Sandbox backends

Backend overview

Backend	Value	Platform	Description
Native	native	macOS, Linux	OS-native sandbox (default)
None	none	all	No isolation (development only)

Native backend

macOS: Seatbelt

Uses Apple’s Seatbelt sandbox mechanism (the same system used by macOS App Sandbox).

• Filesystem: restricts read/write to bound mount paths only
• Network: configurable egress policy (full, restricted, none)
• Process: limits process spawning within the sandbox
• Configuration: profiles are generated per-launch from the SandboxSpec

Requirements:

• macOS 12+ (Monterey)
• System Integrity Protection enabled

Linux: bubblewrap

Uses bubblewrap (bwrap) to create mount and PID namespaces.

• Filesystem: creates a mount namespace with only the bound paths visible
• Network: shares the network namespace by default; can restrict with capabilities
• Process: PID namespace isolation

Requirements:

• bubblewrap package installed (sudo apt install bubblewrap on Debian/Ubuntu)
• Kernel namespace support (standard on modern Linux)

None backend

Disables all sandboxing. The agent CLI runs directly on the host with full access.

Use only for:

• Development and debugging
• Trusted environments
• When sandboxing is incompatible with your workflow

Warning: agents running without sandboxing have unrestricted access to your filesystem, network, and processes.

SandboxSpec

The specification passed to SandboxPort.launch:

Field	Type	Description
sessionId	String	Unique session identifier
workspaceId	String	Owning workspace
agentId	String	The agent being sandboxed
mounts	List<SandboxBindMount>	Host-to-guest bind mounts
networkEgress	bool	Whether network access is allowed
workdir	String	Working directory inside the sandbox
mode	Mode	Affects filesystem write policy

SandboxBindMount

Field	Type	Description
hostPath	String	Path on the host
guestPath	String	Path inside the sandbox
writable	bool	Whether the mount is read-write

SandboxHandle

Returned by SandboxPort.launch:

Field	Type	Description
sessionId	String	Session identifier
backend	SandboxBackend	Which backend is running
state	SandboxState	Lifecycle state
error	String?	Error message if failed

SandboxState

State	Description
starting	Sandbox is being created
running	Sandbox is active
stopped	Sandbox has been torn down
failed	Sandbox failed to start

Sandbox events

Event type	Description
stdout	Standard output from the sandbox
stderr	Standard error from the sandbox
exit	Sandbox process exited
violation	A sandbox policy was violated

SandboxViolation

Field	Type	Description
action	String	The denied action (e.g. “network”, “file-write”)
target	String	The target of the denied action
suggestedCapability	String?	The capability that would allow this action