namespace SVSim.BattleNode.Reliability;

/// <summary>
/// Per-session inbound-emit ledger. Dedupes the client's pubSeq so we never dispatch
/// a retransmitted emit twice; ack-echo (via SIO callback) is the caller's job.
/// </summary>
public sealed class InboundTracker
{
    private readonly HashSet<long> _seen = new();

    /// <summary>Highest pubSeq observed so far. Reported via Gungnir for diagnostics.</summary>
    public long HighWaterMark { get; private set; }

    /// <summary>Record an incoming pubSeq. Returns true if the caller should dispatch the envelope, false on duplicate.</summary>
    public bool Observe(long pubSeq)
    {
        if (pubSeq > HighWaterMark) HighWaterMark = pubSeq;
        return _seen.Add(pubSeq);
    }
}