From 543453404cd1b15c1338b6b70e162d000c8ba5e2 Mon Sep 17 00:00:00 2001
From: edi-oai <edi@openai.com>
Date: Thu, 15 Oct 2026 15:37:09 +0100
Subject: [PATCH] tart exec: use 64 KiB Tart Guest Agent receive windows
 (#1372)

---
 Sources/tart/GuestAgentChannel.swift | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Sources/tart/GuestAgentChannel.swift b/Sources/tart/GuestAgentChannel.swift
index f754f2f..8ff40ae 100644
--- a/Sources/tart/GuestAgentChannel.swift
+++ b/Sources/tart/GuestAgentChannel.swift
@@ -14,8 +14,11 @@ func withGuestAgentChannel<T>(
   let channel = try GRPCChannelPool.with(
     target: .unixDomainSocket(socketPath),
     transportSecurity: .plaintext,
-    eventLoopGroup: .singletonMultiThreadedEventLoopGroup,
-  )
+    eventLoopGroup: .singletonMultiThreadedEventLoopGroup
+  ) { configuration in
+    // Limit guest output in flight to work around VirtIO socket device implementation data loss
+    configuration.http2.targetWindowSize = 64 * 1024
+  }
 
   do {
     let result = try await body(channel)