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Merged
Scriptwonder merged 2 commits into from
Apr 1, 2026
Merged

Prefab stages integration #1013

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Scriptwonder Mar 31, 2026
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Scriptwonder Apr 1, 2026
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2 changes: 1 addition & 1 deletion MCPForUnity/Editor/Tools/GameObjects/ManageGameObject.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ public static object HandleCommand(JObject @params)
return new ErrorResponse(
$"Target '{targetPath}' is a prefab asset. " +
$"Use 'manage_asset' with action='modify' for prefab asset modifications, " +
$"or 'manage_prefabs' with action='modify_contents' to edit the prefab headlessly, or 'manage_editor' with action='close_prefab_stage' to exit prefab editing mode."
$"or 'manage_prefabs' with action='modify_contents' to edit the prefab headlessly, or 'manage_prefabs' with action='close_prefab_stage' to exit prefab editing mode."
);
}
// --- End Prefab Asset Check ---
Expand Down
119 changes: 1 addition & 118 deletions MCPForUnity/Editor/Tools/ManageEditor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@
using MCPForUnity.Editor.Services;
using Newtonsoft.Json.Linq;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEditorInternal; // Required for tag management
using UnityEngine;

Expand Down Expand Up @@ -47,8 +46,6 @@ public static object HandleCommand(JObject @params)
// Parameters for specific actions
string tagName = p.Get("tagName");
string layerName = p.Get("layerName");
string prefabPath = p.Get("prefabPath") ?? p.Get("path");

// Route action
switch (action)
{
Expand Down Expand Up @@ -137,14 +134,6 @@ public static object HandleCommand(JObject @params)
// // Handle string name or int index
// return SetQualityLevel(@params["qualityLevel"]);

// Prefab Stage
case "open_prefab_stage":
return OpenPrefabStage(prefabPath);
case "save_prefab_stage":
return SavePrefabStage();
case "close_prefab_stage":
return ClosePrefabStage();

// Package Deployment
case "deploy_package":
return DeployPackage();
Expand Down Expand Up @@ -182,7 +171,7 @@ public static object HandleCommand(JObject @params)

default:
return new ErrorResponse(
$"Unknown action: '{action}'. Supported actions: play, pause, stop, set_active_tool, add_tag, remove_tag, add_layer, remove_layer, open_prefab_stage, save_prefab_stage, close_prefab_stage, deploy_package, restore_package, undo, redo. Use MCP resources for reading editor state, project info, tags, layers, selection, windows, prefab stage, and active tool."
$"Unknown action: '{action}'. Supported actions: play, pause, stop, set_active_tool, add_tag, remove_tag, add_layer, remove_layer, deploy_package, restore_package, undo, redo. For prefab editing (open/save/close prefab stage), use manage_prefabs. Use MCP resources for reading editor state, project info, tags, layers, selection, windows, prefab stage, and active tool."
);
}
}
Expand Down Expand Up @@ -402,112 +391,6 @@ private static object RemoveLayer(string layerName)
}
}

// --- Prefab Stage Methods ---

private static object OpenPrefabStage(string requestedPath)
{
if (string.IsNullOrWhiteSpace(requestedPath))
{
return new ErrorResponse("'prefabPath' parameter is required for open_prefab_stage.");
}

string sanitizedPath = AssetPathUtility.SanitizeAssetPath(requestedPath);
if (sanitizedPath == null)
{
return new ErrorResponse($"Invalid prefab path (path traversal detected): '{requestedPath}'.");
}

if (!sanitizedPath.StartsWith("Assets/", StringComparison.OrdinalIgnoreCase))
{
return new ErrorResponse($"Prefab path must be within the Assets folder. Got: '{sanitizedPath}'.");
}

if (!sanitizedPath.EndsWith(".prefab", StringComparison.OrdinalIgnoreCase))
{
return new ErrorResponse($"Prefab path must end with '.prefab'. Got: '{sanitizedPath}'.");
}

try
{
GameObject prefabAsset = AssetDatabase.LoadAssetAtPath<GameObject>(sanitizedPath);
if (prefabAsset == null)
{
return new ErrorResponse($"Prefab asset not found at '{sanitizedPath}'.");
}

