assets.build_library

build_library(
    source_dir,
    blend_path,
    *,
    compress=True,
    allow_existing=False,
    resources=None,
    on_missing='error',
    add_reroutes=False,
    arrange=None,
)

Rebuild a .blend asset library from sources written by :func:dump_library.

Imports every root module under source_dir (recursively; _shared group modules are pulled in by the root modules’ own imports), rebuilds each MATERIAL module’s material (re-marking it as an asset when the module carries a MATERIAL_ASSET_METADATA footer), builds each ASSET class via create_group(), re-marks the tree as an asset, applies the dumped ASSET_METADATA/TREE_PROPERTIES/MATERIAL_PROPERTIES, and writes those trees and materials (plus their dependencies) to blend_path with bpy.data.libraries.write. A blender_assets.cats.txt in source_dir is copied next to the .blend.

Datablocks the sources reference but cannot serialise (images, objects, …, recorded in each module’s DATABLOCK_DEPENDENCIES) resolve in order: already present in the session (build “in the presence” of the data — e.g. after opening a working file), appended by name from the resources .blend, or — with on_missing="drop" — replaced by temporary placeholders deleted again before the write, leaving those socket defaults empty. The default on_missing="error" raises upfront, listing everything missing.

arrange tunes how the built trees are laid out: a :class:~nodebpy.SugiyamaOptions with any of its settings (spacing, crossing-reduction iterations, direction, socket alignment, …) is scoped over the build via :func:nodebpy.builder.default_sugiyama_options. add_reroutes=True additionally inserts reroute nodes to route long links around nodes (the node-arrange addon’s behaviour); it composes with arrange. Either only affects modules that leave the arrangement at its default — sources dumped with snapshot_positions disable arrangement and keep their authored layout.

The built trees stay in the current session afterwards. Because create_group() reuses an existing tree of the same name (that is what deduplicates groups shared between asset files), the session must not already hold node groups when the build starts — a stale same-named group would silently end up in the .blend. This raises if any exist, unless allow_existing is passed. The CLI (python -m nodebpy.assets build) runs in a fresh session by construction.

Returns

Name	Type	Description
	list[str]	The names of the asset node groups written to the .blend.