Core and add-ons
fxbot is a small core that every install runs, and add-ons that you add only if you want them. This page is about where that line falls, and why.
The core
The core is what every bot needs, and what fxbot needs to run:
- bots, each with its instructions and one long-running chat
- providers: accounts, keys, and local model servers
- the library, one copy of every file the chats hold
- each bot's history, which the bot can search
- the app, which installs on phones and desktops
- releases, updates, and the database's migrations
- keys and tokens, sealed in Postgres
It also holds the seams that add-ons plug into: Add-ons itself, which finds, adds, and updates them, and the kinds of add-on that fxbot can run.
Add-ons
Everything else is an add-on. Today an add-on is one of these:
- an MCP server, which gives bots tools from a remote service
- a skill, with instructions that a bot reads when a task needs them
Each goes to all bots, or only to the ones you choose. fxbot's own lists suggest a few, tagged fxbot, and search finds more. What each kind may do is in the Security model.
Why the line is there
Every install runs the core, so everything in it costs every owner: code to keep safe, work on each request, and weight in the page. An add-on costs only the owners who add it. So a feature goes in the core only when every bot needs it, when add-ons need it to plug in, or when fxbot needs it to run.
An add-on that you haven't added costs nothing: no process, no timer, no requests, and no space in the app outside Add-ons. Removing one leaves the rest of fxbot as it was.
When a feature can't be built as an add-on, what's missing is a seam. The core gets the smallest seam that the add-on needs, and the feature stays an add-on. fxbot's own add-ons use the same seams as anyone's.