zag

One CLI for all your AI coding agents.

zag wraps Claude, Codex, Gemini, Copilot, and Ollama behind a single command so you can switch between them without learning five different CLIs. It adds cross-provider features on top: model size aliases, automatic provider/model selection, git worktree isolation, Docker sandboxing, structured JSON output with schema validation, unified session logs, and a programmatic Rust API.

Why zag?

• One CLI, five agents — Switch between Claude, Codex, Gemini, Copilot, and Ollama without learning five different CLIs
• Cross-provider features — Model size aliases, JSON schema validation, git worktree isolation, and Docker sandboxing work with every provider
• Orchestration primitives — Spawn, wait, collect, pipe, and chain agents in shell scripts for multi-agent workflows
• Programmatic API — Rust library crate plus TypeScript, Python, C#, Swift, Java, and Kotlin SDKs

Prerequisites

• Rust 1.85+ (edition 2024) — for building from source
• git — required for --worktree isolation
• Docker — required for --sandbox isolation (optional)
• At least one agent CLI installed (see below)

Install

From crates.io

cargo install zag-cli

From GitHub Releases

Download a pre-built binary from GitHub Releases, extract it, and place it in your PATH.

From source

git clone https://github.com/niclaslindstedt/zag.git
cd zag
cargo install --path zag-cli

As a library

cargo add zag

Agent CLIs

You need at least one underlying agent CLI installed:

Provider	Install command	Link
Claude	curl -fsSL https://claude.ai/install.sh | bash	docs
Codex	npm install -g @openai/codex	repo
Gemini	npm install -g @anthropic-ai/gemini-cli	repo
Copilot	npm install -g @github/copilot	docs
Ollama	See ollama.com/download	site

zag checks for the required binary before running and provides install hints if it's missing.

Quick start

# Interactive session with Claude (the default provider)
zag run

# Non-interactive — prints the response and exits
zag exec "write a hello world program in Rust"

# Pick a different provider
zag -p gemini run
zag -p codex exec "add error handling to src/main.rs"

# Use size aliases instead of provider-specific model names
zag -m small exec "what does this function do?"   # fastest/cheapest
zag -m large run                                   # most capable

# Let an LLM pick the best provider and model for the task
zag -p auto -m auto exec "refactor the auth module"

# Code review (delegates to Codex)
zag review --uncommitted

Providers

Provider	Default model	Size aliases (small / medium / large)
claude	default	haiku / sonnet / default
codex	gpt-5.4	gpt-5.4-mini / gpt-5.3-codex / gpt-5.4
gemini	auto	gemini-3.1-flash-lite-preview / gemini-2.5-flash / gemini-3.1-pro-preview
copilot	claude-sonnet-4.6	claude-haiku-4.5 / claude-sonnet-4.6 / claude-opus-4.6
ollama	qwen3.5:9b	2b / 9b / 35b (parameter sizes, any model from ollama.com)

Size aliases let you write zag -m large exec "..." and get the right model regardless of which provider you're using. For Claude, default delegates model selection to the Claude CLI itself.

Commands

zag run [prompt]              Interactive session (optional initial prompt)
zag exec <prompt>             Non-interactive — print output and exit
zag review                    Code review (--uncommitted, --base, --commit)
zag config [key] [value]      View or set configuration
zag session list|show|import|delete|update  List/inspect/manage sessions
zag listen <id>               Tail a session's log events in real-time
zag ps list|show|stop|kill    List, inspect, and manage agent processes
zag search <query>            Search through session logs
zag input [message]           Send a user message to a single session
zag broadcast [message]       Send a message to all sessions in the project

zag spawn <prompt>            Launch background agent, return session ID
zag spawn -I [prompt]         Spawn long-lived interactive session (FIFO-based)
zag wait <id>... [--timeout]  Block until session(s) complete
zag status <id>               Machine-readable session health check
zag collect [--tag <tag>]     Gather results from multiple sessions
zag env [--session <id>]      Export session environment variables
zag pipe <ids>... -- <prompt> Chain session results into a new session
zag events <id> [--type ...]  Query structured events from session logs
zag cancel <id>... [--tag]    Gracefully cancel running sessions
zag summary <id>... [--tag]   Log-based session summary and stats
zag watch <id> --on <event>   Execute command on matching log events
zag subscribe [--tag <tag>]   Multiplexed event stream from all sessions
zag log <message> [--session] Append custom event to a session log
zag output [<id>] [--latest]  Extract final result text from a session
zag retry <id>... [--failed]  Re-run failed sessions with same config
zag gc [--force] [--older-than]  Clean up old session data and logs

zag serve [--port] [--token]   Start HTTP/WS server for remote access
zag connect <url> --token     Connect to a remote zag server
zag disconnect                Disconnect from remote server

zag capability                Show provider capability declarations
zag skills list|show|add|remove|sync|import   Manage provider-agnostic skills
zag mcp list|show|add|remove|sync|import     Manage MCP servers across providers
zag whoami                    Show current session identity (for agents)
zag man [command]             Built-in manual pages

