From cdbe6c34f97415bcc182a130e02d18e3f678fd15 Mon Sep 17 00:00:00 2001
From: Ademola Balogun <34436072+ademicho123@users.noreply.github.com>
Date: Mon, 16 Feb 2026 02:25:15 +0000
Subject: [PATCH] fix(mistralai): update exception retry logic in embeddings
 (#35238)

---
 .../langchain_mistralai/embeddings.py         | 25 ++++++--
 .../tests/unit_tests/test_embeddings.py       | 63 +++++++++++++++++++
 2 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/libs/partners/mistralai/langchain_mistralai/embeddings.py b/libs/partners/mistralai/langchain_mistralai/embeddings.py
index 7c0ad474c68..30311adac8c 100644
--- a/libs/partners/mistralai/langchain_mistralai/embeddings.py
+++ b/libs/partners/mistralai/langchain_mistralai/embeddings.py
@@ -16,7 +16,7 @@ from pydantic import (
     SecretStr,
     model_validator,
 )
-from tenacity import retry, retry_if_exception_type, stop_after_attempt, wait_fixed
+from tenacity import retry, retry_if_exception, stop_after_attempt, wait_fixed
 from tokenizers import Tokenizer  # type: ignore[import]
 from typing_extensions import Self
 
@@ -29,6 +29,25 @@ of tokens that can be sent in a single request to the Mistral API (across multip
 documents/chunks)"""
 
 
+def _is_retryable_error(exception: BaseException) -> bool:
+    """Determine if an exception should trigger a retry.
+
+    Only retries on:
+    - Timeout exceptions
+    - 429 (rate limit) errors
+    - 5xx (server) errors
+
+    Does NOT retry on 400 (bad request) or other 4xx client errors.
+    """
+    if isinstance(exception, httpx.TimeoutException):
+        return True
+    if isinstance(exception, httpx.HTTPStatusError):
+        status_code = exception.response.status_code
+        # Retry on rate limit (429) or server errors (5xx)
+        return status_code == 429 or status_code >= 500
+    return False
+
+
 class DummyTokenizer:
     """Dummy tokenizer for when tokenizer cannot be accessed (e.g., via Huggingface)."""
 
@@ -225,9 +244,7 @@ class MistralAIEmbeddings(BaseModel, Embeddings):
             return func
 
         return retry(
-            retry=retry_if_exception_type(
-                (httpx.TimeoutException, httpx.HTTPStatusError)
-            ),
+            retry=retry_if_exception(_is_retryable_error),
             wait=wait_fixed(self.wait_time),
             stop=stop_after_attempt(self.max_retries),
         )(func)
diff --git a/libs/partners/mistralai/tests/unit_tests/test_embeddings.py b/libs/partners/mistralai/tests/unit_tests/test_embeddings.py
index 3b4a2472fae..ddd6cad6af8 100644
--- a/libs/partners/mistralai/tests/unit_tests/test_embeddings.py
+++ b/libs/partners/mistralai/tests/unit_tests/test_embeddings.py
@@ -1,9 +1,15 @@
 import os
 from typing import cast
+from unittest.mock import MagicMock
 
+import httpx
 from pydantic import SecretStr
 
 from langchain_mistralai import MistralAIEmbeddings
+from langchain_mistralai.embeddings import (
+    DummyTokenizer,
+    _is_retryable_error,
+)
 
 os.environ["MISTRAL_API_KEY"] = "foo"
 
@@ -15,3 +21,60 @@ def test_mistral_init() -> None:
     ]:
         assert model.model == "mistral-embed"
         assert cast("SecretStr", model.mistral_api_key).get_secret_value() == "test"
+
+
+def test_is_retryable_error_timeout() -> None:
+    """Test that timeout exceptions are retryable."""
+    exc = httpx.TimeoutException("timeout")
+    assert _is_retryable_error(exc) is True
+
+
+def test_is_retryable_error_rate_limit() -> None:
+    """Test that 429 errors are retryable."""
+    response = MagicMock()
+    response.status_code = 429
+    exc = httpx.HTTPStatusError("rate limit", request=MagicMock(), response=response)
+    assert _is_retryable_error(exc) is True
+
+
+def test_is_retryable_error_server_error() -> None:
+    """Test that 5xx errors are retryable."""
+    for status_code in [500, 502, 503, 504]:
+        response = MagicMock()
+        response.status_code = status_code
+        exc = httpx.HTTPStatusError(
+            "server error", request=MagicMock(), response=response
+        )
+        assert _is_retryable_error(exc) is True
+
+
+def test_is_retryable_error_bad_request_not_retryable() -> None:
+    """Test that 400 errors are NOT retryable."""
+    response = MagicMock()
+    response.status_code = 400
+    exc = httpx.HTTPStatusError("bad request", request=MagicMock(), response=response)
+    assert _is_retryable_error(exc) is False
+
+
+def test_is_retryable_error_other_4xx_not_retryable() -> None:
+    """Test that other 4xx errors are NOT retryable."""
+    for status_code in [401, 403, 404, 422]:
+        response = MagicMock()
+        response.status_code = status_code
+        exc = httpx.HTTPStatusError(
+            "client error", request=MagicMock(), response=response
+        )
+        assert _is_retryable_error(exc) is False
+
+
+def test_is_retryable_error_other_exceptions() -> None:
+    """Test that other exceptions are not retryable."""
+    assert _is_retryable_error(ValueError("test")) is False
+    assert _is_retryable_error(RuntimeError("test")) is False
+
+
+def test_dummy_tokenizer() -> None:
+    """Test that DummyTokenizer returns character lists."""
+    tokenizer = DummyTokenizer()
+    result = tokenizer.encode_batch(["hello", "world"])
+    assert result == [["h", "e", "l", "l", "o"], ["w", "o", "r", "l", "d"]]