The plugin tree

Every piece claims a stable name in the shared context, and the others look it up by that name.

Piece	What it does	Key
Session log	Records everything that happens	ctx.sessions
Prompt assembler	Builds what the model reads at the start of each request	ctx.systemPrompt
Tool registry	Holds what the model can use and runs it with guards	ctx.tools
Agent definition	Describes what an agent is	ctx.agents
Agent loop	Drives the work forward	ctx.agentLoop
Model adapter	Translates between the internal vocabulary and each provider API	ctx.llm
Per-agent logging	Provides traces scoped to an agent	no key

There are dedicated pieces for files, terminals, language servers, web access, subagents, background tasks, context compaction and quite a few more.

Technical detail optional

The reference documentation publishes one page per subsystem, with signatures extracted from the code and checked in continuous integration. The seventh piece provides agent-scoped logging and claims no context key.