Using hooks with GitHub Copilot agents

Hooks allow you to extend and customize the behavior of GitHub Copilot agents by executing custom shell commands at key points during agent execution. For a conceptual overview of hooks, see About hooks.

Creating a hook in a repository on GitHub

1. Create a new hooks.json file with the name of your choice in the .github/hooks/ folder of your repository. The hooks configuration file must be present on your repository's default branch to be used by Copilot コーディング エージェント. For GitHub Copilot CLI（コマンドラインインターフェース）, hooks are loaded from your current working directory.

2. In your text editor, copy and paste the following hook template. Remove any hooks you don't plan on using from the hooks array.

   JSON

   {
     "version": 1,
     "hooks": {
       "sessionStart": [...],
       "sessionEnd": [...],
       "userPromptSubmitted": [...],
       "preToolUse": [...],
       "postToolUse": [...],
       "errorOccurred": [...]
     }
   }
   

3. Configure your hook syntax under the bash or powershell keys, or directly reference script files you have created.

   • This example runs a script that outputs the start date of the session to a log file using the sessionStart hook:

     JSON

     "sessionStart": [
       {
         "type": "command",
         "bash": "echo \"Session started: $(date)\" >> logs/session.log",
         "powershell": "Add-Content -Path logs/session.log -Value \"Session started: $(Get-Date)\"",
         "cwd": ".",
         "timeoutSec": 10
       }
     ],
     

   • This example calls out to an external log-prompt script:

     JSON

     "userPromptSubmitted": [
       {
         "type": "command",
         "bash": "./scripts/log-prompt.sh",
         "powershell": "./scripts/log-prompt.ps1",
         "cwd": "scripts",
         "env": {
           "LOG_LEVEL": "INFO"
         }
       }
     ],
     

     For a full reference on the input JSON from agent sessions along with sample scripts, see Hooks configuration.

4. Commit the file to the repository and merge it into the default branch. Your hooks will now run during agent sessions.

Troubleshooting

If you run into problems using hooks, use the following table to troubleshoot.

Issue	Action
Hooks are not executing	Verify the JSON file is in the .github/hooks/ directory. Check for valid JSON syntax (for example, jq . hooks.json). Ensure version: 1 is specified in your hooks.json file. Verify the script you are calling from your hook is executable (chmod +x script.sh) Check that the script has a proper shebang (for example, #!/bin/bash)
Hooks are timing out	The default timeout is 30 seconds. Increase timeoutSec in the configuration if needed. Optimize script performance by avoiding unnecessary operations.
Invalid JSON output	Ensure the output is on a single line. On Unix, use jq -c to compact and validate the JSON output. On Windows, use the ConvertTo-Json -Compress command in PowerShell to do the same.

Debugging

You can debug hooks using the following methods:

• Enable verbose logging in the script to inspect the input data and trace script execution.

  Shell

  #!/bin/bash
  set -x  # Enable bash debug mode
  INPUT=$(cat)
  echo "DEBUG: Received input" >&2
  echo "$INPUT" >&2
  # ... rest of script
  

• Test hooks locally by piping test input into your hook to validate its behavior:

  Shell

  # Create test input
  echo '{"timestamp":1704614400000,"cwd":"/tmp","toolName":"bash","toolArgs":"{\"command\":\"ls\"}"}' | ./my-hook.sh
  
  # Check exit code
  echo $?
  
  # Validate output is valid JSON
  ./my-hook.sh | jq .
  

Further reading

• For more information about configuring hooks, see Hooks configuration
• For more information about Copilot コーディング エージェント, see GitHub Copilot コーディング エージェントについて
• For more information about GitHub Copilot CLI（コマンドラインインターフェース）, see GitHub Copilot CLI について
• For information about customizing the agent environment, see GitHub Copilot コーディング エージェント用の開発環境のカスタマイズ