fix: extend retry predicate to cover transient server errors and connection failures

src/smolagents/models.py

@@ -1176,7 +1176,7 @@ def __init__(
             wait_seconds=RETRY_WAIT,
             exponential_base=RETRY_EXPONENTIAL_BASE,
             jitter=RETRY_JITTER,
-            retry_predicate=is_rate_limit_error,
+            retry_predicate=is_transient_error,
             reraise=True,
             before_sleep_logger=(logger, logging.INFO),
             after_logger=(logger, logging.INFO),
@@ -1191,6 +1191,36 @@ def _apply_rate_limit(self):
         self.rate_limiter.throttle()
 
 
+def is_transient_error(exception: BaseException) -> bool:
+    """Return True if the exception is a transient API error worth retrying."""
+    error_str = str(exception).lower()
+    return any(
+        signal in error_str
+        for signal in (
+            # Rate limits
+            "429",
+            "rate limit",
+            "too many requests",
+            "rate_limit",
+            # Transient server errors
+            "500",
+            "502",
+            "503",
+            "504",
+            "service unavailable",
+            "bad gateway",
+            "gateway timeout",
+            "internal server error",
+            # Connection failures
+            "connection error",
+            "connection reset",
+            "connection refused",
+            "timed out",
+            "timeout",
+        )
+    )
+
+
 def is_rate_limit_error(exception: BaseException) -> bool:
     """Check if the exception is a rate limit error."""
     error_str = str(exception).lower()

tests/test_models.py

@@ -37,6 +37,7 @@
     get_clean_message_list,
     get_tool_call_from_text,
     get_tool_json_schema,
+    is_transient_error,
     parse_json_if_needed,
     remove_content_after_stop_sequences,
     supports_stop_parameter,
@@ -1077,3 +1078,38 @@ def test_tool_calls_json_serialization(model_class, model_id):
     assert len(data["tool_calls"]) > 0
     assert data["tool_calls"][0]["function"]["name"] == "final_answer"
     assert data["tool_calls"][0]["function"]["arguments"] == "test_result"
+
+
+class TestIsTransientError:
+    def test_rate_limit_429(self):
+        assert is_transient_error(Exception("HTTP 429 Too Many Requests"))
+
+    def test_rate_limit_string(self):
+        assert is_transient_error(Exception("rate limit exceeded"))
+
+    def test_503_service_unavailable(self):
+        assert is_transient_error(Exception("503 Service Unavailable"))
+
+    def test_502_bad_gateway(self):
+        assert is_transient_error(Exception("502 Bad Gateway"))
+
+    def test_500_internal_server_error(self):
+        assert is_transient_error(Exception("500 Internal Server Error"))
+
+    def test_504_gateway_timeout(self):
+        assert is_transient_error(Exception("504 Gateway Timeout"))
+
+    def test_connection_reset(self):
+        assert is_transient_error(Exception("Connection reset by peer"))
+
+    def test_timeout(self):
+        assert is_transient_error(Exception("request timed out"))
+
+    def test_non_retryable_400(self):
+        assert not is_transient_error(Exception("400 Bad Request"))
+
+    def test_non_retryable_401(self):
+        assert not is_transient_error(Exception("401 Unauthorized"))
+
+    def test_non_retryable_404(self):
+        assert not is_transient_error(Exception("404 Not Found"))