fix: support us-gov. and other multi-character Bedrock geo prefixes

pydantic_ai_slim/pydantic_ai/models/bedrock.py

@@ -155,11 +155,20 @@
     'tool_use': 'tool_call',
 }
 
-_AWS_BEDROCK_INFERENCE_GEO_PREFIXES: tuple[str, ...] = ('us.', 'eu.', 'apac.', 'jp.', 'au.', 'ca.', 'global.')
-"""Geo prefixes for Bedrock inference profile IDs (e.g., 'eu.', 'us.').
+_AWS_BEDROCK_INFERENCE_GEO_PREFIXES: tuple[str, ...] = (
+    'us.',
+    'eu.',
+    'apac.',
+    'jp.',
+    'au.',
+    'ca.',
+    'global.',
+    'us-gov.',
+)
+"""Geo prefixes for Bedrock inference profile IDs (e.g., 'eu.', 'us.', 'us-gov.').
 
 Used to strip the geo prefix so we can pass a pure foundation model ID/ARN to CountTokens,
-which does not accept profile IDs. Extend if new geos appear (e.g., 'global.', 'us-gov.').
+which does not accept profile IDs.
 """
 
 

pydantic_ai_slim/pydantic_ai/providers/bedrock.py

@@ -58,6 +58,23 @@ def bedrock_deepseek_model_profile(model_name: str) -> ModelProfile | None:
     return profile  # pragma: no cover
 
 
+# Known geo prefixes for cross-region inference profile IDs
+_BEDROCK_GEO_PREFIXES: tuple[str, ...] = ('us.', 'eu.', 'apac.', 'jp.', 'au.', 'ca.', 'global.', 'us-gov.')
+
+
+def _strip_geo_prefix(model_name: str) -> str:
+    """Strip geographic/regional prefix from model name if present.
+
+    AWS Bedrock cross-region inference uses prefixes like 'us.', 'eu.', 'us-gov.', 'global.'
+    to route requests to specific regions. This function strips those prefixes so we can
+    identify the underlying provider and model.
+    """
+    for prefix in _BEDROCK_GEO_PREFIXES:
+        if model_name.startswith(prefix):
+            return model_name.removeprefix(prefix)
+    return model_name
+
+
 class BedrockProvider(Provider[BaseClient]):
     """Provider for AWS Bedrock."""
 
@@ -87,13 +104,11 @@ def model_profile(self, model_name: str) -> ModelProfile | None:
             'deepseek': bedrock_deepseek_model_profile,
         }
 
-        # Split the model name into parts
-        parts = model_name.split('.', 2)
-
-        # Handle regional prefixes (e.g. "us.")
-        if len(parts) > 2 and len(parts[0]) == 2:
-            parts = parts[1:]
+        # Strip regional/geo prefix if present (e.g. "us.", "eu.", "us-gov.", "global.")
+        model_name = _strip_geo_prefix(model_name)
 
+        # Split the model name into provider and model parts
+        parts = model_name.split('.', 1)
         if len(parts) < 2:
             return None
 

tests/providers/test_bedrock.py

@@ -100,3 +100,50 @@ def test_bedrock_provider_model_profile(env: TestEnv, mocker: MockerFixture):
 
     unknown_model = provider.model_profile('unknown.unknown-model')
     assert unknown_model is None
+
+
+@pytest.mark.parametrize('prefix', ['us.', 'eu.', 'apac.', 'jp.', 'au.', 'ca.', 'global.', 'us-gov.'])
+def test_bedrock_provider_model_profile_all_geo_prefixes(env: TestEnv, prefix: str):
+    """Test that all cross-region inference geo prefixes are correctly handled.
+
+    This is critical for AWS GovCloud (us-gov.) and other regional deployments
+    where models use prefixes longer than 2 characters.
+    """
+    env.set('AWS_DEFAULT_REGION', 'us-east-1')
+    provider = BedrockProvider()
+
+    # Test Anthropic model with geo prefix
+    model_name = f'{prefix}anthropic.claude-sonnet-4-5-20250929-v1:0'
+    profile = provider.model_profile(model_name)
+
+    assert profile is not None, f'model_profile returned None for {model_name}'
+    assert isinstance(profile, BedrockModelProfile)
+    assert profile.bedrock_supports_tool_choice is True
+    assert profile.bedrock_send_back_thinking_parts is True
+
+
+def test_bedrock_provider_model_profile_us_gov_anthropic(env: TestEnv, mocker: MockerFixture):
+    """Test that us-gov. prefixed Anthropic models get the correct profile.
+
+    This specifically tests the us-gov. prefix which was previously broken
+    because the provider only handled 2-character prefixes.
+    """
+    env.set('AWS_DEFAULT_REGION', 'us-east-1')
+    provider = BedrockProvider()
+
+    ns = 'pydantic_ai.providers.bedrock'
+    anthropic_model_profile_mock = mocker.patch(f'{ns}.anthropic_model_profile', wraps=anthropic_model_profile)
+
+    # Test us-gov. prefix (AWS GovCloud cross-region inference)
+    profile = provider.model_profile('us-gov.anthropic.claude-sonnet-4-5-20250929-v1:0')
+    anthropic_model_profile_mock.assert_called_with('claude-sonnet-4-5-20250929')
+    assert isinstance(profile, BedrockModelProfile)
+    assert profile.bedrock_supports_tool_choice is True
+    assert profile.bedrock_send_back_thinking_parts is True
+
+    # Test global. prefix
+    profile = provider.model_profile('global.anthropic.claude-opus-4-5-20251101-v1:0')
+    anthropic_model_profile_mock.assert_called_with('claude-opus-4-5-20251101')
+    assert isinstance(profile, BedrockModelProfile)
+    assert profile.bedrock_supports_tool_choice is True
+    assert profile.bedrock_send_back_thinking_parts is True