/implement - Task Implementation

Implement a specific task from the backlog with production code and tests.

Purpose

Execute a task by:

• Understanding the requirement and acceptance criteria
• Writing production code following existing patterns
• Creating tests for new functionality
• Preparing a commit message

Inputs

• $ARGUMENTS: Task ID (e.g., "T-001") or task description
• BACKLOG: docs/development/BACKLOG.md for task details
• Architecture: docs/architecture/ARCHITECTURE.md for patterns
• ${PROJECT_NAME}: Current project context

Outputs

• Production code in appropriate source files
• Tests alongside implementation
• Suggested commit message

Workflow

1. Identify Task

Parse $ARGUMENTS to find the task:

• If task ID provided, look up in BACKLOG.md
• If description provided, match to existing task or confirm new work

2. Read Task Details

From BACKLOG.md, extract:

• Task description
• Acceptance criteria
• Epic context
• Dependencies (ensure they're complete)

3. Explore Codebase

Before writing code:

• Find related existing code
• Identify patterns to follow
• Check for similar implementations
• Understand the module structure

4. Plan Implementation

Outline the approach:

• Files to modify/create
• Functions/classes needed
• Test approach
• Edge cases to handle

5. Implement

Write code following these principles:

• Read Before Write: Understand existing code
• Minimal Changes: Only modify what's necessary
• Follow Patterns: Match existing style
• No Over-Engineering: Simple solutions preferred
• Security Aware: Avoid common vulnerabilities

6. Write Tests

For new functionality:

• Unit tests for core logic
• Integration tests if crossing boundaries
• Edge case coverage
• Follow existing test patterns

7. Verify

Check against acceptance criteria:

• Each AC is met
• Tests pass
• No regressions
• Code follows patterns

8. Prepare Commit

Suggest commit message:

type(scope): description

- Detail of change 1
- Detail of change 2

Refs: T-XXX

Types: feat, fix, refactor, test, docs, chore

Implementation Guidelines

Code Quality

• Use descriptive variable/function names
• Keep functions focused (single responsibility)
• Add comments only where logic isn't self-evident
• Handle errors appropriately

Testing

• Test behavior, not implementation
• One assertion per test when possible
• Clear test names describing expected behavior
• Mock external dependencies

Security

• Validate inputs at boundaries
• Escape outputs appropriately
• No secrets in code
• Follow OWASP guidelines

Validation Checklist

Before completing:

• All acceptance criteria met
• Tests written and passing
• Code follows existing patterns
• No hardcoded secrets or credentials
• Commit message prepared
• Task ready to mark complete

Error Handling

If blocked:

1. Document the blocker clearly
2. Suggest alternatives if possible
3. Don't make assumptions without verification
4. Consider invoking /analyse for investigation

Policy References

Should-read from ~/.claude/policy/RULES.md:

• Implementation Completeness - No partial features, no TODOs
• Git Workflow - Feature branches, incremental commits
• Safety Rules - Framework respect, pattern adherence