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.
$npx -y skills add chillerno1/kskills --skill how --agent claude-code
Installs into .claude/skills of the current project.
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---
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."
---
# 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 `pstack-models.md` and a default. Read `.claude/pstack-models.md` in the repo root if it exists, else `~/.claude/pstack-models.md`; a missing file or line uses the default. Set the Agent tool's `model` to that line's value (`opus`, `fable`, `sonnet`, or `haiku`), or omit `model` when the value is `inherit`.
## 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`: `Explore`
- `model`: the `how explorer` line, default `opus`
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 with the Agent tool that explores and explains in one pass:
- `subagent_type`: `general-purpose` (read-only: it explains, it does not edit)
- `model`: the `how explainer` line, default `opus`
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 with the Agent tool to synthesize their findings into one explanation:
- `subagent_type`: `general-purpose` (read-only: it explains, it does not edit)
- `model`: the `how explainer` line, default `opus`
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.
