.skf format reference

This reference is generated from the engine's exported project types, version constants, and archive limits. It describes the serialized contract; see the project format guide for behavior and safety semantics.

For automated project export from a server-backed project, see POST /exports in the REST API guide.

Package identity

Property	Value
Schema	com.sketchforge.project
Current writer format	2
Minimum reader format	2
Created-with version	1.30.0
Media type	application/vnd.sketchforge.project+zip

A packaged file is a ZIP with a root project.json and binary or JSON payloads below assets/. The archive is validated before restoration. ZIP64 and encrypted entries are not supported.

Serialized document fields

SkfProjectDocumentV1

Field	Serialized type
schema	typeof SKF_SCHEMA_ID
formatVersion	`1
minimumReaderVersion	number
createdWithVersion	string
metadata	{ projectId?: string; projectName: string; units: string; createdAt: string; modifiedAt: string; }
assets	SkfAssetRecordV1[]
sceneStateId	string
states	SkfStateV1[]
history	{ entries: Array<{ stateId: string; selectedObjectIds: string[] }>; index: number; }
sketches	Array<{ id: string; nodeId: string; objectId: string; sourceNodeId?: string; sourceObjectId?: string; operation?: SketchOperation; extrusionDepth: number; revolve?: SketchRevolveSettings }>
features	SkfFeatureV1[]
groups	Array<{ id: string; nodeId: string; objectId: string; memberNodeIds: string[]; operation: string }>
workplanes	`Array<{ id: string; kind: "base"
exactCad	Array<{ nodeId: string; objectId: string; brepAssetId?: string; importedStepAssetId?: string }>
editor	{ workspace: WorkplaneWorkspaceSettings; snapGrid: GridSize; selectedWorkplaneId: string; placementElevation: number; placementWorkplane?: PlacementWorkplane; sketchPlacementWorkplane?: PlacementWorkplane; }

SkfAssetRecordV1

Field	Serialized type
id	string
kind	SkfAssetKind
path	string
mediaType	string
byteLength	number
sha256	string
fileName?	string
sourceFormat?	ProjectAssetSourceFormat

SkfShapeNodeV1

Field	Serialized type
nodeId	string
objectId	string
objectType	`"native"
workplaneId	string
definition	Record<string, unknown>
importedMesh?	SkfImportedMeshReferenceV1
groupedShapeNodeIds?	string[]
edgeTreatmentHistory?	Array<{ id: string; createdAt: number; feature: Record<string, unknown>; appliedFrame?: Record<string, unknown>; beforeNodeId: string; }>
cadBrepAssetId?	string
cadDisplayEdgesAssetId?	string

SkfFeatureV1

Field	Serialized type
id	string
type	string
outputObjectId	string
inputObjectIds	string[]
dependsOnFeatureIds	string[]
parameters?	Record<string, unknown>

Reader compatibility

• V2 is the current writer format and requires a reader at least version 2.
• V1 packaged projects are accepted and migrate inline display edges into shared assets on import; the next save writes V2.
• V0 legacy JSON projects are accepted by the explicit migration path, which preserves valid object IDs and history.
• Unsupported future versions are rejected before restoration. The original input bytes are not modified.

Reader safety limits

Limit	Value
archiveBytes	512 * 1024 * 1024
expandedBytes	1024 * 1024 * 1024
projectJsonBytes	64 * 1024 * 1024
assetBytes	256 * 1024 * 1024
entries	4096
states	5001
objectsPerState	100_000
features	300_000
meshNumbers	30_000_000

These are engine validation limits, not suggested project sizes. The expanded archive limit applies across entries; assetBytes limits one asset, and projectJsonBytes limits project.json.

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Documentation version: 1.30.0 · Repository revision: 1cb9fee8dff4d394684c229dd67a21da539d167f · View source