unity-prefab

Before calling any skill in this module: if you are about to call a skill with parameters guessed from its name or description, STOP — read this file (or fetch its schema via GET /skills/recommend?includeSchema=true) first. If you already have the parameter definitions from recommend/schema, you may proceed straight to dryRun.

Triggers

• Creating or editing prefabs
• Instantiating or applying prefab changes
• Finding instances in scenes
• Creating prefab variants
• Create or edit prefabs, instantiate or apply prefab changes, find instances in the scene, create prefab variants

Unity Prefab Skills

BATCH-FIRST: Use prefab_instantiate_batch when spawning 2+ prefab instances.

Operating Mode

In Approval mode, this module is Mixed — read-only skills prefab_get_overrides / prefab_find_instances(marked ReadOnly = true, Mode = SkillMode.SemiAuto) can be executed directly; the other 9 write-type skills (prefab_create / prefab_instantiate / prefab_instantiate_batch / prefab_apply / prefab_unpack / prefab_revert_overrides / prefab_apply_overrides / prefab_create_variant / prefab_set_property) are SkillMode.FullAuto, and require the user to grant a single execution that returns a result. Auto / Bypass execute directly. This moduledoes not contain NeverInSemi high-risk skills(no Delete / PlayMode / Reload).

DO NOT (common hallucinations):

• prefab_create_from_object does not exist → use prefab_create (takes scene object name/instanceId and savePath)
• prefab_spawn does not exist → use prefab_instantiate
• prefab_edit / prefab_modify do not exist → use prefab_set_property (edit prefab asset directly) or instantiate, modify, then prefab_apply
• prefab_save does not exist → use prefab_apply (applies instance changes to source prefab)

Routing:

• To modify components on a prefab instance in scene → use component module skills, then prefab_apply
• To set a property directly on the prefab asset → prefab_set_property (this module)
• To find all instances of a prefab → prefab_find_instances (this module)

Skills Overview

Single Object	Batch Version	Use Batch When
prefab_instantiate	prefab_instantiate_batch	Spawning 2+ instances

No batch needed:

• prefab_create - Create prefab from scene object
• prefab_apply - Apply instance changes to prefab
• prefab_unpack - Unpack prefab instance
• prefab_get_overrides - Get instance overrides
• prefab_revert_overrides - Revert to prefab values
• prefab_apply_overrides - Apply overrides to prefab
• prefab_create_variant - Create a prefab variant
• prefab_find_instances - Find all instances of a prefab in scene
• prefab_set_property - Set a property on a component inside a Prefab asset (supports basic types, vectors, colors, and asset references)

---

Skills

prefab_create

Create a prefab from a scene GameObject.

Parameter	Type	Required	Description
name	string	No*	Source object name
instanceId	int	No*	Instance ID (preferred)
path	string	No*	Object path
savePath	string	Yes	Prefab save path; .prefab is appended when missing

*At least one source identifier required.

Returns: {success, prefabPath, name, connected}: prefabPath is the saved asset's path, connected whether the scene object is now an instance of it. A save Unity refuses is an error, not a success.

prefab_instantiate

Instantiate a prefab into the scene.

Parameter	Type	Required	Default	Description
prefabPath	string	Yes	-	Prefab asset path
name	string	No	prefab name	Instance name
x, y, z	float	No	0	Local position (relative to parent if set)
parentEntityId	string	No	null	Parent entity ID (Unity 6000.4+, preferred)
parentName	string	No	null	Parent object name
parentInstanceId	int	No	0	Parent instance ID
parentPath	string	No	null	Parent hierarchy path

Returns: {success, name, entityId, instanceId, path}

prefab_instantiate_batch

Instantiate multiple prefabs in one call.

