Undo Mod v1.0.5 — Release Notes

Release date: 2026-06-26

🚀 New Features

YACL is now Optional (Recommended)

YACL (Yet Another Config Lib) v3 is no longer required, now a recommended dependency:

Status	YACL installed	YACL not installed
Settings Screen	Full YACL config (General / HUD / History)	Basic vanilla screen (mouse buttons + mode)
Dependency	recommends (optional, recommended)	Not needed — basic config built-in

Download the -bundled JAR to have YACL included automatically.

Basic Settings Screen (No YACL Required)

Press U to open settings:

• Mouse Side Buttons — ON / OFF
• Undo Mode — Full / Block Only

The mod works fully without YACL.

New Mod Icon

A custom icon (assets/undo/icon.png) now displays in the Minecraft mod list and on Modrinth.

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🐛 Bug Fixes

🔴 Critical: Mode Setting Not Synced to Server

• Symptom: Changing the undo mode in settings had no effect in-game
• Cause: Neither UndoBasicSettingsScreen nor UndoYaclConfig called UndoPacketSender.sendSetMode() to notify the server
• Fix: Mode changes now immediately send a SetMode packet to the server, which responds with a ModeSync acknowledgment

🔴 Critical: HUD Count Decremented Twice (MC 26.1.2)

• Symptom: The HUD history count decreased by more than expected after undo
• Cause: The client history_sync handler both set historyCount = payload.remaining() AND called decrementHistory(doneCount), causing a double decrement
• Fix: Removed the redundant decrementHistory() call

🟡 Digit 0 Not Usable for Number Input

• Symptom: Could not enter numbers containing 0 (10, 20, 100, etc.)
• Cause: UndoModClient.onClientTick() used for (int d = 1; d <= 9; d++), skipping GLFW.GLFW_KEY_0
• Fix: Added separate digit 0 detection

🟡 BlockAction Ignored setBlockState Return Value

• Symptom: Undo/Redo reported success even when world.setBlockState() failed (out of bounds, block replaced, etc.)
• Cause: BlockAction.undo() and redo() ignored the boolean return value of setBlockState()
• Fix: Methods now return the actual result of setBlockState()

🟡 placedState Used Default Block State

• Symptom: Stairs, slabs, and walls lost their orientation and shape on redo
• Cause: UndoEventListeners used BlockItem.getBlock().getDefaultState() instead of the actual placed state
• Fix: Updated placeAction.setPlacedState(actualState) in the placement confirmation callback

🔵 commitTransaction Hard-coded doneCount=0

• Fix: syncHistoryCount(playerUuid, 0) → syncHistoryCount(playerUuid, pending.size())

🔵 WorldMixin Reference Comparison

• Fix: currentState == newState → currentState.equals(newState) for safer BlockState comparison

🔵 UndoEventListeners Reference Comparison

• Fix: previousState != currentState → !previousState.equals(currentState)

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🔧 Other Changes

• Removed withSourcesJar() — build output is release JARs only
• Fixed DEFAULT_JVM_OPTS embedded quotes in 26.1.2 gradlew (Git Bash compatibility)
• CHANGELOG.md updated for all three versions

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📦 Build Artifacts

MC Version	Main JAR	Bundled JAR
26.1.2	Undo1.0.5-beta+fabric26.1.2.jar	Undo1.0.5-beta+fabric26.1.2-bundled.jar
1.21.1	Undo1.0.5-beta+fabric1.21.1.jar	Undo1.0.5-beta+fabric1.21.1-bundled.jar
1.21.2	Undo1.0.5-beta+fabric1.21.2.jar	Undo1.0.5-beta+fabric1.21.2-bundled.jar

All JARs are in the release/ directory of each project.