# The view protocol

> How a view talks to the app: one message port, a hello that says what it may do, and nothing else.

Source: https://hivemind.griiken.com/guide/view-protocol/

A view is a web page that draws your workspace. It runs sandboxed and knows only what the app
tells it over one message port. Your agents can open a view, and send it data, while they work.

![Diagram: An agent opens a view](https://hivemind.griiken.com/guide/images/view-open.svg)

1. **Agent** → **main process**: `hive ctl plugin open view:<id>` calls `plugin.open` on the drive socket.
2. Main process → **window**: show that view. The agent gets its answer once the window has it.
3. Window → **view**: load its page from `hm-view://<id>`, in a sandboxed frame. Then hand it a message port.
4. View → window: `ready`, with the protocol version it speaks.
5. Window → view: `hello`, with what its permissions let it do. Then the workspace: `structure`, `status` and more.
6. View → window: a `command`, checked against its permissions before it runs.

## Versions [#versions]

A view says `"protocol": 1` in `hivemind-view.json`. Newer additions to version 1 are features:
`hello` lists the ones this app has, and a view checks with `hm.supports("<feature>")` before
using one.

## Widgets speak it too [#widgets-speak-it-too]

A widget's code runs in a worker, and reaches the workspace through the same client, limited to
the permissions in its `widget.json`. Tools do not: they run inside the app. See
[Trust, permissions and privacy](https://hivemind.griiken.com/guide/security-and-privacy/).

Every call a view can make, and how a script sends it data: [View reference](https://hivemind.griiken.com/guide/extension-authoring/#view-reference).

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