xAI open-sources Grok Build — a Rust coding agent harness and fullscreen TUI around Grok models — unusually early for a first-party tool. It joins Claude Code, Codex and Gemini CLI as the fourth major first-party harness, now with a fourth open one.
DeepSeek releases a macOS and Windows Desktop app for DeepSeek Harness, its open-source agent harness where everything — tools, sub-agents, even the loop — is a plugin. The repo passed 240k stars within three months of its August launch, making it the fastest-growing harness in the field's history.
'Harness Engineering: Anatomy, Architecture, and Evolution of Coding Agents' surveys the field — loops, tool interfaces, context management, memory and recovery — giving the emerging discipline its first comprehensive academic map.
OpenAI releases Symphony — open-source orchestration that turns project work into isolated, autonomous coding-agent implementation runs and surfaces the ones that pass, so teams manage outcomes instead of supervising sessions. Big Tech keeps raising the floor on what counts as a baseline harness.
Gemini 3 debuts with state-of-the-art agentic coding benchmarks, alongside Antigravity — a browser-based agentic development environment where agents plan, edit and execute tasks across editor and browser surfaces.