Fifteen other people
For a long time two players could be in the same raid, five metres apart in clear line of sight, and see nothing.
Not a rendering bug and not a wire-format gap. The snapshot format had carried everything a body needs since crouch and lean landed: position, yaw, height, lean, armour, whether they are firing, whether they are reloading. The renderer draws whatever arrives.
The function that decides what to publish iterated the bots and the target dummies. It never iterated the players. Two people in a shared raid each received exactly the two bots, and not each other.
Why a missing loop and not a missing feature
That is a one-word fix in the end, and it is worth being clear that it was not a lucky one. Every hard part was already done and had been done first.
The simulation runs at a fixed timestep on an authoritative server. The client predicts locally and reconciles against what the server says. The wire protocol exists, is versioned, and has a budget. Sixteen player slots have been in the simulation since before there was anything to do in a raid.
None of that is retrofittable. Bolting other people onto a working single-player shooter means redoing movement so it can be predicted, redoing state so it can be replicated, and redoing every assumption that the thing in front of you is authoritative. It is a rewrite that happens to reuse your art.
So the ordering was deliberate: build the parts you cannot add later, first. Which means for a while there was a game with excellent netcode and nothing much to do, and that is the correct shape for it to have been in.
Other players are not a special case
The interesting part of the fix is what it did not need.
Players are published through the same visibility gate the bots go through. Not a parallel path, not a special case with its own rules: the same code that decides whether you are told about a bot decides whether you are told about a person. Sending anything to a client requires a proof the client can see it, and a player is not exempt from needing one.
That is the difference between a system and a feature. Had visibility been a check written separately at each send site, adding players would have meant a new check, and a new place for it to be wrong.
The tests that matter are the negative ones. One asserts that two players in the open can see each other. Another puts a wall between them and asserts that one is hidden from the other. A third checks a viewer never receives their own body, which sounds trivial and is the kind of thing that produces a ghost of yourself standing where you were.
There is also a test that player IDs cannot collide with bot IDs. It exists because they did.
What is next, and what is not there
Sixteen people in a raid is not the same as squads, and there is currently no notion of a team anywhere in the simulation. No group, no friendly fire rules, no shared identity. There is an armband in the equipment slots, described in a comment as a team identifier, and nothing reads it as one.
Squads are the plan and have been the reason for the sixteen slots from the start: dropping in with people you know, holding an extract together, and losing it together. But the plan is not the feature, and the feature list on this site only lists what runs.
What does run is a raid that other people are in, who can see you, shoot you, and take what you were carrying out through an exit you were heading for.