# Share a room (/docs/haus/rooms/sharing)



A desktop is data, so a reader can check one before running it. A room is
**code**, and no amount of tooling changes that: `haus show --room` reports the
class and checks nothing, which is the honest answer rather than a gap. What you
publish, and what your README says, is the whole of what a stranger has to go
on.

## What you publish [#what-you-publish]

A flake whose `darwinModules` carries the room:

```text
photo-room/
├── README.md
├── flake.nix          # outputs.darwinModules.default = ./module;
├── module/
│   ├── options.nix    # what a host may say
│   └── default.nix    # what happens when they say it
└── LICENSE
```

[`haus add --room`](/docs/haus/reference/haus#pinning-a-room) wires it into the
consumer's flake: the input, the outputs pattern, and the line that imports it.

```nix
extraModules = [ photo-room.darwinModules.default ];
```

`default` is the attribute it assumes, so export `default` unless you have a
reason not to. The module
itself is [Create a room](/docs/haus/rooms/creating): the options/implementation
split, `enable` defaulting to false, and offering through
`haus._contrib.<receiver>` rather than reaching into another room.

## Claim a plain namespace [#claim-a-plain-namespace]

Publishing is what drops the `haus.my.` prefix. That prefix is reserved for
rooms that never leave one Mac, and haus promises never to ship under it; a
published room takes a plain `haus.<name>`, and the person installing it names
that namespace themselves:

```sh
haus add --room --namespace photography github:ada/photo-room
```

haus cannot read the namespace out of your room without running it, which is the
one thing that command must not do before its confirmation. So the installer
types it, haus records the claim, and the next rebuild **refuses** if a second
input turns up wanting the same name. A namespace nobody has claimed only warns,
once per rebuild.

Pick a name that describes the capability rather than your project, and say it
in the README's first paragraph. It is the one string every user of your room
has to type correctly.

## What the README owes a reader [#what-the-readme-owes-a-reader]

Someone installing your room is running your activation scripts as root. Tell
them:

* **the namespace**, and every `haus.<ns>.*` option under it worth setting;
* **what it installs**: packages, casks, launchd jobs, files it writes outside
  the Nix store;
* **what it does as root**, if anything, in the activation step;
* **the permissions it expects them to grant**, and where macOS will ask;
* **which rooms it offers something to** through `haus._contrib`, and what
  disappears when the receiving room is off;
* **which haus revision you tested against**;
* **that `enable` defaults to false**, and what a person gets when they turn it
  on with nothing else set.

There is no room registry, so the flakeref is the distribution. Tag releases, keep the default branch installable, and do not
force-push a revision somebody has pinned.

## Before you share [#before-you-share]

* [ ] `nix flake check` passes, and a real host evaluates with the room imported.
* [ ] You have rebuilt a Mac with it, not only evaluated it.
* [ ] `enable = false` leaves the machine exactly as it was.
* [ ] The namespace is plain, not `haus.my.*`, and the README leads with it.
* [ ] Nothing in it is identity, a secret, or specific to your hardware.
* [ ] The README says what runs as root.