When an input is held and its corresponding action becomes available later, the action is delayed; auto-clutch with water bucket, cobweb, etc. often fails

Description

This report describes an issue which, despite being very long-standing, does not seem to have been reported before. When the player begins holding down one of their inputs while the corresponding action cannot be performed (eg. they are trying to break a block while looking up into the sky, or are trying to interact with something while looking at a stone block), they do not immediately perform the associated action once it becomes available (i.e. once it looks like it should be possible from the player’s point of view). Instead, the action is delayed, seemingly based on the time between the action becoming available and the next server tick, and sometimes the player ends up breaking/interacting with a different block or entity than the first one they saw (see attached videos for an example).

To reproduce

1. Hold a cobweb

2. Stand on the center of a full, solid block with no other blocks above it, not even grass or flowers

3. /spawnpoint @s ~ ~ ~

4. /gamerule keepInventory true

5. /gamerule doImmediateRespawn true

6. Switch to survival mode if not already in it

7. /tick rate 2

8. /execute align xyz run teleport @s ~0.5 ~50 ~0.5 0 90

9. Mash right-click like your life depends on it
   ✅ By mashing hard enough, you are always able to save yourself with the cobweb

10. Repeat the command in step 6, but this time hold down right-click while you are still well above the ground
    ❌ There is a roughly 50% chance that the cobweb will not get placed before you hit the ground and die, even though there was clearly a window where it could have been placed

It would be expected that holding down right-click would always be sufficient to save the player.

Impact

While this issue is generally quite minor in normal gameplay, it can make the difference between life and death in certain critical situations, most commonly when the player is falling from a great height and attempting to save themselves with a water bucket. Assuming for a moment that players being able to save themselves in this way is broadly intended, ideally the player should always be able to survive by holding down right-click well before they hit the ground, but in practice this succeeds no more than 10% of the time (cobwebs seem to be more forgiving for some reason).

Thoughts on a fix

This issue is essentially a client issue, and a fix would likely involve few or no changes to the server code. The main implication of a fix is that it will be significantly easier for many players to save themselves from high falls. Changing water so that it removes fall damage progressively rather than all at once it would have a balancing effect in that players would be forced to obtain a cobweb, slime block or the like for immunity to high falls, but this would force redesigns of many existing builds and would be unpopular with those who relish the “skill” required by the current mechanics. So I would totally understand if Mojang resolved this as Won’t Fix, but I would also be interested to hear whether any changes are in the works to remedy this issue.