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Projects User Guide
Phabricator User Documentation (Application User Guides)

Organize users and objects with projects.


NOTE: This document is only partially complete.

Phabricator projects are flexible, general-purpose groups of objects that you can use to organize information. Projects have some basic information like a name and an icon, and may optionally have members.

For example, you can create projects to provide:

  • Organization: Create a project to represent a product or initiative, then use it to organize related work.
  • Groups: Create a project to represent a group of people (like a team), then add members of the group as project members.
  • Tags: To create a tag, just create a project without any members. Then tag anything you want.
  • Access Control Lists: Add members to a project, then restrict the visibility of objects to members of that project. See "Understanding Policies" below to understand how policies and projects interact in more detail.

Understanding Policies

An important rule to understand about projects is that adding or removing projects to an object never affects who can see the object.

For example, if you tag a task with a project like Backend, that does not change who can see the task. In particular, it does not limit visibility to only members of the "Backend" project, nor does it allow them to see it if they otherwise could not. Likewise, removing projects does not affect visibility.

If you're familiar with other software that works differently, this may be unexpected, but the rule in Phabricator is simple: adding and removing projects never affects policies.

Note that you can write policy rules which restrict capabilities to members of a specific project or set of projects, but you do this by editing an object's policies and adding rules based on project membership, not by tagging or untagging the object with projects.

To manage who can seen an object, use the object's policy controls, Spaces (see Spaces User Guide) and Custom Forms (see User Guide: Customizing Forms).

For more details about rationale, see "Policies In Depth", below.

Joining Projects

Once you join a project, you become a member and will receive mail sent to the project, like a mailing list. For example, if a project is added as a subscriber on a task or a reviewer on a revision, you will receive mail about that task or revision.

If you'd prefer not to receive mail sent to a project, you can go to Members and select Disable Mail. If you disable mail for a project, you will no longer receive mail sent to the project.

Watching Projects

Watching a project allows you to closely follow all activity related to a project.

You can watch a project by clicking Watch Project on the project page. To stop watching a project, click Unwatch Project.

When you watch a project, you will receive a copy of mail about any objects (like tasks or revisions) that are tagged with the project, or that the project is a subscriber, reviewer, or auditor for. For moderately active projects, this may be a large volume of mail.

Edit Notifications

Edit notifications are generated when project details (like the project description, name, or icon) are updated, or when users join or leave projects.

By default, these notifications are are only sent to the acting user. These notifications are usually not very interesting, and project mail is already complicated by members and watchers.

If you'd like to receive edit notifications for a project, you can write a Herald rule to keep you in the loop.

Customizing Menus

Projects support profile menus, which are customizable. For full details on managing and customizing profile menus, see Profile Menu User Guide.

Here are some examples of common ways to customize project profile menus that may be useful:

Link to Tasks or Repositories: You can add a menu item for "Open Tasks" or "Active Repositories" for a project by running the search in the appropriate application, then adding a link to the search results to the menu.

This can let you quickly jump from a project screen to related tasks, revisions, repositories, or other objects.

For more details on how to use search and manage queries, see Search User Guide.

New Task Button: To let users easily make a new task that is tagged with the current project, add a link to the "New Task" form with the project prefilled, or to a custom form with appropriate defaults.

For information on customizing and prefilling forms, see User Guide: Customizing Forms.

Link to Wiki Pages: You can add links to relevant wiki pages or other documentation to the menu to make it easy to find and access. You could also link to a Conpherence if you have a chatroom for a project.

Link to External Resources: You can link to external resources outside of Phabricator if you have other pages which are relevant to a project.

Set Workboard as Default: For projects that are mostly used to organize tasks, change the default item to the workboard instead of the profile to get to the workboard view more easily.

Hide Unused Items: If you have a project which you don't expect to have members or won't have a workboard, you can hide these items to streamline the menu.

Subprojects and Milestones

IMPORTANT: This feature is only partially implemented.

After creating a project, you can use the Subprojects menu item to add subprojects or milestones.

Subprojects are projects that are contained inside the main project. You can use them to break large or complex groups, tags, lists, or undertakings apart into smaller pieces.

Milestones are a special kind of subproject for organizing tasks into blocks of work. You can use them to implement sprints, iterations, milestones, versions, etc.

Subprojects and milestones have some additional special behaviors and rules, particularly around policies and membership. See below for details.

This is a brief summary of the major differences between normal projects, subprojects, parent projects, and milestones.

MembersYesUnion of SubprojectsYesSame as Parent
PoliciesYesYesAffected by ParentSame as Parent


Subprojects are full-power projects that are contained inside some parent project. You can use them to divide a large or complex project into smaller parts.

Subprojects have normal members and normal policies, but note that the policies of the parent project affect the policies of the subproject (see "Parent Projects", below).

Subprojects can have their own subprojects, milestones, or both. If a subproject has its own subprojects, it is both a subproject and a parent project. Thus, the parent project rules apply to it, and are stronger than the subproject rules.

Subprojects can have normal workboards.

The maximum subproject depth is 16. This limit is intended to grossly exceed the depth necessary in normal usage.

Objects may not be tagged with multiple projects that are ancestors or descendants of one another. For example, a task may not be tagged with both Stonework and StoneworkMasonry.

