feat(bedrock): support nova/ and nova-2/ spec prefixes for custom imported models (#21359)

Add routing prefixes bedrock/nova/<ARN> and bedrock/nova-2/<ARN> so
LiteLLM can identify the base model family for custom/imported Nova
models and enable the correct supported params (tools, web_search,
reasoning_effort).

Changes:
- Route nova/ and nova-2/ prefixed models to converse API
- Strip spec prefix before sending ARN to Bedrock
- Return sentinel base models (amazon.nova-custom, amazon.nova-2-custom)
  so downstream Nova checks work
- Recognize nova-2/ prefix in _is_nova_2_model() for reasoning support
- Handle nova/nova-2 in get_bedrock_model_id() for proper ARN encoding
- Add unit tests for all new behavior

litellm/llms/bedrock/base_aws_llm.py

@@ -384,6 +384,14 @@ class BaseAWSLLM:
             model_id = BaseAWSLLM._get_model_id_from_model_with_spec(
                 model_id, spec="moonshot"
             )
+        elif "nova-2/" in model_id:
+            model_id = BaseAWSLLM._get_model_id_from_model_with_spec(
+                model_id, spec="nova-2"
+            )
+        elif "nova/" in model_id:
+            model_id = BaseAWSLLM._get_model_id_from_model_with_spec(
+                model_id, spec="nova"
+            )
         return model_id
 
     @staticmethod

litellm/llms/bedrock/chat/converse_handler.py

@@ -272,7 +272,18 @@ class BedrockConverseLLM(BaseAWSLLM):
         if unencoded_model_id is not None:
             modelId = self.encode_model_id(model_id=unencoded_model_id)
         else:
-            modelId = self.encode_model_id(model_id=model)
+            # Strip nova spec prefixes before encoding model ID for API URL
+            _model_for_id = model
+            _stripped = _model_for_id
+            for rp in ["bedrock/converse/", "bedrock/", "converse/"]:
+                if _stripped.startswith(rp):
+                    _stripped = _stripped[len(rp):]
+                    break
+            for _nova_prefix in ["nova-2/", "nova/"]:
+                if _stripped.startswith(_nova_prefix):
+                    _model_for_id = _model_for_id.replace(_nova_prefix, "", 1)
+                    break
+            modelId = self.encode_model_id(model_id=_model_for_id)
 
         fake_stream = litellm.AmazonConverseConfig().should_fake_stream(
             fake_stream=fake_stream,

litellm/llms/bedrock/chat/converse_transformation.py

@@ -318,7 +318,8 @@ class AmazonConverseConfig(BaseConfig):
                 break
 
         # Check if the model is a Nova 2 model (matches nova-2-lite, nova-2-pro, etc.)
-        return model_without_region.startswith("amazon.nova-2-")
+        # Also check for nova-2/ spec prefix for imported models
+        return model_without_region.startswith("amazon.nova-2-") or model_without_region.startswith("nova-2/")
 
     def _map_web_search_options(
         self, web_search_options: dict, model: str
@@ -490,6 +491,9 @@ class AmazonConverseConfig(BaseConfig):
             supported_params.append("tool_choice")
             supported_params.append("thinking")
             supported_params.append("reasoning_effort")
+            # For nova imported models, also add web_search_options
+            if "nova" in model.lower():
+                supported_params.append("web_search_options")
             return supported_params
 
         ## Filter out 'cross-region' from model name

litellm/llms/bedrock/common_utils.py

@@ -404,7 +404,7 @@ def extract_model_name_from_bedrock_arn(model: str) -> str:
 
 def strip_bedrock_routing_prefix(model: str) -> str:
     """Strip LiteLLM routing prefixes from model name."""
-    for prefix in ["bedrock/", "converse/", "invoke/", "openai/"]:
+    for prefix in ["bedrock/", "converse/", "invoke/", "openai/", "nova-2/", "nova/"]:
         if model.startswith(prefix):
             model = model.split("/", 1)[1]
     return model
@@ -427,7 +427,20 @@ def get_bedrock_base_model(model: str) -> str:
     - "us.meta.llama3-2-11b-instruct-v1:0" -> "meta.llama3-2-11b-instruct-v1"
     - "bedrock/converse/model" -> "model"
     - "anthropic.claude-3-5-sonnet-20241022-v2:0:51k" -> "anthropic.claude-3-5-sonnet-20241022-v2:0"
+    - "bedrock/nova-2/arn:aws:..." -> "amazon.nova-2-custom"
+    - "bedrock/nova/arn:aws:..." -> "amazon.nova-custom"
     """
+    # Detect nova spec prefixes before stripping them
+    stripped = model
+    for rp in ["bedrock/converse/", "bedrock/", "converse/"]:
+        if stripped.startswith(rp):
+            stripped = stripped[len(rp):]
+            break
+    if stripped.startswith("nova-2/"):
+        return "amazon.nova-2-custom"
+    elif stripped.startswith("nova/"):
+        return "amazon.nova-custom"
+
     model = strip_bedrock_routing_prefix(model)
     model = extract_model_name_from_bedrock_arn(model)
     model = strip_bedrock_throughput_suffix(model)
@@ -594,6 +607,11 @@ class BedrockModelInfo(BaseLLMModelInfo):
             if prefix in model:
                 return route_type
 
