fix: recognize Bedrock inference profile ARNs for prompt caching

src/strands/models/bedrock.py

@@ -186,6 +186,16 @@ def _cache_strategy(self) -> str | None:
         model_id = self.config.get("model_id", "").lower()
         if "claude" in model_id or "anthropic" in model_id:
             return "anthropic"
+
+        # Application / cross-region inference profile ARNs don't contain the
+        # foundation model name, so the substring check above misses them.
+        # When the user explicitly opted into caching via cache_config, we
+        # optimistically enable caching for inference-profile ARNs.  Currently
+        # only Anthropic Claude models support prompt caching on Bedrock; for
+        # non-caching models, the cache point is silently ignored by the API.
+        if model_id.startswith("arn:") and "inference-profile" in model_id:
+            return "anthropic"
+
         return None
 
     @override

tests/strands/models/test_bedrock.py

@@ -2597,7 +2597,27 @@ def test_cache_strategy_none_for_non_claude(bedrock_client):
     assert model._cache_strategy is None
 
 
-def test_inject_cache_point_adds_to_last_user(bedrock_client):
+def test_cache_strategy_anthropic_for_inference_profile_arn(bedrock_client):
+    """Test that _cache_strategy returns 'anthropic' for inference profile ARNs.
+
+    Application inference profile ARNs don't contain 'claude' or 'anthropic',
+    but should still support caching when the user explicitly opts in.
+
+    Reproduces: https://github.com/strands-agents/sdk-python/issues/1705
+    """
+    # Application inference profile ARN
+    model = BedrockModel(
+        model_id="arn:aws:bedrock:us-east-1:123456789012:application-inference-profile/abc123def456"
+    )
+    assert model._cache_strategy == "anthropic"
+
+    # Cross-region inference profile ARN
+    model2 = BedrockModel(
+        model_id="arn:aws:bedrock:us-east-1:123456789012:inference-profile/us.anthropic.claude-sonnet-4-20250514-v1:0"
+    )
+    assert model2._cache_strategy == "anthropic"
+
+
     """Test that _inject_cache_point adds cache point to last user message."""
     model = BedrockModel(
         model_id="us.anthropic.claude-sonnet-4-20250514-v1:0", cache_config=CacheConfig(strategy="auto")