---
title: "Daemon"
description: "Background daemon lifecycle, auto-upgrade, and management."
icon: "microchip"
---

The sandbox-agent daemon is a background server process that stays running between sessions. Commands like `sandbox-agent opencode` and `gigacode` automatically start it when needed and restart it when the binary is updated.

## How it works

1. When you run `sandbox-agent opencode`, `sandbox-agent daemon start`, or `gigacode`, the CLI checks if a daemon is already healthy at the configured host and port.
2. If no daemon is running, one is spawned in the background with stdout/stderr redirected to a log file.
3. The CLI writes a PID file and a build ID file to track the running process and its version.
4. On subsequent invocations, if the daemon is still running but was built from a different commit, the CLI automatically stops the old daemon and starts a new one.

## Auto-upgrade

Each build of sandbox-agent embeds a unique **build ID** (the git short hash, or a version-timestamp fallback). When a daemon is started, this build ID is written to a version file alongside the PID file.

On every invocation of `ensure_running` (called by `opencode`, `gigacode`, and `daemon start`), the CLI compares the stored build ID against the current binary's build ID. If they differ, the running daemon is stopped and replaced automatically:

```
daemon outdated (build a1b2c3d -> f4e5d6c), restarting...
```

This means installing a new version of sandbox-agent and running any daemon-aware command is enough to upgrade — no manual restart needed.

## Managing the daemon

### Start

Start a daemon in the background. If one is already running and healthy, this is a no-op.

```bash
sandbox-agent daemon start [OPTIONS]
```

| Option | Default | Description |
|--------|---------|-------------|
| `-H, --host <HOST>` | `127.0.0.1` | Host to bind to |
| `-p, --port <PORT>` | `2468` | Port to bind to |
| `-t, --token <TOKEN>` | - | Authentication token |
| `-n, --no-token` | - | Disable authentication |

```bash
sandbox-agent daemon start --no-token
```

### Stop

Stop a running daemon. Sends SIGTERM and waits up to 5 seconds for a graceful shutdown before falling back to SIGKILL.

```bash
sandbox-agent daemon stop [OPTIONS]
```

| Option | Default | Description |
|--------|---------|-------------|
| `-H, --host <HOST>` | `127.0.0.1` | Host of the daemon |
| `-p, --port <PORT>` | `2468` | Port of the daemon |

```bash
sandbox-agent daemon stop
```

### Status

Show whether the daemon is running, its PID, build ID, and log path.

```bash
sandbox-agent daemon status [OPTIONS]
```

| Option | Default | Description |
|--------|---------|-------------|
| `-H, --host <HOST>` | `127.0.0.1` | Host of the daemon |
| `-p, --port <PORT>` | `2468` | Port of the daemon |

```bash
sandbox-agent daemon status
# Daemon running (PID 12345, build a1b2c3d, logs: ~/.local/share/sandbox-agent/daemon/daemon-127-0-0-1-2468.log)
```

If the daemon was started with an older binary, the status includes an `[outdated, restart recommended]` notice.

## Files

All daemon state files live under the sandbox-agent data directory (typically `~/.local/share/sandbox-agent/daemon/`):

| File | Purpose |
|------|---------|
| `daemon-{host}-{port}.pid` | PID of the running daemon process |
| `daemon-{host}-{port}.version` | Build ID of the running daemon |
| `daemon-{host}-{port}.log` | Daemon stdout/stderr log output |

Multiple daemons can run on different host/port combinations without conflicting.
