Vision

Windows Terminal is a good terminal that moves at the pace of a large product. Mullion is the same codebase, moving at the pace of one person who runs coding agents in it all day. Upstream fixes still flow in. Features land here because they are useful here, whether or not upstream would ever take them.

The Problem

A modern terminal session is not just a shell. It holds agents, multiplexers and long-running work, and it is full of references: pull requests, tickets, chat threads, file paths inside WSL. Stock Windows Terminal forgets what was running when it closes, treats most of those references as plain text, and offers no way for another process to drive a specific pane.

Key Differentiators

Sessions that survive: agents and multiplexers are resumed with the flags they started with.
References you can act on: links resolve across WSL, and cards show what a link points at.
Drivable from outside: a local control pipe lets tools target an exact pane.
Safe to develop in daily: a disposable test slot beside the production slot, with promotion as a deliberate gesture rather than a side effect of a build.