Does GitHub Copilot Support Cancelling a Specific Running Native Subagent?

[MohamedAbdella]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Copilot in GitHub

Body

GitHub Copilot — Native Child-Agent Cancellation Capability Inquiry

Context

We are certifying a native multi-agent orchestration framework integrated with GitHub Copilot in VS Code.

Our framework uses a custom parent agent to delegate work to custom executor subagents through the native Copilot host.

We have successfully verified:

• Native background subagent delegation.
• Host-assigned child-agent identifiers.
• Custom executor-agent targeting.
• Observable child-agent lifecycle.
• Genuine execution overlap between two native subagents.
• Independent executor completion.

The observed maximum concurrent capacity is two workers. We are not claiming this is the platform's maximum capacity.

Environment

• VS Code: 1.143.0
• GitHub Copilot Chat extension: 0.71.0
• Parent custom agent: agentex-copilot-parallel
• Child custom agent: agentex-copilot-executor
• Observed native tools: task, list_agents, read_agent

The host reported that 128 of 218 available tools were exposed to the model.

Blocking Requirement

We need an officially supported mechanism to cancel one specific running native child agent without cancelling its parent or other concurrently running children.

For release certification, we must be able to demonstrate:

1. A native child agent is actively running.
2. The parent targets that child using its real host-assigned identifier.
3. The host accepts or acknowledges the cancellation request.
4. The targeted child reaches a verifiable terminal cancellation state.
5. The targeted child performs no further work after cancellation is confirmed.
6. Another concurrently running child continues unaffected.
7. The parent can observe and record the final lifecycle outcome.

Questions

1. Supported API

Does the current GitHub Copilot VS Code agent host expose an officially supported API or native tool for cancelling an individual running background subagent by its host-assigned agent ID?

2. Tool availability

If supported, what is the exact tool name, invocation contract, and required configuration?

3. Tool exposure limits

Could the 128-tool exposure limit hide such a capability? Is there an officially supported configuration method to make the required lifecycle controls available?

4. Cancellation semantics

Does the host provide separate cancellation-request acknowledgement and terminal cancellation confirmation?

5. Sibling isolation

Can one child agent be cancelled while another delegated child continues executing normally?

6. User interface

Does the VS Code Agents interface provide a supported child-specific cancellation control? If so, is this capability also available programmatically to the parent agent?

7. SDK compatibility

Are session-level abort() or disconnect() operations intended to support individual child-agent cancellation, or do they operate at a broader scope?

8. Current limitations

If child-specific native cancellation is not currently supported, is there a documented limitation, supported alternative, or planned API?

Why This Matters

Our framework already supports worker-state tracking, failure classification, isolated browser-session cleanup, and fail-closed reporting.

However, those mechanisms cannot independently terminate a host-managed native child agent.

We do not want to substitute process termination, fabricated cancellation events, or internal undocumented APIs for genuine host cancellation.

We need authoritative guidance before approving the native parallel execution architecture for production certification.

Thank you.

[github-actions[bot]]

💬 Your Product Feedback Has Been Submitted 🎉

Thank you for taking the time to share your insights with us! Your feedback is invaluable as we build a better GitHub experience for all our users.

Here's what you can expect moving forward ⏩

• Your input will be carefully reviewed and cataloged by members of our product teams. 
  • Due to the high volume of submissions, we may not always be able to provide individual responses.
  • Rest assured, your feedback will help chart our course for product improvements.
• Other users may engage with your post, sharing their own perspectives or experiences. 
• GitHub staff may reach out for further clarification or insight. 
  • We may 'Answer' your discussion if there is a current solution, workaround, or roadmap/changelog post related to the feedback.

Where to look to see what's shipping 👀

• Read the Changelog for real-time updates on the latest GitHub features, enhancements, and calls for feedback.
• Explore our Product Roadmap, which details upcoming major releases and initiatives.

What you can do in the meantime 💻

• Upvote and comment on other user feedback Discussions that resonate with you.
• Add more information at any point! Useful details include: use cases, relevant labels, desired outcomes, and any accompanying screenshots.

As a member of the GitHub community, your participation is essential. While we can't promise that every suggestion will be implemented, we want to emphasize that your feedback is instrumental in guiding our decisions and priorities.

Thank you once again for your contribution to making GitHub even better! We're grateful for your ongoing support and collaboration in shaping the future of our platform. ⭐