style: apply black formatting to fix lint CI (LIT-3274) (#28639) (#28641)

* fix(bedrock): strip bedrock/ prefix and URL-encode ARNs in get_bedrock_model_id for invoke path

The invoke path (used by /v1/messages → Anthropic SDK / Claude Code) called
get_bedrock_model_id() which, when falling back to the raw model string, did
not strip the 'bedrock/' routing prefix and did not URL-encode ARNs.

For a model like:
  bedrock/arn:aws:bedrock:us-east-1:<ACCOUNT>:inference-profile/global.anthropic...

the URL built was:
  /model/bedrock/arn:aws:bedrock:…/invoke-with-response-stream  ❌

Bedrock returned a JSON error body.  LiteLLM's AWSEventStreamDecoder passed
those bytes into botocore's EventStreamBuffer which expects binary event-stream
framing.  Checksum validation failed on the JSON prelude (0x223a7b22 == ':{"')
producing a misleading botocore.eventstream.ChecksumMismatch instead of the
actual Bedrock error.

Fix: strip 'bedrock/' (and 'invoke/') routing prefix from model string, then
URL-encode if the result is an ARN — matching what the converse path already
does in converse_handler.py.

Fixes: LIT-3274

* fix(bedrock): use strip_bedrock_routing_prefix to handle compound prefixes

Address greptile review: the original fix used a loop with break, so
bedrock/invoke/arn:... only stripped bedrock/ leaving invoke/arn:...
which is not an ARN → fell through to .replace('invoke/','',1) →
bare unencoded ARN → same malformed-URL bug.

strip_bedrock_routing_prefix() iterates without break, correctly
stripping bedrock/ then invoke/ in sequence. Also adds test case
for the compound-prefix scenario.

* style: apply black formatting to fix lint CI (LIT-3274)

---------

Co-authored-by: oss-agent-shin <ext-agent-shin@berri.ai>
Co-authored-by: LiteLLM Bot <bot@berri.ai>

litellm/llms/bedrock/base_aws_llm.py

@@ -450,6 +450,24 @@ class BaseAWSLLM:
             model_id = BaseAWSLLM.encode_model_id(model_id=model_id)
         else:
             model_id = model
+            # Strip LiteLLM routing prefixes (e.g. "bedrock/", "invoke/",
+            # "bedrock/invoke/", "bedrock/converse/") that are not part of the
+            # actual Bedrock model ID.  The converse path already does this; the
+            # invoke path must do the same so that ARN models such as
+            #   bedrock/arn:aws:bedrock:…:inference-profile/global.anthropic.…
+            # are not forwarded verbatim to the Bedrock API, which would produce
+            # a malformed URL and cause botocore's EventStreamBuffer to receive
+            # a JSON error body instead of a binary event-stream — surfaced as a
+            # misleading ChecksumMismatch (0x223a7b22 == ':{"').
+            # Use strip_bedrock_routing_prefix (no break) so compound prefixes
+            # like "bedrock/invoke/arn:..." are fully stripped in one call.
+            from litellm.llms.bedrock.common_utils import strip_bedrock_routing_prefix
+
+            model_id = strip_bedrock_routing_prefix(model_id)
+            # URL-encode ARNs so colons and slashes are safe in the URL path.
+            if model_id.startswith("arn:"):
+                model_id = BaseAWSLLM.encode_model_id(model_id=model_id)
+                return model_id
 
         model_id = model_id.replace("invoke/", "", 1)
         if provider == "llama" and "llama/" in model_id:

