From f953c8cbb02db6c1e5df722e0b08efe510397a6d Mon Sep 17 00:00:00 2001
From: Yevhenii Shcherbina <yevhenii@coder.com>
Date: Tue, 7 Jul 2026 14:31:15 +0000
Subject: [PATCH 1/3] feat: add AWS Bedrock mantle endpoint to AI Gateway

---
 aibridge/config/config.go                     |  58 +++++-
 aibridge/config/config_test.go                | 113 ++++++++++
 aibridge/intercept/messages/base.go           | 134 ++++++++++--
 .../intercept/messages/base_internal_test.go  |  80 ++++++-
 .../integrationtest/bridge_internal_test.go   |  59 +++++-
 cli/aibridged.go                              |   2 +
 coderd/aibridged/proto/aibridged.pb.go        | 154 +++++++-------
 coderd/aibridged/proto/aibridged.proto        |   3 +
 coderd/aibridgedserver/aibridgedserver.go     |   1 +
 codersdk/aiproviders.go                       |   7 +
 codersdk/aiproviders_bedrock.go               |  30 +++
 codersdk/aiproviders_test.go                  |  44 ++++
 docs/ai-coder/ai-gateway/providers.md         |  35 ++++
 site/src/api/typesGenerated.ts                |  14 ++
 .../components/ProviderForm.stories.tsx       |  45 ++++
 .../ProvidersPage/components/ProviderForm.tsx | 196 ++++++++++++++----
 .../components/providerFormApiMap.test.ts     |  65 ++++++
 .../components/providerFormApiMap.ts          |  41 ++--
 18 files changed, 928 insertions(+), 153 deletions(-)
 create mode 100644 aibridge/config/config_test.go

diff --git a/aibridge/config/config.go b/aibridge/config/config.go
index b01282b0cc7..45e0be88ba9 100644
--- a/aibridge/config/config.go
+++ b/aibridge/config/config.go
@@ -1,6 +1,8 @@
 package config
 
 import (
+	"errors"
+	"fmt"
 	"time"
 
 	"github.com/coder/coder/v2/aibridge/keypool"
@@ -25,13 +27,34 @@ type Anthropic struct {
 	SendActorHeaders bool
 }
 
+// BedrockProtocol selects which AWS Bedrock wire protocol a provider targets.
+type BedrockProtocol string
+
+const (
+	// BedrockProtocolInvokeModel is the legacy InvokeModel protocol
+	// (bedrock-runtime.{region}.amazonaws.com), which translates the native
+	// Messages request into Bedrock's InvokeModel format. It is the default
+	// for the zero value.
+	BedrockProtocolInvokeModel BedrockProtocol = "invoke-model"
+	// BedrockProtocolMantle is the mantle protocol
+	// (bedrock-mantle.{region}.api.aws/anthropic/v1/messages). It is a
+	// passthrough: the gateway forwards the native Messages request body
+	// unchanged and only applies AWS SigV4 signing (service bedrock-mantle).
+	BedrockProtocolMantle BedrockProtocol = "mantle"
+)
+
 type AWSBedrock struct {
 	Region                     string
 	AccessKey, AccessKeySecret string
 	Model, SmallFastModel      string
-	// If set, requests will be sent to this URL instead of the default AWS Bedrock endpoint
-	// (https://bedrock-runtime.{region}.amazonaws.com).
-	// This is useful for routing requests through a proxy or for testing.
+	// BaseURL configures the upstream Bedrock endpoint.
+	//
+	// For InvokeModel, it is optional. When empty, requests use the default
+	// https://bedrock-runtime.{region}.amazonaws.com endpoint. Set it to route
+	// InvokeModel requests through a proxy or test server.
+	//
+	// For mantle, it is required and must be the Messages API prefix without
+	// /v1/messages, e.g. https://bedrock-mantle.{region}.api.aws/anthropic.
 	BaseURL string
 	// RoleARN, when set, is assumed via STS before calling Bedrock. The base
 	// identity (static keys or the AWS SDK default credential chain, e.g.
@@ -42,6 +65,35 @@ type AWSBedrock struct {
 	// It is meaningful only alongside RoleARN and must match the
 	// sts:ExternalId condition on the target role's trust policy.
 	ExternalID string
+	// Protocol selects the Bedrock wire protocol. The zero value behaves as
+	// BedrockProtocolInvokeModel.
+	Protocol BedrockProtocol
+}
+
+// Validate verifies protocol-specific Bedrock configuration.
+func (c AWSBedrock) Validate() error {
+	switch c.Protocol {
+	case "", BedrockProtocolInvokeModel:
+		if c.Region == "" && c.BaseURL == "" {
+			return errors.New("region or base url required")
+		}
+		if c.Model == "" {
+			return errors.New("model required")
+		}
+		if c.SmallFastModel == "" {
+			return errors.New("small fast model required")
+		}
+	case BedrockProtocolMantle:
+		if c.Region == "" {
+			return errors.New("region required")
+		}
+		if c.BaseURL == "" {
+			return errors.New("base_url required")
+		}
+	default:
+		return fmt.Errorf("unknown bedrock protocol: %q", c.Protocol)
+	}
+	return nil
 }
 
 // OpenAI carries configuration for an OpenAI provider.
diff --git a/aibridge/config/config_test.go b/aibridge/config/config_test.go
new file mode 100644
index 00000000000..f2d80fbc7b2
--- /dev/null
+++ b/aibridge/config/config_test.go
@@ -0,0 +1,113 @@
+package config_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/v2/aibridge/config"
+)
+
+func TestAWSBedrockValidate(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		cfg      config.AWSBedrock
+		errorMsg string
+	}{
+		{
+			name: "invoke model valid",
+			cfg: config.AWSBedrock{
+				Region:         "us-east-1",
+				Model:          "anthropic.claude-sonnet",
+				SmallFastModel: "anthropic.claude-haiku",
+			},
+		},
+		{
+			name: "invoke model valid with base url instead of region",
+			cfg: config.AWSBedrock{
+				BaseURL:        "https://bedrock-runtime.example.com",
+				Model:          "anthropic.claude-sonnet",
+				SmallFastModel: "anthropic.claude-haiku",
+			},
+		},
+		{
+			name: "invoke model missing region and base url",
+			cfg: config.AWSBedrock{
+				Model:          "anthropic.claude-sonnet",
+				SmallFastModel: "anthropic.claude-haiku",
+			},
+			errorMsg: "region or base url required",
+		},
+		{
+			name: "invoke model missing model",
+			cfg: config.AWSBedrock{
+				Region:         "us-east-1",
+				SmallFastModel: "anthropic.claude-haiku",
+			},
+			errorMsg: "model required",
+		},
+		{
+			name: "invoke model missing small fast model",
+			cfg: config.AWSBedrock{
+				Region: "us-east-1",
+				Model:  "anthropic.claude-sonnet",
+			},
+			errorMsg: "small fast model required",
+		},
+		{
+			name: "unknown protocol rejected",
+			cfg: config.AWSBedrock{
+				Protocol: config.BedrockProtocol("unknown"),
+			},
+			errorMsg: "unknown bedrock protocol",
+		},
+		{
+			name: "mantle valid official api prefix",
+			cfg: config.AWSBedrock{
+				Region:   "us-east-1",
+				BaseURL:  "https://bedrock-mantle.us-east-1.api.aws/anthropic",
+				Protocol: config.BedrockProtocolMantle,
+			},
+		},
+		{
+			name: "mantle valid proxy api prefix",
+			cfg: config.AWSBedrock{
+				Region:   "us-east-1",
+				BaseURL:  "https://proxy.internal/proxy",
+				Protocol: config.BedrockProtocolMantle,
+			},
+		},
+		{
+			name: "mantle missing region",
+			cfg: config.AWSBedrock{
+				BaseURL:  "https://bedrock-mantle.us-east-1.api.aws",
+				Protocol: config.BedrockProtocolMantle,
+			},
+			errorMsg: "region required",
+		},
+		{
+			name: "mantle missing base url",
+			cfg: config.AWSBedrock{
+				Region:   "us-east-1",
+				Protocol: config.BedrockProtocolMantle,
+			},
+			errorMsg: "base_url required",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := tt.cfg.Validate()
+			if tt.errorMsg != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tt.errorMsg)
+				return
+			}
+			require.NoError(t, err)
+		})
+	}
+}
diff --git a/aibridge/intercept/messages/base.go b/aibridge/intercept/messages/base.go
index b1e989b6a06..c9566ad724a 100644
--- a/aibridge/intercept/messages/base.go
+++ b/aibridge/intercept/messages/base.go
@@ -1,10 +1,14 @@
 package messages
 
 import (
+	"bytes"
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"math"
 	"net/http"
 	"strconv"
@@ -17,6 +21,7 @@ import (
 	"github.com/anthropics/anthropic-sdk-go/shared"
 	"github.com/anthropics/anthropic-sdk-go/shared/constant"
 	"github.com/aws/aws-sdk-go-v2/aws"
+	v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
 	"github.com/google/uuid"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
@@ -64,6 +69,22 @@ var bedrockSupportedBetaFlags = map[string]bool{
 	"tool-examples-2025-10-29": true,
 }
 
+// BedrockPRMUserAgent is Coder's AWS attribution marker for outbound
+// Bedrock requests.
+//
+// It is appended to Bedrock User-Agent headers so AWS can recognize the
+// traffic as Coder-associated Bedrock usage.
+const BedrockPRMUserAgent = "sdk-ua-app-id/APN_1.1%2Fpc_cdfmjwn8i6u8l9fwz8h82e4w3%24"
+
+// bedrockMantleSigningService is the AWS SigV4 service name for mantle.
+const bedrockMantleSigningService = "bedrock-mantle"
+
+func appendBedrockPRMUserAgent(req *http.Request) {
+	if ua := req.Header.Get("User-Agent"); ua != "" {
+		req.Header.Set("User-Agent", ua+" "+BedrockPRMUserAgent)
+	}
+}
+
 // BedrockRuntime carries everything a Bedrock-backed interception needs: the
 // static Bedrock config plus the AWS credentials provider.
 type BedrockRuntime struct {
@@ -109,12 +130,29 @@ func (i *interceptionBase) CorrelatingToolCallID() *string {
 	return i.reqPayload.correlatingToolCallID()
 }
 
+// isBedrockMantle reports whether the interception targets the Bedrock mantle
+// protocol.
+func (i *interceptionBase) isBedrockMantle() bool {
+	return i.bedrock != nil && i.bedrock.Cfg.Protocol == aibconfig.BedrockProtocolMantle
+}
+
+// isBedrockInvokeModel reports whether the interception targets the Bedrock
+// InvokeModel protocol.
+func (i *interceptionBase) isBedrockInvokeModel() bool {
+	return i.bedrock != nil &&
+		(i.bedrock.Cfg.Protocol == "" || i.bedrock.Cfg.Protocol == aibconfig.BedrockProtocolInvokeModel)
+}
+
 func (i *interceptionBase) Model() string {
 	if len(i.reqPayload) == 0 {
 		return "coder-aibridge-unknown"
 	}
 
