fix(fireworks): strip duplicate /v1 from models endpoint URL (#23113)

_get_openai_compatible_provider_info already returns an api_base
ending in /v1, but get_models prepended another /v1, producing
.../inference/v1/v1/accounts/... which 404s.

Strip the trailing /v1 from api_base before re-adding it so that
both the default and any user-supplied base work correctly.

Add parametrized tests covering the default URL, trailing-slash,
custom base with /v1, and custom base without /v1.

Fixes #23106

litellm/llms/fireworks_ai/chat/transformation.py

@@ -426,8 +426,11 @@ class FireworksAIConfig(OpenAIGPTConfig):
                 "FIREWORKS_ACCOUNT_ID is not set. Please set the environment variable, to query Fireworks AI's `/models` endpoint."
             )
 
+        base = api_base.rstrip("/")
+        if base.endswith("/v1"):
+            base = base[: -len("/v1")]
         response = litellm.module_level_client.get(
-            url=f"{api_base}/v1/accounts/{account_id}/models",
+            url=f"{base}/v1/accounts/{account_id}/models",
             headers={"Authorization": f"Bearer {api_key}"},
         )
 

tests/test_litellm/llms/fireworks_ai/chat/test_fireworks_ai_chat_transformation.py

@@ -110,6 +110,60 @@ def test_get_supported_openai_params_reasoning_effort():
     assert "reasoning_effort" not in unsupported_params
 
 
+@pytest.mark.parametrize(
+    "api_base, expected_url_prefix",
+    [
+        (
+            "https://api.fireworks.ai/inference/v1",
+            "https://api.fireworks.ai/inference/v1/accounts/",
+        ),
+        (
+            "https://api.fireworks.ai/inference/v1/",
+            "https://api.fireworks.ai/inference/v1/accounts/",
+        ),
+        (
+            "https://custom-host.example.com/v1",
+            "https://custom-host.example.com/v1/accounts/",
+        ),
+        (
+            "https://custom-host.example.com/api",
+            "https://custom-host.example.com/api/v1/accounts/",
+        ),
+    ],
+    ids=["default", "trailing-slash", "custom-with-v1", "custom-without-v1"],
+)
+def test_get_models_url_no_double_v1(api_base, expected_url_prefix):
+    """Ensure get_models never produces a /v1/v1/ URL segment (fixes #23106)."""
+    config = FireworksAIConfig()
+    account_id = "fireworks"
+
+    mock_response = MagicMock()
+    mock_response.status_code = 200
+    mock_response.json.return_value = {
+        "models": [{"name": "accounts/fireworks/models/llama-v3-70b"}]
+    }
+
+    with (
+        patch("litellm.module_level_client.get", return_value=mock_response) as mock_get,
+        patch(
+            "litellm.llms.fireworks_ai.chat.transformation.get_secret_str",
+            side_effect=lambda key: {
+                "FIREWORKS_API_KEY": "test-key",
+                "FIREWORKS_API_BASE": api_base,
+                "FIREWORKS_ACCOUNT_ID": account_id,
+            }.get(key),
+        ),
+    ):
+        result = config.get_models(api_key="test-key", api_base=api_base)
+
+        called_url = mock_get.call_args.kwargs.get("url") or mock_get.call_args[1].get("url", "")
+        assert "/v1/v1/" not in called_url, f"Double /v1/ detected in URL: {called_url}"
+        assert called_url.startswith(expected_url_prefix), (
+            f"URL {called_url} does not start with {expected_url_prefix}"
+        )
+        assert result == ["fireworks_ai/accounts/fireworks/models/llama-v3-70b"]
+
+
 def test_transform_messages_helper_removes_provider_specific_fields():
     """
     Test that _transform_messages_helper removes provider_specific_fields from messages.