fix: register undo when deleting GameObjects via manage_gameobject

[Dallon]

Summary

manage_gameobject(action="delete") calls Object.DestroyImmediate directly, bypassing Unity's undo stack — so manage_editor(action="undo") cannot recover GameObjects deleted via MCP. This one-line fix switches to Undo.DestroyObjectImmediate, restoring expected editor-undo behavior with full reference-graph restoration.

The package already uses Undo.DestroyObjectImmediate correctly elsewhere — ComponentOps.cs:130, GameObjectComponentHelpers.cs:88,137. GameObjectDelete.cs was the outlier.

Why the existing comment was stale

// Note: Undo.DestroyObjectImmediate doesn't work reliably in test context,
// so we use Object.DestroyImmediate. This means delete isn't undoable.
// TODO: Investigate Undo.DestroyObjectImmediate behavior in Unity 2022+

package.json targets unity: "2021.3". The TODO is from that era — Undo.DestroyObjectImmediate has been stable across all currently-supported Unity versions. The new undo test plus the existing 11-test baseline pass without regression on Unity 6000.3.10f1.

Tests

Added Delete_RegistersUndo_RestoresOnUndo to the existing ManageGameObjectDeleteTests class — creates a GameObject via new GameObject(name) (no prior undo registration), invokes the delete handler, asserts the object is gone, calls Undo.PerformUndo(), asserts restoration.

Verified

• Existing 11 ManageGameObjectDeleteTests still pass
• New undo test passes
• Live MCP roundtrip on Unity 6000.3.10f1: manage_gameobject(action="delete") → manage_editor(action="undo") restores the object with the same instanceID

Related, not included

ManagePrefabs.cs has several other raw Object.DestroyImmediate call sites (lines ~881, ~1112, ~1119, ~1136, ~1148, ~1198) with the same bug shape — they deserve a separate audit/PR. Kept out of this change to keep scope tight to the manage_gameobject delete path.

Co-authored-by: Claude Opus 4.7 (1M context) noreply@anthropic.com

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • GameObject deletion operations now properly integrate with Unity's Undo/Redo system, allowing users to undo delete actions.

• Tests

  • Added test coverage verifying GameObject deletion operations register correctly with the Undo system.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: f15b3eb5-5433-4ff6-ae1b-dd6ae2655434

📥 Commits

Reviewing files that changed from the base of the PR and between 4c29526 and 9973855.

📒 Files selected for processing (2)

• MCPForUnity/Editor/Tools/GameObjects/GameObjectDelete.cs
• TestProjects/UnityMCPTests/Assets/Tests/EditMode/Tools/ManageGameObjectDeleteTests.cs

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📝 Walkthrough

Walkthrough

This PR enables undo/redo support for GameObject deletion by switching from Object.DestroyImmediate to Undo.DestroyObjectImmediate in the GameObjectDelete handler. A test validates that deleted GameObjects are restored when undo is performed.

Changes

Undo-compatible GameObject deletion

Layer / File(s)	Summary
Undo-aware deletion implementation MCPForUnity/Editor/Tools/GameObjects/GameObjectDelete.cs	GameObjectDelete.Handle replaces Object.DestroyImmediate(targetGo) with Undo.DestroyObjectImmediate(targetGo), removing the previous comment about test unreliability.
Undo behavior verification test TestProjects/UnityMCPTests/Assets/Tests/EditMode/Tools/ManageGameObjectDeleteTests.cs	New Delete_RegistersUndo_RestoresOnUndo test verifies deletion registers with Unity's Undo system, confirms the object is destroyed, performs undo, and asserts the GameObject is restored.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A rabbit hops through undo's gleaming thread,
Where GameObjects once gone now live again—
DestroyImmediate? Nay, let Undo spread,
Each deletion blessed with a second when.
Tests hop along to prove it all just right! 🎯

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly and clearly describes the main change: switching from Object.DestroyImmediate to Undo.DestroyObjectImmediate to register undo when deleting GameObjects via the manage_gameobject function.
Description check	✅ Passed	The description covers all required template sections: Summary, Type of Change (Bug fix), Changes Made, Testing, Related Issues, and notes. It provides detailed context, implementation rationale, test verification, and scoping decisions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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