Quoting Addy Osmani (opens in new tab)

<blockquote cite="https://addyosmani.com/blog/21-lessons/"><p>With enough users, every observable behavior becomes a dependency - regardless of what you promised. Someone is scraping your API, automating your quirks, caching your bugs.</p> <p>This creates a career-level insight: you can’t treat compatibility work as “maintenance” and new features as “real work.” Compatibility is product.</p> <p>Design your deprecations as migrations with time, tooling, and empathy. Most “API design” is actual...