fix(openai): handle content blocks without type key in responses api conversion (#36725)

libs/core/langchain_core/messages/block_translators/openai.py

@@ -335,10 +335,9 @@ def _convert_from_v03_ai_message(message: AIMessage) -> AIMessage:
 
     # Reasoning
     if reasoning := message.additional_kwargs.get("reasoning"):
-        if isinstance(message, AIMessageChunk) and message.chunk_position != "last":
+        if "type" not in reasoning:
-            buckets["reasoning"].append({**reasoning, "type": "reasoning"})
+            reasoning = {**reasoning, "type": "reasoning"}
-        else:
+        buckets["reasoning"].append(reasoning)
-            buckets["reasoning"].append(reasoning)
 
     # Refusal
     if refusal := message.additional_kwargs.get("refusal"):

libs/partners/openai/langchain_openai/chat_models/_compat.py

@@ -407,6 +407,8 @@ def _convert_from_v1_to_responses(
 ) -> list[dict[str, Any]]:
     new_content: list = []
     for block in content:
+        if "type" not in block:
+            continue
         if block["type"] == "text" and "annotations" in block:
             # Need a copy because we're changing the annotations list
             new_block = dict(block)

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -2897,6 +2897,52 @@ def test_convert_from_v1_to_responses(
     assert message_v1 != result
 
 
+def test_convert_from_v1_to_responses_missing_type() -> None:
+    """Regression: blocks without 'type' should be skipped, not raise KeyError."""
+    content: list = [
+        {"type": "text", "text": "Hello", "annotations": []},
+        {"summary": [{"type": "summary_text", "text": "..."}]},  # no "type" key
+        {"index": 0},  # no "type" key
+    ]
+    result = _convert_from_v1_to_responses(content, [])
+    # Blocks without "type" should be skipped
+    assert len(result) == 1
+    assert result[0] == {"type": "text", "text": "Hello", "annotations": []}
+
+
+def test_v03_reasoning_without_type_roundtrip() -> None:
+    """Regression: v0.3 reasoning stored without 'type' key should roundtrip."""
+    message_v03 = AIMessage(
+        content=[
+            {"type": "text", "text": "Hello!", "annotations": []},
+        ],
+        additional_kwargs={
+            # Reasoning stored without "type" (as produced by streaming v0.3 path)
+            "reasoning": {
+                "id": "rs_123",
+                "summary": [{"type": "summary_text", "text": "Thinking..."}],
+            },
+        },
+        response_metadata={"id": "resp_123"},
+        id="msg_123",
+    )
+
+    converted = _convert_from_v03_ai_message(message_v03)
+
+    # Reasoning block should have "type" restored
+    reasoning_blocks = [
+        b
+        for b in converted.content
+        if isinstance(b, dict) and b.get("type") == "reasoning"
+    ]
+    assert len(reasoning_blocks) == 1
+    assert reasoning_blocks[0]["type"] == "reasoning"
+
+    # Full pipeline should not raise
+    result = _construct_responses_api_input([converted])
+    assert len(result) > 0
+
+
 def test_get_last_messages() -> None:
     messages: list[BaseMessage] = [HumanMessage("Hello")]
     last_messages, previous_response_id = _get_last_messages(messages)

libs/partners/openai/uv.lock

@@ -591,6 +591,7 @@ test = [
     { name = "langchain-tests", editable = "../../standard-tests" },
     { name = "pytest", specifier = ">=8.0.0,<10.0.0" },
     { name = "pytest-asyncio", specifier = ">=0.23.2,<2.0.0" },
+    { name = "pytest-benchmark", specifier = ">=5.1.0,<6.0.0" },
     { name = "pytest-cov", specifier = ">=4.0.0,<8.0.0" },
     { name = "pytest-mock" },
     { name = "pytest-socket", specifier = ">=0.6.0,<1.0.0" },
@@ -614,7 +615,7 @@ typing = [
 
 [[package]]
 name = "langchain-core"
-version = "1.2.25"
+version = "1.3.0a2"
 source = { editable = "../../core" }
 dependencies = [
     { name = "jsonpatch" },
@@ -761,7 +762,7 @@ typing = [
 
 [[package]]
 name = "langchain-tests"
-version = "1.1.5"
+version = "1.1.6"
 source = { editable = "../../standard-tests" }
 dependencies = [
     { name = "httpx" },