-	if i.bedrock != nil {
+	// InvokeModel is the only protocol that remaps the model: it replaces the
+	// client's model with the operator-configured one. Every other case (mantle
+	// passthrough, non-Bedrock providers) returns the model the client sent in
+	// the body.
+	if i.isBedrockInvokeModel() {
 		model := i.bedrock.Cfg.Model
 		if i.isSmallFastModel() {
 			model = i.bedrock.Cfg.SmallFastModel
@@ -245,15 +283,25 @@ func (i *interceptionBase) newMessagesService(ctx context.Context, opts ...optio
 		opts = append(opts, option.WithMiddleware(mw))
 	}
 
-	if i.bedrock != nil {
+	if i.isBedrockInvokeModel() {
 		ctx, cancel := context.WithTimeout(ctx, time.Second*30)
 		defer cancel()
-		bedrockOpts, err := i.withAWSBedrockOptions(ctx)
+		bedrockOpts, err := i.withBedrockInvokeModelOptions(ctx)
+		if err != nil {
+			return anthropic.MessageService{}, err
+		}
+		opts = append(opts, bedrockOpts...)
+		i.augmentRequestForBedrockInvokeModel()
+	}
+
+	if i.isBedrockMantle() {
+		ctx, cancel := context.WithTimeout(ctx, time.Second*30)
+		defer cancel()
+		bedrockOpts, err := i.withBedrockMantleOptions(ctx)
 		if err != nil {
 			return anthropic.MessageService{}, err
 		}
 		opts = append(opts, bedrockOpts...)
-		i.augmentRequestForBedrock()
 	}
 
 	return anthropic.NewMessageService(opts...), nil
@@ -267,23 +315,18 @@ func (i *interceptionBase) withBody() option.RequestOption {
 	return option.WithRequestBody("application/json", []byte(i.reqPayload))
 }
 
-// withAWSBedrockOptions returns request options for authenticating with AWS Bedrock.
+// withBedrockInvokeModelOptions returns request options for the AWS Bedrock
+// InvokeModel protocol.
 //
 // Credentials come from i.bedrock.Creds. It is a shared credentials cache, so the per-request Retrieve()
 // below is served from that cache and does not re-resolve or re-assume on every request.
-func (i *interceptionBase) withAWSBedrockOptions(ctx context.Context) ([]option.RequestOption, error) {
+func (i *interceptionBase) withBedrockInvokeModelOptions(ctx context.Context) ([]option.RequestOption, error) {
 	if i.bedrock == nil {
 		return nil, xerrors.New("nil bedrock runtime")
 	}
 	cfg := i.bedrock.Cfg
-	if cfg.Region == "" && cfg.BaseURL == "" {
-		return nil, xerrors.New("region or base url required")
-	}
-	if cfg.Model == "" {
-		return nil, xerrors.New("model required")
-	}
-	if cfg.SmallFastModel == "" {
-		return nil, xerrors.New("small fast model required")
+	if err := cfg.Validate(); err != nil {
+		return nil, err
 	}
 
 	// Fail fast: ensure credentials can be resolved before signing. Served from
@@ -300,9 +343,7 @@ func (i *interceptionBase) withAWSBedrockOptions(ctx context.Context) ([]option.
 
 	var out []option.RequestOption
 	out = append(out, option.WithMiddleware(func(req *http.Request, next option.MiddlewareNext) (*http.Response, error) {
-		if ua := req.Header.Get("User-Agent"); ua != "" {
-			req.Header.Set("User-Agent", ua+" sdk-ua-app-id/APN_1.1%2Fpc_cdfmjwn8i6u8l9fwz8h82e4w3%24")
-		}
+		appendBedrockPRMUserAgent(req)
 		return next(req)
 	}))
 	out = append(out, bedrock.WithConfig(awsCfg))
@@ -315,11 +356,66 @@ func (i *interceptionBase) withAWSBedrockOptions(ctx context.Context) ([]option.
 	return out, nil
 }
 
-// augmentRequestForBedrock will change the model used for the request since AWS Bedrock doesn't support
+// withBedrockMantleOptions returns request options for the AWS Bedrock mantle
+// endpoint (bedrock-mantle.{region}.api.aws/anthropic/v1/messages). It speaks
+// the native Messages wire format, so this middleware only SigV4-signs the
+// request (service "bedrock-mantle") and forwards it; the response is plain
+// SSE.
+func (i *interceptionBase) withBedrockMantleOptions(ctx context.Context) ([]option.RequestOption, error) {
+	cfg := i.bedrock.Cfg
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+
+	// Fail fast: ensure credentials can be resolved before signing. Served from
+	// the shared cache on most requests (no network); on the cold or refresh
+	// path this performs the actual STS/IMDS call.
+	if _, err := i.bedrock.Creds.Retrieve(ctx); err != nil {
+		return nil, xerrors.Errorf("resolve AWS credentials: %w", err)
+	}
+
+	signer := v4.NewSigner()
+	var out []option.RequestOption
+	out = append(out, option.WithBaseURL(cfg.BaseURL))
+	// Appended last so it runs innermost (right before the HTTP send) and signs
+	// the request after all other headers are set.
+	out = append(out, option.WithMiddleware(func(req *http.Request, next option.MiddlewareNext) (*http.Response, error) {
+		appendBedrockPRMUserAgent(req)
+
+		creds, err := i.bedrock.Creds.Retrieve(req.Context())
+		if err != nil {
+			return nil, err
+		}
+
+		// SigV4 requires a payload hash, so read the body to hash it and then
+		// restore it for the downstream HTTP client to send.
+		var body []byte
+		if req.Body != nil {
+			var err error
+			body, err = io.ReadAll(req.Body)
+			if err != nil {
+				return nil, err
+			}
+			_ = req.Body.Close()
+			req.Body = io.NopCloser(bytes.NewReader(body))
+			req.ContentLength = int64(len(body))
+		}
+
+		hash := sha256.Sum256(body)
+		if err := signer.SignHTTP(req.Context(), creds, req, hex.EncodeToString(hash[:]), bedrockMantleSigningService, cfg.Region, time.Now()); err != nil {
+			return nil, err
+		}
+		return next(req)
+	}))
+
+	return out, nil
+}
+
+// augmentRequestForBedrockInvokeModel will change the model used for the request since AWS Bedrock doesn't support
 // Anthropics' model names. It also converts adaptive thinking to enabled with a budget for models that
 // don't support adaptive thinking natively, or enabled thinking to adaptive for models that only support
 // adaptive (Opus 4.7+).
-func (i *interceptionBase) augmentRequestForBedrock() {
+func (i *interceptionBase) augmentRequestForBedrockInvokeModel() {
 	if i.bedrock == nil {
 		return
 	}
diff --git a/aibridge/intercept/messages/base_internal_test.go b/aibridge/intercept/messages/base_internal_test.go
index 714f32b2c0f..eef99ea86e1 100644
--- a/aibridge/intercept/messages/base_internal_test.go
+++ b/aibridge/intercept/messages/base_internal_test.go
@@ -183,7 +183,7 @@ func TestAWSBedrockValidation(t *testing.T) {
 					Creds: credentials.NewStaticCredentialsProvider("test-key", "test-secret", ""),
 				},
 			}
-			opts, err := base.withAWSBedrockOptions(context.Background())
+			opts, err := base.withBedrockInvokeModelOptions(context.Background())
 
 			if tt.expectError {
 				require.Error(t, err)
@@ -198,12 +198,12 @@ func TestAWSBedrockValidation(t *testing.T) {
 
 // TestAWSBedrockOptionsRequireRuntime verifies that option assembly fails when
 // the Bedrock runtime was not set. This should never happen in practice, since
-// withAWSBedrockOptions is only called when i.bedrock != nil.
+// withBedrockInvokeModelOptions is only called when i.bedrock != nil.
 func TestAWSBedrockOptionsRequireRuntime(t *testing.T) {
 	t.Parallel()
 
 	base := &interceptionBase{}
-	_, err := base.withAWSBedrockOptions(context.Background())
+	_, err := base.withBedrockInvokeModelOptions(context.Background())
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "nil bedrock runtime")
 }
@@ -800,7 +800,7 @@ func TestAugmentRequestForBedrock_AdaptiveThinking(t *testing.T) {
 				logger:        slog.Make(),
 			}
 
-			i.augmentRequestForBedrock()
+			i.augmentRequestForBedrockInvokeModel()
 
 			thinkingType := gjson.GetBytes(i.reqPayload, "thinking.type")
 			if tc.expectThinkingType == "" {
@@ -1126,3 +1126,75 @@ func TestWriteUpstreamError(t *testing.T) {
 		})
 	}
 }
+
+// TestBedrockMantleIsPassthrough verifies a mantle provider reports the mantle
+// protocol and that Model() returns the client's model.
+func TestBedrockMantleIsPassthrough(t *testing.T) {
+	t.Parallel()
+
+	i := &interceptionBase{
+		reqPayload: mustMessagesPayload(t,
+			`{"model":"anthropic.claude-opus-4-8","max_tokens":10000,"thinking":{"type":"adaptive"},"metadata":{"user_id":"u123"},"context_management":{"type":"auto"}}`),
+		bedrock: &BedrockRuntime{
+			Cfg: config.AWSBedrock{
+				Region:   "us-east-1",
+				Protocol: config.BedrockProtocolMantle,
+			},
+		},
+		logger: slog.Make(),
+	}
+
+	require.True(t, i.isBedrockMantle())
+	require.False(t, i.isBedrockInvokeModel())
+	require.Equal(t, "anthropic.claude-opus-4-8", i.Model())
+}
+
+// TestAWSMantleOptionsValidation verifies the mantle protocol requires a
+// region (it scopes the SigV4 signature) but NOT model fields.
+func TestAWSMantleOptionsValidation(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		cfg      config.AWSBedrock
+		errorMsg string
+	}{
+		{
+			name: "valid without model fields",
+			cfg: config.AWSBedrock{
+				Region:   "us-east-1",
+				BaseURL:  "https://bedrock-mantle.us-east-1.api.aws/anthropic",
+				Protocol: config.BedrockProtocolMantle,
+			},
+		},
+		{
+			name: "missing region even with base url",
+			cfg: config.AWSBedrock{
+				BaseURL:  "https://proxy.internal",
+				Protocol: config.BedrockProtocolMantle,
+			},
+			errorMsg: "region required",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			base := &interceptionBase{
+				bedrock: &BedrockRuntime{
+					Cfg:   tt.cfg,
+					Creds: credentials.NewStaticCredentialsProvider("test-key", "test-secret", ""),
+				},
+			}
+			opts, err := base.withBedrockMantleOptions(context.Background())
+			if tt.errorMsg != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tt.errorMsg)
+			} else {
+				require.NoError(t, err)
+				require.NotEmpty(t, opts)
+			}
+		})
+	}
+}
diff --git a/aibridge/internal/integrationtest/bridge_internal_test.go b/aibridge/internal/integrationtest/bridge_internal_test.go
index 024652928e7..1b515735da4 100644
--- a/aibridge/internal/integrationtest/bridge_internal_test.go
+++ b/aibridge/internal/integrationtest/bridge_internal_test.go
@@ -36,6 +36,7 @@ import (
 	"github.com/coder/coder/v2/aibridge/config"
 	"github.com/coder/coder/v2/aibridge/fixtures"
 	"github.com/coder/coder/v2/aibridge/intercept"
+	"github.com/coder/coder/v2/aibridge/intercept/messages"
 	"github.com/coder/coder/v2/aibridge/internal/testutil"
 	"github.com/coder/coder/v2/aibridge/mcp"
 	"github.com/coder/coder/v2/aibridge/provider"
@@ -377,7 +378,7 @@ func TestAWSBedrockIntegration(t *testing.T) {
 
