Copilot permissions cannot be revoked while running

- Copilot Chat Extension Version: 1.0.81-0
- VS Code Version: 1.136.1
- OS Version: Windows_NT x64 10.0.22631
- Feature (e.g. agent/edit/ask mode): agent
- Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): Claude Opus 4.8
- Logs: Cannot be shared

If agent execution is started with "Autopilot" permission and then downgraded to "default permissions" while the execution is still in progress, the agent will continue to operate with autopilot permissions.

This is a commonly encountered scenario in the following workflow:
1. Create an execution plan in plan mode
2. leave plan mode using "Start Implementation with Autopilot"
3. Wait for agent to complete
4. Provide corrective feedback to agent
5. Realize that agent still has autopilot permissions from step 2
6. Revoke autopilot permissions
7. Agent keeps using autopilot permissions because it had them at step 5.

Steps to Reproduce:

1. Have an agent running with "Autopilot" permissions on a difficult task where it would ask for clarification.
2. Change permissions to "Default Permissions" while the agent is thinking/considering.
3. Observe that question dialogs are "auto-replied with user is not available" e.g.:
> Q: What should "buildable on Windows" cover for this deliverable right now?
> A: The user is not available to respond and will review your work later. Work autonomously and make good decisions.

Workaround:

1. Explicitly fully stop execution. Tokens spent on incomplete work are lost.
2. Reset agent permissions
3. Re-prompt the agent including a notice that permissions have changed from what appears in repo/agent memories.