Fab

Fab asset import

FabService supports two deliberately separate paths:

• Public free catalog: search exact zero-price listings and directly import eligible glTF/GLB downloads. This does not sign in, purchase, claim an entitlement, or add the listing to My Library.
• Owned library: use the editor/launcher Epic session to list and import assets already owned by the account, including migrated Unreal Marketplace items.

Public free flow (Quixel/Megascans and other sellers)

1. Call search_free_catalog(query="", seller_filter="Quixel Megascans", format_filter="gltf"). Results are compact and include id, title, seller, price, formats, thumbnail, and an opaque next_cursor. Results require an exact-zero Personal tier; UEFN-reference-only offers are excluded. No authentication is required.
2. Show the chosen result and the Fab EULA to the user. Never set accept_eula=true on the user's behalf. It must represent their explicit acceptance.
3. Call import_free_asset(listing_id, quality="High", format="gltf", license_slug="personal", accept_eula=true). The service re-fetches the listing and requires the selected license price to still be exactly zero before it requests a signed download.
4. Poll import_status(listing_id) until imported or failed, then verify a returned asset path with unreal.EditorAssetLibrary.does_asset_exist(path).

Direct free imports land under /Game/Fab/Free/<Title>. The original archive is cached under the project's Saved/Fab/Free directory; no raw-file export API is exposed. ZIP paths are validated before extraction. The first version supports Fab glTF/GLB ZIPs through automated Unreal Interchange import. That is suitable for Quixel 3D assets, but it does not reproduce every private Megascans material setup or support every Fab product format yet.

Owned-library flow

1. Call auth_status() first. If it is not authenticated, tell the user to open the Fab window or launch the editor from the Epic Games Launcher.
2. Call list_library(...); use refresh=true only when the account library may have changed.
3. Call get_asset(asset_id) to inspect versions and compatibility.
4. Call import_asset(asset_id, ...), then poll import_status(asset_id).
5. Verify the returned /Game/... paths before reporting success.

Owned BuildPatch packs and plugins are supported. Sparse or non-BuildPatch owned assets may still be discoverable without being importable through import_asset; use the public-free path only when the listing is currently free and provides a supported source format.

Rules

• Never purchase, claim, call add-to-library, or accept a license on the user's behalf.
• Never treat a search filter as proof of price. import_free_asset performs the authoritative zero-price check immediately before download.
• Never expose signed download URLs or offer to save distributable raw asset files elsewhere.
• Imports are asynchronous and idempotent within the editor session; poll with a finite interval.
• These Fab web endpoints are unofficial and may change. Surface their errors rather than retrying the same request blindly.

Every method returns a JSON string with success: true|false. Errors include error_code and error. If every method returns error_code: "UNSUPPORTED", the engine install VibeUE was built against lacks the engine Fab plugin (Engine/Plugins/Fab) and FabService was compiled out (issue #525) — the rest of VibeUE is unaffected. Report this to the user; do not retry. Discover exact signatures with discover_python_class('unreal.FabService'). Current methods: auth_status, list_library, get_asset, search_free_catalog, import_asset, import_free_asset, and import_status.