[BUG] Notification event doesn't work over SSH with MacOS

Environment

• Platform (select one):
• [ ] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: <!-- output of claude --version -->1.0.51
• Operating System: <!-- e.g. macOS 14.3, Windows 11, Ubuntu 22.04 -->MacOS (local) Ubuntu 22.04 (SSH)
• Terminal: <!-- e.g. iTerm2, Terminal App -->Ghostty 1.1.3

Bug Description

<!-- A clear and concise description of the bug -->Notification event sends OSC 9 correctly when CC runs locally, yet doesn't send OSC 9 over SSH.

Just to be clear:

• Ghostty supports OSC 9 over SSH: https://github.com/ghostty-org/ghostty/discussions/7902
• Can test by running this over SSH: sleep 1; echo -e "\033]9;This is OSC 9\033" and quickly switching windows to get the notification.

Steps to Reproduce

1. <!-- First step -->Trigger notification event in CC locally (works)
2. <!-- Second step -->Trigger notification event in CC over SSH (does NOT work)

Expected Behavior

<!-- What you expected to happen -->Notification event triggers MacOS notification from OSC 9 print over SSH

Actual Behavior

<!-- What actually happened -->Doesn't happen over SSH, yet works locally on MacOS

Additional Context

<!-- Add any other context about the problem here, such as screenshots, logs, etc. -->Can use this hook script to make sure the code is printed:

#!/usr/bin/env python3
import json
import sys


def send_osc9_notification(message, title="Claude Code"):
    """Send OSC 9 notification to terminal"""
    # OSC 9 format: \033]9;[message]\033\\
    osc_sequence = f"\033]9;{message}\033\\"
    print(osc_sequence, end="", flush=True)


def main():
    try:
        # Read JSON input from stdin
        input_data = json.load(sys.stdin)
        message = input_data.get("message", "Claude Code notification")

        send_osc9_notification(message)

    except Exception as e:
        # Fallback notification
        send_osc9_notification(f"Claude Code notification (error: {e})")


if __name__ == "__main__":
    main()