Random OS-assigned TCP port.
HTTPS with a temporary self-signed certificate.
One-hour hard expiry.
Password is entered once in a native Mac setup dialog and once in the browser on the other machine.
Password is hashed in memory; plaintext is not logged or written to disk.
HttpOnly/Secure/SameSite session cookie and CSRF token.
No raw shell, no arbitrary command execution, no attachments.
Messages are atomic, bounded JSON files in a private queue.

The browser terminal is an agent message channel. The Mac agent must poll the inbox and send replies through the local bridge tooling; commands are not executed automatically from browser text.

Start

The listener runs on the Mac's LAN address. The startup dialog asks for the one-hour pairing password. The process prints the exact URL and port.

Example:

PYTHONPATH=/Volumes/1TB_APL_Storage/UmbraAudio/infra \
/usr/bin/python3 -m agent_bridge \
  --host 192.168.123.12 \
  --ttl 3600

Open the printed https://192.168.123.12:<port>/ URL in a browser on oldbox. Accept the temporary certificate warning if the browser requires it, then pair with the same one-hour password.

Queue

The default queue is:

~/.local/state/umbratrans/agent-bridge/
  inbox/       # browser messages waiting for the Mac agent
  outbox/      # Mac-agent replies waiting for the browser
  processed/   # browser messages already read
  delivered/   # browser replies acknowledged by the browser

All files are mode 0600; directories are mode 0700.

Safety

Do not expose the listener to the public internet.
Keep the one-hour timer unchanged.
Do not put passwords or private keys in messages.
Stop the process after the session if the automatic timer is interrupted.