 				// Verify PRM attribution is appended to the User-Agent header.
 				ua := received[0].Header.Get("User-Agent")
-				require.Contains(t, ua, "sdk-ua-app-id/APN_1.1%2Fpc_cdfmjwn8i6u8l9fwz8h82e4w3%24",
+				require.Contains(t, ua, messages.BedrockPRMUserAgent,
 					"expected AWS PRM attribution in User-Agent header")
 
 				interceptions := bridgeServer.Recorder.RecordedInterceptions()
@@ -388,6 +389,62 @@ func TestAWSBedrockIntegration(t *testing.T) {
 		}
 	})
 
+	// The mantle protocol is a passthrough: the client's model is forwarded in the body
+	// without remapping, only SigV4 signing (service "bedrock-mantle") is applied.
+	t.Run("mantle/v1/messages", func(t *testing.T) {
+		t.Parallel()
+
+		ctx, cancel := context.WithTimeout(t.Context(), testutil.WaitLong)
+		t.Cleanup(cancel)
+
+		fix := fixtures.Parse(t, fixtures.AntSingleBuiltinTool)
+		upstream := testutil.NewMockUpstream(ctx, t, testutil.NewFixtureResponse(fix))
+
+		// Mantle needs only region + credentials for signing (no Model fields:
+		// the client supplies the model).
+		bedrockCfg := &config.AWSBedrock{
+			Region:          "us-west-2",
+			AccessKey:       "test-access-key",
+			AccessKeySecret: "test-secret-key",
+			BaseURL:         upstream.URL + "/anthropic", // Use the mock server.
+			Protocol:        config.BedrockProtocolMantle,
+		}
+		// The client's model must be forwarded unchanged.
+		wantModel := gjson.GetBytes(fix.Request(), "model").String()
+		require.NotEmpty(t, wantModel)
+
+		bridgeServer := newBridgeTestServer(ctx, t, upstream.URL,
+			withCustomProvider(aibridgetest.NewAnthropicProvider(t, anthropicCfg(upstream.URL, apiKey), bedrockCfg)),
+		)
+
+		resp, err := bridgeServer.makeRequest(t, http.MethodPost, pathAnthropicMessages, fix.Request())
+		require.NoError(t, err)
+		defer resp.Body.Close()
+
+		received := upstream.ReceivedRequests()
+		require.Len(t, received, 1)
+
+		// Native passthrough: /anthropic Messages path, model kept in the body
+		// unchanged.
+		require.Equal(t, "/anthropic/v1/messages", received[0].Path)
+		require.Equal(t, wantModel, gjson.GetBytes(received[0].Body, "model").String(),
+			"model should be forwarded unchanged")
+
+		// SigV4-signed for the bedrock-mantle service.
+		authHeader := received[0].Header.Get("Authorization")
+		require.True(t, strings.HasPrefix(authHeader, "AWS4-HMAC-SHA256"), "missing SigV4 auth: %q", authHeader)
+		require.Contains(t, authHeader, "/bedrock-mantle/aws4_request",
+			"signature must be scoped to the bedrock-mantle service")
+
+		require.Contains(t, received[0].Header.Get("User-Agent"),
+			messages.BedrockPRMUserAgent)
+
+		interceptions := bridgeServer.Recorder.RecordedInterceptions()
+		require.Len(t, interceptions, 1)
+		require.Equal(t, wantModel, interceptions[0].Model)
+		bridgeServer.Recorder.VerifyAllInterceptionsEnded(t)
+	})
+
 	// Tests that Bedrock-incompatible fields are stripped and adaptive thinking
 	// is handled correctly per model. Different Bedrock model names trigger
 	// different behavior for beta flag filtering and field stripping.
diff --git a/cli/aibridged.go b/cli/aibridged.go
index addeb3f9598..230f33e5119 100644
--- a/cli/aibridged.go
+++ b/cli/aibridged.go
@@ -212,6 +212,7 @@ func protoToProviderSpec(pp *proto.AIProvider) aiProviderSpec {
 		)
 		bedrock.RoleARN = b.GetRoleArn()
 		bedrock.ExternalID = b.GetExternalId()
+		bedrock.Protocol = codersdk.AIProviderBedrockProtocol(b.GetProtocol())
 		spec.Bedrock = ptr.Ref(bedrock)
 	}
 	return spec
@@ -354,6 +355,7 @@ func bedrockConfig(baseURL string, bedrock *codersdk.AIProviderBedrockSettings)
 		SmallFastModel:  bedrockSettings.SmallFastModel,
 		RoleARN:         bedrockSettings.RoleARN,
 		ExternalID:      bedrockSettings.ExternalID,
+		Protocol:        config.BedrockProtocol(bedrockSettings.ResolvedProtocol()),
 	}
 }
 
diff --git a/coderd/aibridged/proto/aibridged.pb.go b/coderd/aibridged/proto/aibridged.pb.go
index 2ca74b6333a..b1f8ae9e506 100644
--- a/coderd/aibridged/proto/aibridged.pb.go
+++ b/coderd/aibridged/proto/aibridged.pb.go
@@ -1583,6 +1583,9 @@ type AIProviderKindBedrock struct {
 	SmallFastModel  string `protobuf:"bytes,5,opt,name=small_fast_model,json=smallFastModel,proto3" json:"small_fast_model,omitempty"`
 	RoleArn         string `protobuf:"bytes,6,opt,name=role_arn,json=roleArn,proto3" json:"role_arn,omitempty"`
 	ExternalId      string `protobuf:"bytes,7,opt,name=external_id,json=externalId,proto3" json:"external_id,omitempty"`
+	// protocol selects the Bedrock wire protocol ("invoke-model" or "mantle").
+	// Empty fallbacks to invoke-model.
+	Protocol string `protobuf:"bytes,8,opt,name=protocol,proto3" json:"protocol,omitempty"`
 }
 
 func (x *AIProviderKindBedrock) Reset() {
@@ -1666,6 +1669,13 @@ func (x *AIProviderKindBedrock) GetExternalId() string {
 	return ""
 }
 
+func (x *AIProviderKindBedrock) GetProtocol() string {
+	if x != nil {
+		return x.Protocol
+	}
+	return ""
+}
+
 var File_coderd_aibridged_proto_aibridged_proto protoreflect.FileDescriptor
 
 var file_coderd_aibridged_proto_aibridged_proto_rawDesc = []byte{
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+	0x74, 0x6f, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
diff --git a/coderd/aibridged/proto/aibridged.proto b/coderd/aibridged/proto/aibridged.proto
index 6b8bd1e7362..de289ff7186 100644
--- a/coderd/aibridged/proto/aibridged.proto
+++ b/coderd/aibridged/proto/aibridged.proto
@@ -218,4 +218,7 @@ message AIProviderKindBedrock {
   string small_fast_model = 5;
   string role_arn = 6;
   string external_id = 7;
+  // protocol selects the Bedrock wire protocol ("invoke-model" or "mantle").
+  // Empty fallbacks to invoke-model.
+  string protocol = 8;
 }
diff --git a/coderd/aibridgedserver/aibridgedserver.go b/coderd/aibridgedserver/aibridgedserver.go
index 1ebfc7e889d..45962d5f221 100644
--- a/coderd/aibridgedserver/aibridgedserver.go
+++ b/coderd/aibridgedserver/aibridgedserver.go
@@ -1011,6 +1011,7 @@ func aiProviderToProto(row database.AIProvider, keys []database.AIProviderKey) (
 			SmallFastModel:  settings.Bedrock.SmallFastModel,
 			RoleArn:         settings.Bedrock.RoleARN,
 			ExternalId:      settings.Bedrock.ExternalID,
+			Protocol:        string(settings.Bedrock.Protocol),
 		}
 	}
 
diff --git a/codersdk/aiproviders.go b/codersdk/aiproviders.go
index 7826a921f2d..61d78a537e8 100644
--- a/codersdk/aiproviders.go
+++ b/codersdk/aiproviders.go
@@ -281,6 +281,13 @@ func (req CreateAIProviderRequest) Validate() []ValidationError {
 				Detail: "external_id is server-generated and cannot be set",
 			})
 		}
+		// The Mantle protocol signs requests with SigV4, which requires a region.
+		if req.Settings.Bedrock.ResolvedProtocol() == AIProviderBedrockProtocolMantle && req.Settings.Bedrock.Region == "" {
+			validations = append(validations, ValidationError{
+				Field:  "settings.region",
+				Detail: "region is required for the mantle protocol",
+			})
+		}
 	}
 	if req.Type == AIProviderTypeCopilot && len(req.APIKeys) > 0 {
 		validations = append(validations, ValidationError{
diff --git a/codersdk/aiproviders_bedrock.go b/codersdk/aiproviders_bedrock.go
index be17f6c95d0..688e18b4710 100644
--- a/codersdk/aiproviders_bedrock.go
+++ b/codersdk/aiproviders_bedrock.go
@@ -8,6 +8,23 @@ const AIProviderSettingsTypeBedrock = "bedrock"
 // AIProviderBedrockSettings.
 const AIProviderBedrockSettingsVersion = 1
 
