GitHub Copilot / GitHub Copilot

GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents

Fix GitHub Copilot CLI preToolUse hooks not executing when commands run via background/task agents Includes evidence for GitHub Copilot troubleshooting demand.

Source-backed Last updated May 11, 2026 1 source Needs local verification

Category: GitHub Copilot
Error signature: preToolUse hooks don't fire for background/task sub-agents
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 11, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for GitHub Copilot, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

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

Confirm the exact error signature matches preToolUse hooks don't fire for background/task sub-agents.
Check the GitHub Copilot account, local tool state, and provider configuration involved in the failing workflow.
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

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

Diagnostic flow for this page

Match preToolUse hooks don't fire for background/task sub-agents exactly before applying the quick fix.
Compare the failing environment with GitHub Copilot versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does preToolUse hooks don't fire for background/task sub-agents mean in GitHub Copilot?

preToolUse hooks don't fire for background/task sub-agents indicates the workflow described by "GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents" failed in a GitHub Copilot context. Start by confirming the exact signature and the component that emitted it.

What should I check first for preToolUse hooks don't fire for background/task sub-agents?

Check whether this cause matches your environment: 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.

Is the preToolUse hooks don't fire for background/task sub-agents guidance source-backed?

The "GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for preToolUse hooks don't fire for background/task sub-agents?

For "GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging preToolUse hooks don't fire for background/task sub-agents?

For "GitHub Copilot CLI preToolUse Hooks Not Firing for Sub-Agents", collect the failing GitHub Copilot command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.