Code Tour

A guided path through a codebase, ordered so each stop makes the next one legible, and annotated with why the code is the way it is rather than what it does. The what is already on screen; the why is what takes a new engineer three weeks to reconstruct and what the person who knows it will lose in six months. Tours rot faster than any other documentation because they point at line numbers, so anchoring and validation are half this skill.

When to use this skill

• Onboarding an engineer onto a service where reading order determines whether week one is productive or archaeological
• Handing off ownership of a system before its author changes team or leaves
• Explaining a subsystem ahead of a design review, so reviewers arrive with shared context
• Documenting a surprising design whose rationale lives only in a closed pull request
• Auditing an existing tour that has silently rotted as files moved and functions were renamed
• Re-entering your own code after six months away, which is functionally the same problem as onboarding

Inputs the skill expects