Add RFC 6750 WWW-Authenticate on OAuth bearer APIs

Introduce BearerChallengeMiddleware on MCP, Console and Connect GraphQL, Files, and OAuth2 userinfo. Call sites record challenge intent in context via NoteUnauthenticated, NoteInvalidToken, and NoteInsufficientScope; the middleware applies resource_metadata, invalid_token, and insufficient_scope on WriteHeader.

OAuth2 access token middleware flags rejected Bearer tokens for invalid_token challenges. Add Authorizer.ScopesForAction for the scope auth-param.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/bearertoken/bearer_challenge.go

@@ -0,0 +1,89 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package bearertoken
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"go.probo.inc/probo/pkg/baseurl"
+	"go.probo.inc/probo/pkg/coredata"
+)
+
+const (
+	BearerErrInvalidToken      = "invalid_token"
+	BearerErrInsufficientScope = "insufficient_scope"
+)
+
+func protectedResourceMetadataURL(baseURL *baseurl.BaseURL) string {
+	return baseURL.WithPath("/.well-known/oauth-protected-resource").MustString()
+}
+
+// BearerChallenge builds the WWW-Authenticate header value per RFC 6750 and RFC 9728.
+// Pass errorCode == "" for discovery-only (401, no Bearer attempt).
+// Pass scopes only when errorCode == BearerErrInsufficientScope.
+func BearerChallenge(
+	baseURL *baseurl.BaseURL,
+	errorCode string,
+	scopes ...coredata.OAuth2Scope,
+) string {
+	metadataURL := protectedResourceMetadataURL(baseURL)
+
+	var parts []string
+
+	if errorCode != "" {
+		parts = append(parts, fmt.Sprintf(`error="%s"`, errorCode))
+	}
+
+	if errorCode == BearerErrInsufficientScope && len(scopes) > 0 {
+		scopeValues := make([]string, len(scopes))
+		for i, scope := range scopes {
+			scopeValues[i] = string(scope)
+		}
+
+		parts = append(parts, fmt.Sprintf(`scope="%s"`, strings.Join(scopeValues, " ")))
+	}
+
+	parts = append(parts, fmt.Sprintf(`resource_metadata="%s"`, metadataURL))
+
+	return "Bearer " + strings.Join(parts, ", ")
+}
+
+func SetBearerChallenge(
+	w http.ResponseWriter,
+	baseURL *baseurl.BaseURL,
+	errorCode string,
+	scopes ...coredata.OAuth2Scope,
+) {
+	w.Header().Set("WWW-Authenticate", BearerChallenge(baseURL, errorCode, scopes...))
+}
+
+// SetBearerUnauthenticated sets a discovery-only challenge (RFC 9728 resource_metadata).
+func SetBearerUnauthenticated(w http.ResponseWriter, baseURL *baseurl.BaseURL) {
+	SetBearerChallenge(w, baseURL, "")
+}
+
+func SetBearerInvalidToken(w http.ResponseWriter, baseURL *baseurl.BaseURL) {
+	SetBearerChallenge(w, baseURL, BearerErrInvalidToken)
+}
+
+func SetBearerInsufficientScope(
+	w http.ResponseWriter,
+	baseURL *baseurl.BaseURL,
+	scopes ...coredata.OAuth2Scope,
+) {
+	SetBearerChallenge(w, baseURL, BearerErrInsufficientScope, scopes...)
+}

pkg/bearertoken/bearer_challenge_test.go

@@ -0,0 +1,89 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package bearertoken
+
+import (
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.probo.inc/probo/pkg/baseurl"
+	"go.probo.inc/probo/pkg/coredata"
+)
+
+func TestBearerChallenge(t *testing.T) {
+	t.Parallel()
+
+	baseURL := baseurl.MustParse("https://example.com")
+
+	tests := []struct {
+		name      string
+		errorCode string
+		scopes    []coredata.OAuth2Scope
+		want      string
+	}{
+		{
+			name:      "discovery",
+			errorCode: "",
+			want:      `Bearer resource_metadata="https://example.com/.well-known/oauth-protected-resource"`,
+		},
+		{
+			name:      "invalid token",
+			errorCode: BearerErrInvalidToken,
+			want:      `Bearer error="invalid_token", resource_metadata="https://example.com/.well-known/oauth-protected-resource"`,
+		},
+		{
+			name:      "insufficient scope",
+			errorCode: BearerErrInsufficientScope,
+			scopes:    []coredata.OAuth2Scope{"v1:org:read", "v1:privacy"},
+			want:      `Bearer error="insufficient_scope", scope="v1:org:read v1:privacy", resource_metadata="https://example.com/.well-known/oauth-protected-resource"`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := BearerChallenge(baseURL, tt.errorCode, tt.scopes...)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestSetBearerChallenge(t *testing.T) {
+	t.Parallel()
+
+	baseURL := baseurl.MustParse("https://example.com")
+	rec := httptest.NewRecorder()
+
+	SetBearerInvalidToken(rec, baseURL)
+
+	assert.Equal(
+		t,
+		`Bearer error="invalid_token", resource_metadata="https://example.com/.well-known/oauth-protected-resource"`,
+		rec.Header().Get("WWW-Authenticate"),
+	)
+}
+
+func TestIsAttempt(t *testing.T) {
+	t.Parallel()
+
+	assert.True(t, IsAttempt("Bearer token"))
+	assert.True(t, IsAttempt("bearer token"))
+	assert.True(t, IsAttempt("BEARER"))
+	assert.False(t, IsAttempt(""))
+	assert.False(t, IsAttempt("Basic dXNlcjpwYXNz"))
+	assert.False(t, IsAttempt("Bear token"))
+}