Flags

Flag	Short	Description
--provider <name>	-p	claude, codex, gemini, copilot, ollama, auto
--model <name>	-m	Model name, size alias (small/medium/large), or auto
--system-prompt <text>	-s	Appended to the agent's system prompt
--root <path>	-r	Root directory for the agent
--auto-approve	-a	Skip permission prompts
--add-dir <path>		Additional directories to include (repeatable)
--worktree [name]	-w	Run in an isolated git worktree
--sandbox [name]		Run inside a Docker sandbox
--json		Request structured JSON output
--json-schema <schema>		Validate output against a JSON schema
--json-stream		Stream JSON events (NDJSON)
--session <uuid>		Pre-set the session ID
--name <name>		Human-readable session name (for discovery)
--description <text>		Short description of the session's purpose
--tag <tag>		Session tag (repeatable, for discovery/filtering)
--max-turns <n>		Maximum number of agentic turns
--size <size>		Ollama parameter size (e.g., 2b, 9b, 35b)
--show-usage		Show token usage statistics (JSON output mode)
--debug	-d	Debug logging
--quiet	-q	Suppress all output except the agent's response
--verbose	-v	Styled output with icons in exec mode

Session management

Every interactive session gets a session ID. You can name and tag sessions for discovery, resume them, and zag tracks provider-native session IDs automatically.

# Create sessions with metadata for discovery
zag exec --name "backend-agent" --tag backend "implement API"
zag run --name "frontend-agent" --tag frontend --description "CSS work"

# Resume a specific session
zag run --resume <session-id>

# Resume the most recent session
zag run --continue

# List and filter sessions
zag session list
zag session list --tag backend     # filter by tag
zag session list --name frontend   # filter by name

# Send messages by name
zag input --name backend-agent "check the auth module"

# Broadcast to all sessions in the project (or filter by tag)
zag broadcast "report status"
zag broadcast --tag backend "report status"

# Update session metadata
zag session update <id> --tag new-tag

# Tail a session's logs in real-time (from another terminal)
zag listen <session-id>
zag listen --latest --rich-text
zag listen --ps <pid>             # by OS PID or zag process UUID

Orchestration

zag provides primitives for launching, synchronizing, and collecting results from multiple agent sessions. These are building blocks — not an orchestration engine — designed for shell scripts and pipelines.

# Spawn parallel agents
sid1=$(zag spawn --name analyzer --tag batch -p claude "analyze auth module")
sid2=$(zag spawn --name reviewer --tag batch -p gemini "review test coverage")
sid3=$(zag spawn --name scanner --tag batch -p codex "find security issues")

# Check health
zag status $sid1                          # → running | idle | completed | failed | dead

# Block until all finish (exit code reflects success)
zag wait --tag batch --timeout 10m

# Collect results
zag collect --tag batch --json > results.json

# Feed a session's result into a new agent
zag exec --context $sid1 "summarize the analysis and suggest fixes"

# Propagate agent failure as a non-zero exit code
zag exec --exit-on-failure "fix the bug" || echo "Agent reported failure"

# Export session env for nested invocations
eval $(zag env --shell --session $sid1)

# Query parent-child process trees
zag ps list --children $PARENT_SESSION_ID
zag session list --parent $PARENT_SESSION_ID

# Filter listen to specific event types
zag listen $sid1 --filter session_ended --filter tool_call

# Chain session results into a new agent session
zag pipe --tag batch -- "synthesize all findings into a report"

# Query structured events from a session log
zag events $sid1 --type tool_call --json
zag events $sid1 --last 10 --after-seq 42

# Gracefully cancel sessions
zag cancel $sid1 --reason "orchestrator timeout"
zag cancel --tag batch

# Get session summaries (no LLM call — log-based)
zag summary --tag batch --json

# Watch for events and react
zag watch $sid1 --on session_ended -- echo "done: {session_id}"
zag watch --tag batch --on session_ended --filter 'success=false' --once

# Subscribe to a multiplexed event stream from all sessions
zag subscribe --tag batch --json | jq 'select(.type == "session_ended")'

# Long-lived interactive sessions (Claude only)
sid=$(zag spawn --interactive --name worker -p claude)
zag input --name worker "analyze the auth module"
zag input --name worker "now refactor the error handling"
zag listen --name worker

# DAG workflows with spawn dependencies
sid_a=$(zag spawn "analyze code")
sid_b=$(zag spawn --depends-on $sid_a "fix issues from analysis")
sid_c=$(zag spawn --depends-on $sid_a --inject-context "write tests")
sid_d=$(zag spawn --depends-on $sid_b --depends-on $sid_c "final report")

Filesystem lifecycle markers are written to ~/.zag/events/ (.started and .ended files) for external non-Rust orchestrators that prefer inotifywait over polling.

