Bind reliable windows to the RUDP ACK horizon

docs/cultnet-transport-parity.md

@@ -258,7 +258,7 @@ Current progress:
   echo against C#/Kotlin/Python/Rust UDP peers; local runtime tests prove timeout
   state transitions.
 - TypeScript, C#, Rust, Python, and Kotlin now share bounded reliable-send
-  backpressure for RUDP sessions. At most 64 reliable packets are admitted to
+  backpressure for RUDP sessions. At most 32 reliable packets are admitted to
   the wire at once; later fragments remain in a session-owned FIFO and exact
   acknowledgements promote the next packets. This keeps the send frontier well
   inside the 4,096-sequence receive history instead of blasting an entire large

packages/cultcache-py/src/cultnet_py/transport.py

@@ -396,7 +396,7 @@ def create_rudp_transport_profile(
 
 
 class CultNetRudpSession:
-    RELIABLE_SEND_WINDOW_PACKETS = 64
+    RELIABLE_SEND_WINDOW_PACKETS = 32
     RECEIVED_SEQUENCE_WINDOW = 4_096
 
     def __init__(self, options: CultNetRudpSessionOptions) -> None:

packages/cultmesh-kotlin/src/main/kotlin/org/gamecult/cultmesh/CultMesh.kt

@@ -2621,7 +2621,7 @@ private data class FragmentBuffer(
 
 class CultNetRudpSession(options: CultNetRudpSessionOptions) {
     companion object {
-        const val ReliableSendWindowPackets = 64
+        const val ReliableSendWindowPackets = 32
         private const val ReceivedSequenceWindow = 4_096
     }
 

packages/cultnet-rs/src/rudp.rs

@@ -29,7 +29,7 @@ const RUDP_MAGIC: [u8; 4] = [0x43, 0x4e, 0x52, 0x30];
 const RUDP_VERSION: u8 = 0;
 const RUDP_FIXED_HEADER_BYTES: usize = 36;
 pub const CULTNET_RUDP_DEFAULT_MAX_PAYLOAD_BYTES: usize = 16 * 1024 * 1024;
-pub const CULTNET_RUDP_RELIABLE_SEND_WINDOW_PACKETS: usize = 64;
+pub const CULTNET_RUDP_RELIABLE_SEND_WINDOW_PACKETS: usize = 32;
 const RUDP_RECEIVED_SEQUENCE_WINDOW: usize = 4_096;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]

packages/cultnet-rs/tests/cultnet.rs

@@ -68,6 +68,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration as StdDuration;
+use std::time::Instant as StdInstant;
 
 const TS_HELLO_FRAME: &[u8] = include_bytes!("fixtures/cultnet-ts-hello.frame");
 const TS_LEGACY_LOGIN_FRAME: &[u8] = include_bytes!("fixtures/cultnet-ts-legacy-login.frame");
@@ -1370,7 +1371,15 @@ fn rudp_socket_flush_waits_for_large_fragment_delivery() -> Result<()> {
         CULTNET_RUDP_RELIABLE_SEND_WINDOW_PACKETS + 17
     );
 
-    let server_worker = thread::spawn(move || receive_rudp_frame(&mut server));
+    let server_worker = thread::spawn(move || -> Result<CultNetTransportFrame> {
+        let delivered = receive_rudp_frame(&mut server)?;
+        let linger_deadline = StdInstant::now() + StdDuration::from_millis(250);
+        while StdInstant::now() < linger_deadline {
+            let _ = server.receive_once()?;
+            server.poll_resends()?;
+        }
+        Ok(delivered)
+    });
     client.flush_reliable(StdDuration::from_secs(5))?;
     let delivered = server_worker
         .join()

packages/cultnet-ts/src/rudp.ts

@@ -16,7 +16,7 @@ const RUDP_MAGIC = [0x43, 0x4e, 0x52, 0x30] as const; // CNR0
 const RUDP_VERSION = 0;
 const RUDP_FIXED_HEADER_BYTES = 36;
 const MAX_CHANNEL_ID_BYTES = 255;
-export const CULTNET_RUDP_RELIABLE_SEND_WINDOW_PACKETS = 64;
+export const CULTNET_RUDP_RELIABLE_SEND_WINDOW_PACKETS = 32;
 const RUDP_RECEIVED_SEQUENCE_WINDOW = 4_096;
 
 export type CultNetRudpPacketType =

src/GameCult.Networking/CultNetTransport.cs

@@ -870,7 +870,7 @@ namespace GameCult.Networking
     public sealed class CultNetRudpSession
     {
         /// <summary>Maximum reliable packets admitted to the wire before acknowledgements advance the window.</summary>
-        public const int ReliableSendWindowPackets = 64;
+        public const int ReliableSendWindowPackets = 32;
         private const int ReceivedSequenceWindow = 4096;
         private sealed class PendingReliablePacket
         {