Bismuth

Bismuth developed an AI software developer designed to handle development tasks autonomously. Its foundation, Asimov Agents, was a Python framework for building agent systems around a graph execution engine, model inference and caching. Developers could define task dependencies, let models direct execution, preserve state through snapshots and trace execution with OpenTelemetry.

Co-founders Ian Butler and Nick Gregory ran the business together; Gregory served as CTO. The team also created SM-100, a benchmark for evaluating whether software engineering agents could find and fix bugs in real codebases. It measured discovery without hints, report accuracy, successful fixes and review of bug-introducing changes. Its single-attempt evaluations emphasized whether an agent could produce useful results without repeated runs.

Bismuth wound down operations and offboarded customers as Butler and Gregory joined XBOW. Butler said the business had paying customers, but growth fell short of the founders’ expectations. Its main API and agent implementation, codenamed Daneel, became a read-only public archive in 2025. The framework and benchmark document its engineering work, rather than establishing an ongoing commercial service.