var prefabStage = PrefabStageUtility.OpenPrefab(sanitizedPath);
bool enteredStage = prefabStage != null
&& string.Equals(prefabStage.assetPath, sanitizedPath, StringComparison.OrdinalIgnoreCase)
&& prefabStage.prefabContentsRoot != null;

if (!enteredStage)
{
return new ErrorResponse($"Failed to open prefab stage for '{sanitizedPath}'. PrefabStageUtility.OpenPrefab did not enter the requested prefab stage.");
}

return new SuccessResponse(
$"Opened prefab stage for '{sanitizedPath}'.",
new
{
prefabPath = sanitizedPath,
openedPrefabPath = prefabStage.assetPath,
rootName = prefabStage.prefabContentsRoot.name,
enteredPrefabStage = enteredStage
}
);
}
catch (Exception e)
{
return new ErrorResponse($"Error opening prefab stage: {e.Message}");
}
}

private static object SavePrefabStage()
{
try
{
var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
if (prefabStage == null)
{
return new ErrorResponse("Not currently in prefab editing mode. Open a prefab stage first with open_prefab_stage.");
}

string prefabPath = prefabStage.assetPath;
EditorSceneManager.MarkSceneDirty(prefabStage.scene);
bool saved = EditorSceneManager.SaveScene(prefabStage.scene);
if (!saved)
{
return new ErrorResponse($"Failed to save prefab stage for '{prefabPath}'. The file may be read-only or the disk may be full.");
}

return new SuccessResponse($"Saved prefab stage changes for '{prefabPath}'.", new { prefabPath, saved });
}
catch (Exception e)
{
return new ErrorResponse($"Error saving prefab stage: {e.Message}");
}
}

private static object ClosePrefabStage()
{
try
{
var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
if (prefabStage == null)
{
return new SuccessResponse("Not currently in prefab editing mode.");
}

string prefabPath = prefabStage.assetPath;
StageUtility.GoToMainStage();
return new SuccessResponse($"Exited prefab stage for '{prefabPath}'.", new { prefabPath });
}
catch (Exception e)
{
return new ErrorResponse($"Error closing prefab stage: {e.Message}");
}
}

// --- Package Deployment Methods ---

private static object DeployPackage()
Expand Down
138 changes: 135 additions & 3 deletions MCPForUnity/Editor/Tools/Prefabs/ManagePrefabs.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,8 @@ namespace MCPForUnity.Editor.Tools.Prefabs
{
[McpForUnityTool("manage_prefabs", AutoRegister = false)]
/// <summary>
/// Tool to manage Unity Prefabs: create, inspect, and modify prefab assets.
/// Uses headless editing (no UI, no dialogs) for reliable automated workflows.
/// Tool to manage Unity Prefabs: create, inspect, modify, and open/save/close prefab stage.
/// Supports both headless editing (modify_contents) and interactive prefab stage workflows.
/// </summary>
public static class ManagePrefabs
{
Expand All @@ -23,7 +23,10 @@ public static class ManagePrefabs
private const string ACTION_GET_INFO = "get_info";
private const string ACTION_GET_HIERARCHY = "get_hierarchy";
private const string ACTION_MODIFY_CONTENTS = "modify_contents";
private const string SupportedActions = ACTION_CREATE_FROM_GAMEOBJECT + ", " + ACTION_GET_INFO + ", " + ACTION_GET_HIERARCHY + ", " + ACTION_MODIFY_CONTENTS;
private const string ACTION_OPEN_PREFAB_STAGE = "open_prefab_stage";
private const string ACTION_SAVE_PREFAB_STAGE = "save_prefab_stage";
private const string ACTION_CLOSE_PREFAB_STAGE = "close_prefab_stage";
private const string SupportedActions = ACTION_CREATE_FROM_GAMEOBJECT + ", " + ACTION_GET_INFO + ", " + ACTION_GET_HIERARCHY + ", " + ACTION_MODIFY_CONTENTS + ", " + ACTION_OPEN_PREFAB_STAGE + ", " + ACTION_SAVE_PREFAB_STAGE + ", " + ACTION_CLOSE_PREFAB_STAGE;

