Data safety

Vaults usually hold a server's most valuable items, so the plugin is designed not to duplicate or lose them.

Protections

Protection	What it prevents
Durable save on close	Closing a vault or quitting waits until the file is on disk. If the server dies right after, the content is already safe — there is no rollback to duplicate.
Q / Ctrl+Q cancelled	Dropping items out of the vault GUI by accident.
Outside clicks cancelled	Losing the item held on the cursor to the void, which a vanilla chest would do.
Off-hand key (F) guarded	The 1.16.x cursor desync vector; the swap is cancelled while a vault is open.
No zombie GUIs	Reloading the plugin closes open vaults, and on enable any surviving vault view is closed, so an old inventory cannot be emptied twice.
Switch without loss	/pv 1 then /pv 2 saves the first vault regardless of event timing differences between versions.
Atomic writes	Every save writes a .tmp file and moves it over the real file: a crash mid-write cannot leave a half-written file.
No cross-session cache	Data is read from disk when the vault opens and dropped when the player quits.
Autosave	storage.autosave-seconds (300 by default) limits the loss if the server crashes while a vault is open.
Backup on unreadable files	A file that cannot be parsed, or an item that fails to deserialize, is copied to <name>.<timestamp>.bak before anything can overwrite it.

Storage format

One readable file per player:

plugins/JPPlayerVaults/data/<uuid>.yml

uuid: 30fecbe1-2271-3418-8553-d3ded0e95f56
last-known-name: TestBot
vaults:
  '1':
    items:
      '0':
        ==: org.bukkit.inventory.ItemStack
        type: DIAMOND
        amount: 5

This makes backups, migrations and manual repairs possible with any text editor. Stop the server (or have the player quit) before editing a file by hand, and never edit it while the server is running.

Known limits

• If the process is killed while a player has a vault open, the last save is restored (hence autosave). Saving on every click would tax the whole server.
• Closing a vault blocks the calling thread until the write finishes, bounded to 5 seconds. That is deliberate: it is what makes the durable-close guarantee possible.
• Do not share one data/ folder between several running servers. The plugin does not sync servers live: two active servers with the same player is not a supported scenario.
• Autosave writes all open vaults every cycle; with hundreds of players holding vaults open at the same time, tune storage.autosave-seconds to your hardware.

Recovering from a bad file

1. Stop the server or ask the player to quit.
2. Look for data/<uuid>.yml.<timestamp>.bak next to the file.
3. Compare both files, keep the good one and rename it to <uuid>.yml.
4. Start the server and open the vault.

If an item cannot be deserialized after a Minecraft update, the console names the player, the vault and the slot, and the rest of the vault loads normally.