fix(sse): normalize CR/LF line endings in frame parser

app/protocols/sse.py

@@ -130,6 +130,11 @@ async def _iter(self) -> AsyncGenerator[dict, None]:
             if isinstance(piece, bytes):
                 piece = piece.decode("utf-8")
             buffer += piece
+            # The SSE spec (W3C) allows \r\n, \r, or \n as line endings.
+            # Some upstream providers (notably Azure-hosted models) send
+            # \r\n\r\n as the frame delimiter instead of \n\n. Normalize
+            # to \n so the split below catches all three forms.
+            buffer = buffer.replace("\r\n", "\n").replace("\r", "\n")
             while "\n\n" in buffer:
                 frame, buffer = buffer.split("\n\n", 1)
                 for line in frame.splitlines():

tests/unit/test_sse_crlf_parsing.py

@@ -0,0 +1,65 @@
+"""Regression: SSE frame parser must handle \\r\\n line endings.
+
+The W3C SSE spec allows \\r\\n, \\r, or \\n as line separators. Some upstream
+providers (notably Azure-hosted OpenAI models) send \\r\\n\\r\\n as the frame
+delimiter. Without normalization the parser never finds the \\n\\n boundary
+and buffers the entire response in memory until the connection closes,
+at which point it yields nothing."""
+
+from __future__ import annotations
+
+import pytest
+
+from app.protocols.sse import OpenAIFrameStream
+
+
+async def _collect(stream: OpenAIFrameStream) -> list[dict]:
+    frames = []
+    async for frame in stream:
+        frames.append(frame)
+    return frames
+
+
+@pytest.mark.asyncio
+async def test_sse_parses_crlf_frame_boundaries():
+    """Frames separated by \\r\\n\\r\\n must parse identically to \\n\\n."""
+    async def source():
+        yield b"data: {\"id\":\"1\",\"content\":\"hello\"}\r\n\r\n"
+        yield b"data: [DONE]\r\n\r\n"
+
+    stream = OpenAIFrameStream(source())
+    frames = await _collect(stream)
+    assert len(frames) == 1
+    assert frames[0]["id"] == "1"
+    assert frames[0]["content"] == "hello"
+    assert stream._done is True
+
+
+@pytest.mark.asyncio
+async def test_sse_parses_mixed_line_endings():
+    """A stream mixing \\r\\n and \\n must still parse correctly."""
+    async def source():
+        yield "data: {\"id\":\"a\"}\r\n\r\n"
+        yield "data: {\"id\":\"b\"}\n\n"
+        yield "data: [DONE]\r\n\r\n"
+
+    stream = OpenAIFrameStream(source())
+    frames = await _collect(stream)
+    assert len(frames) == 2
+    assert frames[0]["id"] == "a"
+    assert frames[1]["id"] == "b"
+    assert stream._done is True
+
+
+@pytest.mark.asyncio
+async def test_sse_parses_cr_only_line_endings():
+    """Bare \\r (classic Mac-style) is a valid SSE line ending."""
+    async def source():
+        yield "data: {\"id\":\"x\"}\r\r"
+        yield "data: [DONE]\r\r"
+
+    stream = OpenAIFrameStream(source())
+    frames = await _collect(stream)
+    assert len(frames) == 1
+    assert frames[0]["id"] == "x"
+    assert stream._done is True