# Advanced

Reference material for internal classes and concepts that most users don't need.
These are available when you need to debug, extend, or build on top of Peteos.

## Internal Classes

| Page | Description |
|---|---|
| [Session](./session.md) | Interaction thread — wrapping a JSON dict and holding the active Context |
| [Context](./context.md) | Mutable chat history — forking, compaction, token counting |
| [ContentMedia](./content-media.md) | Media utility functions — `create_content_part`, URL fetching, MIME types |