Lightweight, agent-native sandboxing with diff · commit · abort.

Give agents a confined workspace with explicit diff, commit, and abort semantics.

deltabox-lite is a standalone sandbox runtime for AI coding agents. Agents keep full execution freedom inside a confined filesystem view, and every change they make can be reviewed, committed, or aborted - per task or per tool call. Linux defaults to a commit-biased FUSE view; macOS uses native APFS clones and FSEvents; Windows uses a WinFsp view. Private modes keep changes hidden from the host until commit.

Think of it as Git for agent sessions: less ceremony, more control, and no anxiety about binary or large files.

📰 News

• [2026/10/21] Release v0.1.4: Windows x64 available now. With WinFsp, and MXC network policy enforcement. Companion DSH 0.1.4 and Pi 0.1.3 add Windows installation and PowerShell integration.

• [2026/10/19] Added Windows WinFsp support with strict durability for private sessions, plus execution-scoped network approvals (PR #33, PR #35).

• [2026/10/16] Open-sourced DeltaBox Lite and published the introduction “DeltaBox Lite: A Lightweight File Sandbox for Terminal AI Agents.”

• [2026/10/14] Released v0.1.0 and v0.1.1, updated DSH / Pi integrations, and fixed read-write execution in macOS sessions.

• [2026/09] Expanded the Native Node API and execution profiles; added npm, Homebrew, an install script, and a multi-platform prebuilt release pipeline.

• [2026/08] Built Linux / macOS file sandboxing, the CB-CoW state engine, and the diff / commit / abort workflow; added DSH / Pi integrations and concurrent private sessions for multiple agents.

Demo

Run a command, inspect its change set, and choose whether to keep or discard it:

Highlights

• Native isolation, not a container - Linux composes Sandlock/Landlock/ seccomp with DeltaFS FUSE; macOS uses Seatbelt plus APFS clones and FSEvents; Windows uses MXC process security with WinFsp filesystem routing.
• Service-free durable sessions - Linux starts a session-scoped filesystem helper and macOS starts a session-scoped event helper automatically. Durable files remain authoritative across independent CLI processes; no global daemon or manual service startup is required.
• Three filesystem modes - cbcow-through makes changes visible immediately and makes commit an O(1) acceptance operation. cbcow-private runs the same DeltaFS engine over a private reflink/copy tree and publishes only touched paths at commit. copy-private remains the compatibility fallback.
• Diff / commit / abort - unified text diffs, binary and large-file markers, and a linear checkpoint chain. Abort restores the selected checkpoint; commit accepts the current state.
• Review-scope savepoints — task and tool adapters choose the correct abort target; normal commit and abort do not require a user-created checkpoint.
• Agent adapters — optional JSON-RPC over stdio for Pi and other integrations; see the adapter protocol.
• Policy-first — filesystem read/write rules, secret-path denial, network allow/audit, deny-all and allowlist modes, scrubbed child environments, and bounded writes/storage.

Install

Let AI agents install

Copy this prompt into an AI coding agent with terminal access:

Install DeltaBox Lite by following the instructions at
https://raw.githubusercontent.com/delta-box/deltabox-lite/main/install-prompt.txt
Detect my environment, install the appropriate runtime and any DSH or Pi
integration I use, and verify the installation with the disposable smoke test.

The plain-text installation prompt covers environment checks, integration setup, and verification. You can also paste its contents directly into your agent.

Manual Install

Run the following on macOS or Linux to install the deltabox-lite CLI:

curl -fsSL https://raw.githubusercontent.com/delta-box/deltabox-lite/main/scripts/install.sh | sh

The prebuilt binaries ship for macOS (arm64, x64), Linux (x64, arm64), and Windows (x64). They can be found on the GitHub release.

On Windows, install WinFsp first, then use PowerShell:

npm install --global deltabox-lite
deltabox --version

Windows deltabox commands run directly from PowerShell. Pi's bash tool uses Pi's own shell selection, which defaults to Git Bash on Windows. The CLI does not require Git Bash. Sandboxed command execution needs Windows MXC process security support; if it is unavailable, session startup reports an error.

deltabox-lite CLI can also be installed via the following package managers:

# Install using npm
npm install --global deltabox-lite

# Install using Homebrew
brew install delta-box/tap/deltabox

Build from source

cargo build --release
export PATH="$PWD/target/release:$PATH"

Plugin

DSH (DeepSeek Harness)

With DeepSeek Harness installed, add the plugin to your Web profile:

dsh plugin --profile web add dsh-deltabox

For Desktop, open Plugins → Add plugin, enter dsh-deltabox, and install it. Alternatively, use Desktop's bundled CLI:

dsh plugin --profile desktop add dsh-deltabox

DSH plugin guide for configuration and review controls.