pkg/bearertoken/bearertoken.go

@@ -12,7 +12,8 @@
 // OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 // PERFORMANCE OF THIS SOFTWARE.
 
-// Package bearertoken parses Bearer tokens according to RFC 6750.
+// Package bearertoken parses Bearer tokens and builds Bearer WWW-Authenticate
+// challenges according to RFC 6750.
 //
 // The grammar is defined as:
 //
@@ -69,6 +70,15 @@ func Parse(credentials string) (string, error) {
 	return token, nil
 }
 
+// IsAttempt reports whether credentials use the Bearer scheme.
+func IsAttempt(credentials string) bool {
+	if len(credentials) < len(scheme) {
+		return false
+	}
+
+	return strings.EqualFold(credentials[:len(scheme)], scheme)
+}
+
 // isValidToken checks if the given string is a valid b64token.
 // A valid b64token consists of 1 or more characters from the set
 // [A-Za-z0-9-._~+/] followed by zero or more '=' characters.

pkg/iam/authorizer.go

@@ -118,7 +118,12 @@ func (a *Authorizer) checkOAuth2Scope(
 	}
 
 	if a.scopeRegistry == nil || !a.scopeRegistry.Allows(accessToken.Scopes, action) {
-		return NewInsufficientOAuth2ScopeError(principal, action)
+		var scopes []coredata.OAuth2Scope
+		if a.scopeRegistry != nil {
+			scopes = a.scopeRegistry.ScopesForAction(action)
+		}
+
+		return NewInsufficientOAuth2ScopeError(principal, scopes...)
 	}
 
 	return nil

pkg/iam/authorizer_oauth2_scope_test.go

@@ -60,7 +60,38 @@ func TestAuthorizer_checkOAuth2Scope(t *testing.T) {
 		scopeErr, ok := errors.AsType[*ErrInsufficientOAuth2Scope](err)
 		require.True(t, ok)
 		assert.Equal(t, principal, scopeErr.IdentityID)
-		assert.Equal(t, action, scopeErr.Action)
+		assert.Empty(t, scopeErr.Scopes)
+	})
+
+	t.Run("reports granting scopes when token lacks authorization", func(t *testing.T) {
+		t.Parallel()
+
+		const (
+			scopeV1OrgWrite = coredata.OAuth2Scope("v1:org")
+			updateAction    = Action("core:organization:update")
+		)
+
+		scopeSet := oauth2scope.NewRegistry().Register(
+			map[coredata.OAuth2Scope][]string{
+				scopeV1OrgRead:  {action},
+				scopeV1OrgWrite: {updateAction},
+			},
+		)
+
+		a := NewAuthorizer(nil, nil, scopeSet)
+
+		ctx := oauth2.ContextWithAccessToken(
+			context.Background(),
+			&coredata.OAuth2AccessToken{Scopes: coredata.OAuth2Scopes{scopeV1OrgRead}},
+		)
+
+		err := a.checkOAuth2Scope(ctx, principal, updateAction)
+		require.Error(t, err)
+
+		scopeErr, ok := errors.AsType[*ErrInsufficientOAuth2Scope](err)
+		require.True(t, ok)
+		assert.Equal(t, principal, scopeErr.IdentityID)
+		assert.Equal(t, []coredata.OAuth2Scope{scopeV1OrgWrite}, scopeErr.Scopes)
 	})
 
 	t.Run("allows when registered scopes authorize the action", func(t *testing.T) {

pkg/iam/errors.go

@@ -17,6 +17,7 @@ package iam
 import (
 	"fmt"
 