+// AIProviderBedrockProtocol selects which AWS Bedrock wire protocol a provider
+// targets.
+type AIProviderBedrockProtocol string
+
+const (
+	// AIProviderBedrockProtocolInvokeModel is the legacy InvokeModel protocol
+	// (bedrock-runtime.{region}.amazonaws.com), which translates the native
+	// Messages request into Bedrock's InvokeModel format. It is the default
+	// for the zero value.
+	AIProviderBedrockProtocolInvokeModel AIProviderBedrockProtocol = "invoke-model"
+	// AIProviderBedrockProtocolMantle is the mantle protocol
+	// (bedrock-mantle.{region}.api.aws/anthropic/v1/messages). It is a
+	// passthrough: the gateway forwards the native Messages request body
+	// unchanged and only applies AWS SigV4 signing (service bedrock-mantle).
+	AIProviderBedrockProtocolMantle AIProviderBedrockProtocol = "mantle"
+)
+
 // AIProviderBedrockSettings configures providers that authenticate
 // against AWS Bedrock. AccessKey and AccessKeySecret are write-only:
 // servers strip them from GET and list responses. Both secret fields
@@ -40,6 +57,19 @@ type AIProviderBedrockSettings struct {
 	// reject any client-supplied value that differs from the stored one (an
 	// update may echo the stored value back).
 	ExternalID string `json:"external_id,omitempty"`
+	// Protocol selects the Bedrock wire protocol. An empty value resolves to
+	// AIProviderBedrockProtocolInvokeModel, so existing rows keep the legacy
+	// behavior.
+	Protocol AIProviderBedrockProtocol `json:"protocol,omitempty"`
+}
+
+// ResolvedProtocol returns the configured protocol, mapping the empty value to
+// the legacy InvokeModel protocol.
+func (b AIProviderBedrockSettings) ResolvedProtocol() AIProviderBedrockProtocol {
+	if b.Protocol == "" {
+		return AIProviderBedrockProtocolInvokeModel
+	}
+	return b.Protocol
 }
 
 // IsConfigured reports whether any load-bearing Bedrock field is set,
diff --git a/codersdk/aiproviders_test.go b/codersdk/aiproviders_test.go
index a0ce28ec4ea..5fd1dd238ca 100644
--- a/codersdk/aiproviders_test.go
+++ b/codersdk/aiproviders_test.go
@@ -212,3 +212,47 @@ func TestAIProviderRequest_ValidateRoleARN(t *testing.T) {
 		})
 	}
 }
+
+func TestAIProviderRequest_ValidateBedrockMantle(t *testing.T) {
+	t.Parallel()
+
+	hasFieldError := func(vs []codersdk.ValidationError, field string) bool {
+		for _, v := range vs {
+			if v.Field == field {
+				return true
+			}
+		}
+		return false
+	}
+
+	t.Run("MantleRequiresRegion", func(t *testing.T) {
+		t.Parallel()
+		create := codersdk.CreateAIProviderRequest{
+			Type:    codersdk.AIProviderTypeBedrock,
+			Name:    "bedrock",
+			BaseURL: "https://bedrock-mantle.us-east-1.api.aws",
+			Settings: codersdk.AIProviderSettings{
+				Bedrock: &codersdk.AIProviderBedrockSettings{
+					Protocol: codersdk.AIProviderBedrockProtocolMantle,
+				},
+			},
+		}
+		require.True(t, hasFieldError(create.Validate(), "settings.region"))
+
+		create.Settings.Bedrock.Region = "us-east-1"
+		require.False(t, hasFieldError(create.Validate(), "settings.region"))
+	})
+
+	t.Run("InvokeModelDoesNotRequireRegionField", func(t *testing.T) {
+		t.Parallel()
+		// The default (invoke-model) protocol keeps its existing rules; the
+		// mantle-specific region check must not fire for it.
+		create := codersdk.CreateAIProviderRequest{
+			Type:     codersdk.AIProviderTypeBedrock,
+			Name:     "bedrock",
+			BaseURL:  "https://bedrock-runtime.us-east-1.amazonaws.com",
+			Settings: codersdk.AIProviderSettings{},
+		}
+		require.False(t, hasFieldError(create.Validate(), "settings.region"))
+	})
+}
diff --git a/docs/ai-coder/ai-gateway/providers.md b/docs/ai-coder/ai-gateway/providers.md
index 4f9567342ec..4b70c2da6fc 100644
--- a/docs/ai-coder/ai-gateway/providers.md
+++ b/docs/ai-coder/ai-gateway/providers.md
@@ -192,6 +192,41 @@ To enforce it, add the external ID to the target role's trust policy as an
 > not enforced, and the role can still be assumed without it. To rotate the
 > external ID, recreate the provider.
 
+#### Protocol: InvokeModel vs Mantle
+
+A Bedrock provider selects a **protocol**:
+
+- **InvokeModel** (default): AI Gateway translates the request into Bedrock's
+  InvokeModel format (`bedrock-runtime.<region>.amazonaws.com`) and configures
+  the model and small-fast model on the provider.
+- **Mantle**: AI Gateway targets the mantle endpoint
+  (`https://bedrock-mantle.<region>.api.aws/anthropic/v1/messages`), which
+  serves Anthropic models through the native Messages API. The gateway forwards
+  the request body **unchanged** and only applies AWS SigV4 signing (service
+  `bedrock-mantle`) with the provider's configured base identity. The client,
+  not the gateway, produces the Bedrock-legal request, so no model identifiers
+  are configured on the provider (the client sends the model in each request).
+
+Both protocols use the same credentials (default chain, static keys, or a
+role ARN) and require a **region**. To route Claude Code through a mantle
+provider, run it in mantle mode with client-side signing disabled so the
+gateway signs centrally, and pass the Coder token as a Bearer credential for
+attribution:
+
+```sh
+export CLAUDE_CODE_USE_MANTLE=1
+export CLAUDE_CODE_SKIP_MANTLE_AUTH=1
+export ANTHROPIC_BEDROCK_MANTLE_BASE_URL=https://<coder-host>/api/v2/aibridge/<provider-name>
+export AWS_REGION=us-east-1
+export ANTHROPIC_CUSTOM_HEADERS="Authorization: Bearer <coder-session-token>"
+```
+
+Use the `Authorization: Bearer` header for the Coder token rather than
+`X-Coder-AI-Governance-Token`: the governance header puts the request in
+[Bring Your Own Key](#bring-your-own-key) mode. A Bearer token is authenticated
+for attribution and stripped before the gateway signs with the provider's AWS
+credentials.
+
 ### GitHub Copilot
 
 GitHub Copilot offers three plans: Individual, Business, and Enterprise,
diff --git a/site/src/api/typesGenerated.ts b/site/src/api/typesGenerated.ts
index 84a8a8c3ae4..0629f7d80be 100644
--- a/site/src/api/typesGenerated.ts
+++ b/site/src/api/typesGenerated.ts
@@ -293,6 +293,14 @@ export interface AIProvider {
 	readonly updated_at: string;
 }
 
+// From codersdk/aiproviders_bedrock.go
+export type AIProviderBedrockProtocol = "invoke-model" | "mantle";
+
+export const AIProviderBedrockProtocols: AIProviderBedrockProtocol[] = [
+	"invoke-model",
+	"mantle",
+];
+
 // From codersdk/aiproviders_bedrock.go
 /**
  * AIProviderBedrockSettings configures providers that authenticate
@@ -342,6 +350,12 @@ export interface AIProviderBedrockSettings {
 	 * update may echo the stored value back).
 	 */
 	readonly external_id?: string;
+	/**
+	 * Protocol selects the Bedrock wire protocol. An empty value resolves to
+	 * AIProviderBedrockProtocolInvokeModel, so existing rows keep the legacy
+	 * behavior without a schema version bump.
+	 */
+	readonly protocol?: AIProviderBedrockProtocol;
 }
 
 // From codersdk/aiproviders_bedrock.go
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
index af492374278..693993079ea 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
@@ -136,6 +136,51 @@ export const AddBedrock: Story = {
 	},
 };
 
+// Mantle is a passthrough protocol selected via the Protocol dropdown. It
+// does not configure model fields (the client sends the model), and the
+// endpoint hint points at the mantle host.
+export const AddBedrockMantle: Story = {
+	args: {
+		initialValues: { type: "bedrock", protocol: "mantle" },
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		expect(canvas.queryByLabelText(/^model\s*\*?$/i)).not.toBeInTheDocument();
+		expect(
+			canvas.queryByLabelText(/^small-fast model\s*\*?$/i),
+		).not.toBeInTheDocument();
+		await expect(canvas.findByText(/bedrock-mantle/i)).resolves.toBeVisible();
+	},
+};
+
+// Switching the Protocol selector from InvokeModel to Mantle hides the model
+// fields and swaps the endpoint hint to the mantle host.
+export const AddBedrockSwitchToMantle: Story = {
+	args: {
+		initialValues: { type: "bedrock" },
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		// Model fields are present for the default InvokeModel protocol.
+		await canvas.findByLabelText(/^model\s*\*?$/i);
+
+		const trigger = canvas.getByRole("combobox");
+		await userEvent.click(trigger);
+		const mantleOption = await screen.findByRole("option", {
+			name: /mantle/i,
+		});
+		await userEvent.click(mantleOption);
+
+		await waitFor(() =>
+			expect(canvas.queryByLabelText(/^model\s*\*?$/i)).not.toBeInTheDocument(),
+		);
+		expect(
+			canvas.queryByLabelText(/^small-fast model\s*\*?$/i),
+		).not.toBeInTheDocument();
+		await expect(canvas.findByText(/bedrock-mantle/i)).resolves.toBeVisible();
+	},
+};
+
 // Regression coverage for CODAGT-626. The create form must accept Bedrock
 // configurations whose credentials come from the AWS environment (IAM
 // role, instance profile, AWS_PROFILE) instead of static access keys.
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
index 7a87b06d14a..7835aa8a0b5 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
@@ -3,7 +3,10 @@ import { TriangleAlertIcon } from "lucide-react";
 import { type FC, useEffect, useRef } from "react";
 import { Link } from "react-router";
 import * as Yup from "yup";
-import type { AIProviderType } from "#/api/typesGenerated";
+import type {
+	AIProviderBedrockProtocol,
+	AIProviderType,
+} from "#/api/typesGenerated";
 import { ErrorAlert } from "#/components/Alert/ErrorAlert";
 import { Button } from "#/components/Button/Button";
 import { CodeExample } from "#/components/CodeExample/CodeExample";
@@ -12,6 +15,13 @@ import { Form, FormFields } from "#/components/Form/Form";
 import { FormField } from "#/components/FormField/FormField";
 import { Label } from "#/components/Label/Label";
 import { Link as DocsLink } from "#/components/Link/Link";
+import {
+	Select,
+	SelectContent,
+	SelectItem,
+	SelectTrigger,
+	SelectValue,
+} from "#/components/Select/Select";
 import { Spinner } from "#/components/Spinner/Spinner";
 import { useUnsavedChangesPrompt } from "#/hooks/useUnsavedChangesPrompt";
 import { docs } from "#/utils/docs";
@@ -23,6 +33,7 @@ export type ProviderFormValues = {
 	name: string;
 	displayName: string;
 	baseUrl: string;
+	protocol: AIProviderBedrockProtocol;
 	model: string;
 	smallFastModel: string;
 	accessKey: string;
@@ -35,14 +46,24 @@ export type ProviderFormValues = {
 const HTTP_SCHEME_REGEX = /^https?:\/\//i;
 const BEDROCK_CANONICAL_URL_REGEX =
 	/^https:\/\/bedrock-runtime\.([a-z0-9-]+)\.amazonaws\.com\/?$/i;
+// Mantle is a passthrough protocol hosted at bedrock-mantle.{region}.api.aws,
+// optionally suffixed with /anthropic.
+const BEDROCK_MANTLE_URL_REGEX =
+	/^https:\/\/bedrock-mantle\.([a-z0-9-]+)\.api\.aws(\/anthropic)?\/?$/i;
 const PROVIDER_NAME_REGEX = /^[a-z0-9]+(-[a-z0-9]+)*$/;
 
 export const SAVED_CREDENTIAL_MASK = "********";
 
