From 78a81f468ea676ac6aef5946dbed065fff9350c2 Mon Sep 17 00:00:00 2001
From: Hendrik Brombeer <hendrik@grounds.gg>
Date: Sun, 2 Aug 2026 10:04:12 +0200
Subject: [PATCH] fix(velocity): never transfer players who are inside a round
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The drain deadline used to transfer everyone left, ending rounds early.
Players inside a round now stay put: either the round finishes within
the grace period and the lobby connect becomes the transfer, or the
pod's termination ends the session — the same outcome a forced transfer
would have produced, without yanking anyone out of a running round.
---
 .../kotlin/gg/grounds/drain/DrainManager.kt   | 23 +++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/velocity/src/main/kotlin/gg/grounds/drain/DrainManager.kt b/velocity/src/main/kotlin/gg/grounds/drain/DrainManager.kt
index 558b2ae..45e9cd5 100644
--- a/velocity/src/main/kotlin/gg/grounds/drain/DrainManager.kt
+++ b/velocity/src/main/kotlin/gg/grounds/drain/DrainManager.kt
@@ -16,8 +16,10 @@ import org.slf4j.Logger
  * - players sitting in a lobby are sent a Minecraft transfer packet right away,
  * - players inside a round stay untouched — Agones keeps their GameServer alive, and the moment the
  *   round sends them back towards a lobby the transfer happens *instead of* that connect,
- * - at the deadline everyone still here is transferred regardless, because a transfer that ends a
- *   round early still beats the kick that is otherwise seconds away.
+ * - at the deadline, whoever is *not* inside a round is transferred; players inside a round are
+ *   never transferred — the round either ends within the grace period (and the lobby connect
+ *   becomes the transfer), or the pod's termination ends the session. A transfer would end the
+ *   round just as surely, only earlier.
  *
  * "Inside a round" is decided by the server's `grounds/server-type` role: anything that is not the
  * lobby role defers the transfer. A server that discovery has no role for cannot be a protected
@@ -75,8 +77,21 @@ class DrainManager(
     private fun onDeadline() {
         val remaining = proxy.allPlayers
         if (remaining.isEmpty()) return
-        logger.warn("Drain deadline reached with {} players left; transferring all", remaining.size)
-        remaining.forEach { transferOut(it, force = true) }
+        val (inRound, drainable) = remaining.partition { shouldDefer(roleOf(it), lobbyValue) }
+        if (drainable.isNotEmpty()) {
+            logger.warn(
+                "Drain deadline reached; transferring {} players not inside a round",
+                drainable.size,
+            )
+            drainable.forEach { transferOut(it, force = true) }
+        }
+        if (inRound.isNotEmpty()) {
+            logger.warn(
+                "Drain deadline reached with {} players still inside a round; leaving them " +
+                    "until the round ends or the pod is terminated",
+                inRound.size,
+            )
+        }
     }
 
     /**