From 4498d3dc84a85688fa4d15476403a900bc7f9114 Mon Sep 17 00:00:00 2001
From: Mason Daugherty <mason@langchain.dev>
Date: Tue, 5 May 2026 11:10:55 -0400
Subject: [PATCH] fix(fireworks): strip non-wire keys from `ToolMessage` text
 content blocks (#37187)
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Fireworks's chat completions endpoint rejects unknown fields on tool
message content blocks — specifically the `id` key that LangChain
auto-generates on `TextContentBlock`. Add
`_sanitize_chat_completions_content` to strip those extra keys before
the payload hits the wire, preventing `Extra inputs are not permitted`
errors on tool message round-trips.
---
 .../langchain_fireworks/chat_models.py        | 23 +++++++++++++++-
 .../tests/unit_tests/test_chat_models.py      | 27 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/libs/partners/fireworks/langchain_fireworks/chat_models.py b/libs/partners/fireworks/langchain_fireworks/chat_models.py
index b05c83f3cdd..671d03d24c4 100644
--- a/libs/partners/fireworks/langchain_fireworks/chat_models.py
+++ b/libs/partners/fireworks/langchain_fireworks/chat_models.py
@@ -170,6 +170,25 @@ def _convert_dict_to_message(_dict: Mapping[str, Any]) -> BaseMessage:
     return ChatMessage(content=_dict.get("content", ""), role=role or "")
 
 
+def _sanitize_chat_completions_content(content: Any) -> Any:
+    """Strip non-wire keys from text content blocks.
+
+    Fireworks's chat completions endpoint rejects unknown fields on tool
+    message content blocks (e.g. the `id` that LangChain auto-generates on
+    `TextContentBlock`). For list content, keep only `type` and `text` on
+    text blocks; pass other blocks and non-list content through unchanged.
+    """
+    if not isinstance(content, list):
+        return content
+    sanitized: list[Any] = []
+    for block in content:
+        if isinstance(block, dict) and block.get("type") == "text" and "text" in block:
+            sanitized.append({"type": "text", "text": block["text"]})
+        else:
+            sanitized.append(block)
+    return sanitized
+
+
 def _format_message_content(content: Any) -> Any:
     """Format message content for the Fireworks chat completions wire format.
 
@@ -296,7 +315,9 @@ def _convert_message_to_dict(message: BaseMessage) -> dict:
     elif isinstance(message, ToolMessage):
         message_dict = {
             "role": "tool",
-            "content": _format_message_content(message.content),
+            "content": _sanitize_chat_completions_content(
+                _format_message_content(message.content)
+            ),
             "tool_call_id": message.tool_call_id,
         }
     else:
diff --git a/libs/partners/fireworks/tests/unit_tests/test_chat_models.py b/libs/partners/fireworks/tests/unit_tests/test_chat_models.py
index 785928214fe..3259cde5726 100644
--- a/libs/partners/fireworks/tests/unit_tests/test_chat_models.py
+++ b/libs/partners/fireworks/tests/unit_tests/test_chat_models.py
@@ -31,6 +31,7 @@ from langchain_fireworks.chat_models import (
     _convert_dict_to_message,
     _convert_message_to_dict,
     _format_message_content,
+    _sanitize_chat_completions_content,
     _usage_to_metadata,
 )
 
@@ -106,6 +107,32 @@ def test_format_message_content_passthrough_string() -> None:
     assert _format_message_content("hello") == "hello"
 
 
+def test_sanitize_chat_completions_text_blocks_strips_id() -> None:
+    """LangChain auto-generated `id` on text blocks must not reach the wire.
+
+    Fireworks's chat completions schema rejects unknown keys on tool message
+    content blocks (`Extra inputs are not permitted, ... [0].id`).
+    """
+    message = ToolMessage(
+        content=[{"type": "text", "text": "foo", "id": "lc_abc123"}],
+        tool_call_id="def456",
+    )
+    assert _convert_message_to_dict(message) == {
+        "role": "tool",
+        "content": [{"type": "text", "text": "foo"}],
+        "tool_call_id": "def456",
+    }
+
+
+def test_sanitize_chat_completions_content_passthrough_string() -> None:
+    assert _sanitize_chat_completions_content("hello") == "hello"
+
+
+def test_sanitize_chat_completions_content_passthrough_non_text_block() -> None:
+    blocks = [{"type": "image_url", "image_url": {"url": "https://x/y.png"}}]
+    assert _sanitize_chat_completions_content(blocks) == blocks
+
+
 def test_format_message_content_translates_v1_image_block() -> None:
     """Canonical v1 image block is translated to OpenAI image_url + data URI."""
     blocks = [{"type": "image", "base64": "abc", "mime_type": "image/png"}]