feat: migrate Bedrock Claude models to native Anthropic Messages API

core/changelog.md

@@ -1,2 +1,3 @@
 - feat: add Filename field to TranscriptionInput schema to carry original filename through the request pipeline
-- fix: add AudioFilenameFromBytes utility to detect audio format from file headers with mp3 fallback
+- fix: add AudioFilenameFromBytes utility to detect audio format from file headers with mp3 fallback
+- feat: shifted to anthropic native API in bedrock provider for claude models

core/providers/anthropic/responses.go

@@ -149,6 +149,18 @@ func releaseAnthropicResponsesStreamState(state *AnthropicResponsesStreamState)
 	}
 }
 
+// AcquireAnthropicResponsesStreamState gets an Anthropic responses stream state from the pool.
+// Exported for use by providers that wrap Anthropic-compatible endpoints (e.g. Bedrock).
+func AcquireAnthropicResponsesStreamState() *AnthropicResponsesStreamState {
+	return acquireAnthropicResponsesStreamState()
+}
+
+// ReleaseAnthropicResponsesStreamState returns an Anthropic responses stream state to the pool.
+// Exported for use by providers that wrap Anthropic-compatible endpoints (e.g. Bedrock).
+func ReleaseAnthropicResponsesStreamState(state *AnthropicResponsesStreamState) {
+	releaseAnthropicResponsesStreamState(state)
+}
+
 // flush resets the state of the stream state to its initial values
 func (state *AnthropicResponsesStreamState) flush() {
 	state.ChunkIndex = nil