+        # Check for nova spec prefixes (nova/ and nova-2/)
+        _model_after_bedrock = model.replace("bedrock/", "", 1)
+        if _model_after_bedrock.startswith("nova-2/") or _model_after_bedrock.startswith("nova/"):
+            return "converse"
+
         base_model = BedrockModelInfo.get_base_model(model)
         alt_model = BedrockModelInfo.get_non_litellm_routing_model_name(model=model)
         if (

tests/litellm/llms/bedrock/test_nova_imported_models.py

@@ -0,0 +1,92 @@
+"""
+Tests for Nova imported/custom model support via spec prefixes (nova/, nova-2/).
+"""
+
+import pytest
+
+from litellm.llms.bedrock.common_utils import (
+    BedrockModelInfo,
+    get_bedrock_base_model,
+    strip_bedrock_routing_prefix,
+)
+from litellm.llms.bedrock.chat.converse_transformation import AmazonConverseConfig
+
+
+NOVA_ARN = "arn:aws:bedrock:us-east-1:123456789012:custom-model-deployment/a1b2c3d4e5f6"
+NOVA_MODEL = f"bedrock/nova/{NOVA_ARN}"
+NOVA2_MODEL = f"bedrock/nova-2/{NOVA_ARN}"
+
+
+class TestGetBedrockRoute:
+    def test_nova_prefix_routes_to_converse(self):
+        assert BedrockModelInfo.get_bedrock_route(NOVA_MODEL) == "converse"
+
+    def test_nova2_prefix_routes_to_converse(self):
+        assert BedrockModelInfo.get_bedrock_route(NOVA2_MODEL) == "converse"
+
+    def test_plain_arn_routes_to_invoke(self):
+        # Without spec prefix, ARN doesn't match converse models
+        result = BedrockModelInfo.get_bedrock_route(f"bedrock/{NOVA_ARN}")
+        assert result == "invoke"
+
+
+class TestGetBedrockBaseModel:
+    def test_nova_prefix_returns_sentinel(self):
+        assert get_bedrock_base_model(f"nova/{NOVA_ARN}") == "amazon.nova-custom"
+
+    def test_nova2_prefix_returns_sentinel(self):
+        assert get_bedrock_base_model(f"nova-2/{NOVA_ARN}") == "amazon.nova-2-custom"
+
+    def test_bedrock_nova_prefix_returns_sentinel(self):
+        assert get_bedrock_base_model(NOVA_MODEL) == "amazon.nova-custom"
+
+    def test_bedrock_nova2_prefix_returns_sentinel(self):
+        assert get_bedrock_base_model(NOVA2_MODEL) == "amazon.nova-2-custom"
+
+
+class TestStripBedrockRoutingPrefix:
+    def test_strips_nova_prefix(self):
+        result = strip_bedrock_routing_prefix(f"nova/{NOVA_ARN}")
+        assert result == NOVA_ARN
+
+    def test_strips_nova2_prefix(self):
+        result = strip_bedrock_routing_prefix(f"nova-2/{NOVA_ARN}")
+        assert result == NOVA_ARN
+
+
+class TestIsNova2Model:
+    def setup_method(self):
+        self.config = AmazonConverseConfig()
+
+    def test_standard_nova2_model(self):
+        assert self.config._is_nova_2_model("amazon.nova-2-lite-v1:0") is True
+
+    def test_nova2_imported_model(self):
+        assert self.config._is_nova_2_model(NOVA2_MODEL) is True
+
+    def test_nova_imported_model_is_not_nova2(self):
+        assert self.config._is_nova_2_model(NOVA_MODEL) is False
+
+    def test_plain_nova_model(self):
+        assert self.config._is_nova_2_model("amazon.nova-pro-v1:0") is False
+
+
+class TestGetSupportedOpenaiParams:
+    def setup_method(self):
+        self.config = AmazonConverseConfig()
+
+    def test_nova_imported_has_tools_and_web_search(self):
+        params = self.config.get_supported_openai_params(NOVA_MODEL)
+        assert "tools" in params
+        assert "tool_choice" in params
+        assert "web_search_options" in params
+
+    def test_nova2_imported_has_reasoning_effort(self):
+        params = self.config.get_supported_openai_params(NOVA2_MODEL)
+        assert "reasoning_effort" in params
+        assert "web_search_options" in params
+
+    def test_nova2_imported_has_tools(self):
+        params = self.config.get_supported_openai_params(NOVA2_MODEL)
+        assert "tools" in params
+        assert "tool_choice" in params