sceptre-mcp-server: Instructions file for Kiro

Refactoring Skill

Activate this skill for safe, systematic code improvement.

Refactoring Principles

• Tests first — Ensure test coverage exists before refactoring
• Small steps — One change at a time, verify tests pass after each
• No behavior change — Refactoring changes structure, not behavior
• Commit often — Each successful refactoring step gets its own commit

Common Refactoring Patterns

Extract Function

When a block of code does something that can be named:

# Before: inline logic
if user.age >= 18 and user.verified and not user.banned:
    ...

# After: extracted with clear name
if is_eligible_user(user):
    ...

Early Return

When deep nesting makes code hard to follow:

# Before: nested
def process(data):
    if data:
        if data.get("valid"):
            # actual logic

# After: early returns
def process(data):
    if not data:
        return
    if not data.get("valid"):
        return
    # actual logic

Replace Magic Numbers

# Before
if retries > 3:
    ...

# After
MAX_RETRIES = 3
if retries > MAX_RETRIES:
    ...

Split Large Files

When a file exceeds 500 lines:

1. Identify distinct responsibilities
2. Extract each into its own module
3. Re-export from original __init__.py if needed for backward compatibility
4. Update imports across codebase

Dead Code Removal

• Remove commented-out code (it's in git history)
• Remove unused imports (use ruff)
• Remove unreachable branches
• Remove unused functions/variables

Workflow

1. Identify the smell (large file, deep nesting, duplication, etc.)
2. Verify test coverage exists for affected code
3. Apply one refactoring pattern
4. Run tests — must still pass (poetry run pytest -q)
5. Commit
6. Repeat

Red Flags That Need Refactoring

• Functions over 50 lines
• Files over 500 lines
• Nesting deeper than 4 levels
• Duplicated code in 3+ places
• God classes/functions that do everything
• Long parameter lists (>4 params — use a dataclass or TypedDict)