AI BriefingClaude Sonnet and Opus Agents Build 11 C# Libraries with 1.14M Lines in 6 Days
·2026.10.28 00:14
Key point
A team of Claude agents generated 1.14M lines of code across 11 foundational C# libraries, with seven already published on NuGet.
Details
- Claude Sonnet and Opus agents built 11 from-scratch C# libraries, including a PDF stack, image codecs, font shaper, HLSL shader compiler, audio, HTML parser, HTML/CSS rendering engine, JavaScript interpreter, compression, OCR, and a game engine.
- The project produced 1.14M lines of code and over 2,100 commits in 6 days, with seven libraries released on NuGet.
- Performance benchmarks show the JS interpreter passed 99.55% of test262 (43,471 tests), the HTML renderer processed a 10k-row table to PDF in 1.8 s / 305 MB (vs headless Chrome's 6.5 s / 2.1 GB), the shader compiler matched Microsoft's DXC on 330/330 GPU tests while compiling 2.4x faster, and the HTML parser passed 100% of html5lib-tests.
- The agent setup uses Sonnet for coding and Opus for planning, orchestration, review, and release, with a build orchestrator splitting work into units with separate git worktrees.
- Context management involves writing handoff notes at 400k tokens so fresh agents can pick up work, while heavy tasks like testing and fuzzing run on a second machine shared via a lock.
- Key lesson: reducing process instructions improved agent performance, with user messages per library dropping from 112 to 11 as the workflow matured.
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