Some decisions are easy to reverse — you can change a UI component, rename a variable, or swap a utility function with no lasting consequences. These are two-way doors: walk through, and if it's wrong, walk back.
Other decisions create gravity. Once traffic, users, or other code depends on them, changing course gets expensive. A database schema migration after launch. An API contract that external consumers rely on. An auth boundary that shapes your entire permission model. These are one-way doors.
The most expensive mistakes in software aren't bugs. They're irreversible architectural decisions made too quickly.
Use this skill when creating new files that represent architectural decisions — data models, infrastructure configs, auth boundaries, API contracts, CI/CD pipelines, or event systems. Flags irreversible decisions and forces a discussion about trade-offs before committing. Source: jamditis/claude-skills-journalism.