| name | epic-slicing-planning |
| description | Plan large features by defining high-level Epic architecture and a vertical slice roadmap before detailed implementation tasks. Use during Phase 3 for multi-slice initiatives. |
| when_to_use | ["Feature spans multiple milestones or vertical slices.","Shared cross-cutting architecture decisions must be made before detailed tasks.","Team needs dependency-aware sequencing and controlled scope."] |
| authoritative_references | [".github/templates/epic-design.template.md",".github/templates/epic-roadmap.template.md",".github/checklists/design-review.md"] |
Epic slicing planning
Goal
Reduce planning risk for large features by separating:
- Epic-level design decisions.
- Slice-level detailed planning and task decomposition.
Deliverables
03-epic-design.md:
- boundaries
- shared decisions
- cross-cutting constraints
- ADR links
- Epic-level
Q-NNN
03a-epic-roadmap.md:
- vertical slice backlog
- dependency order
- milestone intent
- rollout notes
Slicing rules
- Prefer vertical, user-visible slices over horizontal layer slices.
- Keep each slice independently testable and releasable.
- Put shared infrastructure decisions in Epic design, not repeated per slice.
- Avoid planning every implementation task for the entire Epic up front.
Anti-patterns
- A roadmap that is only backend layers then frontend layers.
- Slices that are not user-visible and cannot be validated end-to-end.
- Unresolved Epic decisions pushed down into many slice tasks.
- Giant slices that require multiple teams and have undefined boundaries.
Handoff criteria
- Epic artifacts are approved.
- Epic-level
Q-NNN are resolved or deferred with rationale.
- At least one first slice is ready for
/plan detailed decomposition.
