Merge pull request #11731 from horizon-rust/fix/wool-vibration-drops

🤖 Agent: harness-only. Kills items and corpses between cases (the drop leak between the cow and item cases), and lists server_wool_vibration as known_flaky for the real-time player timing (1 of 4 on a loaded playhorizon).

tools/parity_hosts.json

@@ -57,6 +57,7 @@
  },
  "known_flaky": {
   "world_reopen": "counted 4 minecarts instead of 3 once on a loaded Mac mini runner, then passed at the same head (10-26)",
-  "lunge_motion": "a loaded Mac mini runner: the server catches up with two ticks for one of the jump's moves (Alice falls a tick of gravity more, -0.3015 vs -0.2277; the harness now names it), and vanilla's own run once sent an extra motion while sprinting; the same trees pass alone (#5656, 11-01)"
+  "lunge_motion": "a loaded Mac mini runner: the server catches up with two ticks for one of the jump's moves (Alice falls a tick of gravity more, -0.3015 vs -0.2277; the harness now names it), and vanilla's own run once sent an extra motion while sprinting; the same trees pass alone (#5656, 11-01)",
+  "server_wool_vibration": "real-time dedicated servers: the player cases send one client position per 50 ms sleep, so on a loaded machine the sensor's phase check sometimes runs before or after the landing (shrieker-jump-stone, Horizon's side, 1 of 4 runs on playhorizon at load 15-25, 11-07); the drop and corpse leaks between cow and item cases are cleared in the harness"
  }
 }

tools/test_server_wool_vibration_parity.py

@@ -84,7 +84,13 @@ def walk(x, ground):
 
 
 def arena(floor):
-    return ['step setup', 'cmd Alice time set 1000', 'cmd Alice kill @e[type=!player]',
+    # The previous case's cow drops its loot as /kill runs, after the selector picked the cow, and its corpse stays
+    # for 20 ticks (LivingEntity.tickDeath), still moving: the items, or the corpse once the fill below removes the
+    # carpet or slab under it, hit the ground while the next case measures, at a wall-clock moment (item-stone,
+    # item-carpet and item-slab flaked on vanilla's side, 2026-11-07). The second /kill removes the items, and 25
+    # server ticks let the corpse go before the arena changes.
+    return ['step setup', 'cmd Alice time set 1000', 'cmd Alice kill @e[type=!player]', 'cmd Alice kill @e[type=item]',
+            'ticks 25',
             'cmd Alice fill -3 -61 -3 8 -61 5 minecraft:stone', 'cmd Alice fill -3 -60 -3 8 -57 5 minecraft:air',
             *[f'cmd Alice {command}' for command in FLOORS[floor][1]]]