+// The region lives in the same subdomain slot for both the InvokeModel host
+// (bedrock-runtime.{region}.amazonaws.com) and the mantle host
+// (bedrock-mantle.{region}.api.aws), so either shape yields the region.
 export const parseBedrockRegionFromBaseUrl = (
 	baseUrl: string,
 ): string | undefined => {
-	const match = BEDROCK_CANONICAL_URL_REGEX.exec(baseUrl.trim());
+	const trimmed = baseUrl.trim();
+	const match =
+		BEDROCK_CANONICAL_URL_REGEX.exec(trimmed) ??
+		BEDROCK_MANTLE_URL_REGEX.exec(trimmed);
 	return match?.[1]?.toLowerCase();
 };
 
@@ -65,6 +86,7 @@ const defaultInitialValues: ProviderFormValues = {
 	name: "",
 	displayName: "",
 	baseUrl: "",
+	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -74,6 +96,14 @@ const defaultInitialValues: ProviderFormValues = {
 	enabled: true,
 };
 
+// Base URL prefills used when switching the Bedrock protocol. The region is
+// preserved from whatever the user already entered, falling back to us-east-1.
+const BEDROCK_MANTLE_DEFAULT_REGION = "us-east-1";
+const bedrockInvokeModelBaseUrl = (region: string) =>
+	`https://bedrock-runtime.${region}.amazonaws.com`;
+const bedrockMantleBaseUrl = (region: string) =>
+	`https://bedrock-mantle.${region}.api.aws`;
+
 // Bedrock model defaults mirror codersdk/deployment.go's
 // aiGatewayBedrockModel and aiGatewayBedrockSmallFastModel defaults
 // so the create form lands on the same models the env-seeded path
@@ -162,16 +192,38 @@ const makeBedrockSchema = (editing: boolean) =>
 			.required(),
 		name: makeNameSchema(editing),
 		displayName: makeDisplayNameSchema(editing),
+		protocol: Yup.string()
+			.oneOf(["invoke-model", "mantle"] as const)
+			.required(),
 		baseUrl: Yup.string()
 			.url("Endpoint must be a valid URL")
-			.matches(
-				BEDROCK_CANONICAL_URL_REGEX,
-				"Endpoint must be a standard AWS Bedrock URL.",
-			)
+			.when("protocol", {
+				is: "mantle",
+				then: (schema) =>
+					schema.matches(
+						BEDROCK_MANTLE_URL_REGEX,
+						"Endpoint must be a Bedrock mantle URL (https://bedrock-mantle.{region}.api.aws).",
+					),
+				otherwise: (schema) =>
+					schema.matches(
+						BEDROCK_CANONICAL_URL_REGEX,
+						"Endpoint must be a standard AWS Bedrock URL.",
+					),
+			})
 			.required("Endpoint is required"),
 		apiKey: Yup.string(),
-		model: Yup.string().required("Model is required"),
-		smallFastModel: Yup.string().required("Small-fast model is required"),
+		// Mantle passthrough forwards the model chosen by the client, so the
+		// model fields are not configured on the provider.
+		model: Yup.string().when("protocol", {
+			is: (protocol: string) => protocol !== "mantle",
+			then: (schema) => schema.required("Model is required"),
+			otherwise: (schema) => schema,
+		}),
+		smallFastModel: Yup.string().when("protocol", {
+			is: (protocol: string) => protocol !== "mantle",
+			then: (schema) => schema.required("Small-fast model is required"),
+			otherwise: (schema) => schema,
+		}),
 		accessKey: Yup.string().test(
 			"access-key-paired",
 			BEDROCK_ACCESS_KEY_PAIRED_MESSAGE,
@@ -346,6 +398,23 @@ export const ProviderForm: FC<ProviderFormProps> = ({
 		}
 	};
 
+	// Switching protocols rewrites the base URL to the matching host, keeping
+	// the region the user already entered so they do not retype it.
+	const handleBedrockProtocolChange = (protocol: AIProviderBedrockProtocol) => {
+		void form.setFieldValue("protocol", protocol);
+		const region =
+			parseBedrockRegionFromBaseUrl(form.values.baseUrl) ??
+			BEDROCK_MANTLE_DEFAULT_REGION;
+		void form.setFieldValue(
+			"baseUrl",
+			protocol === "mantle"
+				? bedrockMantleBaseUrl(region)
+				: bedrockInvokeModelBaseUrl(region),
+		);
+	};
+
+	const isMantle = form.values.protocol === "mantle";
+
 	// When the parent's mutation finishes without an error, treat the just-
 	// submitted values as the new baseline so the unsaved-changes prompt does
 	// not fire on subsequent navigations. React Query reports a missing error
@@ -462,49 +531,90 @@ export const ProviderForm: FC<ProviderFormProps> = ({
 								className="w-full"
 							/>
 						</div>
+						<div className="flex flex-col gap-2">
+							<Label htmlFor="bedrock-protocol">Protocol</Label>
+							<Select
+								value={form.values.protocol}
+								onValueChange={(value) =>
+									handleBedrockProtocolChange(
+										value as AIProviderBedrockProtocol,
+									)
+								}
+							>
+								<SelectTrigger id="bedrock-protocol" className="w-full">
+									<SelectValue />
+								</SelectTrigger>
+								<SelectContent>
+									<SelectItem value="invoke-model">
+										InvokeModel (default)
+									</SelectItem>
+									<SelectItem value="mantle">Mantle</SelectItem>
+								</SelectContent>
+							</Select>
+							<p className="text-xs text-content-secondary m-0">
+								{isMantle
+									? "Mantle is a passthrough protocol. The client selects the model at request time."
+									: "InvokeModel calls the standard AWS Bedrock runtime API."}
+							</p>
+						</div>
 						<FormField
 							required
 							field={getFieldHelpers("baseUrl")}
 							label="Endpoint"
 							description={
-								<>
-									In the format of{" "}
-									<code>
-										{"https://bedrock-runtime.{region}.amazonaws.com"}
-									</code>
-								</>
+								isMantle ? (
+									<>
+										In the format of{" "}
+										<code>{"https://bedrock-mantle.{region}.api.aws"}</code>
+									</>
+								) : (
+									<>
+										In the format of{" "}
+										<code>
+											{"https://bedrock-runtime.{region}.amazonaws.com"}
+										</code>
+									</>
+								)
 							}
 							className="w-full"
-							placeholder={baseUrlPlaceholder(form.values.type)}
+							placeholder={
+								isMantle
+									? bedrockMantleBaseUrl(BEDROCK_MANTLE_DEFAULT_REGION)
+									: baseUrlPlaceholder(form.values.type)
+							}
 						/>
-						<div className="grid grid-cols-2 items-start gap-4">
-							<FormField
-								required
-								field={getFieldHelpers("model")}
-								label="Model"
-								className="w-full"
-								placeholder={BEDROCK_DEFAULT_MODEL}
-							/>
-							<FormField
-								required
-								field={getFieldHelpers("smallFastModel")}
-								label="Small-fast model"
-								className="w-full"
-								placeholder={BEDROCK_DEFAULT_SMALL_FAST_MODEL}
-							/>
-						</div>
-						<p className="text-xs text-content-secondary m-0">
-							Find available Bedrock model IDs in the{" "}
-							<DocsLink
-								size="sm"
-								href={BEDROCK_MODEL_CARDS_URL}
-								target="_blank"
-								rel="noreferrer"
-							>
-								AWS Bedrock model cards
-							</DocsLink>
-							.
-						</p>
+						{!isMantle && (
+							<>
+								<div className="grid grid-cols-2 items-start gap-4">
+									<FormField
+										required
+										field={getFieldHelpers("model")}
+										label="Model"
+										className="w-full"
+										placeholder={BEDROCK_DEFAULT_MODEL}
+									/>
+									<FormField
+										required
+										field={getFieldHelpers("smallFastModel")}
+										label="Small-fast model"
+										className="w-full"
+										placeholder={BEDROCK_DEFAULT_SMALL_FAST_MODEL}
+									/>
+								</div>
+								<p className="text-xs text-content-secondary m-0">
+									Find available Bedrock model IDs in the{" "}
+									<DocsLink
+										size="sm"
+										href={BEDROCK_MODEL_CARDS_URL}
+										target="_blank"
+										rel="noreferrer"
+									>
+										AWS Bedrock model cards
+									</DocsLink>
+									.
+								</p>
+							</>
+						)}
 						<div className="grid grid-cols-2 items-start gap-4">
 							<CredentialField
 								label="Access key"
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
index ab71d513590..e6713370551 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
@@ -26,6 +26,7 @@ const baseOpenAIFormValues: ProviderFormValues = {
 	name: "primary-openai",
 	displayName: "Primary OpenAI",
 	baseUrl: "https://api.openai.com",
+	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -40,6 +41,7 @@ const baseBedrockFormValues: ProviderFormValues = {
 	name: "primary-bedrock",
 	displayName: "Primary Bedrock",
 	baseUrl: "https://bedrock-runtime.us-east-1.amazonaws.com",
+	protocol: "invoke-model",
 	model: "anthropic.claude-sonnet-4-5",
 	smallFastModel: "anthropic.claude-haiku-4-5",
 	accessKey: "AKIA-test",
@@ -54,6 +56,7 @@ const baseCopilotFormValues: ProviderFormValues = {
 	name: "copilot",
 	displayName: "GitHub Copilot",
 	baseUrl: "https://api.business.githubcopilot.com",
+	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -86,6 +89,20 @@ describe("parseBedrockRegionFromBaseUrl", () => {
 		).toBe("us-west-2");
 	});
 
+	it("extracts the region from a mantle URL", () => {
+		expect(
+			parseBedrockRegionFromBaseUrl("https://bedrock-mantle.us-east-1.api.aws"),
+		).toBe("us-east-1");
+	});
+
+	it("extracts the region from a mantle URL with the /anthropic suffix", () => {
+		expect(
+			parseBedrockRegionFromBaseUrl(
+				"https://bedrock-mantle.eu-west-1.api.aws/anthropic",
+			),
+		).toBe("eu-west-1");
+	});
+
 	it("lowercases the region", () => {
 		expect(
 			parseBedrockRegionFromBaseUrl(
@@ -379,6 +396,34 @@ describe("providerFormValuesToCreate", () => {
 			expect(s.region).toBe("us-east-1");
 		});
 
