Merge branch 'main' into kerobbi/response-optimisation

Author: kerobbi

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/josephburnett/jd/v2 v2.4.0
 	github.com/lithammer/fuzzysearch v1.1.8
 	github.com/microcosm-cc/bluemonday v1.0.27
-	github.com/modelcontextprotocol/go-sdk v1.3.0
+	github.com/modelcontextprotocol/go-sdk v1.3.1-0.20260220105450-b17143f71798
 	github.com/muesli/cache2go v0.0.0-20221011235721-518229cd8021
 	github.com/shurcooL/githubv4 v0.0.0-20240727222349-48295856cce7
 	github.com/shurcooL/graphql v0.0.0-20230722043721-ed46e5a46466
@@ -35,6 +35,8 @@ require (
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/segmentio/asm v1.1.3 // indirect
+	github.com/segmentio/encoding v0.5.3 // indirect
 	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
 	github.com/spf13/afero v1.15.0 // indirect
 	github.com/spf13/cast v1.10.0 // indirect
@@ -43,8 +45,8 @@ require (
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/exp v0.0.0-20250305212735-054e65f0b394 // indirect
 	golang.org/x/net v0.38.0 // indirect
-	golang.org/x/oauth2 v0.30.0 // indirect
-	golang.org/x/sys v0.31.0 // indirect
+	golang.org/x/oauth2 v0.34.0 // indirect
+	golang.org/x/sys v0.40.0 // indirect
 	golang.org/x/text v0.28.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -15,8 +15,8 @@ github.com/go-openapi/swag v0.23.0 h1:vsEVJDUo2hPJ2tu0/Xc+4noaxyEffXNIs3cOULZ+Gr
 github.com/go-openapi/swag v0.23.0/go.mod h1:esZ8ITTYEsH1V2trKHjAN8Ai7xHb8RV+YSZ577vPjgQ=
 github.com/go-viper/mapstructure/v2 v2.5.0 h1:vM5IJoUAy3d7zRSVtIwQgBj7BiWtMPfmPEgAXnvj1Ro=
 github.com/go-viper/mapstructure/v2 v2.5.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
-github.com/golang-jwt/jwt/v5 v5.2.2 h1:Rl4B7itRWVtYIHFrSNd7vhTiz9UpLdi6gZhZ3wEeDy8=
-github.com/golang-jwt/jwt/v5 v5.2.2/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
+github.com/golang-jwt/jwt/v5 v5.3.0 h1:pv4AsKCKKZuqlgs5sUmn4x8UlGa0kEVt/puTpKx9vvo=
+github.com/golang-jwt/jwt/v5 v5.3.0/go.mod h1:fxCRLWMO43lRc8nhHWY6LGqRcf+1gQWArsqaEUEa5bE=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
@@ -44,8 +44,8 @@ github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
 github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwXFM08ygZfk=
 github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
-github.com/modelcontextprotocol/go-sdk v1.3.0 h1:gMfZkv3DzQF5q/DcQePo5rahEY+sguyPfXDfNBcT0Zs=
-github.com/modelcontextprotocol/go-sdk v1.3.0/go.mod h1:AnQ//Qc6+4nIyyrB4cxBU7UW9VibK4iOZBeyP/rF1IE=
+github.com/modelcontextprotocol/go-sdk v1.3.1-0.20260220105450-b17143f71798 h1:ogb5ErmcnxZgfaTeVZnKEMrwdHDpJ3yln5EhCIPcTlY=
