Matter Project Flow

This section is intended to cover how Matter uses GitHub Projects, Issues, Milestones, Releases, and Branches for program/project management in the code repository.


Matter uses issues as simple problem descriptions or feature requests. In general, all work contributed to the repository in the form of pull requests (PR) should be under the auspices of some open issue. This may seem onerous and in some cases duplicative, so consider these guidelines when deciding whether you can get away with not creating an issue:

  • Trivial fixes: issues can function as TODO lists, simple reminders that something should be addressed. Sometimes, though, the work required to fix is smaller than the work required to write the issue.
  • Issues intended to be addressed by a PR may not actually be fixed or may regress.
  • Issues can span PRs (as PRs should be as small as possible, but no smaller).
  • Issues help form an important basis for release notes. Any PR that addresses a problem that should have release visibility, please do open an issue.

Pull requests

Pull requests should be small and address a single, specific change to the code base. They should be easy to review, as a “yes, that's better”. Refrain from requesting review until all PR checks have completed successfully, lest you tire your reviewers.

PR Don'ts:

  • Don‘t combine unrelated changes. E.g. if the PR addresses a bug in some C code, an update to the top-level .gitignore doesn’t belong.
  • Don't make stacks. E.g. if a change in a component requires a new feature or even a small tweak in one or more of its dependencies, each dependency change belongs in its own separate PR.


In Matter parlance, a milestone is simply a tag for an expected due date or release. Milestones are intended to help contributors and their managers to prioritize work. There are 2 types: Date-based and Release-based.


Date-based milestones are named for their due date, typically a Friday of some week. Date-based milestones are normally assigned based on a guess about when something's likely to bubble up and get done based on current work load and resourcing. They are wishes, guesses.


Release-based milestones are named for the release version and may have flexible or subject-to-change due dates. Release-based milestones are intended to track release blockers.

A special “Not sure when” milestone is a marker for issues whose priority, scope, or blocking status have not been determined. Monthly review of these is a project goal.

Issues without milestones are those that have yet to be considered for one of the above. Weekly review of new issues is a project goal.


Projects are collections of issues, pull requests, and notes intended to capture larger efforts that don't fit in issues, have multiple-subsystems involved, or may span multiple milestones. We use projects 2 ways:

  1. To track burn down on a larger task. When constructing such a project, it's important to think in terms of something that will eventually have an end, i.e. a definite scope.
  2. To categorize issues, denote broader efforts without a definite time scope. These projects might reflect or show burndown or percent complete, but are mostly used to view where effort is going.

Issues can belong to any number of projects, but should generally only belong to one of the task-tracking projects (the first type).

Branches, releases, and general development flow

Master should always be Matter's best branch. Release branches, once cut, are closed for any feature work. Software fixes for release branches must first land on master unless demonstrably infeasible.