---
title: Snapshots
description: Go SDK - Snapshot API reference
---

Create and manage disk-only snapshots of stopped sandboxes. See [Snapshots](/sandboxes/snapshots) for usage and lifecycle concepts.

## Snapshot

Package-level helpers for snapshot artifacts. Access them through the exported `Snapshot` value, e.g. `m.Snapshot.Create(ctx, ...)`.

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Create()</span>

```go
func (snapshotFactory) Create(ctx context.Context, opts SnapshotCreateOptions) (*SnapshotArtifact, error)
```

Create a snapshot from a stopped or crashed sandbox. [`SnapshotCreateOptions.Name`](#snapshotcreateoptionsstruct) (resolved under the default snapshots directory) and [`SnapshotCreateOptions.FromSandbox`](#snapshotcreateoptionsstruct) (the sandbox to capture) are both required.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>opts</code><a className="msb-type" href="#snapshotcreateoptionsstruct">SnapshotCreateOptions</a></div>
    <div className="msb-param-desc">Name, source sandbox, labels, and integrity options.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotartifactstruct">*SnapshotArtifact</a></div>
    <div className="msb-param-desc">The created artifact on disk.</div>
  </div>
</div>

<Accordion title="Example">

```go
snap, err := m.Snapshot.Create(ctx, m.SnapshotCreateOptions{
    Name:            "after-pip-install",
    FromSandbox:     "baseline",
    Labels:          map[string]string{"stage": "post-deps"},
    RecordIntegrity: true,
})
```

</Accordion>

---

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Open()</span>

```go
func (snapshotFactory) Open(ctx context.Context, pathOrName string) (*SnapshotArtifact, error)
```

<Accordion title="Example">

```go
snap, err := m.Snapshot.Open(ctx, "after-pip-install")
```

</Accordion>

Open an existing artifact by bare name or filesystem path. This validates metadata only; call [`s.Verify()`](#s-verify) for content checks.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>pathOrName</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Bare name (resolved under the default snapshots directory) or artifact directory path.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotartifactstruct">*SnapshotArtifact</a></div>
    <div className="msb-param-desc">The artifact on disk.</div>
  </div>
</div>

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Get()</span>

```go
func (snapshotFactory) Get(ctx context.Context, nameOrDigest string) (*SnapshotHandle, error)
```

<Accordion title="Example">

```go
h, err := m.Snapshot.Get(ctx, "after-pip-install")
```

</Accordion>

Look up a lightweight handle in the local index by name, digest, or path.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>nameOrDigest</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Bare name, manifest digest, or artifact path.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshothandlestruct">*SnapshotHandle</a></div>
    <div className="msb-param-desc">Index-backed handle.</div>
  </div>
</div>

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">List()</span>

```go
func (snapshotFactory) List(ctx context.Context) ([]*SnapshotHandle, error)
```

<Accordion title="Example">

```go
handles, err := m.Snapshot.List(ctx)
for _, h := range handles {
    fmt.Println(h.Digest(), h.ImageRef())
}
```

</Accordion>

List indexed snapshots from the local DB cache.

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshothandlestruct">[]*SnapshotHandle</a></div>
    <div className="msb-param-desc">All indexed handles.</div>
  </div>
</div>

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">ListDir()</span>

```go
func (snapshotFactory) ListDir(ctx context.Context, dir string) ([]*SnapshotArtifact, error)
```

Walk a directory and parse each subdirectory's manifest without touching the index.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>dir</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Directory holding snapshot artifact subdirectories.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotartifactstruct">[]*SnapshotArtifact</a></div>
    <div className="msb-param-desc">One artifact per parsed subdirectory.</div>
  </div>
</div>

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Remove()</span>

```go
func (snapshotFactory) Remove(ctx context.Context, pathOrName string, force bool) error
```

<Accordion title="Example">

```go
err := m.Snapshot.Remove(ctx, "after-pip-install", false)
```

</Accordion>

Remove a snapshot artifact and its index row. Refuses to delete a snapshot with indexed children unless `force` is true.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>pathOrName</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Bare name or artifact path.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>force</code><span className="msb-type">bool</span></div>
    <div className="msb-param-desc">Delete even if the snapshot has indexed children.</div>
  </div>
</div>

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Reindex()</span>

```go
func (snapshotFactory) Reindex(ctx context.Context, dir string) (uint32, error)
```

<Accordion title="Example">

```go
n, err := m.Snapshot.Reindex(ctx, "/srv/snapshots")
fmt.Printf("indexed %d snapshots\n", n)
```

</Accordion>

Walk `dir` and rebuild the local index from the artifacts it finds.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>dir</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Directory to scan for snapshot artifacts.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><span className="msb-type">uint32</span></div>
    <div className="msb-param-desc">Number of artifacts indexed.</div>
  </div>
</div>

