enhance client support checks for MCP Apps UI rendering

Author: mattdholloway

pkg/context/request.go

@@ -113,3 +113,19 @@ func GetHeaderFeatures(ctx context.Context) []string {
 	}
 	return nil
 }
+
+// clientNameCtxKey is a context key for the MCP client name
+type clientNameCtxKey struct{}
+
+// WithClientName stores the MCP client name in the context.
+// This is used by HTTP/stateless servers where req.Session may not have
+// InitializeParams available on every request.
+func WithClientName(ctx context.Context, name string) context.Context {
+	return context.WithValue(ctx, clientNameCtxKey{}, name)
+}
+
+// GetClientName retrieves the MCP client name from the context.
+func GetClientName(ctx context.Context) (string, bool) {
+	name, ok := ctx.Value(clientNameCtxKey{}).(string)
+	return name, ok && name != ""
+}

pkg/github/issues.go

@@ -1103,7 +1103,7 @@ Options are:
 			// to distinguish form submissions from LLM calls.
 			uiSubmitted, _ := OptionalParam[bool](args, "_ui_submitted")
 
-			if deps.GetFlags(ctx).InsidersMode && clientSupportsUI(req) && !uiSubmitted {
+			if deps.GetFlags(ctx).InsidersMode && clientSupportsUI(ctx, req) && !uiSubmitted {
 				if method == "update" {
 					issueNumber, numErr := RequiredInt(args, "issue_number")
 					if numErr != nil {

pkg/github/pullrequests.go

@@ -557,7 +557,7 @@ func CreatePullRequest(t translations.TranslationHelperFunc) inventory.ServerToo
 			// to distinguish form submissions from LLM calls.
 			uiSubmitted, _ := OptionalParam[bool](args, "_ui_submitted")
 
-			if deps.GetFlags(ctx).InsidersMode && clientSupportsUI(req) && !uiSubmitted {
+			if deps.GetFlags(ctx).InsidersMode && clientSupportsUI(ctx, req) && !uiSubmitted {
 				return utils.NewToolResultText(fmt.Sprintf("Ready to create a pull request in %s/%s. The user will review and confirm via the interactive form.", owner, repo)), nil, nil
 			}
 

pkg/github/ui_capability.go

@@ -1,6 +1,11 @@
 package github
 
-import "github.com/modelcontextprotocol/go-sdk/mcp"
+import (
+	"context"
+
+	ghcontext "github.com/github/github-mcp-server/pkg/context"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
 
 // uiSupportedClients lists client names (from ClientInfo.Name) known to
 // support MCP Apps UI rendering.
@@ -14,14 +19,21 @@ var uiSupportedClients = map[string]bool{
 }
 
 // clientSupportsUI reports whether the MCP client that sent this request
-// supports MCP Apps UI rendering, based on its ClientInfo.Name.
-func clientSupportsUI(req *mcp.CallToolRequest) bool {
-	if req == nil || req.Session == nil {
-		return false
+// supports MCP Apps UI rendering.
+// It checks the go-sdk Session first (for stdio/stateful servers), then
+// falls back to the request context (for HTTP/stateless servers where
+// the session may not persist InitializeParams across requests).
+func clientSupportsUI(ctx context.Context, req *mcp.CallToolRequest) bool {
+	// Try go-sdk session first (works for stdio/stateful servers)
+	if req != nil && req.Session != nil {
+		params := req.Session.InitializeParams()
+		if params != nil && params.ClientInfo != nil {
+			return uiSupportedClients[params.ClientInfo.Name]
+		}
 	}
-	params := req.Session.InitializeParams()
-	if params == nil || params.ClientInfo == nil {
-		return false
+	// Fall back to context (works for HTTP/stateless servers)
+	if name, ok := ghcontext.GetClientName(ctx); ok {
+		return uiSupportedClients[name]
 	}
-	return uiSupportedClients[params.ClientInfo.Name]
+	return false
 }

pkg/github/ui_capability_test.go

@@ -4,12 +4,14 @@ import (
 	"context"
 	"testing"
 
+	ghcontext "github.com/github/github-mcp-server/pkg/context"
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"github.com/stretchr/testify/assert"
 )
 
 func Test_clientSupportsUI(t *testing.T) {
 	t.Parallel()
+	ctx := context.Background()
 
 	tests := []struct {
 		name       string
@@ -25,22 +27,23 @@ func Test_clientSupportsUI(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			req := createMCPRequestWithSession(t, tt.clientName, nil)
-			assert.Equal(t, tt.want, clientSupportsUI(&req))
+			assert.Equal(t, tt.want, clientSupportsUI(ctx, &req))
 		})
 	}
 
 	t.Run("nil request", func(t *testing.T) {
-		assert.False(t, clientSupportsUI(nil))
+		assert.False(t, clientSupportsUI(ctx, nil))
 	})
 
 	t.Run("nil session", func(t *testing.T) {
 		req := createMCPRequest(nil)
-		assert.False(t, clientSupportsUI(&req))
+		assert.False(t, clientSupportsUI(ctx, &req))
 	})
 }
 
 func Test_clientSupportsUI_nilClientInfo(t *testing.T) {
 	t.Parallel()
+	ctx := context.Background()
 
 	srv := mcp.NewServer(&mcp.Implementation{Name: "test"}, nil)
 	st, _ := mcp.NewInMemoryTransports()
@@ -57,5 +60,23 @@ func Test_clientSupportsUI_nilClientInfo(t *testing.T) {
 	t.Cleanup(func() { _ = session.Close() })
 
 	req := mcp.CallToolRequest{Session: session}
-	assert.False(t, clientSupportsUI(&req))
+	assert.False(t, clientSupportsUI(ctx, &req))
+}
+
+func Test_clientSupportsUI_fromContext(t *testing.T) {
+	t.Parallel()
+
+	t.Run("supported client in context", func(t *testing.T) {
+		ctx := ghcontext.WithClientName(context.Background(), "Visual Studio Code - Insiders")
+		assert.True(t, clientSupportsUI(ctx, nil))
+	})
+
+	t.Run("unsupported client in context", func(t *testing.T) {
+		ctx := ghcontext.WithClientName(context.Background(), "some-other-client")
+		assert.False(t, clientSupportsUI(ctx, nil))
+	})
+
+	t.Run("no client in context or session", func(t *testing.T) {
+		assert.False(t, clientSupportsUI(context.Background(), nil))
+	})
 }