Jul 15, 2026 — SpaceXAI announced that Grok Build, its coding agent and terminal UI (TUI), is now open source on GitHub.
Official rationale: Publishing the code is the most direct way to build a robust, reliable harness. Developers can inspect context assembly through tool-call dispatch; skills, plugins, hooks, MCP servers, and subagents have a definitive source reference; the agent can run fully local-first (compile yourself, point at local inference, configure via config.toml).
Published source includes:
- The agent loop: context assembly, model response parsing, tool-call dispatch
- The tools: read/edit/search code, run commands
- The terminal UI: rendering, input handling, plan review, inline diff viewer
- The extension system: skills, plugins, hooks, MCP servers, and subagents
Supplementary detail from MarkTechPost (Jul 15, 2026): Apache 2.0 license; Rust codebase under crates such as xai-grok-shell, xai-grok-tools, xai-grok-pager, xai-grok-workspace; interactive TUI, headless mode for CI, and Agent Client Protocol (ACP) for editor embeds; Grok Build launched as early beta May 25, 2026; upstream external PRs not accepted; comparison table notes Codex CLI and OpenCode as peer open harnesses, Claude Code as proprietary.
Install path referenced: curl install script from x.ai/cli; cargo build from source for xai-grok-pager binary.