Xamarin Workbooks features two main components which must work in conjunction with each other: Agent and Client.
The Agent component is a small platform-specific assembly which runs in the context of a .NET application.
Xamarin Workbooks provides pre-built "empty" applications for a number of platforms, such as iOS, Android, Mac, and WPF. These applications explicitly host the agent.
During live inspection (Xamarin Inspector), the agent is injected via the IDE debugger into an existing application as part of the regular development & debugging workflow.
The client is responsible (via Roslyn) for compiling source code into small assemblies and sending them over to the connected agent for execution. Results of execution are sent back to the client for rendering. Each cell in a workbook yields one assembly which references the assembly of the previous cell.
Because an agent can be running on any type of .NET platform and has access to anything in the running application, care must be taken to serialize results in a platform-agnostic manner.