InvSee Plugin

Released for NeoForge, Forge and Fabric, and for the Paper and Spigot plugins.

Fixed

• Items lost from old saves (mods). Opening an offline player who last played on an older Minecraft version could show their items wrongly: on 1.20.5 and newer, a save from before 1.20.5 showed a stack of 64 as a single item with no enchantments, and any edit made that permanent. Old saves now go through the game's own upgrade first, the same as when the player logs in.
• /invsee on yourself duplicated items (mods). A shift-click doubled the stack. Opening your own inventory this way is now refused.
• Items duplicated or lost when the player logged in with the menu open. Anything taken out was duplicated, and anything put in disappeared. Changes now save as you make them instead of when the menu closes, so the player logs in with exactly what the menu showed.
• Two moderators could take the same items from an offline player. Each had a private copy, and the later save could undo the earlier one. Everyone viewing the same offline player now shares one copy and sees each other's changes straight away.

Changed

• Saves from a newer Minecraft version (mods): a player file written by a newer version than the server is running no longer opens, because this version can't read what's in it.
• Failed saves (mods): these used to be ignored. The moderator now gets an error in chat, the reason goes in the server log, and the save keeps retrying while the menu is open.
• Menus only write what you changed (plugins): just looking at an offline player no longer rewrites their file, and closing a menu no longer overwrites what an online player picked up since it last refreshed.