Technical ReferenceSemantics

Limitations

Everything 4.1.2-alpha does not do, including settings that are stored but have no runtime effect.

4 min readInputBooster 4.1.2-alphaMinecraft 26.2 / 26.3

This page lists the gaps. It is deliberately long, because a setting that looks live and is not is worse than a missing one.

The alpha itself

4.1.2-alpha is the current source tree. The input engine and the new settings screen are new code and have not been tested in a running client. 4.0.3-stable is the last stable build.

Settings that are stored but have no effect

These five keys are written to the config file, validated, and reachable from the settings screen. No runtime behaviour depends on them.

Key	What you would expect	What actually happens
`show_keystrokes`	A keystroke display	There is no renderer. Nothing is drawn
`fps_check_interval`	FPS sampled every N ticks	The adaptive rate is recomputed every client tick
`keyboard_repeat_guard`	Toggle for "a held key is one press"	Repeat events are discarded unconditionally, before the toggle is read
`debug_mode`	Verbose diagnostics	No log statement is gated on it
`click_sound_volume`	A quieter click sound	The sound instance is created with the pitch only

Features that exist but have no interface

Feature	State
The event log	Collected, bounded at 80 entries and correctly trimmed. No viewer. Only the internal `snapshot()` and `latest()` accessors
Config import, export and presets	Implemented in `ConfigTools`. No button calls them. The `pvp`, `low_fps`, `debug` and `balanced` presets are unreachable
Per-server profile bindings	`PerServerProfileManager.bind()` writes the file correctly. No button calls it. The binding file has to be written by hand

Behaviour that is narrower than it sounds

Setting	Reality
`show_action_bar`	Gates the burst mode start and end messages only. The replay, profile and combo key messages are sent regardless
`cps_mode`	Never validated. An unknown value behaves exactly like `FIXED`, because that is the default arm of the switch
`mouse_scroll_debounce_ms`	The debounce works, but scroll is only counted. The mod never applies scroll input
The overlay	Has no latency average or peak line. Those values live in the profiler and are shown on the settings screen instead

The action rules

Some actions are deliberately narrow:

Attack only fires against a living entity within 36 squared units — the vanilla melee reach. Nothing is ever attacked at a longer distance.
Use only fires when the crosshair hits nothing. A chest, a lever or an entity goes back to vanilla's own startUseItem().
Block breaking is never handled by the mod. It is a held-key mechanic that vanilla already runs every tick.
The offhand swap is never handled by the mod.
Pick block needs the accessor mixin to have applied. If it did not, the log says so once and pick-block input is disabled for the session.

Compatibility

Limit	Detail
Six known input mods	Controlify, Midnight Controls, Controllable, Sodium, Iris and Zoomify are detected by class name. A mod that owns input routing but is not on the list will not trigger the fallback
The alpha keyboard handler	May pass a key twice or drop it on an untested version or mod combination
The event hooks	`require = 0`, so a renamed target degrades to polling instead of crashing. The startup log says whether they applied
The screen router	Falls back to a per-tick HUD check if neither screen hook applied

Versions and platforms

Limit	Detail
Minecraft 26.2 and 26.3 only	No 1.21.x build exists in this tree. The 1.21 jars come from an older codebase with different behaviour
No NeoForge build for 26.3	The NeoForge project targets 26.2 only
Java 25	Required by the mixin manifest and by the Fabric metadata
Fabric Loader 0.19.0+	The bracket-range bug in loader 0.19.5 is worked around, not fixed

The public API repository is no longer maintained. It targets Minecraft >=1.21 <1.22 on Java 21 with Fabric only, and it is not wired into the 26.x tree. Anything built against it will not work with this mod. See the archived API page.

Known documentation discrepancies

The README and the source disagree in two places. This site documents the source.

README says	Source does
The key bindings are in an InputBooster category	They are registered under `KeyMapping.Category.MISC`
The event mixins target `MouseHandler.onPress/onScroll`	They target `onButton` and `onScroll`; `onPress` does not exist in 26.x

What the mod will never do

Generate input without a physical press.
Extend reach or change hit registration.
Cancel another mod's key events or remap another mod's bindings.
Replace vanilla's KeyboardHandler or MouseHandler.
Send anything to a server that vanilla would not send.
Claim a performance improvement it has not measured.

Key reference — the five inert keys in context.
Action semantics — the exact conditions.
Support matrix — what is published.