Parameter	Type	Required	Description
items	jsonstring	Yes	Array of instantiation configs

Item properties: prefabPath, name, x, y, z (local position, relative to the parent if set), rotX, rotY, rotZ, scaleX, scaleY, scaleZ, parentEntityId, parentName, parentInstanceId, parentPath

Returns: {success, totalItems, successCount, failCount, results: [{success, name, entityId, instanceId, position, localPosition}]}: position is the world position read back, localPosition the local one. All-or-nothing: one failed item removes every instance the call created (rolledBack: true).

unity_skills.call_skill("prefab_instantiate_batch", items=[
    {"prefabPath": "Assets/Prefabs/Enemy.prefab", "x": 0, "z": 0, "name": "Enemy_01"},
    {"prefabPath": "Assets/Prefabs/Enemy.prefab", "x": 2, "z": 0, "name": "Enemy_02"},
    {"prefabPath": "Assets/Prefabs/Enemy.prefab", "x": 4, "z": 0, "name": "Enemy_03"}
])

prefab_apply

Apply instance changes back to the prefab asset.

Parameter	Type	Required	Description
name	string	No*	Prefab instance name
instanceId	int	No*	Instance ID (preferred)
path	string	No*	Object path

*At least one identifier required.

Returns: {success, appliedTo} (appliedTo is the prefab asset path)

prefab_unpack

Unpack a prefab instance (break prefab connection).

Parameter	Type	Required	Default	Description
name	string	No*	-	Prefab instance name
instanceId	int	No*	-	Instance ID (preferred)
path	string	No*	-	Object path
completely	bool	No	false	Unpack all nested prefabs

*At least one identifier required.

Returns: {success, unpacked} (unpacked is the instance's GameObject name)

prefab_get_overrides

Get a summary of property overrides on a prefab instance (counts, not the individual override list).

Parameter	Type	Required	Description
name	string	No*	Prefab instance name
instanceId	int	No*	Instance ID

Returns: {success, prefabPath, propertyOverrides, addedComponents, removedComponents, addedGameObjects, hasOverrides} — propertyOverrides/addedComponents/removedComponents/addedGameObjects are counts (int), not arrays; hasOverrides is true when any of those counts is non-zero.

prefab_revert_overrides

Revert all overrides on a prefab instance back to prefab values.

Parameter	Type	Required	Description
name	string	No*	Prefab instance name
instanceId	int	No*	Instance ID

Returns: {success, reverted} (reverted is the prefab root's GameObject name)

prefab_apply_overrides

Apply all overrides from instance to source prefab asset.

Parameter	Type	Required	Description
name	string	No*	Prefab instance name
instanceId	int	No*	Instance ID

Returns: {success, appliedTo} (appliedTo is the prefab asset path)

prefab_create_variant

Create a prefab variant from an existing prefab.

Parameter	Type	Required	Default	Description
sourcePrefabPath	string	Yes	-	Path to the source prefab asset
variantPath	string	Yes	-	Save path for the new variant

Returns: { success, sourcePath, variantPath, name, isVariant }: variantPath is the saved asset's path (.prefab appended when missing), isVariant whether Unity stored it as a variant of the source.

prefab_find_instances

Find all instances of a prefab in the current scene.

Parameter	Type	Required	Default	Description
prefabPath	string	Yes	-	Prefab asset path to search for
limit	int	No	50	Maximum number of instances to return

Returns: { success, prefabPath, count, instances: [{ name, path, entityId, instanceId }] }

prefab_set_property

Set a property on a component inside a Prefab asset file (without instantiating it). Supports basic types, vectors, colors, enums, and asset references.

