ocp

Trigger

This skill activates when the user runs /ocp (optionally with a file path argument, e.g. /ocp src/services/export.py).

Scope Detection

Determine which files to analyze using this priority order:

1. Argument — If the user provided a file or directory path after /ocp, use that directly.
2. Git staged — Run git diff --cached --name-only. If output is non-empty, use those files.
3. Git unstaged — Run git diff --name-only. If output is non-empty, use those files.
4. Ask user — If no git diff is available, ask for a file or directory path.

Always skip: *.lock, package-lock.json, yarn.lock, pnpm-lock.yaml, Gemfile.lock, composer.lock, **/migrations/**, **/__generated__/**, **/fixtures/**, **/*.min.js

OCP Fix Logic

Detection

Code violates OCP when adding new behavior requires modifying existing code. Look for:

• if type == "x": ... elif type == "y": ... chains (Python/Ruby) dispatching on a string or enum type
• switch (type) { case "x": ... case "y": ... } statements (Java/C#/PHP/TypeScript) dispatching on a string or enum type
• when (type) { "x" -> ... "y" -> ... } expressions (Kotlin) dispatching on a string or enum type
• isinstance chains used for dispatch: if isinstance(obj, TypeA): ... elif isinstance(obj, TypeB): ...
• Direct subclass instantiation chosen by condition: if kind == "pdf": return PdfExporter()
• Factory functions with growing if/elif/switch blocks that must be edited to add new variants

Fix Strategy

Replace the conditional dispatch with a registry or strategy pattern:

1. Define a Protocol (Python), interface (TypeScript/Java), or interface type (Go) for the behavior
2. Create a registry mapping type keys to implementations
3. Replace the if/elif chain with a registry lookup
4. New variants are added by registering — not by editing the dispatch function

Language patterns:

Python:

from typing import Protocol

class Renderer(Protocol):
    def render(self, data: list) -> str: ...

_renderers: dict[str, Renderer] = {
    "pdf": PdfRenderer(),
    "csv": CsvRenderer(),
}

def export(data: list, format: str) -> str:
    if format not in _renderers:
        raise ValueError(f"Unknown format: {format}")
    return _renderers[format].render(data)