Single-player worlds lose host/server permissions starting after 26.3-snapshot-5

There appears to be a regression in single-player world permissions introduced after 26.3-snapshot-5.

In 26.3-snapshot-5, single-player worlds behave normally: the pause menu contains the "Open to LAN" option, and the single-player host has the expected permissions.

In newer snapshots, the "Open to LAN" button has been replaced by "World Options". Since this change, the player hosting a single-player world appears to be treated as if they do not have server permissions.

For example, when attempting to change the difficulty or perform actions requiring server permissions, the game reports that server permissions are required.

Steps to reproduce

1. Launch Minecraft Java Edition using a snapshot newer than 26.3-snapshot-5.

2. Create a new single-player survival world.

3. Enter the world.

4. Open the pause menu and select World Options.

5. Attempt to change the difficulty or perform another action requiring server permissions.

6. Observe that the player is told that server permissions are required.

Expected behavior

The player hosting a single-player world should have the appropriate permissions to manage their own world, including changing the difficulty and using commands when command access is enabled.

Actual behavior

The single-player host appears to lack the required server permissions. Actions such as changing the difficulty report that server permissions are required.

Additional information

• Last known working version: 26.3-snapshot-5

• First affected version: A snapshot after 26.3-snapshot-5

• The problem occurs with existing worlds as well as newly created worlds.

• Therefore, the issue does not appear to be caused by corruption or incompatible world data.

• The change coincides with the replacement of "Open to LAN" with "World Options" in the single-player interface.

• The issue is reproducible in a completely new world.