IDE-321 Feat: Finalize multi-step undo/redo system

[harshsomankar123-tech]

Jira Ticket: https://catrobat.atlassian.net/browse/IDE-321

Description

Implements a robust project-scoped multi-step undo/redo system. This PR focuses exclusively on the core reliability of the undo/redo chain, state persistence, and UI synchronization.

Key Fixes & Features:

• Multi-Step Stability: Fixes stale code.xml snapshots by ensuring project saves before every undo/redo push.
• Race Condition Protection: Adds an isUndoRedoInProgress guard to prevent overlapping async project loads during rapid clicking.
• Correct UI Refresh: Fixes the fragment lookup bug (findFragmentByTag → findFragmentById) so the script view correctly updates after every operation.
• Context Preservation: Ensures sceneName and spriteName are correctly stored in all history entries.
• Memory Safety: Deep-copies variable lists to prevent shared reference mutation between history steps.
• Modern UI: Undo/Redo buttons stay visible but greyed out when no history is available, providing better visual feedback.
• History Management: Prunes snapshots after 1 hour (TTL) and clears history during project delete, rename, or copy.

Screen Recording

Screen.Recording.2026-03-31.at.06.33.02.mov

Checklist for this pull request

Please review the contributing guidelines and wiki pages of this repository.

• Include the name of the Jira ticket in the PR’s title
• Include a summary of the changes plus the relevant context
• Choose the proper base branch (develop)
• Confirm that the changes follow the project’s coding guidelines
• Verify that the changes generate no compiler or linter warnings
• Perform a self-review of the changes
• Verify to commit no other files than the intentionally changed ones
• Include reasonable and readable tests verifying the added or changed behavior
• Confirm that new and existing unit tests pass locally
• Check that the commits’ message style matches the project’s guideline
• Stick to the project’s gitflow workflow
• Verify that your changes do not have any conflicts with the base branch
• After the PR, verify that all CI checks have passed
• Post a message in the catroid-stage or catroid-ide Slack channel and ask for a code reviewer

[Copilot]

Pull request overview

Implements a project-scoped multi-step undo/redo mechanism by introducing a dedicated snapshot/history manager, wiring it into ScriptFragment/SpriteActivity, and updating UI/tests to reflect the new enabled/disabled behavior.

Changes:

• Added ProjectUndoManager to manage per-project snapshot stacks (undo/redo) and variable snapshots.
• Updated ScriptFragment and SpriteActivity to drive undo/redo via the new manager and keep menu items visible but disabled when unavailable.
• Added/updated unit + UI tests and ensured undo history is cleared on project delete/rename.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
catroid/src/main/java/org/catrobat/catroid/ui/recyclerview/fragment/ProjectUndoManager.java	New undo/redo snapshot manager with disk-backed snapshots, TTL cleanup, and clear helpers.
catroid/src/main/java/org/catrobat/catroid/ui/recyclerview/fragment/ScriptFragment.java	Integrates multi-step undo/redo, adds async-guard, and refreshes UI after project reload.
catroid/src/main/java/org/catrobat/catroid/ui/SpriteActivity.java	Adds lazy ProjectUndoManager, introduces redo menu handling, and updates menu enable/visibility logic.
catroid/src/main/res/menu/menu_script_activity.xml	Adds redo action and defaults undo/redo to disabled + hidden until prepared.
catroid/src/main/java/org/catrobat/catroid/common/Constants.java	Adds UNDO_DIRECTORY_NAME constant for snapshot storage.
catroid/src/main/java/org/catrobat/catroid/ui/recyclerview/fragment/ProjectListFragment.kt	Clears undo history when deleting/renaming projects from the list.
catroid/src/main/java/org/catrobat/catroid/ui/fragment/ProjectOptionsFragment.kt	Clears undo history on project rename/delete via project options.
catroid/src/androidTest/java/org/catrobat/catroid/uiespresso/ui/fragment/UndoTest.java	Updates existing undo assertions and adds multi-step + rapid-click coverage.
catroid/src/test/java/org/catrobat/catroid/ui/recyclerview/fragment/ProjectUndoManagerTest.java	Adds unit tests for stack limiting/history clearing (currently has issues).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 7 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-advanced-security]

detekt found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud