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fased sandbox

Manage Docker-based sandbox containers for isolated agent execution and inspect the effective sandbox policy that the runtime is actually applying.

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Overview

Fased can run agents in isolated Docker containers for security. The sandbox commands help you manage these containers, especially after updates or configuration changes.

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Commands

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fased sandbox explain

Inspect the effective sandbox mode/scope/workspace access, sandbox tool policy, and elevated gates (with fix-it config key paths). 
fased sandbox explain
fased sandbox explain --session agent:main:main
fased sandbox explain --agent work
fased sandbox explain --json

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fased sandbox list

List all sandbox containers with their status and configuration. 
fased sandbox list
fased sandbox list --browser  # List only browser containers
fased sandbox list --json     # JSON output
Output includes:
  • Container name and status (running/stopped)
  • Docker image and whether it matches config
  • Age (time since creation)
  • Idle time (time since last use)
  • Associated session/agent

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fased sandbox recreate

Remove sandbox containers to force recreation with updated images/config. 
fased sandbox recreate --all                # Recreate all containers
fased sandbox recreate --session main       # Specific session
fased sandbox recreate --agent mybot        # Specific agent
fased sandbox recreate --browser --all      # Only browser containers
fased sandbox recreate --all --force        # Skip confirmation
Options:
  • --all: Recreate all sandbox containers
  • --session <key>: Recreate container for specific session
  • --agent <id>: Recreate containers for specific agent
  • --browser: Only recreate browser containers
  • --force: Skip confirmation prompt
Important: Containers are automatically recreated when the agent is next used.

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Use Cases

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After updating Docker images

# Pull new image
docker pull fased-sandbox:latest
docker tag fased-sandbox:latest fased-sandbox:bookworm-slim

# Update config to use new image
# Edit config: agents.defaults.sandbox.docker.image (or agents.list[].sandbox.docker.image)

# Recreate containers
fased sandbox recreate --all

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After changing sandbox configuration

# Edit config: agents.defaults.sandbox.* (or agents.list[].sandbox.*)

# Recreate to apply new config
fased sandbox recreate --all

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After changing setupCommand

fased sandbox recreate --all
# or just one agent:
fased sandbox recreate --agent family

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For a specific agent only

# Update only one agent's containers
fased sandbox recreate --agent alfred

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Why is this needed?

Problem: When you update sandbox Docker images or configuration:
  • Existing containers continue running with old settings
  • Containers are only pruned after 24h of inactivity
  • Regularly-used agents keep old containers running indefinitely
Solution: Use fased sandbox recreate to force removal of old containers. They’ll be recreated automatically with current settings when next needed. Tip: prefer fased sandbox recreate over manual docker rm. It uses the Gateway’s container naming and avoids mismatches when scope/session keys change.

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Configuration

Sandbox settings live in ~/.fased/fased.json under agents.defaults.sandbox (per-agent overrides go in agents.list[].sandbox): 
{
  "agents": {
    "defaults": {
      "sandbox": {
        "mode": "all", // off, non-main, all
        "scope": "agent", // session, agent, shared
        "docker": {
          "image": "fased-sandbox:bookworm-slim",
          "containerPrefix": "fased-sbx-",
          // ... more Docker options
        },
        "prune": {
          "idleHours": 24, // Auto-prune after 24h idle
          "maxAgeDays": 7, // Auto-prune after 7 days
        },
      },
    },
  },
}

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See Also