/how

Answers how does X work? at the level of a senior engineer onboarding onto a subsystem — enough to build a working mental model, not so much that it reads like annotated source code. Together with pstack-why it forms the framework’s two-skill understanding layer, and the pair is explicitly divided: how is what the code does, why is what forces led to its shape.

The skill is scale-adaptive by an explicit first step. A simple question (one module, a small utility) skips exploration entirely and runs one explainer in a single pass. A complex one (a subsystem spanning files or services, a cross-cutting feature, a full architectural overview) decomposes the question into two to four exploration angles, spawns all explorers in a single message on a fast cheap model, then hands their findings to one explainer on the strongest judgment model for synthesis. When in doubt, take the simple path.

The split is pattern-context-engineering with a model-role split layered on it: exploration is a bulk-reading job routed to a fast model, synthesis is a judgment job routed to a reasoning model, and every subagent runs readonly: true. The raw reading stays in the explorers; only findings reach the parent. The final step is a discipline rather than a mechanism — present the explainer’s output with light edits for clarity, and do not substantially rewrite it.

/how is one of the most heavily consumed capabilities in the framework. pstack-architect runs it to ground Phase A, pstack-teach runs it as one of its two inputs, pstack-blast-radius positions itself against it, and pstack-comment-sicko fires it to check a comment’s claim before killing the comment.

See Also

• pstack-why — the motivation companion; the two are designed as a pair.
• pstack-teach — runs this and why and weaves one plain explanation for a person.
• pstack-blast-radius — the third member of the understanding trio, aimed at consequences rather than mechanism.
• openspec-explore — the cross-framework counterpart that aligns by investigating the codebase.
• stage-align — the canonical stage this implements.