+	"go.probo.inc/probo/pkg/coredata"
 	"go.probo.inc/probo/pkg/gid"
 	"go.probo.inc/probo/pkg/mail"
 )
@@ -205,18 +206,17 @@ func (e ErrInsufficientPermissions) Error() string {
 
 type ErrInsufficientOAuth2Scope struct {
 	IdentityID gid.GID
-	Action     Action
+	Scopes     []coredata.OAuth2Scope
 }
 
-func NewInsufficientOAuth2ScopeError(identityID gid.GID, action Action) error {
+func NewInsufficientOAuth2ScopeError(identityID gid.GID, scopes ...coredata.OAuth2Scope) error {
-	return &ErrInsufficientOAuth2Scope{IdentityID: identityID, Action: action}
+	return &ErrInsufficientOAuth2Scope{IdentityID: identityID, Scopes: scopes}
 }
 
 func (e ErrInsufficientOAuth2Scope) Error() string {
 	return fmt.Sprintf(
-		"identity %q does not have an OAuth2 scope granting action %s",
+		"identity %q does not have an OAuth2 scope granting the requested action",
 		e.IdentityID,
-		e.Action,
 	)
 }
 

pkg/iam/oauth2scope/registry.go

@@ -72,6 +72,13 @@ func (r *Registry) Allows(tokenScopes coredata.OAuth2Scopes, action string) bool
 	return slices.ContainsFunc(grantingScopes, tokenScopes.Contains)
 }
 
+func (r *Registry) ScopesForAction(action string) []coredata.OAuth2Scope {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+
+	return sortedScopes(r.invertedIndex[action])
+}
+
 func (r *Registry) ValidateScopes(scopes coredata.OAuth2Scopes) error {
 	r.mu.RLock()
 	defer r.mu.RUnlock()

pkg/iam/oauth2scope/registry_test.go

@@ -81,6 +81,30 @@ func TestRegistry_ValidateScopes(t *testing.T) {
 	assert.EqualError(t, err, "invalid scope: v1:unknown:read")
 }
 
+func TestRegistry_ScopesForAction(t *testing.T) {
+	t.Parallel()
+
+	const (
+		scopeV1OrgRead  = coredata.OAuth2Scope("v1:org:read")
+		scopeV1OrgWrite = coredata.OAuth2Scope("v1:org")
+	)
+
+	reg := oauth2scope.NewRegistry().Register(
+		map[coredata.OAuth2Scope][]string{
+			scopeV1OrgRead:  {"core:organization:get"},
+			scopeV1OrgWrite: {"core:organization:get", "core:organization:update"},
+		},
+	)
+
+	assert.Equal(
+		t,
+		[]coredata.OAuth2Scope{scopeV1OrgWrite, scopeV1OrgRead},
+		reg.ScopesForAction("core:organization:get"),
+	)
+	assert.Equal(t, []coredata.OAuth2Scope{scopeV1OrgWrite}, reg.ScopesForAction("core:organization:update"))
+	assert.Nil(t, reg.ScopesForAction("core:organization:delete"))
+}
+
 func TestRegistry_RegisteredScopes(t *testing.T) {
 	t.Parallel()
 

pkg/server/api/api.go

@@ -221,6 +221,7 @@ func NewServer(cfg Config) (*Server, error) {
 			cfg.IAM,
 			cfg.Cookie,
 			cfg.TokenSecret,
+			cfg.BaseURL,
 		),
 		mcpHandler: mcp_v1.NewMux(
 			cfg.Logger.Named("mcp.v1"),

pkg/server/api/authn/context.go

@@ -28,7 +28,7 @@ var (
 	identityContextKey = &ctxKey{name: "identity"}
 	sessionContextKey  = &ctxKey{name: "session"}
 	apiKeyContextKey   = &ctxKey{name: "api_key"}
-	TrustCenterKey     = &ctxKey{name: "trust_center"}
+	trustCenterKey     = &ctxKey{name: "trust_center"}
 )
 
 func SessionFromContext(ctx context.Context) *coredata.Session {

pkg/server/api/authn/identity_presence_middleware.go

@@ -20,16 +20,25 @@ import (
 	"github.com/99designs/gqlgen/graphql"
 	"github.com/vektah/gqlparser/v2/gqlerror"
 	"go.gearno.de/kit/httpserver"
+	"go.probo.inc/probo/pkg/baseurl"
+	"go.probo.inc/probo/pkg/bearertoken"
 	"go.probo.inc/probo/pkg/server/gqlutils"
 )
 
