Adaptive Sneak

The mod is a Fabric client mod that updates Minecraft's sneak handling. Players can switch between a toggle style, where a tap keeps crouching on until the next tap, and a hold style, where crouching lasts only while the key is held. A hold is recognized after 150 ms by default, and that threshold can be adjusted in the config file. Even while already sneaking, a longer hold turns the toggle off and stands the player up once the key is released.

The mod sorts out the two gestures on its own, so a quick double tap is read as a toggle and a single press is read as a hold. Typical double-click speed is around 130 ms, which is why someone who taps shift quickly may trigger the toggle by accident. In that case the threshold can be raised, and creative mode is a useful place to test values. A Toggle/Hold accessibility option in the settings matches the most recent gesture. The mod works with rebound sneak keys, but it requires installation on the server as well. Adaptive Sneak depends on Fabric API, and it is released under the GNU Lesser General Public License v3.0 or later, so the source code is open source.