BlockRedstoneEvent not reliably fired for Repeater blocks when redstone-implementation is VANILLA

[Carl-OS15]

Expected behavior

BlockRedstoneEvent should fire for a Repeater block whenever its powered/lit
state changes, consistent with how it fires for Redstone Wire.

Observed/Actual behavior

BlockRedstoneEvent does not fire consistently for Repeater blocks when their
state changes from unpowered to powered (or vice versa), even with
redstone-implementation explicitly set to VANILLA. This was confirmed via
debug logging inside a plugin (CraftBook) that relies on this event to
detect repeater state changes: no BlockRedstoneEvent is logged for the
Repeater block itself, despite Redstone Wire changes in the same circuit
firing the event reliably.

This appears to be part of a recurring pattern of Repeater/Comparator
blocks being poorly supported by Paper's block-update event system,
similar to:

• BlockDestroyEvent doesn't fire for a lot of redstone blocks #10869 (BlockDestroyEvent not firing for repeaters/comparators)
• Certain blocks in certain positions stay in the same state forever #3251 (blocks including repeaters getting permanently stuck in a state)
• Repeater Doesn't Forward Signal To Next Repeater #2643 (repeater not reliably forwarding signal to next repeater)
• [1.16.1] Dispenser behavior  #3967 (levers and redstone pulses not firing the same events)

A CraftBook maintainer confirmed this as a longstanding, recurring issue:
"Repeaters have been notoriously poorly supported in both Spigot/Paper
over the years. This issue has disappeared and re-appeared a few times
over the lifecycle of the Bukkit API, as the server platforms have
rewritten how their redstone systems work."

Steps/models to reproduce

1. Set redstone-implementation: VANILLA in paper-world-defaults.yml
2. Register a plugin listener for BlockRedstoneEvent (EventPriority.HIGH)
   that logs every event received, including block type and location
3. Place a Redstone Repeater block facing into an adjacent solid block
   (e.g. a Wall Sign)
4. Power the repeater's input so it turns on/lit, sending its output
   into the adjacent block
5. Observe: no BlockRedstoneEvent (or an inconsistent/missing one) is
   logged for the Repeater block itself

Plugin and Datapack List

Server Plugins (16):
Paper Plugins (1):

• BKCommonLib
  Bukkit Plugins (15):
• CraftBook, Essentials, MachinaBuilder, MachinaChem, MachinaCore, MachinaDrill,
  MachinaPump, mcMMO, Movecraft, ProtocolLib, SignManager, Train_Carts,
  TreeFeller, WorldEdit, WorldGuard

Datapacks:
There are 4 data pack(s) enabled: [vanilla (built-in)], [file/bukkit (world)],
[file/movecraft-data.zip (world)], [paper (built-in)]
There are no more data packs available

Paper version

This server is running Paper version 1.21.11-132-ver/1.21.11@c5eb079 (2026-05-11T11:43:09Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)
You are running the latest version

Other

Diagnosed via CraftBook (github.com/EngineHub/CraftBook), where a
wireless-redstone IC failed to activate when powered directly by a
Repeater, but worked correctly when powered via Redstone Wire.