Hermes Completion Notification Script Explanation | Generated by AI

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Question: Can you explain what this Bash script does?

Answer:

This script is a post-processing hook for the Hermes agent on macOS. It’s designed to notify the user whenever Hermes completes a turn in a conversation. Let’s break it down step by step:

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1. Script Metadata

#!/usr/bin/env bash
# ~/.hermes/agent-hooks/on-agent-done.sh

• Shebang (#!/usr/bin/env bash) ensures the script runs with Bash.
• The script lives in ~/.hermes/agent-hooks/ and is triggered when Hermes finishes a turn.

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2. Bash Safety Options

set -euo pipefail

• -e → Exit if any command fails.
• -u → Treat unset variables as an error.
• -o pipefail → Makes the script fail if any part of a pipeline fails.

This makes the script robust and avoids silent errors.

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3. Read Payload

payload="$(cat -)"

• Reads JSON input from stdin. Hermes passes info about the turn to the hook via JSON.

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4. Extract Data Using Python

extracted=$(echo "$payload" | python3 -c "
import json, sys
data = json.load(sys.stdin)

# Directory name from cwd
cwd = data.get('cwd', '')
import os
dirname = os.path.basename(cwd) if cwd else 'unknown'

# First 10 chars of user message
extra = data.get('extra', {})
user_msg = extra.get('user_message', '')[:10]

# Conversation history item count
history = extra.get('conversation_history', [])
hist_count = len(history)

print(f'{dirname}|{user_msg}|{hist_count}')
" 2>/dev/null) || extracted="unknown||0"

• Uses Python to parse the JSON safely.

• Extracts three key pieces of info:

  1. dirname → Current working directory name (if available).
  2. user_msg → First 10 characters of the user’s last message.
  3. hist_count → Number of conversation turns so far.
• Outputs a |-separated string for Bash to parse.
• If anything fails, defaults to "unknown||0".

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5. Split Extracted Values

IFS='|' read -r dirname user_preview hist_count <<< "$extracted"

• Uses IFS='|' to split the string into three variables:

  • dirname → folder name
  • user_preview → snippet of user message
  • hist_count → conversation turns

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6. Build Notification Subtitle

subtitle="msg: ${user_preview}  |  turns: ${hist_count}"

• Combines the extracted info into a small string for the macOS notification.

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7. Send macOS Notification

osascript -e "
display notification \"Hermes has completed one turn.\" with title \"Hermes Agent — ${dirname}\" subtitle \"${subtitle}\" sound name \"Glass\"
" >/dev/null 2>&1 || true

• Uses osascript (AppleScript via shell) to display a notification:

  • Title: "Hermes Agent — <directory>"
  • Subtitle: "msg: <first 10 chars> | turns: <count>"
  • Sound: "Glass"
• Redirects all output to /dev/null to keep it silent.
• || true ensures the script doesn’t fail even if notifications are blocked.

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8. Return Empty JSON

printf '{}\n'

• Outputs {} so Hermes’ hook system knows the script completed successfully.
• Acts as a “silent no-op” response.

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✅ Summary

• This hook triggers after each Hermes agent turn.
• Extracts basic context: directory, user message preview, and conversation length.
• Sends a non-intrusive macOS notification.
• Fails gracefully if anything goes wrong.

It’s a simple but effective way to keep track of Hermes’ activity visually on macOS.

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If you want, I can also draw a small flow diagram showing how JSON moves from Hermes → this script → macOS notification, which makes the flow easier to understand.

Do you want me to do that?

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