---

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Save()</span>
<div className="msb-tags"><span className="msb-tag is-static">function</span></div>

```go
func (snapshotFactory) Save(ctx context.Context, nameOrPath, outPath string, opts SnapshotSaveOptions) error
```

Bundle a snapshot into a `.tar.zst` archive at `outPath`. Set [`SnapshotSaveOptions.PlainTar`](#snapshotsaveoptionsstruct) to skip compression.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>nameOrPath</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Bare name or artifact path to save.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>outPath</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Destination archive path.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>opts</code><a className="msb-type" href="#snapshotsaveoptionsstruct">SnapshotSaveOptions</a></div>
    <div className="msb-param-desc">Whether to include parents, the base image, and compression.</div>
  </div>
</div>

<Accordion title="Example">

```go
err := m.Snapshot.Save(ctx, "after-pip-install", "/tmp/snap.tar.zst",
    m.SnapshotSaveOptions{WithParents: true},
)
```

</Accordion>

---

#### <span className="msb-recv">Snapshot.</span><span className="msb-hn">Load()</span>
<div className="msb-tags"><span className="msb-tag is-static">function</span></div>

```go
func (snapshotFactory) Load(ctx context.Context, archive, dest string) (*SnapshotHandle, error)
```

Unpack a snapshot archive into the snapshots directory or an explicit `dest` directory. Pass `""` for the default destination.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>archive</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Path to the snapshot archive.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>dest</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Destination directory, or <code>""</code> for the default snapshots directory.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshothandlestruct">*SnapshotHandle</a></div>
    <div className="msb-param-desc">Handle to the loaded snapshot.</div>
  </div>
</div>

<Accordion title="Example">

```go
h, err := m.Snapshot.Load(ctx, "/tmp/snap.tar.zst", "")
```

</Accordion>

## SandboxHandle

Snapshots are taken from a metadata handle, so stop the sandbox first and then call [`GetSandbox`](/sdk/go/sandbox#getsandbox).

```go
_ = sb.Stop(ctx)
_ = sb.Close()

h, err := m.GetSandbox(ctx, "baseline")
if err != nil {
    return err
}
snap, err := h.Snapshot(ctx, "after-pip-install")
```

#### <span className="msb-recv">h.</span><span className="msb-hn">Snapshot()</span>

```go
func (h *SandboxHandle) Snapshot(ctx context.Context, name string) (*SnapshotArtifact, error)
```

Snapshot this sandbox under a bare name in the default snapshots directory. The sandbox must be stopped or crashed. To place the artifact elsewhere, use [`Snapshot.Save`](#snapshot-save) / [`Snapshot.Load`](#snapshot-load) or move the self-contained artifact directory.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>name</code><span className="msb-type">string</span></div>
    <div className="msb-param-desc">Bare name for the artifact.</div>
  </div>
</div>

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotartifactstruct">*SnapshotArtifact</a></div>
    <div className="msb-param-desc">The created artifact.</div>
  </div>
</div>

<Accordion title="Example">

```go
snap, err := h.Snapshot(ctx, "after-pip-install")
```

</Accordion>

## SnapshotArtifact

<div className="msb-tags"><span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span></div>


<p className="msb-backref">Returned by <a href="#snapshot-create">Snapshot.Create()</a> · <a href="#snapshot-open">Snapshot.Open()</a> · <a href="#snapshot-listdir">Snapshot.ListDir()</a> · <a href="#h-snapshot">h.Snapshot()</a> · <a href="#h-open">h.Open()</a></p>

A snapshot artifact on disk.

#### <span className="msb-recv">s.</span><span className="msb-hn">Verify()</span>

```go
func (s *SnapshotArtifact) Verify(ctx context.Context) (*SnapshotVerifyReport, error)
```

Recompute the upper layer's recorded content integrity and compare against the descriptor. Current BLAKE3 Merkle integrity skips known all-hole subtrees and hashes allocated leaves in batches; released SHA descriptors retain their exact, potentially O(logical size), verifier. The report's `Upper.Kind` is `"not_recorded"` when the artifact was created without [`RecordIntegrity`](#snapshotcreateoptionsstruct), and `"verified"` when the recorded value matched.

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotverifyreportstruct">*SnapshotVerifyReport</a></div>
    <div className="msb-param-desc">Recomputed digest and upper-layer status.</div>
  </div>
</div>

<Accordion title="Example">

```go
report, err := snap.Verify(ctx)
if err != nil {
    return err
}
if report.Upper.Kind == "not_recorded" {
    fmt.Println("snapshot has no recorded payload integrity")
} else {
    fmt.Println(report.Upper.Digest)
}
```

</Accordion>

#### <span className="msb-recv">s.</span><span className="msb-hn">Path()</span>

```go
func (s *SnapshotArtifact) Path() string
```

Artifact directory on disk.