core/providers/bedrock/anthropic_compat.go

@@ -0,0 +1,132 @@
+package bedrock
+
+import (
+	"fmt"
+
+	"github.com/bytedance/sonic"
+	"github.com/maximhq/bifrost/core/providers/anthropic"
+	providerUtils "github.com/maximhq/bifrost/core/providers/utils"
+	schemas "github.com/maximhq/bifrost/core/schemas"
+)
+
+// getBedrockAnthropicChatRequestBody prepares the Anthropic Messages API-compatible request body
+// for Bedrock's InvokeModel endpoint. It adds the required anthropic_version body field and
+// removes the model field (which is specified in the URL path, not the body).
+// Note: streaming is determined by the URL endpoint (invoke vs invoke-with-response-stream),
+// NOT by a "stream" field in the request body — so isStreaming only affects caller routing.
+func getBedrockAnthropicChatRequestBody(ctx *schemas.BifrostContext, request *schemas.BifrostChatRequest, deployment string, providerName schemas.ModelProvider) ([]byte, *schemas.BifrostError) {
+	// Handle raw request body passthrough
+	if rawBody, ok := ctx.Value(schemas.BifrostContextKeyUseRawRequestBody).(bool); ok && rawBody {
+		rawJSON := request.GetRawRequestBody()
+		var requestBody map[string]interface{}
+		if err := sonic.Unmarshal(rawJSON, &requestBody); err != nil {
+			return nil, providerUtils.NewBifrostOperationError(schemas.ErrRequestBodyConversion, fmt.Errorf("failed to unmarshal request body: %w", err), providerName)
+		}
+		if _, exists := requestBody["max_tokens"]; !exists {
+			requestBody["max_tokens"] = anthropic.AnthropicDefaultMaxTokens
+		}
+		if _, exists := requestBody["anthropic_version"]; !exists {
+			requestBody["anthropic_version"] = DefaultBedrockAnthropicVersion
+		}
+		delete(requestBody, "model")
+		delete(requestBody, "fallbacks")
+		// Do NOT add "stream" to the body — Bedrock uses the endpoint path for streaming
+		delete(requestBody, "stream")
+		jsonBody, err := sonic.Marshal(requestBody)
+		if err != nil {
+			return nil, providerUtils.NewBifrostOperationError(schemas.ErrProviderRequestMarshal, err, providerName)
+		}
+		return jsonBody, nil
+	}
+
+	reqBody, err := anthropic.ToAnthropicChatRequest(ctx, request)
+	if err != nil {
+		return nil, providerUtils.NewBifrostOperationError(schemas.ErrRequestBodyConversion, err, providerName)
+	}
+	if reqBody == nil {
+		return nil, providerUtils.NewBifrostOperationError("request body is not provided", nil, providerName)
+	}
+	reqBody.Model = deployment
+	// Do NOT set Stream — Bedrock uses the endpoint path for streaming
+
+	return marshalBedrockAnthropicBody(reqBody, reqBody.GetExtraParams(), ctx, providerName)
+}
+
+// getBedrockAnthropicResponsesRequestBody prepares the Anthropic Messages API-compatible request body
+// for Bedrock's InvokeModel endpoint when handling Responses API requests.
+// Note: streaming is determined by the URL endpoint, NOT a "stream" body field.
+func getBedrockAnthropicResponsesRequestBody(ctx *schemas.BifrostContext, request *schemas.BifrostResponsesRequest, deployment string, providerName schemas.ModelProvider) ([]byte, *schemas.BifrostError) {
+	// Handle raw request body passthrough
+	if rawBody, ok := ctx.Value(schemas.BifrostContextKeyUseRawRequestBody).(bool); ok && rawBody {
+		rawJSON := request.GetRawRequestBody()
+		var requestBody map[string]interface{}
+		if err := sonic.Unmarshal(rawJSON, &requestBody); err != nil {
+			return nil, providerUtils.NewBifrostOperationError(schemas.ErrRequestBodyConversion, fmt.Errorf("failed to unmarshal request body: %w", err), providerName)
+		}
+		if _, exists := requestBody["max_tokens"]; !exists {
+			requestBody["max_tokens"] = anthropic.AnthropicDefaultMaxTokens
+		}
+		if _, exists := requestBody["anthropic_version"]; !exists {
+			requestBody["anthropic_version"] = DefaultBedrockAnthropicVersion
+		}
+		delete(requestBody, "model")
+		delete(requestBody, "fallbacks")
+		// Do NOT add "stream" to the body — Bedrock uses the endpoint path for streaming
+		delete(requestBody, "stream")
+		jsonBody, err := sonic.Marshal(requestBody)
+		if err != nil {
+			return nil, providerUtils.NewBifrostOperationError(schemas.ErrProviderRequestMarshal, err, providerName)
+		}
+		return jsonBody, nil
+	}
+
+	// Mutate the model before conversion so converters see the resolved deployment name
+	request.Model = deployment
+	reqBody, err := anthropic.ToAnthropicResponsesRequest(ctx, request)
+	if err != nil {
+		return nil, providerUtils.NewBifrostOperationError(schemas.ErrRequestBodyConversion, err, providerName)
+	}
+	if reqBody == nil {
+		return nil, providerUtils.NewBifrostOperationError("request body is not provided", nil, providerName)
+	}
+	// Do NOT set Stream — Bedrock uses the endpoint path for streaming
+
+	return marshalBedrockAnthropicBody(reqBody, reqBody.GetExtraParams(), ctx, providerName)
+}
+
+// marshalBedrockAnthropicBody converts an AnthropicMessageRequest to JSON suitable for
+// Bedrock's InvokeModel endpoint. It adds anthropic_version, removes the model field
+// (specified in the URL path), and merges extra params if passthrough is enabled.
+func marshalBedrockAnthropicBody(reqBody *anthropic.AnthropicMessageRequest, extraParams map[string]interface{}, ctx *schemas.BifrostContext, providerName schemas.ModelProvider) ([]byte, *schemas.BifrostError) {
+	reqBytes, err := sonic.Marshal(reqBody)
+	if err != nil {
+		return nil, providerUtils.NewBifrostOperationError(schemas.ErrProviderRequestMarshal, err, providerName)
+	}
+
+	var requestBody map[string]interface{}
+	if err := sonic.Unmarshal(reqBytes, &requestBody); err != nil {
+		return nil, providerUtils.NewBifrostOperationError(schemas.ErrProviderRequestMarshal, err, providerName)
+	}
+
+	// Add Bedrock-specific anthropic_version if not already present
+	if _, exists := requestBody["anthropic_version"]; !exists {
+		requestBody["anthropic_version"] = DefaultBedrockAnthropicVersion
+	}
+
+	// Remove model and stream — model is in URL path; streaming is via endpoint path, not body field
+	delete(requestBody, "model")
+	delete(requestBody, "stream")
+
+	// Merge extra params if passthrough is enabled
+	if ctx.Value(schemas.BifrostContextKeyPassthroughExtraParams) != nil && ctx.Value(schemas.BifrostContextKeyPassthroughExtraParams) == true {
+		if len(extraParams) > 0 {
+			providerUtils.MergeExtraParams(requestBody, extraParams)
+		}
+	}
+
+	jsonBody, err := sonic.Marshal(requestBody)
+	if err != nil {
+		return nil, providerUtils.NewBifrostOperationError(schemas.ErrProviderRequestMarshal, err, providerName)
+	}
+	return jsonBody, nil
+}