claude-code - 💡(How to fix) Fix Plugin SessionStart hooks execute but additionalContext stdout is silently discarded [5 comments, 2 participants]

Stop hooks in the same plugin work correctly (blocking error prompts appear). Only SessionStart additionalContext is affected.

TL;DR

The issue can be resolved by verifying the JSON output of the session-start.sh script and ensuring it is correctly formatted to include the additionalContext in the agent conversation.

Guidance

• Verify that the session-start.sh script is producing the correct JSON output with additionalContext by running it manually and checking its stdout.
• Check the plugin's documentation to ensure that the hooks.json format is correct and supported for SessionStart hooks.
• Test the plugin with a simplified session-start.sh script that only outputs the required JSON to isolate the issue.
• Confirm that the issue is not specific to the interactive terminal sessions by testing it in a different environment.

Example

{
  "hookSpecificOutput": {
    "hookEventName": "SessionStart",
    "additionalContext": "This text should appear in conversation context"
  }
}

This example shows the expected JSON output of the session-start.sh script.

Notes

The issue might be specific to the SessionStart hooks or the way the additionalContext is being processed. Further investigation is needed to determine the root cause.

Recommendation

Apply a workaround by modifying the session-start.sh script to log its output to a file, allowing for further debugging and verification of the issue. This will help determine if the problem lies in the script's output or the plugin's processing of it.