how

# 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. ## 1. Assess complexity If the scope is ambiguous, state your interpretation and explore. The user can redirect. - **Simple** (a single module, a small utility, or one continuous trace): read and explain directly using `references/explainer-prompt.md` without explorer findings. Go to step 4. Do not delegate a small lookup. - **Complex** (multiple independent research threads needing substantial separate context): go to step 2. File count alone does not justify fan-out. When in doubt, take the simple path. ## 2. Explore (complex only) Each spawn below names a role line in the `pstack-models.instructions.md` configuration (Copilot home `instructions/`) and its default. Use that line's value. If the configuration or the line is missing, omit `model`. Omit `model` when the value is `auto` or `inherit-parent`. If the Task tool rejects a slug, omit `model` and say so. Decompose the question into 2 to 4 independent angles. Spawn all explorers in a single message, each with `references/explorer-prompt.md` and its angle filled in: - `agent_type`: `explore` - `model`: your configured how-explorer model; omit it when unconfigured or set to `auto` Then go to step 3. ## 3. Synthesize (complex only) Once all explorers have returned, spawn one Task subagent to synthesize their findings into one explanation: - `agent_type`: `general-purpose` - `model`: your configured how-explainer model; omit it when unconfigured or set to `auto` - Prompt: read-only; do not edit files Build its prompt from `references/explainer-prompt.md` with every explorer's findings filled in. ## 4. Present Present the explanation. For a delegated synthesis, light edits for clarity or conversation context 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.