Build Command - Implement Features

Purpose

Implement features or changes, either from a plan or from a direct request.

When to Use

• After a plan has been created and approved
• For small, straightforward implementations
• When building new functionality

Instructions

When this command is invoked:

Step 1: Identify What to Build

1. Check if there's a recent plan in specs/
2. If no plan exists, clarify requirements with user
3. Understand the scope of work
4. Identify dependencies

Step 2: Review Standards

Before writing code:

1. Read the coding standards in CLAUDE.md
2. Look at existing code patterns in app/
3. Ensure consistency with project style
4. Note any required testing patterns

Step 3: Implement

For each piece of work:

1. Create/modify files following this order:

   • Core logic files first
   • Utility/helper files second
   • Configuration files third
   • Tests last

2. Per file, follow this pattern:

   • Add imports at top
   • Add any necessary comments
   • Implement the logic
   • Export what needs to be exported

3. Show progress:

   • Show each file change to user
   • Wait for approval before continuing
   • Explain what each change does

Step 4: Write Tests

For each new function or module:

1. Create corresponding test file
2. Cover happy path
3. Cover edge cases
4. Cover error conditions

Step 5: Verify

After implementation:

1. List all files created/modified
2. Summarize what was done
3. Run tests if available
4. Suggest next steps (review, documentation)

Implementation Principles

DO:

• Follow existing patterns in the codebase
• Write self-documenting code
• Handle errors gracefully
• Keep functions small and focused
• Add appropriate input validation
• Write tests alongside implementation

DON'T:

• Over-engineer simple solutions
• Add unnecessary dependencies
• Ignore existing conventions
• Skip error handling
• Create overly complex abstractions
• Leave code without tests

Example Output

After building:

Implementation Complete!

Files Created:
- app/utils/newHelper.js (45 lines)
- tests/unit/newHelper.test.js (30 lines)

Files Modified:
- app/index.js (added import)

Summary:
Created the newHelper utility function with full error handling
and comprehensive tests covering all edge cases.

Next Steps:
1. Run tests: node tests/run.js
2. Review changes: /review
3. Commit if satisfied: git add . && git commit

Notes

• Always ask for approval before creating/modifying files
• Explain why you made specific implementation choices
• If something is unclear, ask rather than assume
• Consider delegating to the builder agent for complex implementations