Companions and Creatures
You will not travel alone for long, and the game keeps track of who is actually with you.
The Companions file
@Missing file is the party itself, and it is meant to stay pinned so it is always in view.
It holds the people traveling with you, the creatures traveling with you, the shared purse, the gear the group owns together, and a notes tab for whatever the whole table needs to remember.
Membership is earned by scenes rather than announcements. Nobody declares they are joining the party. Whoever keeps showing up at your side, through days and trouble and mornings after, is on the roster. Whoever peels off stops being on it. The roster gets reconciled against what actually happened, usually at the end of an in game day.
Creatures
Beasts, mounts, machines, and anything else alive enough to matter get a Creature file. @Missing file is the example, a road hound who tracks by scent.
A creature works almost exactly like a character. It has Feats on the same three lists, sits on the same tier ladder, carries its own gear, and has a condition and bonds that change as the story treats it. What it does not have is the twelve humanoid worn slots, because a harness is not a hat.
That means your mount is not equipment. It is a thing with wants and a temperament that can be frightened, hurt, loyal, or stubborn at an inconvenient moment.
Why the roster matters to you
Anyone on the Companions list is somebody the GM is expected to give a voice, a want, and a line in the ordinary scenes between the big ones. A traveling companion who never says anything is a bug in this system, not a feature. If someone has been at your shoulder for six sessions, they should have opinions about you by now.