---

name: vertical-slice-planning description: Use this skill when discussing feature breakdown, PR structure, implementation ordering, or how to decompose work. Guides thinking about vertical slices (end-to-end functionality) rather than horizontal layers (all of one layer first). Triggers on "how should we break this down?", "what order should we implement?", "how many PRs?", or decomposition discussions.

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.

Copy┌─────────────────────────────────────────┐
│              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:

1. User can view empty product list (UI → API → DB)
2. User can add a product (UI → API → DB)
3. 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:

CopySLICE 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

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.