tests/test_litellm/llms/bedrock/test_base_aws_llm.py

@@ -2112,3 +2112,102 @@ def test_is_already_running_as_role_ssl_verify_passed():
                 mock_boto3_client.assert_called_once_with(
                     "sts", verify="/path/to/ca-bundle.crt"
                 )
+
+
+# ---------------------------------------------------------------------------
+# LIT-3274: get_bedrock_model_id must strip "bedrock/" prefix and URL-encode
+# ARNs for the invoke path (invoke-with-response-stream).  Without this fix
+# the Bedrock API receives a malformed URL, returns a JSON error body, and
+# botocore's EventStreamBuffer raises ChecksumMismatch instead of the real
+# error.  0x223a7b22 == ':{\"' — the start of a JSON object.
+# ---------------------------------------------------------------------------
+
+
+class TestGetBedrockModelIdArnHandling:
+    """Unit tests for get_bedrock_model_id with inference-profile ARNs."""
+
+    ARN = "arn:aws:bedrock:us-east-1:086734376398:inference-profile/global.anthropic.claude-sonnet-4-5-20250929-v1:0"
+
+    def _call(self, model: str, optional_params: dict | None = None) -> str:
+        from litellm.llms.bedrock.base_aws_llm import BaseAWSLLM
+
+        provider = BaseAWSLLM.get_bedrock_invoke_provider(model)
+        return BaseAWSLLM.get_bedrock_model_id(
+            model=model,
+            provider=provider,
+            optional_params=optional_params or {},
+        )
+
+    def test_arn_with_bedrock_prefix_is_stripped_and_encoded(self):
+        """bedrock/arn:... must not appear verbatim in the model_id."""
+        model_id = self._call(f"bedrock/{self.ARN}")
+        assert (
+            "bedrock/arn" not in model_id
+        ), f"'bedrock/' prefix not stripped; got: {model_id}"
+        # Must be URL-encoded (colons → %3A)
+        assert "%3A" in model_id, f"ARN not URL-encoded; got: {model_id}"
+        assert "%2F" in model_id, f"ARN slashes not URL-encoded; got: {model_id}"
+
+    def test_arn_with_compound_bedrock_invoke_prefix_is_fully_stripped_and_encoded(
+        self,
+    ):
+        """bedrock/invoke/arn:... — compound prefix — must be fully stripped.
+
+        The old fix used ``break`` after the first matched prefix, so
+        ``bedrock/invoke/arn:...`` would only strip ``bedrock/``, leaving
+        ``invoke/arn:...``.  The subsequent ``.replace('invoke/', '')`` call
+        then returned the bare unencoded ARN, reproducing the same
+        malformed-URL bug the fix aimed to prevent.
+
+        strip_bedrock_routing_prefix() has no break and handles this correctly.
+        """
+        model_id = self._call(f"bedrock/invoke/{self.ARN}")
+        assert (
+            "invoke/" not in model_id
+        ), f"'invoke/' prefix not stripped; got: {model_id}"
+        assert (
+            "bedrock/" not in model_id
+        ), f"'bedrock/' prefix not stripped; got: {model_id}"
+        assert "%3A" in model_id, f"ARN not URL-encoded; got: {model_id}"
+        assert "%2F" in model_id, f"ARN slashes not URL-encoded; got: {model_id}"
+
+    def test_bare_arn_is_encoded(self):
+        """Direct ARN without routing prefix must also be URL-encoded."""
+        model_id = self._call(self.ARN)
+        assert "%3A" in model_id, f"ARN not URL-encoded; got: {model_id}"
+        assert "%2F" in model_id, f"ARN slashes not URL-encoded; got: {model_id}"
+
+    def test_arn_url_matches_expected(self):
+        """Full URL built from messages config must match expected encoded form."""
+        import urllib.parse
+        from litellm.llms.bedrock.messages.invoke_transformations.anthropic_claude3_transformation import (
+            AmazonAnthropicClaudeMessagesConfig,
+        )
+
+        config = AmazonAnthropicClaudeMessagesConfig()
+        url = config.get_complete_url(
+            api_base=None,
+            api_key=None,
+            model=f"bedrock/{self.ARN}",
+            optional_params={"aws_region_name": "us-east-1"},
+            litellm_params={},
+            stream=True,
+        )
+        encoded_arn = urllib.parse.quote(self.ARN, safe="")
+        expected = (
+            f"https://bedrock-runtime.us-east-1.amazonaws.com"
+            f"/model/{encoded_arn}/invoke-with-response-stream"
+        )
+        assert (
+            url == expected
+        ), f"URL mismatch:\n  got:      {url}\n  expected: {expected}"
+
+    def test_regular_model_id_unaffected(self):
+        """Non-ARN model IDs must continue to work as before."""
+        model_id = self._call("anthropic.claude-3-sonnet-20240229-v1:0")
+        assert model_id == "anthropic.claude-3-sonnet-20240229-v1:0"
+
+    def test_invoke_prefixed_model_unaffected(self):
+        """invoke/ prefix stripping still works after the fix."""
+        model_id = self._call("invoke/anthropic.claude-3-sonnet-20240229-v1:0")
+        assert model_id == "anthropic.claude-3-sonnet-20240229-v1:0"