Blame Archaeology

Old code is often older for a reason. The rule "anything > 2 years old should be deleted" ships bugs. This skill is the disciplined way to find out why before you touch.

When to use

• About to delete code that "looks unused" or "looks old."
• Refactoring a confusing function whose original intent isn't clear.
• Bisecting a regression — finding the commit that introduced behavior X.
• Onboarding to a codebase and trying to understand why X is the way it is.
• Code review of a delete PR — verify the deleter did this homework.

When NOT to use

• Definitely-dead code from a static analyzer with full reference search done (see find-dead-code tier 1).
• Trivial surface fix (rename a variable in a 5-line function).
• New code (no history yet).

The archaeology workflow