We’re trained to think bugs live in code. Logic errors Edge cases Race conditions Bad assumptions in systems But there’s a class of bugs most engineers never debug: Validation bugs. And they’re worse — because your code can be perfect and still fail. A Familiar Pattern (But Not Where You Expect) Imagine this function: def validate_idea (): signals = [] signals . append ( ask_friends ()) signals . append ( post_online ()) signals . append ( check_competitors ()) return any ( signals ) Enter fullscreen mode Exit fullscreen mode Looks reasonable. Now look closer: ask_friends() → always returns True (politeness bias) post_online() → returns True on weak engagement check_competitors() → returns True if they exist, and also if they don’t This function is broken. It always returns True . This Is What Most Validation Looks Like You think you're testing an idea.…