feat(multiplayer): dispatch completed result events

server/store/outbox.go

@@ -35,6 +35,18 @@ WHERE published_at IS NULL AND event_type = 'proposal_changed'
 ORDER BY created_at, event_id
 LIMIT $1`
 
+const OutboxUnpublishedResultSelectSQL = `SELECT event_id, aggregate_type, aggregate_id, revision,
+    event_type, payload, created_at, published_at
+FROM outbox
+WHERE published_at IS NULL AND event_type = 'match_completed'
+ORDER BY created_at, event_id
+LIMIT $1`
+
+const MatchParticipantIDsSQL = `SELECT player_id
+FROM match_participants
+WHERE match_id = $1
+ORDER BY player_id`
+
 const OutboxMarkPublishedSQL = `UPDATE outbox
 SET published_at = $2
 WHERE event_id = $1 AND published_at IS NULL`
@@ -106,6 +118,36 @@ func ReadUnpublishedProposalOutbox(ctx context.Context, db *sql.DB, limit int) (
 	return readUnpublishedOutbox(ctx, db, limit, OutboxUnpublishedProposalSelectSQL)
 }
 
+// ReadUnpublishedResultOutbox returns only durable match-completion events.
+// Proposal and result consumers acknowledge separate event types so one
+// transient fan-out outage cannot hide rows owned by another consumer.
+func ReadUnpublishedResultOutbox(ctx context.Context, db *sql.DB, limit int) ([]OutboxEvent, error) {
+	return readUnpublishedOutbox(ctx, db, limit, OutboxUnpublishedResultSelectSQL)
+}
+
+func ReadMatchParticipantIDs(ctx context.Context, db *sql.DB, matchID string) ([]string, error) {
+	if db == nil || matchID == "" {
+		return nil, fmt.Errorf("invalid match participant read arguments")
+	}
+	rows, err := db.QueryContext(ctx, MatchParticipantIDsSQL, matchID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var players []string
+	for rows.Next() {
+		var playerID string
+		if err := rows.Scan(&playerID); err != nil {
+			return nil, err
+		}
+		players = append(players, playerID)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return players, nil
+}
+
 func readUnpublishedOutbox(ctx context.Context, db *sql.DB, limit int, query string) ([]OutboxEvent, error) {
 	if db == nil || limit < 1 || limit > 1000 {
 		return nil, fmt.Errorf("invalid outbox read arguments")