datum

Datum is a parametric solid-modeling kernel built from scratch in Rust to use every CPU core while staying bit-for-bit deterministic. Its full name is Design Automation Toolkit for Universal Modeling, and under the hood it stands for Distributed Architecture for Topology-based Unified Modeling.

It is designed around immutable bodies, so an operation never modifies its input and unchanged parts are shared; a dependency graph instead of a list, so independent features rebuild in parallel and only what changed is recomputed; stable topology IDs, so references survive edits and results do not depend on thread count; symbolic intersections, so faces can be split independently on different cores and stitched back exactly; and no modeling box, so a site plan and an M6 bolt live in one model. It is agent-native: every operation is a JSON command with a generated schema, and the same commands drive the CLI, the UI and an MCP server.

The proof of concept is complete, stages M0 to M5, and Datum now grows into an open CAD system, starting with sheet metal. It is not yet a tool for daily work: models are built as JSON feature graphs by hand, by script or by an AI agent over MCP, and the viewer edits their parameters live. The README's own proof-of-concept measurements report 1,000 independent bodies rebuilding in 230 ms on 1 thread versus 61 ms on 6 threads, editing the last of 200 features costing 0.14 ms over the operation itself, and hashes identical on 1, 4 and 16 threads and between Linux and Windows.