code/skills/builtins/feature-dev/SKILL.md

metadata

name: feature-dev
description: >-
  Guided feature development with codebase understanding and architecture focus.
  Use when the user asks to implement a feature or build something non-trivial.
language: any
tags: workflow, architecture, planning, implementation

Feature Development

You are helping a developer implement a new feature. Follow a systematic approach: understand the codebase deeply, identify and ask about all underspecified details, design elegant architectures, then implement.

Core Principles

• Ask clarifying questions: Identify all ambiguities, edge cases, and underspecified behaviors. Ask specific, concrete questions rather than making assumptions.
• Understand before acting: Read and comprehend existing code patterns first
• Simple and elegant: Prioritize readable, maintainable, architecturally sound code
• Use TodoWrite: Track all progress throughout

Phase 1: Discovery

Goal: Understand what needs to be built

Actions:

1. Create a todo list with all phases
2. If feature unclear, ask user for:
   • What problem are they solving?
   • What should the feature do?
   • Any constraints or requirements?
3. Summarize understanding and confirm with user

Phase 2: Codebase Exploration

Goal: Understand relevant existing code and patterns

Actions:

1. Use list_dir and glob to map the project structure
2. Use grep to find similar features and patterns
3. Use read_file on 5-10 key files identified
4. Present comprehensive summary of findings and patterns discovered

Phase 3: Clarifying Questions

Goal: Fill in gaps and resolve all ambiguities before designing

CRITICAL: This is one of the most important phases. DO NOT SKIP.

Actions:

1. Review the codebase findings and original feature request
2. Identify underspecified aspects: edge cases, error handling, integration points, scope boundaries, design preferences, backward compatibility, performance needs
3. Present all questions to the user in a clear, organized list
4. Wait for answers before proceeding to architecture design

If the user says "whatever you think is best", provide your recommendation and get explicit confirmation.

Phase 4: Architecture Design

Goal: Design an implementation approach with concrete trade-offs

Actions:

1. Design the implementation: minimal changes (smallest change, maximum reuse), clean architecture (maintainability, elegant abstractions), or pragmatic balance (speed + quality)
2. Present to user: brief summary, trade-offs, your recommendation with reasoning, concrete implementation differences
3. Ask user to approve the approach

Phase 5: Implementation

Goal: Build the feature

DO NOT START WITHOUT USER APPROVAL

Actions:

1. Wait for explicit user approval
2. Read all relevant files identified in previous phases
3. Implement following chosen architecture
4. Follow codebase conventions strictly
5. Write clean, well-documented code
6. Update todos as you progress

Phase 6: Quality Review

Goal: Ensure code is simple, DRY, elegant, easy to read, and functionally correct

Actions:

1. Self-review for: simplicity/DRY/elegance, bugs/functional correctness, project conventions/abstractions
2. Consolidate findings and identify highest severity issues that you recommend fixing
3. Present findings to user and ask what they want to do (fix now, fix later, or proceed as-is)
4. Address issues based on user decision

Phase 7: Summary

Goal: Document what was accomplished

Actions:

1. Mark all todos complete
2. Summarize:
   • What was built
   • Key decisions made
   • Files modified
   • Suggested next steps