devplacepy/.claude/commands/explain.md

---
description: Explain a DevPlace subsystem, route, or file - read the relevant nested CLAUDE.md and the code, then summarize architecture, data flow, invariants, and entry points. Read-only.
argument-hint: <area, route, or file>
allowed-tools: Read, Grep, Glob, Bash(git log:*)
---
Orient me on: **$ARGUMENTS**

Investigate before explaining; confirm every claim against the source.

1. Locate the code: the router under `devplacepy/routers/`, the template under `devplacepy/templates/`, data helpers in `devplacepy/database.py`, schemas in `devplacepy/schemas.py`, and any service under `devplacepy/services/`.
2. Read the matching nested `CLAUDE.md` for the subsystem (e.g. `devplacepy/services/devii/CLAUDE.md`), plus the relevant cross-cutting part of the root `CLAUDE.md`.
3. Trace the data flow: input model (`models.py`) -> router handler + guard -> data helper -> response (HTML via `respond` + template, JSON via the `*Out` schema), plus the Devii action (`catalog.py`) and API docs (`docs_api.py`) where present.

Then give a tight explanation:
- What it does and where it lives, with `file:line` references.
- The request pipeline and data flow.
- Key invariants and gotchas (pull these from the nested CLAUDE.md).
- The fan-out: which of the nine feature layers exist for it.

Do not modify anything.