# Systems Playbook

> A timeless, interlinked markdown knowledge graph of durable ideas for engineering, systems, architecture, product, design, organization, decision-making, and complexity. Every entity is a markdown file with frontmatter and related links; a generated graph artifact maps how they connect. Markdown is the source of truth, so always follow an entity back to its file before quoting or summarizing it.

The collection is organized into five entity types. Concepts are the core ideas, patterns are recurring solutions, mental models are reusable thinking tools, categories group everything for orientation, and references are durable summaries of the books and papers the ideas come from. Start with the machine-readable graph to see all entities and their relationships, then read the underlying markdown for any entity you intend to cite.

## Knowledge graph

- [knowledge-graph.json](/knowledge-graph.json): Generated map of every entity and relationship, with each entity's source file `path` and canonical site `urlPath`. Read this first to navigate without crawling the site.

## Browse by type

- [Concepts](/concepts/): Core durable ideas. Source markdown lives in `concepts/`.
- [Patterns](/patterns/): Recurring solutions and approaches. Source markdown lives in `patterns/`.
- [Mental models](/mental-models/): Reusable thinking tools. Source markdown lives in `mental-models/`.
- [Categories](/categories/): Topic groupings for broad orientation and traversal. Source markdown lives in `categories/`.
- [References](/references/): Durable provenance for each source. The summary for a source lives in `references/<source-slug>/summary.md`.

## How to read this knowledge graph

- Begin with knowledge-graph.json to get a map of entities and relationships.
- Follow each entity's `path` back to its source markdown before making claims about its content.
- Use category pages for broad orientation and an entity's related links for local traversal.
- Use a reference's summary for durable source provenance and to trace an idea to its origin.
- Each entity may include a `urlPath` to its canonical page; when working directly in the repository, prefer the repository-relative `path` instead.