how · diff
git:20261026.385852f to git:20261102.8cdc2d3
1 added, 1 removed. Audit A to A.
---
name: how
- description: "Explain how code works by reading it: a subsystem's runtime flow, its architecture, where something should live. Use for \"how does X work\", \"X 는 어떻게 동작해\", \"이 구조 설명해줘\", \"이건 어디에 둬야 해\", or a walkthrough before changing code. Why it is this way, or why it was decided, is why."
+ description: "Use before editing a subsystem that neither you nor an upstream report has read. Explain how code works by reading it: a subsystem's runtime flow, its architecture, where something should live. Use for \"how does X work\", \"X 는 어떻게 동작해\", \"이 구조 설명해줘\", \"이건 어디에 둬야 해\". Why it is this way, or why it was decided, is why."
---
# 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.
Explorers are the built-in read-only `Explore` subagent. The explainer is one `general-purpose` `Agent` on `opus`, told in its prompt that it only reads and writes the explanation and must not edit files.
## 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 and no explainer. Explore and explain it yourself in one pass, following the Instructions and Output Format in `references/explainer-prompt.md` (skip its explorer-findings parts). 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.
## 3. Synthesize (complex only)
Once all explorers have returned, spawn one explainer with `references/explainer-prompt.md` and every explorer's findings filled in. Synthesize once; do not re-run it per explorer.
## 4. Present
Present the explainer's output. Light edits for clarity or context from the conversation are fine. Do not substantially rewrite it.
## Output format
The explanation uses the sections defined in `references/explainer-prompt.md`, dropping any that do not apply: Overview, Key Concepts, How It Works, Where Things Live, Gotchas.