Feature Dev

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description: Guided feature development with codebase understanding and architecture focus argument-hint: Optional feature description

Feature Development

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

References

New features must be implemented in src/mvvm/ following the MVVM architecture (.agents/skills/mvvm-architecture/SKILL.md).

Shared logic extracted out of an app goes to shared/, domain/ or features/, not to libs/.

Core Principles

• Ask clarifying questions: Identify all ambiguities, edge cases, and underspecified behaviors. Ask specific, concrete questions rather than making assumptions. Wait for user answers before proceeding with implementation. Ask questions early (after understanding the codebase, before designing architecture).
• Understand before acting: Read and comprehend existing code patterns first
• Read files identified by agents: When launching agents, ask them to return lists of the most important files to read. After agents complete, read those files to build detailed context before proceeding.
• Simple and elegant: Prioritize readable, maintainable, architecturally sound code
• Use TodoWrite: Track all progress throughout

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Phase 1: Discovery

Goal: Understand what needs to be built

Initial request: $ARGUMENTS

Actions:

1. Create 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

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Phase 2: Codebase Exploration

Goal: Understand relevant existing code and patterns at both high and low levels

Actions:

1. Launch 2-3 code-explorer agents in parallel. Each agent should:

   • Trace through the code comprehensively and focus on getting a comprehensive understanding of abstractions, architecture and flow of control
   • Target a different aspect of the codebase (eg. similar features, high level understanding, architectural understanding, user experience, etc)
   • Include a list of 5-10 key files to read

   Example agent prompts:

   • "Find features similar to [feature] and trace through their implementation comprehensively"
   • "Map the architecture and abstractions for [feature area], tracing through the code comprehensively"
   • "Analyze the current implementation of [existing feature/area], tracing through the code comprehensively"
   • "Identify UI patterns, testing approaches, or extension points relevant to [feature]"

2. Once the agents return, please read all files identified by agents to build deep understanding

3. Present comprehensive summary of findings and patterns discovered

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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.

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