---
type: Section
title: Bundle Structure
---

# Bundle Structure

A Knowledge Bundle is a self-contained, hierarchical collection of knowledge documents. The bundle root contains an `index.md` file that lists all concepts in the bundle. Each concept is a separate markdown file with its own frontmatter and body.

## Directory Layout

```
bundle-root/
├── index.md          # Bundle-level index (conventional filename)
├── concept-a.md      # Top-level concept
└── subdir/
    └── concept-b.md  # Nested concept; ID = "subdir/concept-b"
```

Concept IDs are the file path without `.md`. A concept at `bundle-root/subdir/concept-b.md` has ID `subdir/concept-b`.

## Index File

The `index.md` at the bundle root is a conventional entry point listing all top-level concepts. It serves as progressive disclosure for large bundles.