How

Explore the codebase to answer "how does X work?" questions. Produce architectural explanations 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.

Every spawn is a general-purpose, read-only subagent. Explorers use a fast model, and every explainer uses your strongest judgment model.

1. Assess complexity

If the scope is ambiguous, state your interpretation and explore. The user can redirect.

• Simple (a single module, a small utility, a narrow question such as "how does function X work"): no explorers. Spawn one explainer that explores and explains in one pass, built from references/explainer-prompt.md without the explorer-findings section. Go to step 4.
• Complex (a subsystem spanning multiple files or services, a cross-cutting feature, a full architectural overview): go to step 2.

When in doubt, take the simple path.

2. Explore (complex only)

Decompose the question into 2 to 4 angles, each a distinct slice of the subsystem. Spawn all explorers in a single message, each with references/explorer-prompt.md and its angle filled in.