Personal keepInventory

Plugin category: Mechanics

Suggested name: KeepCommand

What I want: I'd like a plugin that allows player to toggle whether they are affected by pvp, and whether they can keep their items when they die, but only if they die within 20 seconds of being attacked by another player.
Ex: "Player 1 attacks Player 2, who has /keeptoggle enabled. Player 2 dies, but keeps his inventory. Player 2 later falls in lava more than 20 seconds after being pvp'd, and loses his things because he wasn't killed by anything close to a player."

If it's unclear, post a reply.
Ideas for commands:
/pvptoggle - Toggles pvp for player running the command.
/keeptoggle - Toggles keeping inventory upon death, ONLY

Ideas for permissions:
keep.togglepvp - allows player to use /pvptoggle
keep.togglekeep - allows player to use /keeptoggle
When I'd like it by: Anytime