-func NewIdentityPresenceMiddleware() func(next http.Handler) http.Handler {
+func NewIdentityPresenceMiddleware(baseURL *baseurl.BaseURL) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(
 			func(w http.ResponseWriter, r *http.Request) {
-				identity := IdentityFromContext(r.Context())
+				ctx := r.Context()
+				identity := IdentityFromContext(ctx)
 
 				if identity == nil {
+					if bearertoken.IsAttempt(r.Header.Get("Authorization")) {
+						bearertoken.SetBearerInvalidToken(w, baseURL)
+					} else {
+						bearertoken.SetBearerUnauthenticated(w, baseURL)
+					}
+
 					httpserver.RenderJSON(
 						w,
 						http.StatusUnauthorized,

pkg/server/api/authn/oauth2_access_token_middleware.go

@@ -36,15 +36,19 @@ func NewOAuth2AccessTokenMiddleware(svc *iam.Service) func(next http.Handler) ht
 					return
 				}
 
-				tokenValue, err := bearertoken.Parse(r.Header.Get("Authorization"))
+				authorization := r.Header.Get("Authorization")
+
+				tokenValue, err := bearertoken.Parse(authorization)
 				if err != nil {
 					next.ServeHTTP(w, r)
+
 					return
 				}
 
 				accessToken, err := svc.OAuth2ServerService.LoadAccessToken(ctx, tokenValue)
 				if err != nil {
 					next.ServeHTTP(w, r)
+
 					return
 				}
 

pkg/server/api/connect/v1/oauth2_handler.go

@@ -77,7 +77,7 @@ func (h *OAuth2Handler) BearerTokenMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		tokenValue, err := bearertoken.Parse(r.Header.Get("Authorization"))
 		if err != nil {
-			w.Header().Set("WWW-Authenticate", `Bearer error="invalid_token"`)
+			bearertoken.SetBearerInvalidToken(w, h.baseURL)
 			http.Error(w, "unauthorized", http.StatusUnauthorized)
 
 			return
@@ -85,7 +85,7 @@ func (h *OAuth2Handler) BearerTokenMiddleware(next http.Handler) http.Handler {
 
 		accessToken, err := h.iam.OAuth2ServerService.LoadAccessToken(r.Context(), tokenValue)
 		if err != nil {
-			w.Header().Set("WWW-Authenticate", `Bearer error="invalid_token"`)
+			bearertoken.SetBearerInvalidToken(w, h.baseURL)
 			http.Error(w, "unauthorized", http.StatusUnauthorized)
 
 			return
@@ -402,7 +402,7 @@ func (h *OAuth2Handler) RegisterHandler(w http.ResponseWriter, r *http.Request)
 func (h *OAuth2Handler) UserInfoHandler(w http.ResponseWriter, r *http.Request) {
 	accessToken, ok := oauth2.AccessTokenFromContext(r.Context())
 	if !ok {
-		w.Header().Set("WWW-Authenticate", `Bearer error="invalid_token"`)
+		bearertoken.SetBearerInvalidToken(w, h.baseURL)
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
 
 		return

pkg/server/api/connect/v1/resolver.go

@@ -76,11 +76,16 @@ func NewMux(
 	sessionMiddleware := authn.NewSessionMiddleware(svc, cookieConfig)
 	apiKeyMiddleware := authn.NewAPIKeyMiddleware(svc, tokenSecret)
 	oauth2Middleware := authn.NewOAuth2AccessTokenMiddleware(svc)
+	identityPresenceMiddleware := authn.NewIdentityPresenceMiddleware(baseURL)
 	graphqlHandler := NewGraphQLHandler(svc, logger, fileManagerSvc, baseURL, cookieConfig)
 	samlHandler := NewSAMLHandler(svc, cookieConfig, baseURL, logger)
 	scimHandler := NewSCIMHandler(svc, logger.Named("scim"))
 
-	router := r.With(sessionMiddleware, apiKeyMiddleware, oauth2Middleware)
+	router := r.With(
+		sessionMiddleware,
+		apiKeyMiddleware,
+		oauth2Middleware,
+	)
 
 	oidcHandler := NewOIDCHandler(svc, cookieConfig, logger, allowedRedirectHost, isTrustCenterDomain)
 
@@ -115,7 +120,7 @@ func NewMux(
 	// Session-authenticated endpoints.
 	router.Get("/oauth2/authorize", oauth2Handler.AuthorizeHandler)
 
