GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents

What this error means

preToolUse hooks don't fire for background/task sub-agents is a GitHub Copilot failure pattern reported for developers trying to fix github copilot cli pretooluse hooks not executing when commands run via background/task agents. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Open issue with 1 comment. Copilot CLI v1.0.37. All sub-agent types tested (task/Haiku, general-purpose/Sonnet) bypass preToolUse hooks. Both global (~/.copilot/hooks/) and project-level (.github/hooks/) hooks affected. sessionStart hooks also don’t fire for sub-agents.

Common causes

• Developers configure preToolUse hooks in Copilot CLI to enforce security policies (file permissions, lock checks, scanning), but these hooks are completely bypassed when Copilot spawns sub-agents (task agents or general-purpose agents). This means any security guardrail defined in hooks can be circumvented by the agent simply delegating to a sub-agent. Both global and project-level hooks are affected. sessionStart hooks also don’t fire for sub-agents.
• Open issue with 1 comment. Copilot CLI v1.0.37. All sub-agent types tested (task/Haiku, general-purpose/Sonnet) bypass preToolUse hooks. Both global (~/.copilot/hooks/) and project-level (.github/hooks/) hooks affected. sessionStart hooks also don’t fire for sub-agents.

Quick fixes

1. Confirm the exact error signature matches preToolUse hooks don't fire for background/task sub-agents.
2. Check the GitHub Copilot account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/github/copilot-cli/issues/3013

Evidence note: Open issue with 1 comment. Copilot CLI v1.0.37. All sub-agent types tested (task/Haiku, general-purpose/Sonnet) bypass preToolUse hooks. Both global (~/.copilot/hooks/) and project-level (.github/hooks/) hooks affected. sessionStart hooks also don’t fire for sub-agents.

Related errors

• Copilot CLI hooks not working
• Copilot agent sandbox escape
• GitHub Copilot security hooks bypassed

FAQ

What should I check first?

Start with the exact preToolUse hooks don't fire for background/task sub-agents text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed GitHub Copilot workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without preToolUse hooks don't fire for background/task sub-agents.