension to be installed in the default profile.

Current workaround

The only current workaround is to:

1. Package the extension as a .vsix
2. Install it with code --install-extension ... --force
3. Reload the Agents Window manually

This workflow is slow and prevents any real-time debugging (breakpoints, variable inspection, etc.) in the Agents Window context.

Proposed solution

We would love to see one (or both) of the following:

• Option A: Make the extensionHost debug type respect --agents, opening the Agents Window as the Extension Development Host (with debugger attached).
• Option B: When an Agents Window is opened from an Extension Development Host (a VS Code window launched with --extensionDevelopmentPath), have the Agents Window's extension host also load extensions from --extensionDevelopmentPath instead of (or in addition to) the installed profile.

Context

• VS Code version: 1.120.0-insider
• OS: macOS
• Reproduces with any extension that needs to interact with the Agents Window UI (e.g. an extension that triggers chat commands or contributes to the Agents Window layout)

Thanks again for the great work, and for considering this improvement! 🙏

[SebastianNiegel]

Best regards

[SebastianNiegel]

Hello VS Code team 👋, and thank you for the incredible work on the Agents Window — it's already a game-changer for agent-first development!

Problem

Currently, developing and testing a VS Code extension inside the Agents Window is not possible with the standard extension development workflow. The two core pain points are:

1. --agents flag is ignored by the extensionHost debug type

When adding --agents to the args of an extensionHost launch configuration, VS Code opens a regular editor window instead of the Agents Window. The flag is handled by the code CLI wrapper, not by the Electron binary that the debug adapter spawns directly.

Expected: launching with --agents + --extensionDevelopmentPath opens an Agents Window with the extension under development loaded, and the debugger attached.

2. Agents Window loads installed extensions, not the development one

Even when an extension is correctly loaded via --extensionDevelopmentPath in a regular Extension Development Host, opening the Agents Window from that host loads extensions from the default installed profile — not from --extensionDevelopmentPath. This means the production version of the extension is loaded instead of the one being developed.

extensions.supportAgentsWindow does not help here, as it also requires the extension to be installed in the default profile.

Current workaround

The only current workaround is to:

1. Package the extension as a .vsix
2. Install it with code --install-extension ... --force
3. Reload the Agents Window manually

This workflow is slow and prevents any real-time debugging (breakpoints, variable inspection, etc.) in the Agents Window context.

Proposed solution

We would love to see one (or both) of the following:

• Option A: Make the extensionHost debug type respect --agents, opening the Agents Window as the Extension Development Host (with debugger attached).
• Option B: When an Agents Window is opened from an Extension Development Host (a VS Code window launched with --extensionDevelopmentPath), have the Agents Window's extension host also load extensions from --extensionDevelopmentPath instead of (or in addition to) the installed profile.

Context

• VS Code version: 1.120.0-insider
• OS: macOS
• Reproduces with any extension that needs to interact with the Agents Window UI (e.g. an extension that triggers chat commands or contributes to the Agents Window layout)

Thanks again for the great work, and for considering this improvement! 🙏

Danke für dein Feedback.