Parameter	Type	Required	Default	Description
prefabPath	string	Yes	-	Path to the prefab asset
componentType	string	Yes	-	Component type name
propertyName	string	Yes	-	Serialized property name
value	string	Cond.	null	Value for basic types (int/float/bool/string/enum/vector/color/quaternion)
assetReferencePath	string	Cond.	null	Asset path for Object reference fields (Material, Texture, AudioClip, ScriptableObject, etc.)
gameObjectName	string	No	null	Child object name inside prefab (defaults to root)

Provide either value (basic types) or assetReferencePath (asset references).

value covers Integer, Float, Boolean, String, Enum, Color, Vector2/3/4, Vector2Int/3Int, Quaternion, Rect, Bounds and LayerMask. A quaternion (localRotation) accepts 3 components as euler degrees ("0,90,0") or 4 as raw x,y,z,w. A bool is true/false/1/0/yes/no/on/off (anything else is rejected). An enum takes a name, display name, A,B for flags, or a number with the same rules as component_set_serialized_property (0..n-1 = member index, warned when the member's value differs; undeclared bits rejected). Any other serialized type answers SEMANTIC_INVALID naming the type — that is the signal to use assetReferencePath, not to reformat value.

Returns: { success, prefabPath, gameObject, component, property, valueSet, valueRequested?, warnings? }: component / property are the resolved type name and serialized path; valueSet is read back from the asset after saving (serialized form: an enum reads as its index, a quaternion as x,y,z,w; for assetReferencePath the referenced asset's path); valueRequested appears only when the stored value differs from what was written (clamped by the component, or a reference of the wrong type not stored).

# Set a float property on prefab root
unity_skills.call_skill("prefab_set_property",
    prefabPath="Assets/Prefabs/Enemy.prefab",
    componentType="EnemyStats",
    propertyName="maxHealth",
    value="100"
)

# Assign an asset reference to a prefab component
unity_skills.call_skill("prefab_set_property",
    prefabPath="Assets/Prefabs/Enemy.prefab",
    componentType="AudioSource",
    propertyName="m_audioClip",
    assetReferencePath="Assets/Audio/hit.wav"
)

# Edit a child object inside a prefab
unity_skills.call_skill("prefab_set_property",
    prefabPath="Assets/Prefabs/Player.prefab",
    componentType="MeshRenderer",
    propertyName="m_Materials.Array.data[0]",
    assetReferencePath="Assets/Materials/PlayerSkin.mat",
    gameObjectName="Body"
)

---

Example: Efficient Enemy Spawning

import unity_skills

# BAD: 10 API calls for 10 enemies
for i in range(10):
    unity_skills.call_skill("prefab_instantiate",
        prefabPath="Assets/Prefabs/Enemy.prefab",
        name=f"Enemy_{i}",
        x=i * 2
    )

# GOOD: 1 API call for 10 enemies
unity_skills.call_skill("prefab_instantiate_batch", items=[
    {"prefabPath": "Assets/Prefabs/Enemy.prefab", "name": f"Enemy_{i}", "x": i * 2}
    for i in range(10)
])

Best Practices

1. Organize prefabs in dedicated folders
2. Use prefabs for repeated objects
3. Apply changes to update all instances
4. Unpack only when unique modifications needed
5. Use batch instantiation for level generation

---

Exact Signatures

Exact names, parameters, defaults, and returns are defined by GET /skills/schema or unity_skills.get_skill_schema(), not by this file.

Common Errors

Full transport-level codes (COMPILING/RATE_LIMIT etc.) → ../../references/protocol-error-codes.md

Error	Trigger	Fix
TARGET_NOT_FOUND	The prefab asset, source prefab, child GameObject inside a prefab, component, or asset reference could not be found.	Confirm the prefab path with asset_find / prefab_find_instances, check child/component names, and retry with exact identifiers.
MISSING_PARAM	A required parameter is missing, such as savePath, prefabPath, sourcePrefabPath, componentType, or propertyName.	Provide the missing parameter; use mode=dryRun to inspect the full schema.
SEMANTIC_INVALID	The target is not a prefab instance, the property is not an Object reference field, or a serialized value could not be parsed.	Ensure the object is a prefab instance (prefab_get_overrides can verify), match the property type, and retry with a valid value.
SKILL_ERROR	A low-level operation failed, such as Failed to instantiate prefab or Failed to set value ... (type: ...).	Resolve the underlying cause named in the message (e.g., prefab corruption, type mismatch) and retry.