Pi

Install Pi if needed, then add the extension:

npm install --global @earendil-works/pi-coding-agent
pi install npm:pi-deltabox

Start a new Pi session in your project and run /sandbox-status to verify that the extension is active. Use /sandbox-review, /sandbox-commit, and /sandbox-abort to review, keep, or discard changes. See the Pi extension guide for configuration, including explicit command isolation settings.

Both integrations use FUSE on Linux for CB-CoW (/dev/fuse and fusermount3 or fusermount), APFS/FSEvents on macOS, and WinFsp on Windows.

Quick start

For a first transaction, create a project with one ordinary file and discard a command's changes. No package manifest or policy file is needed:

demo=$(mktemp -d)
cd "$demo"
printf 'original\n' > notes.txt

deltabox run --abort -- sh -c '
  printf "sandboxed\n" >> notes.txt
  printf "generated\n" > generated.txt
  find . -maxdepth 1 -type f -print
'

cat notes.txt
test ! -e generated.txt

The command runs inside the sandbox view, prints the diff, and then aborts. The original notes.txt remains unchanged and generated.txt is removed.

To keep a result, use the same one-command interface with --commit:

deltabox run --commit -- sh -c 'printf "accepted by deltabox\n" > accepted.txt'
cat accepted.txt

run creates and cleans up a temporary transaction. Scripts and agent integrations should select --commit or --abort explicitly; the child exit status is preserved after that decision.

For multiple independent commands, start a persistent session. Commands run from the project directory can omit --project; use it only when invoking Deltabox from another directory:

cd /abs/path/my-project
session_id=$(deltabox session start .)
deltabox exec "$session_id" -- sh -c 'printf "step one\n" > step-one.txt'
deltabox exec "$session_id" -- sh -c 'printf "step two\n" > step-two.txt'
deltabox diff "$session_id"
deltabox commit "$session_id"
deltabox session stop "$session_id"

Session records live in <project>/.deltabox by default, so each project stays self-contained. Set DELTABOX_STATE_DIR=/path/to/state to relocate session records and engine state to an arbitrary path instead.

Shell command syntax

deltabox exec and deltabox run execute the argv after -- directly. Commands that do not require shell parsing can be passed as ordinary arguments:

deltabox exec "$session_id" -- git status --short
deltabox exec "$session_id" -- curl -fL -o source.tar.gz https://example.com/source.tar.gz

Redirection, pipes, variable expansion, globbing, and command lists require an explicit shell. Keep the complete script inside quotes so the outer host shell cannot perform the filesystem operation before Deltabox starts:

deltabox exec "$session_id" -- sh -c 'printf "%s\n" hello > hello.txt'
deltabox run --abort -- sh -c 'printf "%s\n" trial > trial.txt'
deltabox exec "$session_id" -- sh -c 'find . -type f | sort > files.txt'
deltabox exec "$session_id" -- sh -c 'command-that-may-be-quiet >/dev/null 2>&1'

This form is wrong because the host shell handles > and creates hello.txt outside the sandbox transaction:

deltabox exec "$session_id" -- echo hello > hello.txt

Quoting the whole command without sh -c is also wrong: Deltabox would treat the complete string as an executable filename. Sandboxed commands do not receive a terminal on stdin, so use non-interactive flags for tools such as Git.

Choosing a filesystem mode

Linux and macOS request cbcow-through by default and visibly fall back to copy-private if the native provider is unavailable. Windows supports cbcow-through and cbcow-private with WinFsp. Select the mode explicitly when a workflow requires it:

deltabox session start /abs/path/my-project --fs-mode copy-private
deltabox session start /abs/path/my-project --fs-mode cbcow-private --require-fs-mode
deltabox session start /abs/path/my-project --fs-mode cbcow-through --require-fs-mode
deltabox session start /abs/path/my-project --fs-mode cbcow-through --durable
deltabox session start /abs/path/my-project --fs-mode cbcow-through --durable --group-commit-ms 2

Fast mode is the default and recovers helper/process failures. --durable adds ordered storage barriers; success from commit means changed files, affected directories, and the acceptance marker are synchronized. --group-commit-ms lets concurrent mutations share an APPLIED journal barrier while preserving that per-operation success boundary. Strict mode requires cbcow-through or cbcow-private; startup fails instead of falling back to copy-private when the requested provider is unavailable. On macOS, fast cbcow-through also assumes Deltabox is the exclusive project writer. Fast exec defers FSEvents accounting to the next state operation; strict mode closes a sentinel boundary before each result, detects external writes, and refuses an unsafe abort. Use cbcow-private when host isolation is required before commit.