#### <span className="msb-recv">s.</span><span className="msb-hn">Digest()</span>

```go
func (s *SnapshotArtifact) Digest() string
```

Canonical manifest digest (`sha256:...`).

#### <span className="msb-recv">s.</span><span className="msb-hn">SizeBytes()</span>

```go
func (s *SnapshotArtifact) SizeBytes() uint64
```

Apparent upper-layer size in bytes.

#### <span className="msb-recv">s.</span><span className="msb-hn">ImageRef()</span>

```go
func (s *SnapshotArtifact) ImageRef() string
```

Image reference the snapshot was taken from.

#### <span className="msb-recv">s.</span><span className="msb-hn">ImageManifestDigest()</span>

```go
func (s *SnapshotArtifact) ImageManifestDigest() string
```

Pinned OCI manifest digest of the base image.

#### <span className="msb-recv">s.</span><span className="msb-hn">Format()</span>

```go
func (s *SnapshotArtifact) Format() string
```

Upper-layer disk format: `"raw"` or `"qcow2"`.

---

#### <span className="msb-recv">s.</span><span className="msb-hn">Scope()</span>
<div className="msb-tags"><span className="msb-tag is-instance">method</span></div>

```go
func (s *SnapshotArtifact) Scope() string
```

Snapshot scope: `SnapshotScopeDisk` (`"disk"`) or `SnapshotScopeResumable` (`"resumable"`). Always `SnapshotScopeDisk` today; `SnapshotScopeResumable` is reserved for resumable snapshots.

---

#### <span className="msb-recv">s.</span><span className="msb-hn">Fstype()</span>

```go
func (s *SnapshotArtifact) Fstype() string
```

Filesystem type inside the upper layer.

#### <span className="msb-recv">s.</span><span className="msb-hn">Parent()</span>

```go
func (s *SnapshotArtifact) Parent() *string
```

Parent digest, or `nil` if this snapshot has no parent. Returns a defensive copy.

#### <span className="msb-recv">s.</span><span className="msb-hn">CreatedAt()</span>

```go
func (s *SnapshotArtifact) CreatedAt() string
```

RFC 3339 creation timestamp.

#### <span className="msb-recv">s.</span><span className="msb-hn">Labels()</span>

```go
func (s *SnapshotArtifact) Labels() map[string]string
```

User labels recorded at creation. Returns a defensive copy.

#### <span className="msb-recv">s.</span><span className="msb-hn">SourceSandbox()</span>

```go
func (s *SnapshotArtifact) SourceSandbox() *string
```

Best-effort source sandbox name, or `nil`. Returns a defensive copy.

## SnapshotHandle

<div className="msb-tags"><span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span></div>


<p className="msb-backref">Returned by <a href="#snapshot-get">Snapshot.Get()</a> · <a href="#snapshot-list">Snapshot.List()</a> · <a href="#snapshot-load">Snapshot.Load()</a></p>

A snapshot handle backed by the local index.

#### <span className="msb-recv">h.</span><span className="msb-hn">Open()</span>

```go
func (h *SnapshotHandle) Open(ctx context.Context) (*SnapshotArtifact, error)
```

<Accordion title="Example">

```go
snap, err := h.Open(ctx)
```

</Accordion>

Open the underlying artifact metadata. Equivalent to [`Snapshot.Open`](#snapshot-open) on this handle's path.

<p className="msb-label">Returns</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><a className="msb-type" href="#snapshotartifactstruct">*SnapshotArtifact</a></div>
    <div className="msb-param-desc">The opened artifact.</div>
  </div>
</div>

#### <span className="msb-recv">h.</span><span className="msb-hn">Remove()</span>

```go
func (h *SnapshotHandle) Remove(ctx context.Context, force bool) error
```

<Accordion title="Example">

```go
err := h.Remove(ctx, false)
```

</Accordion>

Remove this snapshot. Equivalent to [`Snapshot.Remove`](#snapshot-remove) on this handle's digest.

<p className="msb-label">Parameters</p>

<div className="msb-params">
  <div className="msb-param">
    <div className="msb-param-key"><code>ctx</code><span className="msb-type">context.Context</span></div>
    <div className="msb-param-desc">Cancellation and deadline.</div>
  </div>
  <div className="msb-param">
    <div className="msb-param-key"><code>force</code><span className="msb-type">bool</span></div>
    <div className="msb-param-desc">Delete even if the snapshot has indexed children.</div>
  </div>
</div>

#### <span className="msb-recv">h.</span><span className="msb-hn">Digest()</span>

```go
func (h *SnapshotHandle) Digest() string
```

Manifest digest.

#### <span className="msb-recv">h.</span><span className="msb-hn">Name()</span>

```go
func (h *SnapshotHandle) Name() *string
```

Bare-name alias, if the snapshot was indexed with one; otherwise `nil`. Returns a defensive copy.

