Anthropic makes Claude Code generally available and holds its first developer conference — with Claude Code for web, enterprise features, and hooks/MCP improvements central to agent workflows.
'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.
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.
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.
Anthropic began enforcing its terms against third-party clients using Claude Code subscriptions, forcing alternative harnesses like opencode to rework authentication (its issue thread became the debate's ground zero). A defining platform-risk moment for the open-harness ecosystem: the model provider owns the login, the harness does not.