The PLEX plugin

The learning path builds one plugin: Stash, a reading list like Pocket: each stashed link has an address, a note on why it is worth reading, and whether you have read it. This page explains what a plugin is made of, and shows Stash finished.

What a plugin is

A PLEX plugin is metadata and a set of modules. The metadata names the plugin and describes it in the registry. Each module waits for an activation event, such as the app starting or a view first needing it, and then contributes capabilities: typed values that the rest of the app looks up. Strings, types, views, operations and entries in the navigation tree are all capabilities. A module’s code loads only when it activates, so a plugin costs nothing until it is used.

Composer is built this way: every feature in it is a plugin, and your plugin uses the same APIs. Plugins and modules describes the parts in full.

The finished plugin

Below, Stash runs in the plugin inspector, a small PLEX app that loads one plugin and shows each of its modules working. The sidebar lists the modules. Click New in the header to create a sample link, then select Operations to mark it as read with Mark as read, App Graph to see where links sit in the navigation tree, and Surface to see a link’s view.

Each page of the learning path builds one piece of it, and ends with that piece in the inspector:

Page	Files	What it adds
Create a plugin	dx.config.ts, translations.ts	The plugin’s metadata and its strings
Define a type	types/StashedLink.ts, capabilities/schema.ts	The Stashed link type
Add an operation	types/StashedLinkOperation.ts, operations/, capabilities/operation-handler.ts, capabilities/create-object.ts	A way to create a link from the + menu, and Mark as read
Extend the App Graph	capabilities/app-graph-builder.ts	A Stashed links section in the navigation tree, with Mark as read on each link’s toolbar
Add a surface	containers/StashedLinkArticle.tsx, capabilities/react-surface.ts	The view that edits a link’s title, address and note, and shows whether it has been read
Run it in Composer	skills/, capabilities/skill-definition.ts	The plugin in Composer, and the skill that gives Mark as read to the assistant

From the next page on, the inspector on each page loads your own plugin from its dev server, and checks what that page adds.