When a project tag is added that is the ancestor or descendant of one or more existing tags, the old tags are replaced. For example, adding StoneworkMasonry to a task tagged with Stonework will replace Stonework with the newer, more specific tag.

This restriction does not apply to projects which share some common ancestor but are not themselves mutual ancestors. For example, a task may be tagged with both StoneworkMasonry and StoneworkSculpting.

This restriction does apply when the descendant is a milestone. For example, a task may not be tagged with both Stonework and StoneworkIteration II.


Milestones are simple subprojects for tracking sprints, iterations, versions, or other similar blocks of work. Milestones make it easier to create and manage a large number of similar subprojects (for example: Sprint 1, Sprint 2, Sprint 3, etc).

Milestones can not have direct members or policies. Instead, the membership and policies of a milestones are always the same as the milestone's parent project. This makes large numbers of milestones more manageable when changes occur.

Milestones can not have subprojects, and can not have their own milestones.

By default, Milestones do not have their own hashtags.

Milestones can have normal workboards.

Objects may not be tagged with two different milestones of the same parent project. For example, a task may not be tagged with both StoneworkIteration III and StoneworkIteration V.

When a milestone tag is added to an object which already has a tag from the same series of milestones, the old tag is removed. For example, adding the StoneworkIteration V tag to a task which already has the StoneworkIteration III tag will remove the Iteration III tag.

This restriction does not apply to milestones which are not part of the same series. For example, a task may be tagged with both StoneworkIteration V and HeraldryIteration IX.

Parent Projects

When you add the first subproject to an existing project, it is converted into a parent project. Parent projects have some special rules.

No Direct Members: Parent projects can not have members of their own. Instead, all of the users who are members of any subproject count as members of the parent project. By joining (or leaving) a subproject, a user is implicitly added to (or removed from) all ancestors of that project.

Consequently, when you add the first subproject to an existing project, all of the project's current members are moved to become members of the subproject instead. Implicitly, they will remain members of the parent project because the parent project is an ancestor of the new subproject.

You can edit the project afterward to change or remove members if you want to split membership apart in a more granular way across multiple new subprojects.

Searching: When you search for a parent project, results for any subproject are returned. For example, if you search for Engineering, your query will match results in Engineering itself, but also subprojects like EngineeringWarp Drive and EngineeringShield Batteries.

Policy Effects: To view a subproject or milestone, you must be able to view the parent project. As a result, the parent project's view policy now affects child projects. If you restrict the visibility of the parent, you also restrict the visibility of the children.

In contrast, permission to edit a parent project grants permission to edit any subproject. If a user can Root Project, they can also edit Root ProjectChild and Root ProjectChildSprint 3.

Policies In Depth

As discussed above, adding and removing projects never affects who can see an object. This is an explicit product design choice aimed at reducing the complexity of policy management.

Phabricator projects are a flexible, general-purpose, freeform tool. This is a good match for many organizational use cases, but a very poor match for policies. It is important that policies be predictable and rigid, because the cost of making a mistake with policies is high (inadvertent disclosure of private information).

In Phabricator, each object (like a task) can be tagged with multiple projects. This is important in a flexible organizational tool, but is a liability in a policy tool.

If each project potentially affected visibility, it would become more difficult to predict the visibility of objects and easier to make mistakes with policies. There are different, reasonable expectations about how policies might be affected when tagging objects with projects, but these expectations are in conflict, and different users have different expectations. For example:

  • if a user adds a project like Backend to a task, their intent might be to open the task up and share it with the "Backend" team;
  • if a user adds a project like Security Vulnerability to a task, their intent might be to close the task down and restrict it to just the security team;
  • if a user adds a project like Easy Starter Task to a task, their intent might be to not affect policies at all;
  • if a user adds Secret Inner Council to a task already tagged with Security Vulnerability, their intent might be to open the task to members of either project, or close the task to just members of both projects;
  • if a user adds Backend to a task already tagged with Security Vulnerability, their intent is totally unclear;
  • in all cases, users may be adding projects purely to organize objects without intending to affect policies.

We can't distinguish between these cases without adding substantial complexity, and even if we made an attempt to navigate this it would still be very difficult to predict the effect of tagging an object with multiple policy-affecting projects. Users would need to learn many rules about how these policy types interacted to predict the policy effects of adding or removing a project.

Because of the implied complexity, we almost certainly could not prevent some cases where a user intends to take a purely organizational action (like adding a Needs Documentation tag) and accidentally opens a private object to a wide audience. The policy system is intended to make these catastrophically bad cases very difficult, and allowing projects to affect policies would make these mistakes much easier to make.

We believe the only reasonable way we could reduce ambiguity and complexity is by making project policy actions explicit and rule-based. But we already have a system for explicit, rule-based management of policies: the policy system. The policy tools are designed for policy management and aimed at making actions explicit and mistakes very difficult.

Many of the use cases where project-based access control seems like it might be a good fit can be satisfied with Spaces instead (see Spaces User Guide). Spaces are explicit, unambiguous containers for groups of objects with similar policies.

Form customization also provides a powerful tool for making many policy management tasks easier (see User Guide: Customizing Forms).