Enhanced long term planning by assigning a milestone to an epic
### Release notes
You can now assign [milestones](https://docs.gitlab.com/user/project/milestones/) directly to epics, creating a natural planning cascade from strategic initiatives down to execution. This allows you align your longer-term planning cadences (like quarterly planning or SAFe program increments) with epics, while keeping iterations focused on development sprints. By maintaining this clear hierarchy, you'll reduce administrative overhead and gain better visibility into how your strategic initiatives are progressing against organizational timeframes.

## Summary
Based on recent [research findings](https://gitlab.com/gitlab-org/ux-research/-/issues/2855#note_2012895008) we've made the decision to add GitLab's `Milestone` feature to epics. This will allow users to associate longer term planning cadances (quarterly, annual, program increment) with an epic (feature, initiative, project).
Introducing milestones at the epic level bridges the gap between strategic planning and execution, empowering teams to align their long-term initiatives with organizational timeframes while maintaining flexibility in delivery.
### Value
1. **Streamlined planning hierarchy**. Assigning milestones directly to epics creates a natural planning cascade from strategic initiatives down to execution, allowing teams to:
- Connect high-level planning (epics) with time-bound delivery cycles (milestones)
- Automatically cascade timeframes to child items, reducing manual work
- Maintain a single source of truth for delivery timeframes
2. **Enhanced visibility of progress vs. plan**. Epic milestones enable teams to:
- Clearly distinguish between planned dates and actual delivery dates
- Identify drift between strategic planning and execution reality
- Provide early signals when initiatives are at risk of missing deadlines
3. **Reduced administrative overhead**. This feature significantly reduces manual work by:
- Eliminating the need to individually assign milestones to dozens of issues
- Providing inheritance of milestones to new child items
- Simplifying milestone reassignment when delivery timeframes change
4. **Better support for enterprise planning methodologies**. Epic milestones align with established frameworks by:
- Supporting SAFe and other scaled agile approaches that use program increments
- Enabling quarterly/annual planning cycles at the initiative level
- Facilitating the connection between strategic planning and sprint-level execution
5. **Improved stakeholder communication**. With epic milestones, teams can:
- Provide clearer timelines for feature delivery to stakeholders
- Show progress against planned delivery dates in roadmaps
- Communicate timeline changes more effectively across the organization
### Intended behavior
- Users should be able to set a milestone at any epic level
- The milestone set at the epic level should cascade down to descendant items (subepics, issues, tasks)
- Users should be able to overwrite the inherited milestone on descendant records
### Milestone feature name considerations
We've learned that users naturally utilize the term "Milestone" to represent a key date or point in a project (e.g. release date, significant event like SOX audit, market announcement, etc.) and they do not think about "Milestone" in the context in which we have applied it (longer period timebox like program increments, quarters, or fiscal year). As a result of this learning, we will explore whether we should rename the existing Milestone feature.
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## Rollout Plan
[Rollout issue](https://gitlab.com/gitlab-org/gitlab/-/issues/538993)
* [ ] Switch FF actors - https://gitlab.com/gitlab-org/gitlab/-/merge_requests/194444 (MR in progress)
* [ ] Enable on GitLab Org group first to test
* [ ] Gradual rollout plan, for the `work_item_epic_milestones` feature flag - 2025-06-18
* [ ] 50 % - 2025-06-19
* [ ] 100 % - 2025-06-20
* [ ] Default enable in %"18.2"
* [ ] Announcements
* [ ] Clean up - remove the feature flag
epic