Remote access

Run agents on your home machine and control them from anywhere (mobile, laptop, another server).

# On the server machine — start the zag server
zag serve --generate-token --port 2100
# Output: Generated token: a1b2c3...

# With TLS (recommended for non-VPN networks)
zag serve --token a1b2c3... --tls-cert cert.pem --tls-key key.pem

# On the client machine — connect to the server
zag connect https://home.local:2100 --token a1b2c3...

# Now all commands transparently proxy through the remote server
zag spawn "write tests for the auth module"
zag listen --latest
zag session list
zag status <session-id>

# Spawn an interactive session on the remote machine
sid=$(zag spawn --interactive --name worker -p claude)
zag input --name worker "analyze the auth module"
zag listen --name worker

# Disconnect when done
zag disconnect

The server exposes REST and WebSocket endpoints at /api/v1/. See zag man serve and zag man connect for details.

Worktree and sandbox isolation

# Worktree: isolated git worktree per session
zag -w run                        # auto-named
zag -w my-feature exec "..."      # named

# Sandbox: Docker microVM isolation
zag --sandbox run                  # auto-named
zag --sandbox my-sandbox exec "..."

# Both track sessions — resume restores the correct workspace
zag run --resume <id>

After interactive sessions, you're prompted to keep or remove the workspace. Exec sessions with changes are kept automatically with a resume command printed.

JSON output

# Request JSON output
zag exec --json "list 3 programming languages"

# Validate against a schema (inline or file path)
zag exec --json-schema '{"type":"object","required":["languages"]}' "list 3 languages"

# Stream events as NDJSON
zag exec --json-stream "complex task"

Claude uses its native --json-schema support. Other providers get JSON instructions injected into the system prompt. On validation failure, zag retries up to 3 times via session resume.

Output formats

With exec -o <format>:

Format	Description
(default)	Streamed text — beautiful formatting for Claude, plain for others
text	Raw agent output, no parsing
json	Compact unified JSON (AgentOutput)
json-pretty	Pretty-printed unified JSON
stream-json	NDJSON event stream (unified format)
native-json	Claude's raw JSON format (Claude only)

Configuration

Per-project config lives at ~/.zag/projects/<sanitized-path>/zag.toml. Falls back to ~/.zag/zag.toml outside of git repos.

zag config                          # Print current config
zag config provider gemini          # Set default provider
zag config model.claude=opus        # Set per-agent model default
zag config auto_approve true        # Skip permission prompts by default
zag config max_turns 10             # Set default max agentic turns
zag config system_prompt "Be concise" # Set default system prompt
zag config unset provider           # Unset a config key (revert to default)

[defaults]
provider = "claude"
model = "medium"
auto_approve = false
# max_turns = 10
# system_prompt = ""

[models]
claude = "opus"
codex = "gpt-5.4"

[auto]
provider = "claude"
model = "sonnet"

[ollama]
model = "qwen3.5"
size = "9b"

Settings priority: CLI flags > config file > agent defaults.

Skills

zag supports provider-agnostic skills using the Agent Skills open standard. Skills are stored in ~/.zag/skills/ and automatically synced to each provider's native skill directory via symlinks.

zag skills list                     # List all skills
zag skills add commit               # Create a new skill
zag skills import --from claude     # Import existing Claude skills
zag skills sync                     # Sync to all providers

MCP Servers

Manage MCP (Model Context Protocol) servers across all providers from a single place. Each server is stored as an individual TOML file in ~/.zag/mcp/ (global) or ~/.zag/projects/<path>/mcp/ (project-scoped), and synced into each provider's native config format with a zag- prefix.

zag mcp add github --command npx --args -y @modelcontextprotocol/server-github
zag mcp add sentry --transport http --url https://mcp.sentry.dev/sse
zag mcp list                        # List all MCP servers
zag mcp sync                        # Sync to all providers
zag mcp import --from claude        # Import from provider config
zag mcp remove github               # Remove + clean provider configs

Supported providers: Claude (~/.claude.json), Gemini (~/.gemini/settings.json), Copilot (~/.copilot/mcp-config.json), Codex (~/.codex/config.toml).

Programmatic API

The zag-agent crate exposes an AgentBuilder for driving agents from Rust code:

use zag::builder::AgentBuilder;

let output = AgentBuilder::new()
    .provider("claude")
    .model("sonnet")
    .auto_approve(true)
    .exec("write a hello world program")
    .await?;

println!("{}", output.result.unwrap_or_default());

See the zag-agent crate for the full API including JSON schema validation, custom progress handlers, and interactive sessions.

