Want to contribute? Great! First, read this page (including the small print at the end).

Pull requests

Pull requests can be hard to review if they try to tackle too many things at once. Phabricator's “Writing Reviewable Code” provides a set of guidelines that help increase the likelihood of your pull request getting merged.

In short (slightly modified from the original article):

  • A pull request should be as small as possible, but no smaller.
  • The smallest a pull request can be is a single cohesive idea: don't make pull requests so small that they are meaningless on their own.
  • Turn large pull requests into small pull requests by dividing large problems into smaller problems and solving the small problems one at a time.
  • Write sensible pull request descriptions.


This repository follows a file layout convention that ensures consistency and predictability across all of our components. The conventions are described in the GOS-conventions repository.

Before you contribute

Before we can use your code, you must sign the Google Individual Contributor License Agreement (CLA), which you can do online. The CLA is necessary mainly because you own the copyright to your changes, even after your contribution becomes part of our codebase, so we need your permission to use and distribute your code. We also need to be sure of various other things—for instance that you‘ll tell us if you know that your code infringes on other people’s patents. You don‘t have to sign the CLA until after you’ve submitted your code for review and a member has approved it, but you must do it before we can put your code into our codebase. Before you start working on a larger contribution, you should get in touch with us first through the issue tracker with your idea so that we can help out and possibly guide you. Coordinating up front makes it much easier to avoid frustration later on.

Code reviews

All submissions, including submissions by project members, require review.

The small print

Contributions made by corporations are covered by a different agreement than the one above, the Software Grant and Corporate Contributor License Agreement.