+		it("omits the protocol discriminator and includes the model fields for InvokeModel", () => {
+			// InvokeModel is the default protocol, so the protocol is left out
+			// to keep the settings blob minimal; the model fields are configured
+			// on the provider.
+			const req = providerFormValuesToCreate(baseBedrockFormValues);
+			const s = req.settings as unknown as Record<string, unknown>;
+			expect(s.protocol).toBeUndefined();
+			expect(s.model).toBe("anthropic.claude-sonnet-4-5");
+			expect(s.small_fast_model).toBe("anthropic.claude-haiku-4-5");
+		});
+
+		it("sets protocol=mantle, derives the region, and omits the model fields", () => {
+			// Mantle is a passthrough: the client sends the model, so the
+			// provider stores neither model field but keeps the region so the
+			// backend recognises the Bedrock provider.
+			const req = providerFormValuesToCreate({
+				...baseBedrockFormValues,
+				protocol: "mantle",
+				baseUrl: "https://bedrock-mantle.us-east-1.api.aws",
+			});
+			const s = req.settings as unknown as Record<string, unknown>;
+			expect(s._type).toBe("bedrock");
+			expect(s.protocol).toBe("mantle");
+			expect(s.region).toBe("us-east-1");
+			expect(s.model).toBeUndefined();
+			expect(s.small_fast_model).toBeUndefined();
+		});
+
 		it("omits the region when the URL is non-canonical", () => {
 			// The form schema blocks non-canonical endpoints before submit; the
 			// helper itself stays strict, returning an undefined region rather
@@ -715,6 +760,26 @@ describe("aiProviderToFormValues", () => {
 		expect(values.smallFastModel).toBe("anthropic.claude-haiku-4-5");
 	});
 
+	it("reads protocol=mantle back and leaves the model fields blank", () => {
+		const provider: AIProvider = {
+			...MockAIProviderBedrock,
+			settings: settings({
+				_type: "bedrock",
+				protocol: "mantle",
+				region: "us-east-1",
+			}),
+		};
+		const values = aiProviderToFormValues(provider);
+		expect(values.protocol).toBe("mantle");
+		expect(values.model).toBe("");
+		expect(values.smallFastModel).toBe("");
+	});
+
+	it("defaults protocol to invoke-model for a legacy provider without one", () => {
+		const values = aiProviderToFormValues(MockAIProviderBedrock);
+		expect(values.protocol).toBe("invoke-model");
+	});
+
 	it("never round-trips Bedrock secrets back to the form", () => {
 		// AccessKey and AccessKeySecret are write-only; the API strips
 		// them from responses, so the form must seed them as empty.
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
index 71ca37dcbef..b5887c0f17f 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
@@ -1,5 +1,6 @@
 import type {
 	AIProvider,
+	AIProviderBedrockProtocol,
 	AIProviderBedrockSettings,
 	AIProviderKeyMutation,
 	AIProviderSettings,
@@ -113,22 +114,30 @@ export const getProviderDisplayType = (
 };
 
 const buildBedrockSettings = (
+	protocol: AIProviderBedrockProtocol,
 	region: string | undefined,
 	model: string,
 	smallFastModel: string,
 	accessKey: string,
 	accessKeySecret: string,
 	roleArn: string,
-): BedrockSettingsWire => ({
-	_type: BEDROCK_SETTINGS_TYPE,
-	_version: BEDROCK_SETTINGS_VERSION,
-	...(region ? { region } : {}),
-	model,
-	small_fast_model: smallFastModel,
-	...(accessKey ? { access_key: accessKey } : {}),
-	...(accessKeySecret ? { access_key_secret: accessKeySecret } : {}),
-	...(roleArn ? { role_arn: roleArn } : {}),
-});
+): BedrockSettingsWire => {
+	// Mantle is a passthrough protocol: the client sends the model, so the
+	// provider omits the model fields. The protocol discriminator is only
+	// emitted for mantle to keep InvokeModel blobs minimal (an absent
+	// protocol resolves to InvokeModel server-side).
+	const isMantle = protocol === "mantle";
+	return {
+		_type: BEDROCK_SETTINGS_TYPE,
+		_version: BEDROCK_SETTINGS_VERSION,
+		...(region ? { region } : {}),
+		...(isMantle ? { protocol } : {}),
+		...(isMantle ? {} : { model, small_fast_model: smallFastModel }),
+		...(accessKey ? { access_key: accessKey } : {}),
+		...(accessKeySecret ? { access_key_secret: accessKeySecret } : {}),
+		...(roleArn ? { role_arn: roleArn } : {}),
+	};
+};
 
 // Bedrock credentials live in `settings`; openai/anthropic keys go in
 // `api_keys`. `display_name` is omitted when blank so the server stores
@@ -147,6 +156,7 @@ export const providerFormValuesToCreate = (
 	if (values.type === "bedrock") {
 		const region = parseBedrockRegionFromBaseUrl(base.base_url);
 		const settings = buildBedrockSettings(
+			values.protocol,
 			region,
 			values.model.trim(),
 			values.smallFastModel.trim(),
@@ -222,6 +232,7 @@ export const providerFormValuesToUpdate = (
 	const region = parseBedrockRegionFromBaseUrl(base.base_url ?? "");
 
 	const settings = buildBedrockSettings(
+		values.protocol,
 		region,
 		values.model.trim(),
 		values.smallFastModel.trim(),
@@ -242,13 +253,19 @@ export const aiProviderToFormValues = (
 	const displayName = provider.display_name || provider.name;
 	if (isBedrockProvider(provider)) {
 		const s = (provider.settings as SettingsWire | null) ?? {};
+		// A missing protocol resolves to InvokeModel (legacy rows). Mantle
+		// providers store no model fields, so leave them blank.
+		const protocol: AIProviderBedrockProtocol =
+			s.protocol === "mantle" ? "mantle" : "invoke-model";
+		const isMantle = protocol === "mantle";
 		return {
 			type: "bedrock",
 			name: provider.name,
 			displayName,
 			baseUrl: provider.base_url,
-			model: s.model ?? "",
-			smallFastModel: s.small_fast_model ?? "",
+			protocol,
+			model: isMantle ? "" : (s.model ?? ""),
+			smallFastModel: isMantle ? "" : (s.small_fast_model ?? ""),
 			accessKey: "",
 			accessKeySecret: "",
 			roleArn: s.role_arn ?? "",

From bc6ba3657bade80f4076c8fb5a5c083c5218a544 Mon Sep 17 00:00:00 2001
From: Yevhenii Shcherbina <yevhenii@coder.com>
Date: Thu, 9 Jul 2026 19:41:18 +0000
Subject: [PATCH 2/3] chore(aibridge): defer Bedrock mantle UI and docs to
 follow-up

---
 docs/ai-coder/ai-gateway/providers.md         |  35 ----
 .../components/ProviderForm.stories.tsx       |  45 ----
 .../ProvidersPage/components/ProviderForm.tsx | 196 ++++--------------
 .../components/providerFormApiMap.test.ts     |  65 ------
 .../components/providerFormApiMap.ts          |  41 ++--
 5 files changed, 55 insertions(+), 327 deletions(-)

diff --git a/docs/ai-coder/ai-gateway/providers.md b/docs/ai-coder/ai-gateway/providers.md
index 4b70c2da6fc..4f9567342ec 100644
--- a/docs/ai-coder/ai-gateway/providers.md
+++ b/docs/ai-coder/ai-gateway/providers.md
@@ -192,41 +192,6 @@ To enforce it, add the external ID to the target role's trust policy as an
 > not enforced, and the role can still be assumed without it. To rotate the
 > external ID, recreate the provider.
 
-#### Protocol: InvokeModel vs Mantle
-
-A Bedrock provider selects a **protocol**:
-
-- **InvokeModel** (default): AI Gateway translates the request into Bedrock's
-  InvokeModel format (`bedrock-runtime.<region>.amazonaws.com`) and configures
-  the model and small-fast model on the provider.
-- **Mantle**: AI Gateway targets the mantle endpoint
-  (`https://bedrock-mantle.<region>.api.aws/anthropic/v1/messages`), which
-  serves Anthropic models through the native Messages API. The gateway forwards
-  the request body **unchanged** and only applies AWS SigV4 signing (service
-  `bedrock-mantle`) with the provider's configured base identity. The client,
-  not the gateway, produces the Bedrock-legal request, so no model identifiers
-  are configured on the provider (the client sends the model in each request).
-
-Both protocols use the same credentials (default chain, static keys, or a
-role ARN) and require a **region**. To route Claude Code through a mantle
-provider, run it in mantle mode with client-side signing disabled so the
-gateway signs centrally, and pass the Coder token as a Bearer credential for
-attribution:
-
-```sh
-export CLAUDE_CODE_USE_MANTLE=1
-export CLAUDE_CODE_SKIP_MANTLE_AUTH=1
-export ANTHROPIC_BEDROCK_MANTLE_BASE_URL=https://<coder-host>/api/v2/aibridge/<provider-name>
-export AWS_REGION=us-east-1
-export ANTHROPIC_CUSTOM_HEADERS="Authorization: Bearer <coder-session-token>"
-```
-
-Use the `Authorization: Bearer` header for the Coder token rather than
-`X-Coder-AI-Governance-Token`: the governance header puts the request in
-[Bring Your Own Key](#bring-your-own-key) mode. A Bearer token is authenticated
-for attribution and stripped before the gateway signs with the provider's AWS
-credentials.
-
 ### GitHub Copilot
 
 GitHub Copilot offers three plans: Individual, Business, and Enterprise,
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
index 693993079ea..af492374278 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.stories.tsx
@@ -136,51 +136,6 @@ export const AddBedrock: Story = {
 	},
 };
 