-	requireIdentity := router.With(authn.NewIdentityPresenceMiddleware())
+	requireIdentity := router.With(identityPresenceMiddleware)
 	requireIdentity.Post("/oauth2/register", oauth2Handler.RegisterHandler)
 
 	return r

pkg/server/api/console/v1/resolver.go

@@ -120,7 +120,7 @@ func NewMux(
 		r.Use(authn.NewSessionMiddleware(iamSvc, cookieConfig))
 		r.Use(authn.NewAPIKeyMiddleware(iamSvc, tokenSecret))
 		r.Use(authn.NewOAuth2AccessTokenMiddleware(iamSvc))
-		r.Use(authn.NewIdentityPresenceMiddleware())
+		r.Use(authn.NewIdentityPresenceMiddleware(baseURL))
 		r.Use(dataloader.NewMiddleware(proboSvc, iamSvc, cookieBannerSvc, thirdPartySvc))
 
 		r.Handle("/graphql", graphqlHandler)

pkg/server/api/files/v1/handler.go

@@ -22,6 +22,8 @@ import (
 
 	"github.com/go-chi/chi/v5"
 	"go.gearno.de/kit/log"
+	"go.probo.inc/probo/pkg/baseurl"
+	"go.probo.inc/probo/pkg/bearertoken"
 	"go.probo.inc/probo/pkg/brand"
 	"go.probo.inc/probo/pkg/coredata"
 	"go.probo.inc/probo/pkg/filemanager"
@@ -41,6 +43,7 @@ type Handler struct {
 	probo   *probo.Service
 	iamSvc  *iam.Service
 	assets  *brand.Assets
+	baseURL *baseurl.BaseURL
 }
 
 func NewMux(
@@ -50,6 +53,7 @@ func NewMux(
 	iamSvc *iam.Service,
 	cookieConfig securecookie.Config,
 	tokenSecret string,
+	baseURL *baseurl.BaseURL,
 ) *chi.Mux {
 	h := &Handler{
 		logger:  logger,
@@ -57,6 +61,7 @@ func NewMux(
 		probo:   proboSvc,
 		iamSvc:  iamSvc,
 		assets:  brand.NewAssets(),
+		baseURL: baseURL,
 	}
 
 	r := chi.NewRouter()
@@ -68,7 +73,7 @@ func NewMux(
 		r.Use(authn.NewSessionMiddleware(iamSvc, cookieConfig))
 		r.Use(authn.NewAPIKeyMiddleware(iamSvc, tokenSecret))
 		r.Use(authn.NewOAuth2AccessTokenMiddleware(iamSvc))
-		r.Use(authn.NewIdentityPresenceMiddleware())
+		r.Use(authn.NewIdentityPresenceMiddleware(baseURL))
 		r.Get("/{fileID}", h.handleGetFile)
 	})
 
@@ -157,8 +162,10 @@ func (h *Handler) handleGetFile(w http.ResponseWriter, r *http.Request) {
 
 	scope, err := h.iamSvc.Authorizer.Authorize(ctx, params)
 	if err != nil {
-		if _, ok := errors.AsType[*iam.ErrInsufficientOAuth2Scope](err); ok {
+		if scopeErr, ok := errors.AsType[*iam.ErrInsufficientOAuth2Scope](err); ok {
+			bearertoken.SetBearerInsufficientScope(w, h.baseURL, scopeErr.Scopes...)
 			jsonx.RenderForbidden(w)
+
 			return
 		}
 

pkg/server/api/files/v1/handler_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.gearno.de/kit/log"
+	"go.probo.inc/probo/pkg/baseurl"
 	"go.probo.inc/probo/pkg/securecookie"
 )
 
@@ -79,6 +80,7 @@ func TestHandleGetStaticFile(t *testing.T) {
 		nil,
 		securecookie.Config{},
 		"test-secret",
+		baseurl.MustParse("https://example.com"),
 	)
 
 	rec := httptest.NewRecorder()
@@ -118,6 +120,7 @@ func TestHandleGetFile_UnauthenticatedReturns401(t *testing.T) {
 		nil, // iamSvc — not reached when no token/cookie present
 		securecookie.Config{},
 		"test-secret",
+		baseurl.MustParse("https://example.com"),
 	)
 
 	rec := httptest.NewRecorder()

pkg/server/api/mcp/v1/v1_handler.go

@@ -86,7 +86,7 @@ func NewMux(
 	r := chi.NewMux()
 	r.Use(authn.NewAPIKeyMiddleware(iamSvc, tokenSecret))
 	r.Use(authn.NewOAuth2AccessTokenMiddleware(iamSvc))
-	r.Use(authn.NewIdentityPresenceMiddleware())
+	r.Use(authn.NewIdentityPresenceMiddleware(baseURL))
 	r.Handle("/", protectedHandler)
 
 	logger.Info("MCP server initialized successfully")