- name
- how
- description
- Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions ("where should this live", "which package owns this", "is this the right layer"). Explains subsystem architecture, runtime flow, onboarding mental models. Use why for motivation.
- disable-model-invocation
- true
# How
Before delegating, read [the harness instructions](../../harness/README.md) and the active harness file. Map agent names, tool arguments, and model roles there.
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.
## Step 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. One explainer explores and explains in a single pass. Go to Step 2b.
- **Complex** (a subsystem spanning multiple files or services, a cross-cutting feature, a full architectural overview): spawn parallel explorers first, then hand off to the explainer. Go to Step 2a.
When in doubt, take the simple path.
## Step 2a. Explore (complex questions only)
Decompose the question into 2 to 4 exploration angles, each a distinct slice of the subsystem. Spawn all explorers in a single message:
- `subagent_type`: the harness's general-purpose agent (`general-purpose` on Claude Code, `generalPurpose` on Cursor)
- `model`: your configured how-explorer model (harness default)
- `readonly`: `true`
Each explorer gets the prompt in `references/explorer-prompt.md` with its angle filled in. Then go to Step 3.
## Step 2b. Direct Explain (simple questions)
Spawn one subagent that explores and explains in one pass:
- `subagent_type`: the harness's general-purpose agent
- `model`: your configured how-explainer model (harness default)
- `readonly`: `true`
Build its prompt from `references/explainer-prompt.md` without the explorer-findings section. Go to Step 4.
## Step 3. Synthesize (complex questions only)
Once all explorers have returned, spawn one subagent to synthesize their findings into one explanation:
- `subagent_type`: the harness's general-purpose agent
- `model`: your configured how-explainer model (harness default)
- `readonly`: `true`
Build its prompt from `references/explainer-prompt.md` with every explorer's findings filled in.
## Step 4. Present
Present the explainer's output to the user. 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.
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