-// Mantle is a passthrough protocol selected via the Protocol dropdown. It
-// does not configure model fields (the client sends the model), and the
-// endpoint hint points at the mantle host.
-export const AddBedrockMantle: Story = {
-	args: {
-		initialValues: { type: "bedrock", protocol: "mantle" },
-	},
-	play: async ({ canvasElement }) => {
-		const canvas = within(canvasElement);
-		expect(canvas.queryByLabelText(/^model\s*\*?$/i)).not.toBeInTheDocument();
-		expect(
-			canvas.queryByLabelText(/^small-fast model\s*\*?$/i),
-		).not.toBeInTheDocument();
-		await expect(canvas.findByText(/bedrock-mantle/i)).resolves.toBeVisible();
-	},
-};
-
-// Switching the Protocol selector from InvokeModel to Mantle hides the model
-// fields and swaps the endpoint hint to the mantle host.
-export const AddBedrockSwitchToMantle: Story = {
-	args: {
-		initialValues: { type: "bedrock" },
-	},
-	play: async ({ canvasElement }) => {
-		const canvas = within(canvasElement);
-		// Model fields are present for the default InvokeModel protocol.
-		await canvas.findByLabelText(/^model\s*\*?$/i);
-
-		const trigger = canvas.getByRole("combobox");
-		await userEvent.click(trigger);
-		const mantleOption = await screen.findByRole("option", {
-			name: /mantle/i,
-		});
-		await userEvent.click(mantleOption);
-
-		await waitFor(() =>
-			expect(canvas.queryByLabelText(/^model\s*\*?$/i)).not.toBeInTheDocument(),
-		);
-		expect(
-			canvas.queryByLabelText(/^small-fast model\s*\*?$/i),
-		).not.toBeInTheDocument();
-		await expect(canvas.findByText(/bedrock-mantle/i)).resolves.toBeVisible();
-	},
-};
-
 // Regression coverage for CODAGT-626. The create form must accept Bedrock
 // configurations whose credentials come from the AWS environment (IAM
 // role, instance profile, AWS_PROFILE) instead of static access keys.
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
index 7835aa8a0b5..7a87b06d14a 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/ProviderForm.tsx
@@ -3,10 +3,7 @@ import { TriangleAlertIcon } from "lucide-react";
 import { type FC, useEffect, useRef } from "react";
 import { Link } from "react-router";
 import * as Yup from "yup";
-import type {
-	AIProviderBedrockProtocol,
-	AIProviderType,
-} from "#/api/typesGenerated";
+import type { AIProviderType } from "#/api/typesGenerated";
 import { ErrorAlert } from "#/components/Alert/ErrorAlert";
 import { Button } from "#/components/Button/Button";
 import { CodeExample } from "#/components/CodeExample/CodeExample";
@@ -15,13 +12,6 @@ import { Form, FormFields } from "#/components/Form/Form";
 import { FormField } from "#/components/FormField/FormField";
 import { Label } from "#/components/Label/Label";
 import { Link as DocsLink } from "#/components/Link/Link";
-import {
-	Select,
-	SelectContent,
-	SelectItem,
-	SelectTrigger,
-	SelectValue,
-} from "#/components/Select/Select";
 import { Spinner } from "#/components/Spinner/Spinner";
 import { useUnsavedChangesPrompt } from "#/hooks/useUnsavedChangesPrompt";
 import { docs } from "#/utils/docs";
@@ -33,7 +23,6 @@ export type ProviderFormValues = {
 	name: string;
 	displayName: string;
 	baseUrl: string;
-	protocol: AIProviderBedrockProtocol;
 	model: string;
 	smallFastModel: string;
 	accessKey: string;
@@ -46,24 +35,14 @@ export type ProviderFormValues = {
 const HTTP_SCHEME_REGEX = /^https?:\/\//i;
 const BEDROCK_CANONICAL_URL_REGEX =
 	/^https:\/\/bedrock-runtime\.([a-z0-9-]+)\.amazonaws\.com\/?$/i;
-// Mantle is a passthrough protocol hosted at bedrock-mantle.{region}.api.aws,
-// optionally suffixed with /anthropic.
-const BEDROCK_MANTLE_URL_REGEX =
-	/^https:\/\/bedrock-mantle\.([a-z0-9-]+)\.api\.aws(\/anthropic)?\/?$/i;
 const PROVIDER_NAME_REGEX = /^[a-z0-9]+(-[a-z0-9]+)*$/;
 
 export const SAVED_CREDENTIAL_MASK = "********";
 
-// The region lives in the same subdomain slot for both the InvokeModel host
-// (bedrock-runtime.{region}.amazonaws.com) and the mantle host
-// (bedrock-mantle.{region}.api.aws), so either shape yields the region.
 export const parseBedrockRegionFromBaseUrl = (
 	baseUrl: string,
 ): string | undefined => {
-	const trimmed = baseUrl.trim();
-	const match =
-		BEDROCK_CANONICAL_URL_REGEX.exec(trimmed) ??
-		BEDROCK_MANTLE_URL_REGEX.exec(trimmed);
+	const match = BEDROCK_CANONICAL_URL_REGEX.exec(baseUrl.trim());
 	return match?.[1]?.toLowerCase();
 };
 
@@ -86,7 +65,6 @@ const defaultInitialValues: ProviderFormValues = {
 	name: "",
 	displayName: "",
 	baseUrl: "",
-	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -96,14 +74,6 @@ const defaultInitialValues: ProviderFormValues = {
 	enabled: true,
 };
 
-// Base URL prefills used when switching the Bedrock protocol. The region is
-// preserved from whatever the user already entered, falling back to us-east-1.
-const BEDROCK_MANTLE_DEFAULT_REGION = "us-east-1";
-const bedrockInvokeModelBaseUrl = (region: string) =>
-	`https://bedrock-runtime.${region}.amazonaws.com`;
-const bedrockMantleBaseUrl = (region: string) =>
-	`https://bedrock-mantle.${region}.api.aws`;
-
 // Bedrock model defaults mirror codersdk/deployment.go's
 // aiGatewayBedrockModel and aiGatewayBedrockSmallFastModel defaults
 // so the create form lands on the same models the env-seeded path
@@ -192,38 +162,16 @@ const makeBedrockSchema = (editing: boolean) =>
 			.required(),
 		name: makeNameSchema(editing),
 		displayName: makeDisplayNameSchema(editing),
-		protocol: Yup.string()
-			.oneOf(["invoke-model", "mantle"] as const)
-			.required(),
 		baseUrl: Yup.string()
 			.url("Endpoint must be a valid URL")
-			.when("protocol", {
-				is: "mantle",
-				then: (schema) =>
-					schema.matches(
-						BEDROCK_MANTLE_URL_REGEX,
-						"Endpoint must be a Bedrock mantle URL (https://bedrock-mantle.{region}.api.aws).",
-					),
-				otherwise: (schema) =>
-					schema.matches(
-						BEDROCK_CANONICAL_URL_REGEX,
-						"Endpoint must be a standard AWS Bedrock URL.",
-					),
-			})
+			.matches(
+				BEDROCK_CANONICAL_URL_REGEX,
+				"Endpoint must be a standard AWS Bedrock URL.",
+			)
 			.required("Endpoint is required"),
 		apiKey: Yup.string(),
-		// Mantle passthrough forwards the model chosen by the client, so the
-		// model fields are not configured on the provider.
-		model: Yup.string().when("protocol", {
-			is: (protocol: string) => protocol !== "mantle",
-			then: (schema) => schema.required("Model is required"),
-			otherwise: (schema) => schema,
-		}),
-		smallFastModel: Yup.string().when("protocol", {
-			is: (protocol: string) => protocol !== "mantle",
-			then: (schema) => schema.required("Small-fast model is required"),
-			otherwise: (schema) => schema,
-		}),
+		model: Yup.string().required("Model is required"),
+		smallFastModel: Yup.string().required("Small-fast model is required"),
 		accessKey: Yup.string().test(
 			"access-key-paired",
 			BEDROCK_ACCESS_KEY_PAIRED_MESSAGE,
@@ -398,23 +346,6 @@ export const ProviderForm: FC<ProviderFormProps> = ({
 		}
 	};
 
-	// Switching protocols rewrites the base URL to the matching host, keeping
-	// the region the user already entered so they do not retype it.
-	const handleBedrockProtocolChange = (protocol: AIProviderBedrockProtocol) => {
-		void form.setFieldValue("protocol", protocol);
-		const region =
-			parseBedrockRegionFromBaseUrl(form.values.baseUrl) ??
-			BEDROCK_MANTLE_DEFAULT_REGION;
-		void form.setFieldValue(
-			"baseUrl",
-			protocol === "mantle"
-				? bedrockMantleBaseUrl(region)
-				: bedrockInvokeModelBaseUrl(region),
-		);
-	};
-
-	const isMantle = form.values.protocol === "mantle";
-
 	// When the parent's mutation finishes without an error, treat the just-
 	// submitted values as the new baseline so the unsaved-changes prompt does
 	// not fire on subsequent navigations. React Query reports a missing error
@@ -531,90 +462,49 @@ export const ProviderForm: FC<ProviderFormProps> = ({
 								className="w-full"
 							/>
 						</div>
-						<div className="flex flex-col gap-2">
-							<Label htmlFor="bedrock-protocol">Protocol</Label>
-							<Select
-								value={form.values.protocol}
-								onValueChange={(value) =>
-									handleBedrockProtocolChange(
-										value as AIProviderBedrockProtocol,
-									)
-								}
-							>
-								<SelectTrigger id="bedrock-protocol" className="w-full">
-									<SelectValue />
-								</SelectTrigger>
-								<SelectContent>
-									<SelectItem value="invoke-model">
-										InvokeModel (default)
-									</SelectItem>
-									<SelectItem value="mantle">Mantle</SelectItem>
-								</SelectContent>
-							</Select>
-							<p className="text-xs text-content-secondary m-0">
-								{isMantle
-									? "Mantle is a passthrough protocol. The client selects the model at request time."
-									: "InvokeModel calls the standard AWS Bedrock runtime API."}
-							</p>
-						</div>
 						<FormField
 							required
 							field={getFieldHelpers("baseUrl")}
 							label="Endpoint"
 							description={
-								isMantle ? (
-									<>
-										In the format of{" "}
-										<code>{"https://bedrock-mantle.{region}.api.aws"}</code>
-									</>
-								) : (
-									<>
-										In the format of{" "}
-										<code>
-											{"https://bedrock-runtime.{region}.amazonaws.com"}
-										</code>
-									</>
-								)
+								<>
+									In the format of{" "}
+									<code>
+										{"https://bedrock-runtime.{region}.amazonaws.com"}
+									</code>
+								</>
 							}
 							className="w-full"
-							placeholder={
-								isMantle
-									? bedrockMantleBaseUrl(BEDROCK_MANTLE_DEFAULT_REGION)
-									: baseUrlPlaceholder(form.values.type)
-							}
+							placeholder={baseUrlPlaceholder(form.values.type)}
 						/>
-						{!isMantle && (
-							<>
-								<div className="grid grid-cols-2 items-start gap-4">
-									<FormField
-										required
-										field={getFieldHelpers("model")}
-										label="Model"
-										className="w-full"
-										placeholder={BEDROCK_DEFAULT_MODEL}
-									/>
-									<FormField
-										required
-										field={getFieldHelpers("smallFastModel")}
-										label="Small-fast model"
-										className="w-full"
-										placeholder={BEDROCK_DEFAULT_SMALL_FAST_MODEL}
-									/>
-								</div>
-								<p className="text-xs text-content-secondary m-0">
-									Find available Bedrock model IDs in the{" "}
-									<DocsLink
-										size="sm"
-										href={BEDROCK_MODEL_CARDS_URL}
-										target="_blank"
-										rel="noreferrer"
-									>
-										AWS Bedrock model cards
-									</DocsLink>
-									.
-								</p>
-							</>
-						)}
+						<div className="grid grid-cols-2 items-start gap-4">
+							<FormField
+								required
+								field={getFieldHelpers("model")}
+								label="Model"
+								className="w-full"
+								placeholder={BEDROCK_DEFAULT_MODEL}
+							/>
+							<FormField
+								required
+								field={getFieldHelpers("smallFastModel")}
+								label="Small-fast model"
+								className="w-full"
+								placeholder={BEDROCK_DEFAULT_SMALL_FAST_MODEL}
+							/>
+						</div>
+						<p className="text-xs text-content-secondary m-0">
+							Find available Bedrock model IDs in the{" "}
+							<DocsLink
+								size="sm"
+								href={BEDROCK_MODEL_CARDS_URL}
+								target="_blank"
+								rel="noreferrer"
+							>
+								AWS Bedrock model cards
+							</DocsLink>
+							.
+						</p>
 						<div className="grid grid-cols-2 items-start gap-4">
 							<CredentialField
 								label="Access key"
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
index e6713370551..ab71d513590 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.test.ts
@@ -26,7 +26,6 @@ const baseOpenAIFormValues: ProviderFormValues = {
 	name: "primary-openai",
 	displayName: "Primary OpenAI",
 	baseUrl: "https://api.openai.com",
-	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -41,7 +40,6 @@ const baseBedrockFormValues: ProviderFormValues = {
 	name: "primary-bedrock",
 	displayName: "Primary Bedrock",
 	baseUrl: "https://bedrock-runtime.us-east-1.amazonaws.com",
-	protocol: "invoke-model",
 	model: "anthropic.claude-sonnet-4-5",
 	smallFastModel: "anthropic.claude-haiku-4-5",
 	accessKey: "AKIA-test",
@@ -56,7 +54,6 @@ const baseCopilotFormValues: ProviderFormValues = {
 	name: "copilot",
 	displayName: "GitHub Copilot",
 	baseUrl: "https://api.business.githubcopilot.com",
-	protocol: "invoke-model",
 	model: "",
 	smallFastModel: "",
 	accessKey: "",
@@ -89,20 +86,6 @@ describe("parseBedrockRegionFromBaseUrl", () => {
 		).toBe("us-west-2");
 	});
 
