Code Implementation Skill

Implement features and write code following best practices and language conventions.

Implementation Principles

Core Rules

• Follow language conventions
• Avoid unnecessary comments; document only when naming cannot convey intent (@DisplayName, JSDoc, docstrings)
• Minimal changes: implement what is requested

Language-Specific Guidelines

Load only when working in that stack:

• Java: references/java-guidelines.md
• Kotlin: references/kotlin-guidelines.md
• Python: references/python-guidelines.md
• JavaScript/TypeScript: references/js-ts-guidelines.md
• Go: references/go-guidelines.md
• C/C++: references/cpp-guidelines.md

Implementation Process

1. Understand requirements: clarify scope, I/O contracts, existing patterns. Tools: mcp__serena__get_symbols_overview, mcp__context7__get-library-docs, mcp__jetbrains__get_symbol_info.
2. Plan: break into tasks, note dependencies, design interface first.
3. Write code:
   1. Skeleton (interfaces/signatures)
   2. Core logic
   3. Edge cases
   4. Error handling
4. Validate: run narrow, relevant checks (lint/typecheck/build) for the touched stack.

Code Quality Guidelines

Self-Documenting Code

// BAD: Comment explains obvious code
// Increment counter by one
counter++;

// GOOD: Code is self-explanatory
userLoginAttempts++;

When to Add Documentation

Use documentation annotations when:

• Method name cannot fully express behavior
• Complex algorithm needs explanation
• Public API requires usage examples
• Prefer doc comments (Javadoc/KDoc/JSDoc/reStructuredText/GoDoc) over inline line comments for reusable helpers.

@DisplayName("Should retry up to 3 times with exponential backoff")
@Test
void retryWithExponentialBackoff() {
    // test implementation
}

def calculate_compound_interest(principal, rate, time, n=12):
    """
    Calculate compound interest.

    Uses formula: A = P(1 + r/n)^(nt)

    Args:
        principal: Initial amount
        rate: Annual interest rate (decimal)
        time: Time in years
        n: Compounding frequency per year

    Returns:
        Final amount after compound interest
    """
    return principal * (1 + rate / n) ** (n * time)

Error Handling

function parseConfig(path: string): Config {
    const content = readFileSync(path, 'utf-8');
    if (!content.trim()) {
        throw new EmptyConfigError(path);
    }
    return JSON.parse(content);
}

Output Format

## Implementation Summary

### Files Changed

| File | Change Type | Description |
| ---- | ----------- | ----------- |
| path | Added | Description |

### Implementation Details

[Key design decisions and approach]

### Testing

[If tests are needed, use the `generate-tests` skill to add/extend coverage.]

### Usage

(example code)

Edge Cases

• Unclear requirements: Ask 1-3 clarifying questions
• Large features: Break into smaller PRs
• Legacy code: Match existing style, suggest improvements separately
• Performance-critical: Document algorithmic complexity

Tips

• MCP tools are optional; omit if unavailable or add others as needed
• Always run tests before completing implementation
• Check for existing similar implementations in the codebase