InputBooster 4.1.3-alpha1 — Minecraft 26.1 – 26.3

Alpha build. Client-side only; install it in mods/ alongside Fabric API.

Supported Minecraft versions

Jar	Minecraft
inputbooster-4.1.3-alpha1-mc263.jar	26.3
inputbooster-4.1.3-alpha1-mc262.jar	26.2
inputbooster-4.1.3-alpha1-mc2612.jar	26.1.2
inputbooster-4.1.3-alpha1-mc2611.jar	26.1.1
inputbooster-4.1.3-alpha1-mc261.jar	26.1

Each jar declares its own exact Minecraft range, requires Java 25, Fabric loader 0.19+, and Fabric API at or above the build it was compiled against.

Verified bug fixes

Native input no longer sampled off the game thread

glfwGetKey is a main-thread function, and the high-frequency poller was calling it (directly and through InputConstants.isKeyDown) from its own thread. That is undefined behaviour: it usually appears to work, then returns stale data or crashes under load. The poller now only reads an immutable 512-bit snapshot that the game thread publishes once per rendered frame (HUD hook) and once per tick. Sampling therefore still happens above tick rate, but only where the platform API is allowed to be called. Native failures are reported once with the exception and fall back to tick-rate sampling instead of being swallowed.

One key bound to several actions

KeyBindingProcessor resolved a key code to the first matching slot, while the polling path applied every slot. With two actions on one key the two sources disagreed: a press produced one action or two depending on which saw it first. Codes now resolve to a bit mask of every bound slot and both paths dispatch all of them.

POLL mode left slot state stale

The event path returned before updating slots when the engine was in POLL mode, so the documented "the event source always updates state" contract was not met and a live mode switch started from old data. Slots are now updated in POLL mode with dispatch suppressed.

Shared mutable key-binding state

KeyBindingSet.codes was a public array and KeyBindingProcessor.codes() returned its internal array, so any caller could rebind an action mid-fight. Both now hand out copies (copyCodes(), codes()), with regression tests.

Click and scroll windows raced

InputEventDispatcher.lastClickNanos and MouseProcessor.lastScrollNanos were plain fields written by both the game thread and the poller. Two clicks on different threads could both pass the check. Both windows are now claimed with an atomic compare-and-set, so exactly one click per window is accepted.

Custom keyboard handler and key mapping

Handler mode selection was not deterministic

The poller skipped the tick snapshot whenever the alpha custom handler was enabled, and nothing checked whether that handler could actually see events. On a client where the keyboard/mouse mixins did not apply this left the mod with no input source at all, silently. Source selection is now one pure decision (InputPollingThread.chooseSource, with a RAW/SNAPSHOT/IDLE result):

• native sampler usable -> raw, frame-rate sampled state;
• otherwise, custom handler disabled -> tick snapshot;
• otherwise, custom handler enabled and its hooks have delivered an event -> the handler owns input;
• otherwise (enabled but no event ever seen) -> tick snapshot plus one warning line, instead of dead input.

The active source is logged whenever it changes, a source switch resets the engine so no key is inherited as held, and the overlay's keyboard line now distinguishes "custom (alpha, live)" from "custom (alpha, no events yet)".

The player's real binding is respected, and fallbacks are named

Slot resolution still falls back to the vanilla default when a mapping cannot be read, but it no longer does so invisibly: KeyBindingSet records which slots fell back and whether the cause was a missing mapping or a failed accessor, and the fallback warning lists the affected slot names once. A mapping that resolves always keeps the key the player actually bound, including custom mouse buttons.

Registration happens exactly once

Fabric does not detect duplicate key mappings: registering the same KeyMapping twice adds a second row to the Controls screen and the player's rebind then applies to only one of them. The entrypoint now claims the single registration pass before registering, and createKeyMappings() still runs during mod construction, before registration and before any input path is wired.

Tests

StabilityAuditTest covers: one key bound to two actions (mask, event path and POLL mode), reset clearing every slot and allowing the next press, defensive copies, stale-resolution removal after a rebind, eight concurrent threads claiming one click window, four concurrent threads hammering the state manager followed by a reset, one edge per press/release at 60/200/500/750/1000 Hz, and the unavailable-native-state path. The suite is 106 tests on the modern targets and 102 on the legacy targets.