SmoothLogin 0.1.0

Initial release of SmoothLogin, a server-side Fabric mod focused on asynchronous player-login preparation for Minecraft 26.1+.

Asynchronous login pipeline

• Added off-thread player NBT loading and preparation.
• Added off-thread statistics and advancement file reads and JSON parsing.
• Added a configurable login worker pool with runtime resizing.
• Added prepared-data ownership and lifecycle guards for login, configuration, disconnect and spawn transitions.
• Added serialized asynchronous usercache.json writes to prevent concurrent updates from being lost.

Optional UUID migration toolkit

• Added opt-in automatic UUID migration for authentication-mode changes, including offline mode, authenticated skin stations, and Mojang authentication.
• Automatic migration is disabled by default; asynchronous login preparation works independently without enabling it.
• Added manual inspection, binding, migration and undo commands that remain available while automatic migration is disabled.
• Added migration support for:
  • player NBT data;
  • statistics;
  • advancements;
  • operator, whitelist and ban entries;
  • supported UUID-named files and directories;
  • supported UUID references in JSON and NBT world data.

Migration safety

• Added per-migration backups and configurable backup retention.
• Added migration history and exact-backup undo support.
• Added rollback attempts when a migration step fails.
• Added source/target login guards to prevent migration while either identity is active.
• Added target-data collision detection; existing target data is never overwritten automatically.
• Added persistent conflict records and administrator decision tracking.
• Added strict evidence mode and configurable skin-station name uniqueness assumptions.

Administration

• Added /smoothlogin info <name>.
• Added /smoothlogin migrate <name>.
• Added /smoothlogin bind <name> <old-uuid>.
• Added /smoothlogin undo <name>.
• Added /smoothlogin conflicts list.
• Added /smoothlogin conflicts resolve <name> <keep|old|new>.
• Added /smoothlogin automigrate and /smoothlogin automigrate <on|off> for status and persistent runtime control.
• Added /smoothlogin reload with runtime worker-pool resizing.
• Added config/smoothlogin.json for migration scope, safety policy, cache limits, backup retention and login worker count.

Compatibility

• Minecraft 26.1+
• Fabric Loader 0.17.3+
• Fabric API
• Java 25
• Server-side only; clients do not need SmoothLogin installed

Before changing a production server's authentication mode, create a complete external backup and review the generated SmoothLogin configuration.