v0.42.0

Highlights

• Cloud sandboxes. Docker Sandboxes 0.42.0 introduces sbx --cloud for running AI agents on Docker-managed cloud infrastructure. Use the sbx CLI to create and manage hosted sandboxes alongside your local sandboxes.

  Cloud sandboxes have separate resources, credentials, and network policies from local sandboxes. Cloud compute requires an active Docker Agentic Platform plan and is billed based on usage. Model inference is billed separately by your model provider.

• BREAKING: sbx ports --publish and kit-declared ports now default to tcp4 instead of dual-stack tcp, so a published port no longer listens on ::1 unless you name the protocol explicitly (--publish 8080:3000/tcp); this makes http://localhost:<port>/ reach a sandbox service that listens only on IPv4.

• sbx run and sbx create now accept sandbox kit references as the agent positional: sbx run <sandbox-kit-ref>. The old form sbx run <sandbox-kit-name> --kit <sandbox-kit-ref> is deprecated; use the --kit flag for mixins.

• Sandboxes can now be created without a workspace bind mount by omitting the path in sbx create. Note that this only affects the create command; sbx run still defaults to mounting the current directory as the primary workspace.

What's New

Cloud sandboxes

• Run agents in the cloud with commands such as sbx --cloud run claude --name cloud-project.
• Transfer files with sbx --cloud cp, publish services through public HTTPS URLs, and connect using SSH.
• Configure cloud-specific credentials and outbound network policy with sbx --cloud secret and sbx --cloud policy.
• Use sbx move to copy a sandbox filesystem between local and cloud environments.

CLI

• Read-only sbx commands including secret ls, version, mcp ls, skills ls, policy inspect and the kit verification commands now accept --json for machine-readable output.
• Clipboard commands inside local sandboxes can now copy text to the host clipboard.
• Add, update, list, and remove sandbox skills directly from Git repositories with sbx skills.

Environment files

• sbx env now reads a non-hidden sbxenv.yaml in preference to .sbxenv.yaml when a directory holds both, and merges an sbxenv.yaml from your home directory beneath the project file as defaults shared across projects.
• sbx env now shows a plan of everything an environment file changes on the host — host lifecycle: commands, credentials, bindings, MCP servers, workspaces, kits, ports and the sandbox itself — asks before applying it and asks again for every run of a command on this machine unless env.rememberHostCommands is set, binds the environment file read-only into the sandbox it describes, and reads a directory for sbxenv.yaml alone with ~/.sbxenv.yaml as the user-level base beneath it.
• sbx env: an environment file that declares no workspace: now creates a sandbox with no workspace bind mount instead of mounting the directory holding the file; write workspace: . to mount the project directory.
• Environment files can now declare their own arguments in an args: block, referenced as ${{ env.args.NAME }} and supplied with sbx env --env-arg; ${VAR} interpolation in .sbxenv.yaml is no longer expanded.
• Relative kit paths in an environment file now resolve against the file's directory instead of the directory sbx was run from.
• sbx env create now shares imported skills by default and accepts display, GPU, and USB options in sbxenv.yaml.

Daemon

• Sandboxes now get a 10 GB Docker volume instead of 50 GB, which significantly reduces host disk usage; set DOCKER_SANDBOXES_DOCKER_SIZE to change it.

Agents

• Added Devin as a built-in agent.

Kits

• Kits can now declare their arguments in an args: block and receive values with --kit-arg name=value, or --kit-arg kit.name=value to target a single kit.
• A kits: entry in sbxenv.yaml carries the arguments for that kit under kits[].args.

