From 4dc9d4d059d0fbbf369a075c613810618e0dce61 Mon Sep 17 00:00:00 2001
From: Brennan Butler <64561607+brennanbutler01@users.noreply.github.com>
Date: Sun, 20 Sep 2026 09:45:29 +0700
Subject: [PATCH 1/2] fix(streaming): preserve literal double brackets in
 ChatAdapter output

---
 dspy/streaming/streaming_listener.py |  6 +++---
 tests/streaming/test_streaming.py    | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/dspy/streaming/streaming_listener.py b/dspy/streaming/streaming_listener.py
index 32e9f9eb57..6ffb400162 100644
--- a/dspy/streaming/streaming_listener.py
+++ b/dspy/streaming/streaming_listener.py
@@ -327,9 +327,9 @@ def flush(self) -> str:
                 boundary_index = len(last_tokens)
             return last_tokens[:boundary_index]
         elif isinstance(settings.adapter, ChatAdapter) or settings.adapter is None:
-            boundary_index = last_tokens.find("[[")
-            if boundary_index == -1:
-                boundary_index = len(last_tokens)
+            end_identifier = self.adapter_identifiers["ChatAdapter"]["end_identifier"]
+            boundary = end_identifier.search(last_tokens)
+            boundary_index = boundary.start() if boundary else len(last_tokens)
             return last_tokens[:boundary_index]
         else:
             raise ValueError(
diff --git a/tests/streaming/test_streaming.py b/tests/streaming/test_streaming.py
index c71080f571..0e6937484c 100644
--- a/tests/streaming/test_streaming.py
+++ b/tests/streaming/test_streaming.py
@@ -1621,6 +1621,28 @@ async def multi_field_stream(*args, **kwargs):
     assert "second response" in second_content
 
 
+@pytest.mark.parametrize("adapter", [None, dspy.ChatAdapter()])
+@pytest.mark.parametrize(
+    "content_chunks",
+    [
+        ["Matrix: [[1, 2], [3, 4]]"],
+        ["Matrix: [", "[", "1, 2], [3, 4]]"],
+        ["Matrix: [[1, 2], [3, 4]]\n\n[[ ## completed ## ]]"],
+    ],
+)
+def test_stream_listener_preserves_literal_double_brackets(adapter, content_chunks):
+    listener = dspy.streaming.StreamListener(signature_field_name="answer")
+    chunks = ["[[ ## answer", " ## ]]\n\n", *content_chunks, "\n\n[[ ## completed ## ]]"]
+    outputs = []
+    with dspy.context(adapter=adapter):
+        for text in chunks:
+            chunk = ModelResponseStream(choices=[StreamingChoices(delta=Delta(content=text))])
+            if output := listener.receive(chunk):
+                outputs.append(output)
+    assert "".join(output.chunk for output in outputs) == "Matrix: [[1, 2], [3, 4]]"
+    assert outputs[-1].is_last_chunk
+
+
 def test_stream_listener_could_form_end_identifier_chat_adapter():
     listener = dspy.streaming.StreamListener(signature_field_name="answer")
 

From d6e88bbf5187aabb739a48d8d519866d31d1cddc Mon Sep 17 00:00:00 2001
From: Brennan Butler <64561607+brennanbutler01@users.noreply.github.com>
Date: Sun, 20 Sep 2026 10:22:02 +0700
Subject: [PATCH 2/2] test(dspy): require inline markers to terminate the
 stream

---
 tests/streaming/test_streaming.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/streaming/test_streaming.py b/tests/streaming/test_streaming.py
index 0e6937484c..d20e744039 100644
--- a/tests/streaming/test_streaming.py
+++ b/tests/streaming/test_streaming.py
@@ -1625,14 +1625,14 @@ async def multi_field_stream(*args, **kwargs):
 @pytest.mark.parametrize(
     "content_chunks",
     [
-        ["Matrix: [[1, 2], [3, 4]]"],
-        ["Matrix: [", "[", "1, 2], [3, 4]]"],
+        ["Matrix: [[1, 2], [3, 4]]", "\n\n[[ ## completed ## ]]"],
+        ["Matrix: [", "[", "1, 2], [3, 4]]", "\n\n[[ ## completed ## ]]"],
         ["Matrix: [[1, 2], [3, 4]]\n\n[[ ## completed ## ]]"],
     ],
 )
 def test_stream_listener_preserves_literal_double_brackets(adapter, content_chunks):
     listener = dspy.streaming.StreamListener(signature_field_name="answer")
-    chunks = ["[[ ## answer", " ## ]]\n\n", *content_chunks, "\n\n[[ ## completed ## ]]"]
+    chunks = ["[[ ## answer", " ## ]]\n\n", *content_chunks]
     outputs = []
     with dspy.context(adapter=adapter):
         for text in chunks: