majiayu000 Vertical Slice Planning Skill
This skill guides the decomposition of features into vertical slices - thin, end-to-end pieces of functionality that can be shipped independently.
When to Use
Apply this skill when:
- Breaking down a feature into Subtasks
- Deciding implementation order for a feature
- Planning PR structure for a feature
- Users ask "how should we break this down?"
- Discussing what to build first
- Reviewing feature decomposition plans
What is a Vertical Slice?
A vertical slice cuts through ALL layers of the application to deliver a thin piece of complete functionality.
┌─────────────────────────────────────────┐
│ HORIZONTAL LAYERS │
├─────────────────────────────────────────┤
│ UI Layer │ █ │ │ │ │
├────────────────┼───┼─────┼─────┼────────┤
│ API Layer │ █ │ │ │ │
├────────────────┼───┼─────┼─────┼────────┤
│ Service Layer │ █ │ │ │ │
├────────────────┼───┼─────┼─────┼────────┤
│ Data Layer │ █ │ │ │ │
└────────────────┴───┴─────┴─────┴────────┘
↑
Vertical Slice
(Complete feature)
Vertical vs Horizontal
Horizontal Approach (Avoid)
Building all of one layer before moving to the next.
Problems: Nothing works until everything is done, late integration issues.
Vertical Approach (Prefer)
Building thin, complete features:
- User can view empty product list (UI → API → DB)
- User can add a product (UI → API → DB)
- User can edit a product (UI → API → DB)
Benefits: Each slice is shippable, visible progress, early feedback.
Naming Convention for Jira Subtasks
Since Jira Subtasks are flat (no nesting), use prefixes:
SLICE 1: Basic product list display
SLICE 1.1: Add product image support
SLICE 2: Product search functionality
REFACTOR: Extract shared product utils
TEST: Integration tests for product API
Slice Sizing Guidelines
| Size | Indicators |
|---|---|
| Too Big | Multiple user actions, >2 days work, many acceptance criteria |
| Too Small | Just infrastructure, just types, <1 hour work |
| Just Right | One capability, 1-2 days, 3-5 acceptance criteria |
Integration with Jira Workflow
When creating Jira Stories:
- Parent Story = Full feature context
- Subtasks = Vertical slices (potential PRs)
Each Subtask should be independently deployable, testable, and valuable.
Remember: Ship working software frequently. Slices make this possible.