How it works

flowchart LR
    A[CLI or agent adapter] --> C[Session coordinator]
    C --> X[Lazy session command helper]
    X --> Y[Short-lived confined child]
    C --> T[Linux cbcow-through]
    T --> H[Session-scoped DeltaFS helper]
    H --> P[(Host-visible LIVE tree)]
    C --> V[Linux cbcow-private]
    V --> F[Session-scoped DeltaFS helper]
    F --> L[(Private LIVE tree)]
    L -->|touched-path commit| P
    C --> M[macOS native APFS plus FSEvents]
    M --> E[Session-scoped event helper]
    E --> P
    E --> L
    C --> R[copy-private fallback]
    R --> S[(Private working tree)]
    S -->|commit| P

On Linux with FUSE available, session start launches a helper that mounts the host project through the commit-biased state engine. Writes update the host tree through DeltaFS after recording rollback data; commit accepts the current state and abort replays undo records. cbcow-private preserves the same fast per-command path while keeping its LIVE tree hidden from the host until a conflict-checked commit. In copy-private, each command updates a durable private working tree and commit publishes it to the project. On macOS, the same modes use APFS-cloned state and a restartable FSEvents helper instead of a mount. The helper only keeps the event stream warm; persisted cursors and indexes remain authoritative. The first CB-CoW exec also launches a restartable command helper. Later CLI operations reuse its warm Sandlock worker on Linux or Seatbelt profile/proxy on macOS without making that helper authoritative session state. Durable files, not a long-running process, remain the source of session truth. See session semantics.

Policy

session start --policy policy.toml accepts filesystem, network, and resource limits. The default agent policy uses the allow_audit network mode, denies common secret paths, passes only a small environment allowlist to commands, caps one direct write at 16 MiB, and caps pending added/modified file content at 1 GiB. Network policy can instead deny all access or allow only explicit host-and-port targets:

[network]
mode = "allowlist"
allow = ["registry.npmjs.org:443", "127.0.0.1:3000"]

[limits]
max_write_bytes = 16777216
max_storage_bytes = 1073741824

See policy reference for the full schema and enforcement semantics, and macOS compatibility for path mapping and tool support.

The policy is the session's standing breadth. A single command can request a wider execution profile — workspace-write (default) or read-write — so a session.exec call can reach the host filesystem without changing the session:

deltabox exec "$SESSION" --project /abs/path/my-project \
  --execution-profile read-write -- sh -c 'sudo apt-get install -y ripgrep'

Workspace changes stay visible to diff, commit, and abort under either profile. Linux FUSE and private-workspace modes deny direct access to the backing project; macOS cbcow-through writes the real project and tracks those changes with APFS/FSEvents. Engine state and helper endpoints stay denied in both cases. Host writes outside the workspace cannot be rolled back.

Performance

Measured on x86-server (Linux 6.18, ext4, release build). Each row reports 50 no-op commands after five warmups. Deltabox uses independent CLI processes over one cbcow-through session.

The no-op path does not scan or copy the project per command. Empty DeltaFS checkpoint and commit operations remain below 1 ms in the scaling benchmark.

The delta-driven path can outperform repeated Sandlock copy-up work when a workload makes many small changes.

Raw Sandlock has no durable cross-command session, so the second row commits each one-shot command independently.

On macOS, the native provider materializes its APFS accepted base once at session start. Fast commands do not clone or scan the project per invocation; status, diff, checkpoint, commit, and abort close the FSEvents reconciliation boundary. Private mode additionally materializes a private APFS LIVE tree and therefore trades more startup and command-path work for pre-commit host isolation.

Project layout

• crates/deltabox-core — sessions, checkpoints, diff/commit/abort, policy, journal, platform backends.
• crates/deltabox-cli — the deltabox command-line binary.
• crates/deltabox-node - the deltabox Node-API bindings.
• deltafs-fuse — the standalone commit-biased state engine, FUSE adapter, helper, and local control protocol.
• plugin - dsh and pi plugin
• npm - npm package
• docs/policy.md — policy schema and enforcement boundaries.
• docs/macos.md — macOS backend behavior and compatibility matrix.

Citation

If you find deltabox-lite useful, please cite the original paper of DeltaBox (which is based on microVM) or this github repo:

@misc{dong2026deltaboxscalingstatefulai,
      title={DeltaBox: Scaling Stateful AI Agents with Millisecond-Level Sandbox Checkpoint/Rollback}, 
      author={Yunpeng Dong and Jingkai He and Shiqi Liu and Yuze Hou and Dong Du and Zhonghu Xu and Si Yu and Baochuan Yang and Yubin Xia and Haibo Chen},
      year={2026},
      eprint={2605.22781},
      archivePrefix={arXiv},
      primaryClass={cs.OS},
      url={https://arxiv.org/abs/2605.22781}, 
}

License

Apache-2.0.

Acknowledgments

This project utilizes excellent work of existing sandbox projects like sandlock.

⭐ Star this repo if you find deltabox-lite helpful!