fix: keep invader game reset watchdog active

src/sammo/AutoResetProgress.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace sammo;
+
+/**
+ * Wall-clock inactivity anchor used only by the reserved reset watchdog.
+ *
+ * GameClock ticks remain authoritative for gameplay. This timestamp records
+ * when a united or invader game last changed phase or actually advanced, so
+ * j_autoreset can distinguish a healthy running event from a stalled server.
+ */
+final class AutoResetProgress
+{
+    public const STORAGE_KEY = 'autoreset_united_wall_anchor';
+
+    private function __construct()
+    {
+    }
+
+    public static function record(
+        KVStorage $gameStorage,
+        ?\DateTimeInterface $wallTime = null,
+    ): void {
+        $wallTime ??= GameClock::readWallTime();
+        $gameStorage->setValue(self::STORAGE_KEY, TimeUtil::format($wallTime, true));
+    }
+
+    public static function recordIfAdvanced(
+        KVStorage $gameStorage,
+        int $beforeTick,
+        int $afterTick,
+        ?\DateTimeInterface $wallTime = null,
+    ): bool {
+        if ($afterTick <= $beforeTick) {
+            return false;
+        }
+        self::record($gameStorage, $wallTime);
+        return true;
+    }
+}