#### <span className="msb-recv">h.</span><span className="msb-hn">ParentDigest()</span>

```go
func (h *SnapshotHandle) ParentDigest() *string
```

Parent digest, or `nil`. Returns a defensive copy.

#### <span className="msb-recv">h.</span><span className="msb-hn">ImageRef()</span>

```go
func (h *SnapshotHandle) ImageRef() string
```

Pinned image reference.

#### <span className="msb-recv">h.</span><span className="msb-hn">Format()</span>

```go
func (h *SnapshotHandle) Format() string
```

Upper-layer disk format: `"raw"` or `"qcow2"`.

---

#### <span className="msb-recv">h.</span><span className="msb-hn">Scope()</span>
<div className="msb-tags"><span className="msb-tag is-instance">method</span></div>

```go
func (h *SnapshotHandle) Scope() string
```

Snapshot scope: `SnapshotScopeDisk` (`"disk"`) or `SnapshotScopeResumable` (`"resumable"`). Always `SnapshotScopeDisk` today.

---

#### <span className="msb-recv">h.</span><span className="msb-hn">SizeBytes()</span>

```go
func (h *SnapshotHandle) SizeBytes() *uint64
```

Apparent upper size at index time, or `nil` if unknown. Returns a defensive copy.

#### <span className="msb-recv">h.</span><span className="msb-hn">Path()</span>

```go
func (h *SnapshotHandle) Path() string
```

Artifact directory on disk.

#### <span className="msb-recv">h.</span><span className="msb-hn">CreatedAt()</span>

```go
func (h *SnapshotHandle) CreatedAt() time.Time
```

Snapshot creation time, decoded from the index's Unix timestamp.

## Constants

<p className="msb-member-group">Snapshot scopes</p>

<p className="msb-backref">Returned by <a href="#s-scope">s.Scope()</a> · <a href="#h-scope">h.Scope()</a></p>

Scope of what a snapshot captures. Every snapshot today is disk-only; the resumable scope (disk plus VM state) is reserved for resumable snapshots.

| Constant | Value | Description |
|----------|-------|-------------|
| `SnapshotScopeDisk` | `"disk"` | Disk-only snapshot |
| `SnapshotScopeResumable` | `"resumable"` | Disk plus VM state (not yet supported) |

## Types

### SnapshotCreateOptions<span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span>

<p className="msb-backref">Accepted by <a href="#snapshot-create">Snapshot.Create()</a></p>

Configures [`Snapshot.Create`](#snapshot-create). `Name` and `FromSandbox` are both required.

| Field | Type | Description |
|-------|------|-------------|
| Name | `string` | Bare name; always the artifact directory's basename |
| FromSandbox | `string` | Name of the stopped or crashed sandbox to capture |
| DestDir | `string` | Parent directory for the artifact (`DestDir/<name>`); empty = the default snapshots directory |
| Labels | `map[string]string` | Arbitrary user labels recorded in the manifest |
| Force | `bool` | Overwrite an existing artifact with the same name |
| RecordIntegrity | `bool` | Record content hashes so [`Verify`](#s-verify) can recompute them later |
| Resumable | `bool` | Request a resumable snapshot; returns an unsupported-feature error today |

### SnapshotSaveOptions<span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span>

<p className="msb-backref">Accepted by <a href="#snapshot-save">Snapshot.Save()</a></p>

Configures [`Snapshot.Save`](#snapshot-save).

| Field | Type | Description |
|-------|------|-------------|
| WithParents | `bool` | Include the snapshot's parent chain in the archive |
| WithImage | `bool` | Include the base OCI image in the archive |
| PlainTar | `bool` | Write an uncompressed `.tar` instead of `.tar.zst` |

### SnapshotVerifyReport<span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span>

<p className="msb-backref">Returned by <a href="#s-verify">s.Verify()</a></p>

Result of [`Verify`](#s-verify).

| Field | Type | Description |
|-------|------|-------------|
| Digest | `string` | Recomputed manifest digest |
| Path | `string` | Artifact directory that was verified |
| Upper | [`SnapshotUpperVerifyStatus`](#snapshotupperverifystatusstruct) | Upper-layer integrity status |

### SnapshotUpperVerifyStatus<span className="msb-tag is-type" style={{marginLeft: "8px"}}>struct</span>

<p className="msb-backref">Field of <a href="#snapshotverifyreportstruct">SnapshotVerifyReport</a></p>

Upper-layer integrity details inside a [`SnapshotVerifyReport`](#snapshotverifyreportstruct).

| Field | Type | Description |
|-------|------|-------------|
| Kind | `string` | Integrity record kind |
| Algorithm | `string` | Hash algorithm used |
| Digest | `string` | Recomputed upper-layer digest |