Singleplayer integrated server only allows crawl control from the host.

[FamroFexl]

Describe the bug
An "Open to LAN" integrated server only has crawl control assigned to the host. The host determines if all other players can crawl based on if the host is crawling. Client-side crawling is not affected. The server doesn't acknowledge player guests are crawling, both visually and mechanically. When the host crawls, the player guests receive a slight pose stuttering, indicating the server is attempting to put them into crawl mode, but it is quickly overridden by the client.

Mod version affected
1.0.2

Other mods used
Unknown except for fabric api

Minecraft version used
1.20

To Reproduce
Set a single-player world "Open to LAN", have another player on, and have the host shift.

Additional information
Other mod versions and Minecraft versions are likely affected as well

[yermachello]

Got the same issue on 1.19.2 quilt

[yermachello]

This is how it looks from a host perspective:

[FamroFexl]

It's such an annoying bug. The real issue is that behavior on dedicated servers and integrated servers should be the same since both versions are basically identical, but it isn't. In all my testing, nothing has been amiss logically, so it's a very frustrating discrepancy.

[FamroFexl]

Crawling functionality is handled by the client-side implementation when using the integrated server for multiplayer. Both ServerPlayer and LocalPlayer instances are handled this way.

Since the client wasn't programmed to expect multiple players (and rather delegate that task to the server), it automatically forces all player instances to crawl at the request of the integrated server host. Because the client handles all player instances, the server-side doesn't process crawl request packets from guest clients, meaning they can only crawl through 1-block holes when the server host is crawling.

[FamroFexl]

The Crawl mod solves this issue by injecting a custom enum into the player pose states and passing it on the network. The Crawl On Demand mod solves this issue by using Forge's capability system.

[Kazuhiko-Gushiken]

The Crawl mod solves this issue by injecting a custom enum into the player pose states and passing it on the network. The Crawl On Demand mod solves this issue by using Forge's capability system.

Although sadly (to my knowledge) your is the only one that works whether the player has the mod installed or not. I was using the Crawl mod, but it uses a custom EntityPose so every time someone who does have the mod installed (obviously on the server as well) crawls, the person without the mod installed client side would get kicked. Your mod uses the SWIMMING EntityPose, so it doesn't do that. Sadly I do like the custom entity pose, but it wont do for my use case.