TimeLens

First public test release.

TimeLens reconstructs how an area of your world looked at an earlier point in time and shows it to a single player, using block history recorded by CoreProtect. The world itself is never written to.

Please read

This is an alpha. The central promise, that a historical view is visible only to the player who requested it, has been verified by design and by code review, but it has not yet been confirmed with two clients on a live server. Please do not run this on a production server.

What works

• Views given as an age (30m, 2h, 7d, 2w) or as a calendar date and time (2026-08-20 14:30), read in the server's time zone
• An optional per-view radius, so a view that falls short of a build can be widened without editing the configuration
• History lookups run off the main server thread
• Two independent limits bound the cost of a single view, and a request exceeding either is refused with an explanation rather than rendered slowly
• Views are cleaned up on exit, disconnect, world change, teleport and death. Nothing about a player is modified, so no plugin state can survive a crash

Measured

• Reconstruction agrees with an independent SQL calculation on 1,971 of 1,971 positions from a real CoreProtect database
• Main-thread render preparation costs 0.5 to 2.8 ms for up to 2,400 blocks, where one tick is 50 ms
• 83 unit tests, clean build from a fresh checkout

Requirements

Paper 1.21.11 or a fork, Java 21 or newer, and CoreProtect 24.0 or newer with its API enabled. Will not load on Spigot or CraftBukkit. Folia is untested.

Not included

Entities, inventories and most block-entity data are not reconstructed. Timeline playback, graphical interfaces and block inspection are deliberately absent. The foundation should prove itself first.