How

Explore the codebase to answer "how does X work?" Produce an architectural explanation at the level of a senior engineer onboarding onto a subsystem.

Two modes:

1. Explain (default). Explore and produce a clear explanation.
2. Critique. Explain first, then spawn independent critics.

Companion to why. This skill answers what the code does. why answers what forces led to its shape.

Contract

Inputs:

• A how-question: subsystem, feature flow, architectural overview, or runtime trace