Writing Feature Specs

Guides the creation of comprehensive feature specification documents through structured research and user interviews.

Workflow

1. Gather Requirements

Ask the user:

• •What is the feature we are building?
• •What problem are we solving?
• •Who asked for this / user feedback if any?
• •Any constraints: timeline, dependencies, etc.?
• •What is the local path for the backend, frontend and documentation?

2. Clarify the Data Model

Before assuming domain terms, clarify:

• •What entities exist and how do they relate?
• •Are there similar-sounding concepts that are actually distinct? (e.g., User vs Membership, Account vs Organization)
• •Ask the user to confirm your understanding before proceeding

3. Research (do in parallel)

Before writing the spec, research:

1. •Explore existing system - Search the codebase to understand current architecture
2. •External API/integration docs - Read official docs if applicable
3. •Similar features - Find prior art for consistency and patterns

Search these directories for relevant information:

• •Backend source code in the local path from earlier
• •Frontend source code in the local path from earlier
• •Documentation directories in the local path from earlier
• •Any other related files or directories from earlier

4. Write the Spec

Use the template at templates/spec.md in this skill directory.

Output the spec to the project's specs directory (e.g., .specs/[FEATURE-NAME].md or specs/[FEATURE-NAME].md).

Code References

For references to code files, use GitHub URLs (not local file:// URLs):

• •Get the repo URL from git remote get-url origin
• •Use format: https://github.com/{org}/{repo}/blob/{branch}/{path}#L{line}-L{line}

Minimize Implementation Details

• •Describe the contract (what), not the implementation (how)
• •Use JSON schema for data models, not internal formats like protobuf
• •Omit infrastructure choices (databases, queues, frameworks) unless they constrain the design
• •If an implementation detail is necessary, explain why it matters to the reader

Design Principles

Always remember:

• •Start from user goals and tasks, not screens
• •Design the smallest useful version that can be shipped
• •Avoid implying future functionality that is not committed

Frontend Design Rules

Apply these rules ONLY for frontend/UI features:

Hierarchy & Structure:

• •Treat hierarchy as the primary UX tool - decide what matters most on every screen
• •Use constraints to reduce complexity and decision fatigue
• •Separate semantic correctness from visual importance
• •Prefer clarity and scannability over completeness

User Actions:

• •Explicitly identify primary, secondary, and tertiary user actions
• •Describe what information users must notice first and why
• •Do not assume the user will understand the feature

Iteration:

• •Assume designs will be iterated after real usage
• •Recommend when to defer design decisions until implementation feedback exists
• •Call out assumptions, risks, and unknowns instead of masking them with UI
• •Optimize for learnability and reduction of cognitive load