Language bindings

SDK packages are available for TypeScript, Python, C#, Swift, Java, and Kotlin. Each wraps the zag CLI and exposes a fluent builder API with typed output models.

TypeScript (bindings/typescript/)

import { ZagBuilder } from "@nlindstedt/zag-agent";

const output = await new ZagBuilder()
  .provider("claude")
  .model("sonnet")
  .autoApprove()
  .exec("write a hello world program");

console.log(output.result);

// Streaming
for await (const event of new ZagBuilder().provider("claude").stream("analyze code")) {
  console.log(event.type);
}

Python (bindings/python/)

from zag import ZagBuilder

output = await ZagBuilder() \
    .provider("claude") \
    .model("sonnet") \
    .auto_approve() \
    .exec("write a hello world program")

print(output.result)

# Streaming
async for event in await ZagBuilder().provider("claude").stream("analyze code"):
    print(event.type)

C# (bindings/csharp/)

using Zag;

var output = await new ZagBuilder()
    .Provider("claude")
    .Model("sonnet")
    .AutoApprove()
    .ExecAsync("write a hello world program");

Console.WriteLine(output.Result);

// Streaming
await foreach (var evt in new ZagBuilder().Provider("claude").StreamAsync("analyze code"))
{
    Console.WriteLine(evt.Type);
}

Swift (bindings/swift/)

import Zag

let output = try await ZagBuilder()
    .provider("claude")
    .model("sonnet")
    .autoApprove()
    .exec("write a hello world program")

print(output.result ?? "")

// Streaming
for try await event in ZagBuilder().provider("claude").stream("analyze code") {
    print(event)
}

Java (bindings/java/)

import io.zag.ZagBuilder;

var output = new ZagBuilder()
    .provider("claude")
    .model("sonnet")
    .autoApprove()
    .exec("write a hello world program");

System.out.println(output.result());

// Streaming
for (var event : new ZagBuilder().provider("claude").stream("analyze code")) {
    System.out.println(event.type());
}

Kotlin (bindings/kotlin/)

import zag.ZagBuilder

val output = ZagBuilder()
    .provider("claude")
    .model("sonnet")
    .autoApprove()
    .exec("write a hello world program")

println(output.result)

// Streaming
ZagBuilder().provider("claude").stream("analyze code").collect { event ->
    println(event.type)
}

Examples

The examples/ directory contains complete projects demonstrating zag usage:

• cv-review — A Rust program that uses the zag library crate to review CVs against job descriptions using parallel agent invocations
• orchestration — Shell scripts demonstrating multi-agent patterns: sequential pipelines, fan-out/gather, generator-critic loops, coordinator dispatch, and more
• react-claude-interface — A React web app that provides a Claude Code-like chat interface powered by zag exec and zag input with streaming NDJSON events over Server-Sent Events

See the examples directory for details on each.

Troubleshooting

"CLI not found in PATH" — The agent CLI binary isn't installed or isn't in your PATH. Install it using the commands in the Agent CLIs table above.

"Invalid model 'X' for Y" — You specified a model name that the provider doesn't recognize. Use zag capability -p <provider> --pretty to see available models, or use size aliases (small, medium, large).

--worktree fails — You must be inside a git repository. The worktree is created under ~/.zag/worktrees/.

--sandbox fails — Docker must be installed and running. Sandbox mode uses docker sandbox run for microVM isolation.

Config not taking effect — Check which config file is being used with zag config path. Config is per-project (based on git repo root). CLI flags always override config.

Documentation

• Getting Started — Step-by-step tutorial for new users
• Providers — Feature comparison, model recommendations
• Configuration — Complete config reference
• Events & Logging — NDJSON event format reference
• Troubleshooting — Common issues and solutions
• Contributing — Development workflow and guidelines
• zag man <command> — Built-in manual pages for every command

Architecture

zag (binary crate)
  CLI parsing (clap) → dispatch to zag-agent and zag-orch
  Session logs, worktree/sandbox lifecycle, JSON mode, auto-selection

zag-agent (library crate)
  Agent trait, provider implementations, AgentBuilder API
  Config, output types, session logs, skills, process helpers

zag-orch (orchestration crate)
  spawn, wait, collect, pipe, cancel, status, events
  watch, subscribe, summary, retry, gc, and more

Each provider implementation spawns the respective CLI tool as a subprocess. The Agent trait defines the common interface (run, resume, cleanup, model resolution). AgentOutput normalizes output from all providers into a unified event stream.

Development

make build          # Dev build
make test           # Run tests
make clippy         # Lint (zero warnings)
make fmt            # Format
make release        # Release build

License

MIT