Zerostack

// Overview

Zerostack is a minimal coding agent written in Rust, described by its author as inspired by pi and opencode. It gives you the usual agent loop — read files, write files, run shell commands, search — inside a crossterm-based terminal UI with Markdown rendering, mouse selection and copy, and scrollback, and it is built to stay small: roughly 30,000 lines of core code, a 26MB binary, about 16MB of RAM in normal use and 0.0% CPU while idle.

Control over what the agent may do is explicit. Five permission modes — restrictive, readonly, guarded, standard and yolo — set the baseline, with granular overrides on top, and an optional sandbox isolates execution through bubblewrap on Linux or zerobox on macOS. For parallel work it supports a branch-per-task flow using git worktrees, and sessions can be saved, loaded and resumed with automatic compaction so a long task survives a restart.

It is provider-agnostic: OpenRouter, OpenAI, Anthropic, Gemini, Ollama and any custom OpenAI-compatible endpoint, selected per run from the command line. Prompt modes such as code, plan, review and debug can be switched at runtime, a Markdown memory system persists notes across sessions, and MCP and ACP support let you extend the tool set.

// What it does

• Small by design: ~30,000 lines of core code, a 26MB binary, ~16MB average RAM and 0.0% CPU at idle
• Five permission modes — restrictive, readonly, guarded, standard, yolo — with granular control
• Optional sandboxing via bubblewrap (Linux) or zerobox (macOS)
• Git-worktree branch-per-task workflow for parallel work
• Sessions save, load and resume with auto-compaction
• Runtime-switchable prompt modes: code, plan, review, debug
• MCP and ACP support for extra tooling, plus a persistent Markdown memory system
• Providers: OpenRouter, OpenAI, Anthropic, Gemini, Ollama and custom OpenAI-compatible endpoints

// Getting started

Install the binary through the install script, cargo, Homebrew or Nix, then set the API key for whichever provider you want to use.

curl -fsSL https://raw.githubusercontent.com/gi-dellav/zerostack/main/install.sh | bash

# or
cargo install zerostack
cargo install zerostack --all-features

# or
brew tap gi-dellav/tap
brew install zerostack

zerostack                    # interactive session
zerostack -p "Prompt text"   # one-shot mode
zerostack -c                 # resume last session

zerostack --provider openrouter --model deepseek/deepseek-v4-flash

Commands and code are distilled from the project's own documentation — always check the official repo for the latest.

// When to use it

• Run a coding agent on a small or resource-constrained machine where an Electron or Node-based agent is too heavy
• Keep tight control over what an agent may touch, using readonly or guarded permissions plus a sandbox
• Work several tasks in parallel on one repository with git-worktree branch-per-task sessions
• Switch between hosted and fully local models — the same agent runs against OpenRouter or a local Ollama endpoint

// How Zerostack compares

Zerostack alongside other open-source autonomous coding agents tools AI/TLDR tracks, ranked by GitHub stars.