Bug fixes

• Docker Sandboxes no longer opens the setup wizard automatically; run sbx setup to launch it explicitly.
• Fixed a vulnerability where a sandboxed process could get the daemon to open a host D-Bus transport and execute an arbitrary command on the host.
• On macOS, sbx now accepts a workspace path whose casing differs from the spelling on disk instead of failing to create the sandbox.
• Fixed a rare case where a spotty network right after your computer woke
  from sleep could cause an unexpected Docker Hub sign-out.
• Agent crashes now identify the terminating signal and provide scoped recovery guidance.
• Fixed a vulnerability where a malicious sandbox could hijack another sandbox's OAuth login by pre-claiming its callback port.
• Removing or pruning a local sandbox now also deletes its sandbox-scoped secrets.
• sbx secret ls no longer prints a stored secret unmasked when its value happens to match one of the status labels the listing displays.
• sbx now warns when a stored credential is not sent to a sandbox because no binding authorizes it, instead of starting the sandbox and failing later with an authentication error.
• Fixed several MCP-related bugs.
• Standardized error message formatting for sbx rm, sbx stop, MCP authorization, and sbx reset.
• Sandbox and agent not-found errors now use one sentence pattern and quote style across commands: sandbox '' not found.
• Docker Hub template pulls created through the TUI now use your Docker Sandboxes login credentials.
• sbx ports --publish now automatically starts stopped local sandboxes before publishing ports.
• Docker volume sizes below 512 MiB are now rejected before sandbox creation.
• Creating a sandbox from a Docker Hardened Image template no longer results in a delay.
• Fixed OAuth authentication for custom agent kits that declare resource hosts without a fallback API key.
• Kits can now set a sandbox's CPU and memory limits through the sandbox.resources block in their spec.
• Fixed SSH connections from editors by keeping non-interactive probes quiet and delivering their exit status before closing the channel.
• Deleting a sandbox now reliably reclaims its disk volumes, and creating a new sandbox that reuses a deleted sandbox's name no longer inherits its files, Docker images, or agent session history.
• Running sbx setup explicitly no longer causes the setup screen to appear again on the next interactive command.
• Fixed sandbox connections to a server that sends data first — including passive FTP transfers and a serial console relayed to the host — failing with a timeout instead of receiving the server's output.
• sbx kit push no longer uploads an empty payload layer for kits that ship no files.
• sbx kit push now authenticates from the sbx credential store, so a single sbx login or docker login is enough for pushing, signing, and attaching provenance.
• Kits using extends: now inherit the parent's setup commands, credentials, network allowlist, volumes, and environment variables instead of replacing them when the child declares its own.
• Fixed Docker Hub credential refresh retrying without backoff after a rate limit, and a non-interactive login discarding the stored OAuth refresh token.
• Nightly Homebrew installs no longer fail with checksum mismatches while a nightly publish is in flight: the sbx@nightly cask now downloads from immutable per-build release URLs.

Other

• Docker Sandboxes now provides a machine-wide Windows MSI for administrator-managed installations.
• A declined @requireApproval prompt on a local MCP server now gets its own audit record, with policy attribution and a context digest, instead of leaving the original approval-required decision as the only trace of the exchange.
• A registry mirror configured with platform.images.registryMirror is now also used by Docker running inside a sandbox, when the value is a bare host (no path prefix) that is not a loopback or wildcard address.
• sbx version --json now reports a server.state of running or unavailable, so scripts can check whether the backend was reachable without parsing the error text.
• SSH agent forwarding can be explicitly disabled and use either each client's current agent socket or a fixed socket path.
• sbx terminal output now adapts colors for light terminal backgrounds and
  uses a distinct pink spinner glyph; CJK and combining-mark column widths in
  table output are now measured correctly; piped and JSON output is unchanged
  for ASCII-only content.
• sbx mcp add now accepts --skip-auth (the old --skip_auth still works), and a --url on a private, loopback, or cloud-metadata address is resolved and registered with a warning instead of being rejected.
• On Linux hosts without an available OS keychain, newly stored secrets are now read and written much faster; secrets already on disk keep their previous cost until they are next written.
• Fixed a gateway defect where a remote MCP server's reconnect could silently wipe its tool routing, causing the server's tools to disappear from agents and be denied by organization MCP policy as unrecognized built-in tools until the daemon was restarted.
• Docker Sandboxes can now upload a diagnostics bundle automatically when the daemon hits an error, after you opt in.
• Governance resolution issues are now shown in sbx policy output and the dashboard.
• sbx mcp auth now requests only the scopes you chose (or the set the resource itself requires, suppressible with the new --no-scope flag) instead of every scope a server advertises, explains which scopes a server refused along with a narrower retry command, and reports the scope sets of an existing grant in sbx mcp auth status: what was granted, what was requested, and what the server supports — with scopes sorted, duplicates collapsed, and differences such as unrequested or no-longer-advertised grants called out.
• Sandbox listing and creation output now share one rendering package; on a terminal, sbx ls column headers are now styled bold.
• Sandbox agent instruction files no longer include generic language-specific development guidance.
• The sandboxd runtime state directory left behind by versions before v0.25.0 is now migrated to its current name instead of being used in place.