System Layers¶
The D2 diagram below shows the runtime topology: the orchestrator coordinates one or more agents, each of which can use the tool bus and memory store, while the LLM provider supplies reasoning and generation.
The layers are intentionally separated so each can scale and fail independently. The orchestrator owns task state, agents are stateless workers, the tool bus enforces policy, and the memory store persists context and artifacts. The LLM provider is treated as an external dependency, not as a core part of the system.
D2 conventions used here: each shape is declared as key: Label { shape: ... }; direction: right produces a left-to-right layout; person, rectangle, cloud, and cylinder shapes distinguish humans, software components, external services, and data stores; and style.fill / style.stroke add color coding so the orchestrator, agents, tool bus, and memory are visually distinct [Terrastruct, n.d.].
The diagram maps the runtime topology to baseline concepts: the Orchestrator coordinates agents and calls the LLM Provider for reasoning; Agent A executes and Agent B verifies; both agents read from and write to the Memory Store; and the Tool Bus discovers, routes, validates, and executes external tools. Color coding supports the separation of concerns: blue for orchestration, purple for agents, orange for the tool bus, and a cylinder for the memory store.
