Bill Cox's Ensemble is an AI coding agent built from his executable teaching book "The Art of Building AI Coding Agents." Edition 3 uses C# 14 / .NET 10 and introduces Development-Driven Specifications, where code and specifications are built together rather than planned upfront. The workflow involves pair-programming with an AI: discussing design, drafting chapter TL;DRs and exercises, implementing code, and recording decisions. Once implementation passes exercise graders, the notes become the chapter body covering process, lessons, and tradeoffs. This creates an executable specification transferring judgment, not just feature lists. Ensemble V2 built V3, with Bill and Cadence refining both the agent and teaching. Individual chapters have documented verification limits. The human expertise grows during development rather than depending on final code inspection. The code is an output; the reusable asset is the knowledge to build it again. Users need .NET 10 SDK to build and run the C# GUI and terminal client via Make commands. The project includes preserved chapter solutions, promotion evidence, and frozen histories of Editions 1 and 2 with their books and graders.
The application teaches how and why to build systems with AI, offering chapter guides and assembled manuscripts. It emphasizes that expertise cannot be learned upfront but starts with the book. The codebook transfers the judgment needed to build the system again.
Source: Hacker News · Summarized by HeadlinesBriefing