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Penumbra has two surfaces, and they cascade. You design your domain in the Shapes Workbench, then you operate it with the SDK. This tab is the first half. The Shapes Workbench is a design-time MCP server. You connect it to an AI client (Claude Code, Cursor, Codex), and author your domain model conversationally: define the types, properties, and relationships that structure your graph, compile them, and materialize them to a project. Everything the runtime reads is governed by what you design here.

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Design time vs. run time

Shapes Workbench (here)SDK
WhenDesign timeRun time
SurfaceMCP server, in your AI clientTypeScript client
YouAuthor the shapes that structure the graphOperate a graph governed by those shapes
The questionWhat does my domain look like?How do I put knowledge in and get it back out?
If you are deciding what your knowledge looks like, you are in the Workbench. If you are capturing, searching, and reasoning over it from an app or agent, you are in the SDK. The two are meant to be used together: design a shape here, then read and write against it with the SDK.

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The loop

1

Connect

Add the Workbench MCP server to your AI client. See Connect.
2

Model your domain

Open a session and define types, properties, and relationships. See Authoring.
3

Compile and materialize

Compile the model and materialize it to a project, so the runtime can use it. See Materialize.
4

Operate with the SDK

Extract, capture, and search against the shape you just designed, with the SDK.

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Next

Connect the MCP

Endpoint, key, and client config for Claude Code, Cursor, and Codex.

Author shapes

The workbench tools: open, model, compile, diff, version, preview.