+github.com/modelcontextprotocol/go-sdk v1.3.1-0.20260220105450-b17143f71798/go.mod h1:Nxc2n+n/GdCebUaqCOhTetptS17SXXNu9IfNTaLDi1E=
 github.com/muesli/cache2go v0.0.0-20221011235721-518229cd8021 h1:31Y+Yu373ymebRdJN1cWLLooHH8xAr0MhKTEJGV/87g=
 github.com/muesli/cache2go v0.0.0-20221011235721-518229cd8021/go.mod h1:WERUkUryfUWlrHnFSO/BEUZ+7Ns8aZy7iVOGewxKzcc=
 github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
@@ -57,6 +57,10 @@ github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/sagikazarmark/locafero v0.11.0 h1:1iurJgmM9G3PA/I+wWYIOw/5SyBtxapeHDcg+AAIFXc=
 github.com/sagikazarmark/locafero v0.11.0/go.mod h1:nVIGvgyzw595SUSUE6tvCp3YYTeHs15MvlmU87WwIik=
+github.com/segmentio/asm v1.1.3 h1:WM03sfUOENvvKexOLp+pCqgb/WDjsi7EK8gIsICtzhc=
+github.com/segmentio/asm v1.1.3/go.mod h1:Ld3L4ZXGNcSLRg4JBsZ3//1+f/TjYl0Mzen/DQy1EJg=
+github.com/segmentio/encoding v0.5.3 h1:OjMgICtcSFuNvQCdwqMCv9Tg7lEOXGwm1J5RPQccx6w=
+github.com/segmentio/encoding v0.5.3/go.mod h1:HS1ZKa3kSN32ZHVZ7ZLPLXWvOVIiZtyJnO1gPH1sKt0=
 github.com/shurcooL/githubv4 v0.0.0-20240727222349-48295856cce7 h1:cYCy18SHPKRkvclm+pWm1Lk4YrREb4IOIb/YdFO0p2M=
 github.com/shurcooL/githubv4 v0.0.0-20240727222349-48295856cce7/go.mod h1:zqMwyHmnN/eDOZOdiTohqIUKUrTFX62PNlu7IJdu0q8=
 github.com/shurcooL/graphql v0.0.0-20230722043721-ed46e5a46466 h1:17JxqqJY66GmZVHkmAsGEkcIu0oCe3AM420QDgGwZx0=
@@ -97,8 +101,8 @@ golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug
 golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.38.0 h1:vRMAPTMaeGqVhG5QyLJHqNDwecKTomGeqbnfZyKlBI8=
 golang.org/x/net v0.38.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
-golang.org/x/oauth2 v0.30.0 h1:dnDm7JmhM45NNpd8FDDeLhK6FwqbOf4MLCM9zb1BOHI=
-golang.org/x/oauth2 v0.30.0/go.mod h1:B++QgG3ZKulg6sRPGD/mqlHQs5rB3Ml9erfeDY7xKlU=
+golang.org/x/oauth2 v0.34.0 h1:hqK/t4AKgbqWkdkcAeI8XLmbK+4m4G5YeQRrmiotGlw=
+golang.org/x/oauth2 v0.34.0/go.mod h1:lzm5WQJQwKZ3nwavOZ3IS5Aulzxi68dUSgRHujetwEA=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -108,8 +112,8 @@ golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
-golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
+golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
+golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
@@ -124,8 +128,8 @@ golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
-golang.org/x/tools v0.35.0 h1:mBffYraMEf7aa0sB+NuKnuCy8qI/9Bughn8dC2Gu5r0=
-golang.org/x/tools v0.35.0/go.mod h1:NKdj5HkL/73byiZSJjqJgKn3ep7KjFkBOkR/Hps3VPw=
+golang.org/x/tools v0.41.0 h1:a9b8iMweWG+S0OBnlU36rzLp20z1Rp10w+IY2czHTQc=
+golang.org/x/tools v0.41.0/go.mod h1:XSY6eDqxVNiYgezAVqqCeihT4j1U2CCsqvH3WhQpnlg=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=

