Inconsistent (default) gamemode in Singleplayer/LAN in various different scenarios

Due to the changes made recently, gamemode and defaultgamemode have become extremely inconsistent, inconvenient and incomprehensible. Let me explain all the different scenarios that cause unexpected behavior after I lay down the expected behavior.

Terminology

• World visibility state

  • Singleplayer: A world that is created through singleplayer world creation, is NOT open to LAN only housing a single player.

  • Open to LAN: A world that is created through singleplayer world creation, but is opened to LAN. It houses 1 or more players.

  • Multiplayer: A world that is created through dedicated server multiplayer world creation. It houses 0 or more players.

• Gamemode state

  • (Player) Gamemode: The gamemode of an individual player.

  • Default Gamemode: the default gamemode of the world which is traditionally modified with /defaultgamemode and shows up on the level select screen in singleplayer. (or in server.properties > gamemode=<GAMEMODE> for servers)

  • LAN Gamemode: the temporary default gamemode which applies only in Open to LAN worlds to other players.

  • Forced Gamemode: the gamemode to switch players to upon joining. Found in server.properties force-gamemode=<bool>

Expected

Assume all worlds created start with Survival gamemode and commands enabled to be able to switch gamemode.

• Singleplayer

  • if I change my gamemode to adventure mode, and upload the world for others to download, they should also be in adventure mode, this is a courtesy of the newly introduced changes.

  • if I deliberately force the defaultgamemode to be survival, and I change to creative mode, I do NOT expect the defaultgamemode to change, I want to have control, and being explicit and deliberate about changing it, should not make gamemode changes in the future change this. it would be very confusing.

    • Take for example, I want to make a fix to an existing world download, I quickly pop into creative to make my fixes and close the world and reupload it. Now it messes up the defaultgamemode, despite me having deliberately set it to survival prior to changing gamemode.

• Open To LAN

  • open to LAN without changing any settings should inherit the default gamemode for any newly joining players.

  • open to LAN with overriding the LAN gamemode should instead of the world’s defaultgamemode, now use this gamemode for newly joining players

  • as a guest player, exiting and rejoining a world during the same open to LAN session, should NOT change my gamemode. did I leave in survival? then I should join in survival.

  • as a host player, changing my own gamemode during open to LAN session should not change the defaultgamemode/open to lan gamemode. any guest players joining should not copy my gamemode, but follow the open-to-lan override/defaultgamemode.

  • changing defaultgamemode in an open-to-lan world should NOT adjust ANYONE’s gamemode.

• Multiplayer

  • force-gamemode=false

    • gamemode in server.properties applies to new players

    • /defaultgamemode works as an override for gamemode in server.properties for new players.

    • changing any or all player’s gamemode of players currently online should not affect defaultgamemode

    • /defaultgamemode should not affect anyone’s gamemode

  • force-gamemode=true

    • gamemode in server.properties applies to joining players

    • /defaultgamemode works as an override for gamemode in server.properties for joining players

    • /defaultgamemode should force everyone’s gamemode, anyone currently online and joining players

    • /gamemode only affects targeted players' gamemode, upon rejoining, the defaultgamemode is applied again

Actual

• Singleplayer

  • if I change my gamemode to adventure mode, and upload the world for others to download, they should also be in adventure mode, this is a courtesy of the newly introduced changes. (Works as expected)

    • singleplayer will take over the shared inventory, gamemode, location etc. (as expected)

  • if I deliberately force the defaultgamemode to be survival, and I change to creative mode, the defaultgamemode changes. (Not as expected)

• Open To LAN

  • open to LAN without changing any settings should inherit the default gamemode for any newly joining players. (expected)

  • open to LAN with overriding the LAN gamemode should instead of the world’s defaultgamemode, now use this gamemode for newly joining players (expected)

  • as a guest player, exiting and rejoining a world during the same open to LAN session, changes my gamemode back to the open-to-lan/defaultgamemode (not expected, behaves as if force-gamemode is enabled)

  • as a host player, changing my own gamemode during open to LAN session modifies the open-to-lan gamemode if it wasn’t modified as well as the default gamemode. If I changed the open-to-lan gamemode, it will no longer change this seemingly through /defaultgamemode or /gamemode. (not expected)

  • changing defaultgamemode in an open-to-lan world changes everyone’s gamemode to the open-to-lan gamemode (or defaultgamemode) (not expected)

    • ANY PLAYER INCLUDING GUESTS and datapacks could run /defaultgamemode thus changing everyone’s gamemode.

    • ANY PLAYER INCLUDING GUESTS and datapacks could run /gamemode for the host, thus changing the defaultgamemode through proxy.

  • The host changes the gamemode for other players in OPEN to LAN settings: this changes everyone’s gamemode except the host (weird, maybe expected, maybe not? on one hand it does change other players as advertised, but maybe I expect it to only affect newly joining players?)

• Multiplayer

  • Seems to work as expected

Please check the attached video, as it is too long to explain all this behavior, as it visually show many of these scenarios. https://www.youtube.com/watch?v=kUegubINAiw