dev-guidelisted

# Developer Guide This skill is for producing and maintaining a **developer guide**: the document a new contributor reads to understand how the system is built well enough to change it. It is not user-facing documentation and not an API reference dump — it is the mental model of the codebase. A good developer guide has three properties (this is the bar to hit): 1. **It is accurate.** The architecture and component descriptions reflect how the code _actually_ works, not how it was once intended to work. An inaccurate guide is worse than no guide because it confidently misleads. 2. **Every component is explained by its responsibility**, not just named. The reader learns _what each part is for_ and _how the parts connect_, in plain language. 3. **Flows are shown with the right kind of diagram.** Structure, sequence, and data pipelines each call for a different diagram type, and the guide uses the correct one. A good starting point is to start with a top-level architecture diagram, then one section per major component, each stating a single responsibility, listing its parts as one-line descriptions linked to source, and tracing processes as numbered steps. ## Operating principles (non-negotiable) - **Ground everything in code you have actually read.** Never describe a component from its name, from a typical pattern, or from memory of how similar systems work. Open the file and confirm. This is the whole value of the guide. - **Document responsibility, not ex