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name: implementation description: Systematic approaches to writing high-quality code with contract-first discipline and validation gates when_to_use: when implementing any backend, frontend, database, or test code version: 1.0.0

Implementation Skill

Overview

This skill provides systematic workflows for implementing code across backend APIs, frontend components, databases, and tests. It emphasizes:

1. Contract-first discipline - DTOs and interfaces defined and validated before business logic
2. Validation gates - Quality checkpoints before considering work complete
3. Coding standards - Consistent patterns and best practices
4. Error handling - Systematic approach to errors and edge cases
5. Testing requirements - Comprehensive test coverage expectations

When to Use This Skill

Use this skill when:

• Implementing backend API endpoints and services
• Building frontend components and UI features
• Creating database schemas and migrations
• Writing tests for any code
• Following a PRP implementation blueprint

This skill integrates with:

• shark-task-management - Task lifecycle tracking with shark CLI
• test-driven-development - TDD methodology for test-first development
• testing-anti-patterns - What to avoid when writing tests
• frontend-design - UI design patterns and aesthetics
• architecture - Design documentation that guides implementation

Workflow Selection

Choose the appropriate workflow based on what you're implementing:

Backend Implementation

API Endpoints → workflows/implement-api.md

• REST/GraphQL endpoint implementation
• Request/response handling
• Authentication and authorization
• API testing

Backend Services → workflows/implement-backend.md

• Business logic implementation
• Service layer patterns
• Repository patterns
• Backend utilities

Database Changes → workflows/implement-database.md

• Schema design and migrations
• Database queries and optimization
• Data modeling patterns

Frontend Implementation

UI Components → workflows/implement-frontend.md

• Component implementation
• State management
• API integration
• Frontend testing

Testing

Test Creation → workflows/implement-tests.md

• Unit test implementation
• Integration test implementation
• Contract test implementation
• E2E test implementation

Critical Context

Before implementing, always review these context documents:

Contract-First Discipline

context/contract-first.md

THE GOLDEN RULE: DTOs are defined in design docs, implemented identically on frontend and backend, and validated BEFORE any business logic is written.

This prevents frontend/backend divergence and enables parallel development.

Validation Gates

context/validation-gates.md

Quality checkpoints that must pass before work is considered complete:

• Linting and formatting
• Type checking
• Unit tests
• Contract tests
• Integration tests

Coding Standards

context/coding-standards.md

Consistent code style, naming conventions, and best practices.

Error Handling

context/error-handling.md

Systematic approach to error handling, logging, and user-facing error messages.

Testing Requirements

context/testing-requirements.md

Test coverage expectations and testing strategies.

Implementation Process

The standard implementation flow is:

Copy1. Read design documentation
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2. Start task tracking: shark task start <task-id>
   ↓
3. Select appropriate workflow (this SKILL.md)
   ↓
4. Follow contract-first discipline (if applicable)
   ↓
5. Implement code following the workflow
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6. Apply coding standards
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7. Implement error handling
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8. Write/run tests (TDD when applicable)
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9. Run validation gates
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10. Document implementation
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11. Complete task tracking: shark task complete <task-id>

Key Principles

1. Contracts First - Define and validate DTOs/interfaces before logic
2. Test-Driven - Write tests first when using TDD skill
3. Incremental - Implement in small, testable increments
4. Validated - Pass all gates before considering work complete
5. Documented - Update implementation notes and TODOs

Anti-Patterns to Avoid

• Implementing business logic before validating contracts
• Skipping validation gates "to save time"
• Diverging DTO/interface names from specification
• Writing code without tests
• Assuming frontend will adapt to backend naming
• Creating database migrations before contracts validated
• Manual testing only (no automated tests)

Integration with Other Skills

test-driven-development

• Use TDD skill for test-first workflow
• Follow RED-GREEN-REFACTOR cycle
• Reference from implement-* workflows

testing-anti-patterns

• Consult before writing tests
• Avoid testing mock behavior
• Don't add test-only methods to production

frontend-design

• Reference for UI aesthetic guidance
• Complement implement-frontend workflow

architecture

• Read architecture docs first
• Implementation follows design decisions

Success Criteria

Implementation is complete when:

• All contracts validated and synchronized
• All validation gates pass
• Tests provide adequate coverage
• Code follows standards
• Error handling is comprehensive
• Documentation is updated
• No outstanding TODOs in critical paths

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Remember: Quality is built in through systematic workflows, not added later. Follow the discipline, trust the process, and deliver production-ready code.