-	it("extracts the region from a mantle URL", () => {
-		expect(
-			parseBedrockRegionFromBaseUrl("https://bedrock-mantle.us-east-1.api.aws"),
-		).toBe("us-east-1");
-	});
-
-	it("extracts the region from a mantle URL with the /anthropic suffix", () => {
-		expect(
-			parseBedrockRegionFromBaseUrl(
-				"https://bedrock-mantle.eu-west-1.api.aws/anthropic",
-			),
-		).toBe("eu-west-1");
-	});
-
 	it("lowercases the region", () => {
 		expect(
 			parseBedrockRegionFromBaseUrl(
@@ -396,34 +379,6 @@ describe("providerFormValuesToCreate", () => {
 			expect(s.region).toBe("us-east-1");
 		});
 
-		it("omits the protocol discriminator and includes the model fields for InvokeModel", () => {
-			// InvokeModel is the default protocol, so the protocol is left out
-			// to keep the settings blob minimal; the model fields are configured
-			// on the provider.
-			const req = providerFormValuesToCreate(baseBedrockFormValues);
-			const s = req.settings as unknown as Record<string, unknown>;
-			expect(s.protocol).toBeUndefined();
-			expect(s.model).toBe("anthropic.claude-sonnet-4-5");
-			expect(s.small_fast_model).toBe("anthropic.claude-haiku-4-5");
-		});
-
-		it("sets protocol=mantle, derives the region, and omits the model fields", () => {
-			// Mantle is a passthrough: the client sends the model, so the
-			// provider stores neither model field but keeps the region so the
-			// backend recognises the Bedrock provider.
-			const req = providerFormValuesToCreate({
-				...baseBedrockFormValues,
-				protocol: "mantle",
-				baseUrl: "https://bedrock-mantle.us-east-1.api.aws",
-			});
-			const s = req.settings as unknown as Record<string, unknown>;
-			expect(s._type).toBe("bedrock");
-			expect(s.protocol).toBe("mantle");
-			expect(s.region).toBe("us-east-1");
-			expect(s.model).toBeUndefined();
-			expect(s.small_fast_model).toBeUndefined();
-		});
-
 		it("omits the region when the URL is non-canonical", () => {
 			// The form schema blocks non-canonical endpoints before submit; the
 			// helper itself stays strict, returning an undefined region rather
@@ -760,26 +715,6 @@ describe("aiProviderToFormValues", () => {
 		expect(values.smallFastModel).toBe("anthropic.claude-haiku-4-5");
 	});
 
-	it("reads protocol=mantle back and leaves the model fields blank", () => {
-		const provider: AIProvider = {
-			...MockAIProviderBedrock,
-			settings: settings({
-				_type: "bedrock",
-				protocol: "mantle",
-				region: "us-east-1",
-			}),
-		};
-		const values = aiProviderToFormValues(provider);
-		expect(values.protocol).toBe("mantle");
-		expect(values.model).toBe("");
-		expect(values.smallFastModel).toBe("");
-	});
-
-	it("defaults protocol to invoke-model for a legacy provider without one", () => {
-		const values = aiProviderToFormValues(MockAIProviderBedrock);
-		expect(values.protocol).toBe("invoke-model");
-	});
-
 	it("never round-trips Bedrock secrets back to the form", () => {
 		// AccessKey and AccessKeySecret are write-only; the API strips
 		// them from responses, so the form must seed them as empty.
diff --git a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
index b5887c0f17f..71ca37dcbef 100644
--- a/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
+++ b/site/src/pages/AISettingsPage/ProvidersPage/components/providerFormApiMap.ts
@@ -1,6 +1,5 @@
 import type {
 	AIProvider,
-	AIProviderBedrockProtocol,
 	AIProviderBedrockSettings,
 	AIProviderKeyMutation,
 	AIProviderSettings,
@@ -114,30 +113,22 @@ export const getProviderDisplayType = (
 };
 
 const buildBedrockSettings = (
-	protocol: AIProviderBedrockProtocol,
 	region: string | undefined,
 	model: string,
 	smallFastModel: string,
 	accessKey: string,
 	accessKeySecret: string,
 	roleArn: string,
-): BedrockSettingsWire => {
-	// Mantle is a passthrough protocol: the client sends the model, so the
-	// provider omits the model fields. The protocol discriminator is only
-	// emitted for mantle to keep InvokeModel blobs minimal (an absent
-	// protocol resolves to InvokeModel server-side).
-	const isMantle = protocol === "mantle";
-	return {
-		_type: BEDROCK_SETTINGS_TYPE,
-		_version: BEDROCK_SETTINGS_VERSION,
-		...(region ? { region } : {}),
-		...(isMantle ? { protocol } : {}),
-		...(isMantle ? {} : { model, small_fast_model: smallFastModel }),
-		...(accessKey ? { access_key: accessKey } : {}),
-		...(accessKeySecret ? { access_key_secret: accessKeySecret } : {}),
-		...(roleArn ? { role_arn: roleArn } : {}),
-	};
-};
+): BedrockSettingsWire => ({
+	_type: BEDROCK_SETTINGS_TYPE,
+	_version: BEDROCK_SETTINGS_VERSION,
+	...(region ? { region } : {}),
+	model,
+	small_fast_model: smallFastModel,
+	...(accessKey ? { access_key: accessKey } : {}),
+	...(accessKeySecret ? { access_key_secret: accessKeySecret } : {}),
+	...(roleArn ? { role_arn: roleArn } : {}),
+});
 
 // Bedrock credentials live in `settings`; openai/anthropic keys go in
 // `api_keys`. `display_name` is omitted when blank so the server stores
@@ -156,7 +147,6 @@ export const providerFormValuesToCreate = (
 	if (values.type === "bedrock") {
 		const region = parseBedrockRegionFromBaseUrl(base.base_url);
 		const settings = buildBedrockSettings(
-			values.protocol,
 			region,
 			values.model.trim(),
 			values.smallFastModel.trim(),
@@ -232,7 +222,6 @@ export const providerFormValuesToUpdate = (
 	const region = parseBedrockRegionFromBaseUrl(base.base_url ?? "");
 
 	const settings = buildBedrockSettings(
-		values.protocol,
 		region,
 		values.model.trim(),
 		values.smallFastModel.trim(),
@@ -253,19 +242,13 @@ export const aiProviderToFormValues = (
 	const displayName = provider.display_name || provider.name;
 	if (isBedrockProvider(provider)) {
 		const s = (provider.settings as SettingsWire | null) ?? {};
-		// A missing protocol resolves to InvokeModel (legacy rows). Mantle
-		// providers store no model fields, so leave them blank.
-		const protocol: AIProviderBedrockProtocol =
-			s.protocol === "mantle" ? "mantle" : "invoke-model";
-		const isMantle = protocol === "mantle";
 		return {
 			type: "bedrock",
 			name: provider.name,
 			displayName,
 			baseUrl: provider.base_url,
-			protocol,
-			model: isMantle ? "" : (s.model ?? ""),
-			smallFastModel: isMantle ? "" : (s.small_fast_model ?? ""),
+			model: s.model ?? "",
+			smallFastModel: s.small_fast_model ?? "",
 			accessKey: "",
 			accessKeySecret: "",
 			roleArn: s.role_arn ?? "",

From 989e2988f1f19bfc7ec2d64c9145236ba2a63873 Mon Sep 17 00:00:00 2001
From: Yevhenii Shcherbina <yevhenii@coder.com>
Date: Fri, 10 Jul 2026 11:45:28 +0000
Subject: [PATCH 3/3] ci: make fmt

---
 aibridge/config/config.go | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/aibridge/config/config.go b/aibridge/config/config.go
index 45e0be88ba9..acc1192319f 100644
--- a/aibridge/config/config.go
+++ b/aibridge/config/config.go
@@ -1,10 +1,10 @@
 package config
 
 import (
-	"errors"
-	"fmt"
 	"time"
 
+	"golang.org/x/xerrors"
+
 	"github.com/coder/coder/v2/aibridge/keypool"
 )
 
@@ -75,23 +75,23 @@ func (c AWSBedrock) Validate() error {
 	switch c.Protocol {
 	case "", BedrockProtocolInvokeModel:
 		if c.Region == "" && c.BaseURL == "" {
-			return errors.New("region or base url required")
+			return xerrors.New("region or base url required")
 		}
 		if c.Model == "" {
-			return errors.New("model required")
+			return xerrors.New("model required")
 		}
 		if c.SmallFastModel == "" {
-			return errors.New("small fast model required")
+			return xerrors.New("small fast model required")
 		}
 	case BedrockProtocolMantle:
 		if c.Region == "" {
-			return errors.New("region required")
+			return xerrors.New("region required")
 		}
 		if c.BaseURL == "" {
-			return errors.New("base_url required")
+			return xerrors.New("base_url required")
 		}
 	default:
-		return fmt.Errorf("unknown bedrock protocol: %q", c.Protocol)
+		return xerrors.Errorf("unknown bedrock protocol: %q", c.Protocol)
 	}
 	return nil
 }