public static object HandleCommand(JObject @params)
{
Expand All @@ -50,6 +53,18 @@ public static object HandleCommand(JObject @params)
return GetHierarchy(@params);
case ACTION_MODIFY_CONTENTS:
return ModifyContents(@params);
case ACTION_OPEN_PREFAB_STAGE:
{
string prefabPath = @params["prefabPath"]?.ToString() ?? @params["path"]?.ToString();
return OpenPrefabStage(prefabPath);
}
case ACTION_SAVE_PREFAB_STAGE:
return SavePrefabStage();
case ACTION_CLOSE_PREFAB_STAGE:
{
bool saveBeforeClose = @params["saveBeforeClose"]?.ToObject<bool>() ?? false;
return ClosePrefabStage(saveBeforeClose);
}
default:
return new ErrorResponse($"Unknown action: '{action}'. Valid actions are: {SupportedActions}.");
}
Expand Down Expand Up @@ -1261,5 +1276,122 @@ private static void BuildHierarchyItemsRecursive(Transform transform, Transform
}

#endregion

#region Prefab Stage

private static object OpenPrefabStage(string requestedPath)
{
if (string.IsNullOrWhiteSpace(requestedPath))
{
return new ErrorResponse("'prefabPath' parameter is required for open_prefab_stage.");

Copilot AI Mar 31, 2026

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OpenPrefabStage accepts both prefabPath and the path alias, but the validation error message only mentions 'prefabPath' parameter is required. This is misleading for callers using the alias; consider updating the message to mention both accepted parameter names.

Suggested change
return new ErrorResponse("'prefabPath' parameter is required for open_prefab_stage.");
return new ErrorResponse("Either 'prefabPath' or 'path' parameter is required for open_prefab_stage.");

Copilot uses AI. Check for mistakes.
}

string sanitizedPath = AssetPathUtility.SanitizeAssetPath(requestedPath);
if (sanitizedPath == null)
{
return new ErrorResponse($"Invalid prefab path (path traversal detected): '{requestedPath}'.");
}

if (!sanitizedPath.StartsWith("Assets/", StringComparison.OrdinalIgnoreCase))
{
return new ErrorResponse($"Prefab path must be within the Assets folder. Got: '{sanitizedPath}'.");
}

if (!sanitizedPath.EndsWith(".prefab", StringComparison.OrdinalIgnoreCase))
{
return new ErrorResponse($"Prefab path must end with '.prefab'. Got: '{sanitizedPath}'.");
}

try
{
GameObject prefabAsset = AssetDatabase.LoadAssetAtPath<GameObject>(sanitizedPath);
if (prefabAsset == null)
{
return new ErrorResponse($"Prefab asset not found at '{sanitizedPath}'.");
}

var prefabStage = PrefabStageUtility.OpenPrefab(sanitizedPath);
bool enteredStage = prefabStage != null
&& string.Equals(prefabStage.assetPath, sanitizedPath, StringComparison.OrdinalIgnoreCase)
&& prefabStage.prefabContentsRoot != null;

if (!enteredStage)
{
return new ErrorResponse($"Failed to open prefab stage for '{sanitizedPath}'. PrefabStageUtility.OpenPrefab did not enter the requested prefab stage.");
}

return new SuccessResponse(
$"Opened prefab stage for '{sanitizedPath}'.",
new
{
prefabPath = sanitizedPath,
openedPrefabPath = prefabStage.assetPath,
rootName = prefabStage.prefabContentsRoot.name,
enteredPrefabStage = enteredStage
}
);
}
catch (Exception e)
{
return new ErrorResponse($"Error opening prefab stage: {e.Message}");
}
}

private static object SavePrefabStage()
{
try
{
var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
if (prefabStage == null)
{
return new ErrorResponse("Not currently in prefab editing mode. Open a prefab stage first with open_prefab_stage.");
}

string prefabPath = prefabStage.assetPath;
EditorSceneManager.MarkSceneDirty(prefabStage.scene);
bool saved = EditorSceneManager.SaveScene(prefabStage.scene);
if (!saved)
{
return new ErrorResponse($"Failed to save prefab stage for '{prefabPath}'. The file may be read-only or the disk may be full.");
}

