From 38c78fb5758807ddfd01b9826cb2854c949e8222 Mon Sep 17 00:00:00 2001
From: Brian Krabach <brkrabac@microsoft.com>
Date: Sat, 28 Mar 2026 08:50:43 -0700
Subject: [PATCH] =?UTF-8?q?fix:=20WebSocket=20proxy=20drops=20text=20frame?=
 =?UTF-8?q?s=20=E2=80=94=20receive=5Fbytes()=20silently=20fails=20on=20aut?=
 =?UTF-8?q?h=20token?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

terminal.js sends the ttyd auth token as a TEXT WebSocket frame. The proxy's
client_to_ttyd() called receive_bytes() which fails silently on text frames,
swallows the exception, and exits — auth never reached ttyd, ttyd never
started streaming, resulting in permanent black screen and reconnect loop.

Fix: use receive() and dispatch on message type, handling both bytes and text.
---
 muxplex/main.py                |  7 +++++--
 muxplex/tests/test_ws_proxy.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 muxplex/tests/test_ws_proxy.py

diff --git a/muxplex/main.py b/muxplex/main.py
index 9ce87d6..59b84c5 100644
--- a/muxplex/main.py
+++ b/muxplex/main.py
@@ -365,8 +365,11 @@ async def terminal_ws_proxy(websocket: WebSocket) -> None:
             async def client_to_ttyd() -> None:
                 try:
                     while True:
-                        data = await websocket.receive_bytes()
-                        await ttyd_ws.send(data)
+                        msg = await websocket.receive()
+                        if msg.get("bytes"):
+                            await ttyd_ws.send(msg["bytes"])
+                        elif msg.get("text"):
+                            await ttyd_ws.send(msg["text"])
                 except Exception:
                     pass
 
diff --git a/muxplex/tests/test_ws_proxy.py b/muxplex/tests/test_ws_proxy.py
new file mode 100644
index 0000000..00c2fee
--- /dev/null
+++ b/muxplex/tests/test_ws_proxy.py
@@ -0,0 +1,28 @@
+"""
+Regression tests for the WebSocket proxy in muxplex/main.py.
+"""
+
+import inspect
+
+from muxplex.main import terminal_ws_proxy
+
+
+def test_terminal_ws_proxy_does_not_use_receive_bytes():
+    """Regression: receive_bytes() silently drops TEXT frames (like the ttyd auth token).
+
+    terminal.js sends {"AuthToken": ""} as a TEXT WebSocket frame. The original
+    proxy used receive_bytes() which fails on text frames, swallowed the exception,
+    and exited — meaning ttyd never received the auth token, never started
+    streaming, resulting in a permanent black screen and reconnect loop.
+
+    The proxy MUST use receive() and dispatch on message type to handle both
+    binary and text frames correctly.
+    """
+    source = inspect.getsource(terminal_ws_proxy)
+    assert "receive_bytes" not in source, (
+        "client_to_ttyd must not use receive_bytes() — silently drops text frames "
+        'like the ttyd auth token {"AuthToken": ""}'
+    )
+    assert ".receive()" in source, (
+        "client_to_ttyd must use receive() to handle both text and binary frames"
+    )