From 8c9bb6c8ba771e47e1101e23b2864001d15ea20d Mon Sep 17 00:00:00 2001
From: Wes Ladd <wesladd@traingrc.com>
Date: Mon, 13 Jul 2026 01:36:18 -0500
Subject: [PATCH] Send complete XMODEM frames over Wi-Fi

---
 CHANGELOG.md                    |  1 +
 carveracontroller/WIFIStream.py |  3 ++-
 tests/unit/test_wifi_stream.py  | 46 +++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit/test_wifi_stream.py

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 603ca7b9..8d83bc2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,4 @@
+- Fixed: Ensure complete XMODEM packets are written over Wi-Fi
 - Enhancement: Add multi-select to the remote file browser
 - Enhancement: Display error message in halt popup. Requires halt errors to start with "ERROR: " in the firmware
 - Enhancement: Add popup notice when using stock firmware instead of the Community Firmware
diff --git a/carveracontroller/WIFIStream.py b/carveracontroller/WIFIStream.py
index da0c7bac..8d10ae77 100644
--- a/carveracontroller/WIFIStream.py
+++ b/carveracontroller/WIFIStream.py
@@ -158,7 +158,8 @@ def getc(self, size, timeout=0.5):
         return None
 
     def putc(self, data, timeout=0.5):
-        return self.socket.send(data) or None
+        self.socket.sendall(data)
+        return len(data)
 
     def upload(self, filename, local_md5, callback):
         # do upload
diff --git a/tests/unit/test_wifi_stream.py b/tests/unit/test_wifi_stream.py
new file mode 100644
index 00000000..56c9e6cc
--- /dev/null
+++ b/tests/unit/test_wifi_stream.py
@@ -0,0 +1,46 @@
+"""Tests for WIFIStream socket write semantics."""
+
+from carveracontroller.WIFIStream import WIFIStream
+from carveracontroller.XMODEM import XMODEM
+
+
+class DeterministicShortWriteSocket:
+    """Socket double that accepts only a prefix from each ``send`` call."""
+
+    def __init__(self, short_write_size):
+        self.short_write_size = short_write_size
+        self.send_calls = 0
+        self.sendall_calls = 0
+        self.wire = bytearray()
+
+    def send(self, data):
+        self.send_calls += 1
+        accepted = min(self.short_write_size, len(data))
+        self.wire.extend(data[:accepted])
+        return accepted
+
+    def sendall(self, data):
+        self.sendall_calls += 1
+        self.wire.extend(data)
+
+
+def _xmodem8k_frame():
+    modem = XMODEM(lambda _size, _timeout=0.5: None, lambda data, _timeout=0.5: len(data))
+    payload = b"x" * 8192
+    framed_payload = bytes([len(payload) >> 8, len(payload) & 0xFF]) + payload
+    return bytes(modem._make_send_header(8192, 1) + framed_payload + modem._make_send_checksum(1, framed_payload))
+
+
+def test_putc_sends_the_complete_xmodem_frame_and_returns_its_length():
+    stream = WIFIStream.__new__(WIFIStream)
+    stream.socket = DeterministicShortWriteSocket(short_write_size=2048)
+    frame = _xmodem8k_frame()
+    assert len(frame) == 8199, "fixture must model a complete xmodem8k frame"
+
+    result = stream.putc(frame)
+
+    assert len(stream.socket.wire) == len(frame)
+    assert bytes(stream.socket.wire) == frame
+    assert stream.socket.send_calls == 0
+    assert stream.socket.sendall_calls == 1
+    assert result == len(frame)