preferences.json

preferences.json holds the personal context Fabric Agents injects into the agent's system prompt so responses feel personalised — your name, timezone, where you are, notes you want every session to know about you.

~/.fabric-agent/preferences.json

It's separate from config.json on purpose: config is about app behaviour; preferences are about you.

Schema

A note on language

There used to be a language field here. It's deprecated — Fabric Agents now reads the UI language from your i18n setting (Settings → Appearance → Language) and passes that to the agent. The old language field is ignored if present.

Example

{
  "name": "Alex",
  "timezone": "America/Los_Angeles",
  "location": {
    "city": "San Francisco",
    "region": "California",
    "country": "USA"
  },
  "notes": "I prefer concise, code-first answers. I work mostly in TypeScript and Python.\nWhen explaining concepts, assume I'm comfortable with Go and React.",
  "diffViewer": {
    "diffStyle": "split",
    "disableBackground": false
  },
  "includeCoAuthoredBy": true,
  "updatedAt": 1705000000000
}

How it's used

At session start, Fabric Agents formats preferences.json into a short block of "User context" and prepends it to the system prompt. Fields only appear in the prompt when set — an empty notes isn't shown; a missing location isn't fabricated.

You can ask the agent to update your preferences at any time:

"Remember that I always want concise answers, and my timezone is Berlin."

The agent writes to preferences.json through the preferences tool (assuming the session has permission). You can also edit it by hand — the file is re-read on every session start.

Privacy

• preferences.json lives on your machine. It's not uploaded with shared sessions.
• Credentials, API keys, and OAuth tokens never go here — those live in the OS keychain or the encrypted credential store.
• When you share a session, the viewer does not see your preferences — the shared payload contains only the session's messages and tool calls, not the system prompt that fed the agent.

Editing

Close the app before editing to avoid race conditions with auto-save. Standard JSON rules apply — the app fails loud (a user-facing error dialog) rather than silently dropping a malformed preferences file.

Related

• config.json — app-wide settings (separate file).
• LLM connections — provider credentials and defaults.
• Conversations — where per-session settings live (vs per-user here).