how

Files (3)

• SKILL.md
• explainer-prompt.md · references/
• explorer-prompt.md · references/

SKILL.md (first lines)

# 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.

Each spawn below names a role line in the `pstack models` section of `AGENTS.md` (written by `/skill:setup-pstack`). Resolve the spawn's model from that line; run the seat on your own model (pass your own `--provider`/`--model`) when the section or the line is missing, and for the aliases `auto` and `inherit-parent`. If a configured model fails to resolve (`pi --list-models <entry>` finds nothing), run the seat on your own model and say so. Pick each subagent's thinking level and fast or standard speed for the job, per the Subagents section of the **poteto-mode** skill.

## 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 exploration angles, each a distinct slice of the subsystem. Spawn all explorers as backgrounded pi processes (one bash call), then wait and read the output files:

```bash
pi -p --no-session --tools read [--provider <p> --model <m>[:<thinking>]] \
  "<explorer prompt>" > /tmp/how-explorer-<n>.out 2>&1 &
```

- Prompt: `references/explorer-prompt.md` with its angle filled in
- `--tools read`: explorers are read-only
- model: the `how explorer` line, or your own model when unset

Then go to Step 3.

## 4. Present

Spawn one pi process that explores and explains in one pass:

```bash
pi -p --no-session --tools read [--provider <p> --model <m>[:<thinking>]] \
  "<explainer prompt>" > /tmp/how-explainer.out 2>&1
```

- Prompt: `references/explainer-prompt.md` without the explorer-findings section
- model: the `how explainer` line, or your own model when unset

Go to Step 4.

## Step 3. Synthesize (complex questions only)

Once all explorers have returned, spawn one pi process to synthesize their findings into one explanation:

```bash
pi -p --no-session --tools read [--provider <p> --model <m>[:<thinking>]] \
  "<explainer prompt with findings>" > /tmp/how-explainer.out 2>&1
```

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.

From qapquiz/qstack, MIT.

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