return new SuccessResponse($"Saved prefab stage changes for '{prefabPath}'.", new { prefabPath, saved });
}
catch (Exception e)
{
return new ErrorResponse($"Error saving prefab stage: {e.Message}");
}
}

private static object ClosePrefabStage(bool saveBeforeClose = false)
{
try
{
var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
if (prefabStage == null)
{
return new SuccessResponse("Not currently in prefab editing mode.");
}

if (saveBeforeClose)
{
var saveResult = SavePrefabStage();
if (saveResult is ErrorResponse)
{
return saveResult;
}
}

string prefabPath = prefabStage.assetPath;
StageUtility.GoToMainStage();
return new SuccessResponse($"Exited prefab stage for '{prefabPath}'.", new { prefabPath });
}
catch (Exception e)
{
return new ErrorResponse($"Error closing prefab stage: {e.Message}");
}
}

#endregion
}
}
6 changes: 3 additions & 3 deletions Server/src/cli/commands/prefab.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ def open_stage(path: str):
config = get_config()

params: dict[str, Any] = {
"action": "open_stage",
"action": "open_prefab_stage",
"prefabPath": path,
}

Expand Down Expand Up @@ -57,7 +57,7 @@ def close_stage(save: bool):
config = get_config()

params: dict[str, Any] = {
"action": "close_stage",
"action": "close_prefab_stage",
}
if save:
params["saveBeforeClose"] = True
Expand All @@ -83,7 +83,7 @@ def save_stage():
"action": "save_prefab_stage",
}

result = run_command("manage_editor", params, config)
result = run_command("manage_prefabs", params, config)
click.echo(format_output(result, config.format))
if result.get("success"):
print_success("Saved prefab stage")
Expand Down
2 changes: 1 addition & 1 deletion Server/src/services/resources/prefab.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@ async def get_prefab_api_docs(_ctx: Context) -> MCPResponse:
"workflow": [
"1. Use manage_asset action=search filterType=Prefab to find prefabs",
"2. Use the asset path to access detailed data via resources below",
"3. Use manage_editor action=open_prefab_stage / save_prefab_stage / close_prefab_stage for prefab editing UI transitions"
"3. Use manage_prefabs action=open_prefab_stage / save_prefab_stage / close_prefab_stage for prefab editing UI transitions"

@coderabbitai coderabbitai Bot Mar 31, 2026

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⚠️ Potential issue | 🟠 Major

Fix contradictory prefab tool guidance in this resource payload.

Line 60 correctly routes stage lifecycle to manage_prefabs, but related_tools still says manage_editor owns open/save/close stages. This inconsistency can send callers to unsupported actions.

Suggested doc fix 
         "related_tools": {
-            "manage_editor": "Open/save/close prefab stages in the Unity Editor UI",
-            "manage_prefabs": "Headless prefab inspection and modification without opening prefab stages",
+            "manage_editor": "Editor controls (play/pause/stop, active tool, tags/layers, package deploy/restore)",
+            "manage_prefabs": "Prefab stage lifecycle (open/save/close) and headless prefab inspection/modification",
             "manage_asset": "Search for prefab assets, get asset info",
             "manage_gameobject": "Modify GameObjects in open prefab stage",
             "manage_components": "Add/remove/modify components on prefab GameObjects"
         }

Also applies to: 83-85

🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@Server/src/services/resources/prefab.py` at line 60, The resource payload
text references stage lifecycle actions under manage_prefabs but the
related_tools field still lists manage_editor, causing inconsistency; update the
related_tools entries that refer to "manage_editor" (the ones associated with
the prefab stage guidance string "Use manage_prefabs action=open_prefab_stage /
save_prefab_stage / close_prefab_stage") to "manage_prefabs" in the prefab
resource definition (also fix the same mismatch at the other occurrence around
lines 83–85) so callers are guided to the correct action owner.

],
"path_encoding": {
"note": "Prefab paths must be URL-encoded when used in resource URIs",
Expand Down
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