Carbon-based humans, in a silicon world. Deep dives on how AI systems actually get built.https://thecarbonlayer.com/https://thecarbonlayer.com/meta-harness-build/https://thecarbonlayer.com/meta-harness-build/An agent told my prototype it had committed a fix, the commit didn't exist, and the only thing that caught it was code that asked Git instead of asking the agent.Sun, 02 Aug 2026 00:00:00 GMThttps://thecarbonlayer.com/meta-harness/https://thecarbonlayer.com/meta-harness/I run four agent sessions to get one change reviewed properly and the coordination between them is still done by hand; writing down what that glue actually does produced eight components, none of which belong in a supervisor model's context.Sun, 26 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/agent-evaluation/https://thecarbonlayer.com/agent-evaluation/The same agent answered one question straight from the database and confidently invented the next; a 25-question eval harness is how I found out which failures matter and what to fix first.Mon, 20 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/self-evolving-harness/https://thecarbonlayer.com/self-evolving-harness/An outside model found a real bug in my agent's harness, wrote a fix, and proved it helped; every safety property in that sentence had to be built by hand.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/building-an-agent-from-scratch/https://thecarbonlayer.com/building-an-agent-from-scratch/Fifteen chapters after the empty file, the model's weights hadn't changed once; everything that reads as agentic came from code we wrote around one API call.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/context-management/https://thecarbonlayer.com/context-management/Forty turns into a real bug the agent started contradicting itself; the model never changed, the window did.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/agent-skills/https://thecarbonlayer.com/agent-skills/Your strongest reviewer cannot sit inside every pull request; a skill captures the repeatable part of their procedure so the agent stops rediscovering the job.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/agent-sandboxing/https://thecarbonlayer.com/agent-sandboxing/The word sandbox covers five very different mechanisms, from a V8 isolate to a microVM, and the right one depends on the failure you need to contain.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/agent-memory-architecture/https://thecarbonlayer.com/agent-memory-architecture/The model forgets everything at the session boundary; whatever feels like memory is the harness deciding what to keep, recall, update, and forget.Thu, 16 Jul 2026 00:00:00 GMThttps://thecarbonlayer.com/harness-engineering/https://thecarbonlayer.com/harness-engineering/When an agent fails, the model takes the blame; the more useful questions are about the ten layers wrapped around it.Thu, 16 Jul 2026 00:00:00 GMT