Skip to main content

​
Install Prefab

We recommend using uv to install and manage Prefab. 
uv add prefab-ui
Or with pip: 
pip install prefab-ui
Prefab requires Python 3.10+.

​
Verify Installation

prefab version

​
Versioning Policy

Prefab is pre-1.0 software under extremely active development. The API surface is evolving quickly — components get added, renamed, and reworked as the project discovers what patterns work best for building agent-native UIs.

​
What This Means in Practice

Minor versions (0.x.0) may include breaking changes. Prefab follows semantic versioning with the standard pre-1.0 caveat: while the major version is 0, any minor version bump can change the public API. A bump from 0.5.0 to 0.6.0 might rename components, change default behaviors, or restructure modules. Patch versions (0.0.x) are safe updates. Patch releases contain only bug fixes without breaking changes.

​
Pin Your Version

For any use beyond experimentation, pin to an exact version: 
prefab-ui==0.5.0  # Good
prefab-ui>=0.5.0  # Bad — may install breaking changes
Or pin to a minor range if you want patch fixes: 
prefab-ui>=0.5,<0.6  # OK — gets patches, not breaking changes

​
Breaking Change Philosophy

Prefab is young, and that means being willing to fix API mistakes early rather than carrying them forever. Each breaking change is a deliberate decision to keep the framework simple and consistent rather than accumulating design debt. When breaking changes occur:
  • They only happen in minor versions (e.g., 0.5.x to 0.6.0)
  • Release notes explain what changed and how to migrate
  • Changes must substantially benefit users to justify disruption

​
Public API

The public API — what’s covered by compatibility guarantees within a minor version — consists of:
  • All classes exported from prefab_ui.components and prefab_ui.actions
  • PrefabApp and related app-level utilities
  • The prefab CLI commands
  • The JSON wire protocol schema
Everything else (internal modules, private methods, renderer internals) may change without notice. Pin your dependencies and check release notes before upgrading.