feat(multiplayer): persist live reconnect abandonments

server/domain/reconnect.go

@@ -156,6 +156,38 @@ type Abandonment struct {
 	AbandonedAt time.Time
 }
 
+// ReconnectParticipant is the durable subset needed to evaluate an expired
+// live reconnect lease. Connected players are deliberately absent: only a
+// persisted disconnect can start a player-caused abandon clock.
+type ReconnectParticipant struct {
+	PlayerID       string
+	DisconnectedAt time.Time
+}
+
+// PlanRankedAbandonments turns expired durable reconnect leases into the
+// same rolling cooldown ladder used by pre-live ranked no-shows. Future
+// disconnect timestamps are ignored rather than penalised: they can only be
+// an infrastructure clock anomaly, not a player abandonment.
+func PlanRankedAbandonments(now time.Time, participants []ReconnectParticipant, priorAbandons map[string][]time.Time) ([]Abandonment, error) {
+	if now.IsZero() {
+		return nil, fmt.Errorf("invalid reconnect-abandonment time")
+	}
+	seen := make(map[string]bool, len(participants))
+	result := make([]Abandonment, 0, len(participants))
+	for _, participant := range participants {
+		if participant.PlayerID == "" || participant.DisconnectedAt.IsZero() || seen[participant.PlayerID] {
+			return nil, fmt.Errorf("invalid reconnect participant")
+		}
+		seen[participant.PlayerID] = true
+		if now.Before(participant.DisconnectedAt) || now.Sub(participant.DisconnectedAt) <= RankedReconnectGrace {
+			continue
+		}
+		result = append(result, Abandonment{PlayerID: participant.PlayerID, Cooldown: abandonCooldown(priorAbandons[participant.PlayerID], now), AbandonedAt: now})
+	}
+	sort.Slice(result, func(i, j int) bool { return result[i].PlayerID < result[j].PlayerID })
+	return result, nil
+}
+
 // ExpireGrace marks every disconnected player whose 60-second reclaim window
 // has elapsed. The returned list is lexical for stable audit/event ordering.
 func (r *RankedConnections) ExpireGrace(now time.Time, priorAbandons map[string][]time.Time) []Abandonment {