Prefab commands

Commands covering the prefab lifecycle an agent needs to build content procedurally: saving a configured GameObject as a prefab asset, instantiating it into a scene, deriving a variant, applying/reverting instance overrides, unpacking, and editing prefab contents through the prefab stage. Asset paths are sandboxed to the authoring root; scene-side mutations are Undo-able, but prefab asset writes are AssetDatabase operations and are not part of Unity's Undo system.

create_prefab

Save a GameObject as a prefab asset at a project path; the source becomes a connected instance.

Parameter	Required	Default	Description
source	yes	–	Reference to the source GameObject to save as a prefab (globalId/path/guid/instanceId/hierarchyPath).
path	yes	–	Prefab asset path relative to the authoring root (the Assets/ prefix is optional and the .prefab extension is added if missing). e.g. Prefabs/Enemy or Prefabs/Enemy.prefab

Returns: AuthoringResult Notes: Scene-side effects are Undo-able; the prefab asset write is not undoable.

instantiate_prefab

Instantiate a prefab asset into a loaded scene and return the created instance.

Parameter	Required	Default	Description
prefab	yes	–	Reference to the prefab asset to instantiate (path/guid/globalId).
scene_path	no	–	Optional path of a loaded scene to instantiate into; defaults to the active scene.
name	no	–	Optional name for the created instance; defaults to the prefab name.

Returns: AuthoringResult Notes: Undo-able.

create_prefab_variant

Create a prefab variant asset that inherits from a base prefab.

Parameter	Required	Default	Description
base	yes	–	Reference to the base prefab asset (path/guid/globalId).
path	yes	–	Variant prefab asset path relative to the authoring root (.prefab added if missing).

Returns: AuthoringResult Notes: Prefab asset write is not undoable.

apply_prefab_overrides

Apply a prefab instance's overrides back to its source prefab asset.

Parameter	Required	Default	Description
instance	yes	–	Reference to a prefab instance GameObject in a scene (instanceId/hierarchyPath/globalId).

Returns: AuthoringResult Notes: Scene-side effects are Undo-able; the asset write is not. The instance's source prefab asset must live under the authoring root.

revert_prefab_overrides

Revert a prefab instance's overrides so it matches its source prefab asset.

Parameter	Required	Default	Description
instance	yes	–	Reference to a prefab instance GameObject in a scene (instanceId/hierarchyPath/globalId).

Returns: AuthoringResult Notes: Undo-able.

unpack_prefab

Unpack a prefab instance into plain GameObjects (outermost level or completely).

Parameter	Required	Default	Description
instance	yes	–	Reference to a prefab instance GameObject in a scene (instanceId/hierarchyPath/globalId).
completely	no	false	If true, unpack all nested prefab levels (Completely); if false, only the outermost level (OutermostRoot).

Returns: AuthoringResult Notes: Undo-able.

save_prefab_contents

Open a prefab asset in an isolated prefab stage, apply a declarative edit, and save it back (nested-prefab safe).

Parameter	Required	Default	Description
prefab	yes	–	Reference to the prefab asset to edit (path/guid/globalId).
rename_child	no	–	Optional child name (relative path under the root, e.g. 'Body/Head') to rename.
new_name	no	–	New name for the child identified by rename_child.
set_active_child	no	–	Optional child name (relative path under the root) whose active state to set.
active	no	true	Active state to apply when set_active_child is provided.

Returns: AuthoringResult Notes: Prefab asset write (prefab-stage save) is not part of Unity's Undo system. The prefab asset must live under the authoring root.

See Creating commands and Connectivity.