Publish a Window

An AI publishes a Window with the publish_window tool. It sends the title, the kind and the files of the Window, with a declaration of what its pages do, and gets back the address where the Window opens. This page is for people who write prompts, skills or MCP clients. The MCP tools reference gives the full schema.

In the house style

Before it makes a Window, an AI calls get_house_style with its kind: document, deck, dashboard or site. It gets the name of the organization, its colors and fonts, what it asks of AIs, a guide to the classes of its style sheet, and a template to start from. The page links the sheet from the root of the domain, <link rel="stylesheet" href="/-/house-style.css">, and a deck the engine, <script src="/-/deck.js" defer></script>. See House style.

A publication

The arguments of publish_window:

{
  "title": "Q3 review",
  "kind": "deck",
  "declaration": { "scripts": true, "origins": ["https://cdn.jsdelivr.net"] },
  "files": [
    { "path": "index.html", "content": "<!doctype html><html lang=\"en\">...</html>" },
    { "path": "css/deck.css", "content": "body { margin: 0; }" },
    { "path": "img/chart.png", "content": "iVBORw0KGgo...", "encoding": "base64" }
  ]
}

Field	What it holds
title	The title of the Window, at most 200 bytes. The name in its address comes from it.
kind	document, deck, dashboard or site.
room	Optional: the name of a Room of the person the AI acts for. Without it, the Window goes to their personal Room.
files	The files, with index.html at the root: it is the page that opens.
declaration	What the pages do: see The declaration.

Cahut answers with the Window:

{
  "name": "q3-review",
  "title": "Q3 review",
  "kind": "deck",
  "url": "https://cahut.example.com/you/q3-review/",
  "room": "you",
  "version": 1,
  "size": 48213,
  "file_count": 3,
  "created_by": "you",
  "created_at": "2026-10-21T12:02:31.418Z",
  "updated_at": "2026-10-21T12:02:31.418Z",
  "access": "room",
  "declaration": { "scripts": true, "origins": ["https://cdn.jsdelivr.net"] }
}

The AI gives the url to the user. The new Window opens to the members of its Room: see Share a Window.

Files

• A path is relative, with / as separator, such as img/logo.svg, and at most 255 bytes long. No part of it starts with a dot.
• Two paths cannot differ by case alone, and a path cannot be both a file and the folder of another file.
• Text goes as it is, in UTF-8. Binary files, such as images and fonts, go in base64, with "encoding": "base64".
• A Window holds at most 500 files and 32 MiB, once decoded.
• Pages link their files with relative paths, such as css/deck.css. A path that starts with / points to the root of the Cahut, not to the Window: only the house style and the deck engine are there, under /-/.
• A folder opens on its own index.html, so a site can have pages such as about/index.html. Cahut lists no folder.

The declaration

Every publication declares what its pages do, and Cahut lets them do that and nothing more:

Field	What it holds
scripts	true when the pages run scripts, inline or in files.
origins	Every origin the pages load anything from or call: scripts, styles, fonts, images, fetch calls, WebSockets. Such as https://cdn.jsdelivr.net, https://fonts.googleapis.com and https://fonts.gstatic.com. https://*.example.com covers the subdomains of example.com, not example.com itself.
forms	The origins that the forms of the pages send to, if any.

• An origin is https:// or wss://, a host and an optional port, without a path. Each list holds 20 origins at most.
• The files of the Window, and the house style under /-/, need no origin: they come from the Cahut, which the policy always allows. A deck that uses the engine declares scripts.
• A page that loads from an origin it did not declare does not get it: the browser blocks the request, and the console of the browser says so. Declare every origin, or put the files in the Window.
• A deck that only shows text and images declares {"scripts": false}: it can then call nothing at all.

Rooms and Windows gives the policy that Cahut writes from it.

The sandbox

Every file of a Window is served with the header Content-Security-Policy: sandbox, which gives its page an origin of its own. In that sandbox:

• Scripts, forms, dialogs, downloads and links that open in a new tab work.
• localStorage, sessionStorage, IndexedDB and cookies throw an error. Keep state in memory or in the address, and check that the libraries of the page do not stop on that error.
• The page cannot read the other Windows of the Cahut, nor the session of its reader.
• Module scripts, fetch calls and web fonts load as cross-origin requests, which the files of the Window allow.

Rooms and Windows gives the full header.

Names and addresses

Cahut names the Window after its title: up to 40 lowercase ASCII letters, digits and hyphens, with accents folded. “Q3 review: Été” becomes q3-review-ete. When the Room already holds a Window of that name, Cahut adds -2, then -3, and so on. The Window opens at https://<domain>/<room>/<name>/.

After publishing

get_window describes a Window, given its address or room/name: its access, its two versions, its declaration, and its files, with their contents when asked. list_windows lists the Windows of the person’s Rooms, or of one of them with room, most recently updated first; with trashed, it lists the trash.

Update a Window

update_window publishes a new version at the same address. It takes the Window, all the files of the new version and their declaration, and optionally a new title:

{
  "window": "you/q3-review",
  "declaration": { "scripts": false },
  "files": [{ "path": "index.html", "content": "<!doctype html>..." }]
}

The version it replaces is kept. rollback_window, with the Window alone, goes back to it, and a second rollback returns. Publishing again with publish_window creates another Window, such as q3-review-2: to change a Window, update it.

Share a Window

set_window_access sets who opens a Window:

{ "window": "you/q3-review", "access": "key", "ends_at": "2026-12-31T18:00:00Z" }

Field	What it holds
access	room, internal, key or public. public knocks first: the person the AI acts for approves it in the console.
ends_at	Optional: when the access ends, after which the Window opens to its Room only.
key	Optional, for key: the Key to set, of 10 characters at least. Without it, the Window keeps its Key, or Cahut draws one.
new_key	Optional, for key: draw a new Key; the old one stops working.

When a Key is set, the answer holds it in key, this once. The AI gives the address and the Key to the user. See Who can open a Window.

Put a Window in the trash

trash_window takes a Window out of the lists, and it no longer opens. restore_window brings it back as it was.

When a call fails

When the arguments are wrong, the tool returns an error that says what to change:

invalid input: index.html is missing: it is the page that opens

The AI can fix its call and try again. Failed calls go to the Logbook too.