Zerostack - A Unix-Inspired Coding Agent Built in Pure Rust

zerostack is a lightweight coding agent built in Rust, inspired by pi and opencode.

It bundles the following features.

• Uses OpenRouter as the default provider, with support for OpenAI, Anthropic, Gemini, Ollama, OpenAI-compatible endpoints, and custom providers.
• Provides file read·write·edit, grep, find, directory listing, bash execution gated by permissions, MCP, and Exa-based WebFetch·WebSearch.
• On a crossterm-based TUI, it supports session save·load·resume, automatic context compaction, and /prompt, /model, /thinking, /mode, /loop, /worktree.

The built-in prompts consist of code, plan, review, debug, ask, brainstorm, frontend-design, review-security, simplify, write-prompt. Permission modes span 4 levels—restrictive, standard, accept-all, yolo—and it includes a session allowlist and doom-loop detection for repeated calls to the same tool.

The project reports about 7k LoC, an 8.9MB binary, 8MB RAM for an empty session / 12MB while working, and 0.0% CPU when idle / about 1.5% while using tools. It's installed via cargo install zerostack, and bubblewrap is required to use Bash isolation with --sandbox. The license is GPL-3.0-only.