pkg/context/request.go

@@ -113,3 +113,19 @@ func GetHeaderFeatures(ctx context.Context) []string {
 	}
 	return nil
 }
+
+// uiSupportCtxKey is a context key for MCP Apps UI support
+type uiSupportCtxKey struct{}
+
+// WithUISupport stores whether the client supports MCP Apps UI in the context.
+// This is used by HTTP/stateless servers where the go-sdk session may not
+// persist client capabilities across requests.
+func WithUISupport(ctx context.Context, supported bool) context.Context {
+	return context.WithValue(ctx, uiSupportCtxKey{}, supported)
+}
+
+// HasUISupport retrieves the MCP Apps UI support flag from context.
+func HasUISupport(ctx context.Context) (supported bool, ok bool) {
+	v, ok := ctx.Value(uiSupportCtxKey{}).(bool)
+	return v, ok
+}

pkg/github/helper_test.go

@@ -291,10 +291,16 @@ func createMCPRequest(args any) mcp.CallToolRequest {
 	}
 }
 
+// Well-known MCP client names used in tests.
+const (
+	ClientNameVSCodeInsiders = "Visual Studio Code - Insiders"
+	ClientNameVSCode         = "Visual Studio Code"
+)
+
 // createMCPRequestWithSession creates a CallToolRequest with a ServerSession
-// that has the given client name in its InitializeParams. This is used to test
-// UI capability detection based on ClientInfo.Name.
-func createMCPRequestWithSession(t *testing.T, clientName string, args any) mcp.CallToolRequest {
+// that has the given client name in its InitializeParams. When withUI is true
+// the session advertises MCP Apps UI support via the capability extension.
+func createMCPRequestWithSession(t *testing.T, clientName string, withUI bool, args any) mcp.CallToolRequest {
 	t.Helper()
 
 	argsMap, ok := args.(map[string]any)
@@ -306,11 +312,19 @@ func createMCPRequestWithSession(t *testing.T, clientName string, args any) mcp.
 
 	srv := mcp.NewServer(&mcp.Implementation{Name: "test"}, nil)
 
+	caps := &mcp.ClientCapabilities{}
+	if withUI {
+		caps.AddExtension("io.modelcontextprotocol/ui", map[string]any{
+			"mimeTypes": []string{"text/html;profile=mcp-app"},
+		})
+	}
+
 	st, _ := mcp.NewInMemoryTransports()
 	session, err := srv.Connect(context.Background(), st, &mcp.ServerSessionOptions{
 		State: &mcp.ServerSessionState{
 			InitializeParams: &mcp.InitializeParams{
-				ClientInfo: &mcp.Implementation{Name: clientName},
+				ClientInfo:   &mcp.Implementation{Name: clientName},
+				Capabilities: caps,
 			},
 		},
 	})

pkg/github/issues.go

@@ -689,7 +689,12 @@ func AddIssueComment(t translations.TranslationHelperFunc) inventory.ServerTool
 				return ghErrors.NewGitHubAPIStatusErrorResponse(ctx, "failed to create comment", resp, body), nil, nil
 			}
 
-			r, err := json.Marshal(createdComment)
+			minimalResponse := MinimalResponse{
+				ID:  fmt.Sprintf("%d", createdComment.GetID()),
+				URL: createdComment.GetHTMLURL(),
+			}
+
+			r, err := json.Marshal(minimalResponse)
 			if err != nil {
 				return utils.NewToolResultErrorFromErr("failed to marshal response", err), nil, nil
 			}
@@ -1101,7 +1106,7 @@ 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/issues_test.go

@@ -458,13 +458,12 @@ func Test_AddIssueComment(t *testing.T) {
 			// Parse the result and get the text content if no error
 			textContent := getTextResult(t, result)
 
-			// Unmarshal and verify the result
-			var returnedComment github.IssueComment
-			err = json.Unmarshal([]byte(textContent.Text), &returnedComment)
+			// Unmarshal and verify the result contains minimal response
+			var minimalResponse MinimalResponse
+			err = json.Unmarshal([]byte(textContent.Text), &minimalResponse)
 			require.NoError(t, err)
-			assert.Equal(t, *tc.expectedComment.ID, *returnedComment.ID)
-			assert.Equal(t, *tc.expectedComment.Body, *returnedComment.Body)
-			assert.Equal(t, *tc.expectedComment.User.Login, *returnedComment.User.Login)
+			assert.Equal(t, fmt.Sprintf("%d", tc.expectedComment.GetID()), minimalResponse.ID)
+			assert.Equal(t, tc.expectedComment.GetHTMLURL(), minimalResponse.URL)
 
 		})
 	}
@@ -958,7 +957,7 @@ func Test_IssueWrite_InsidersMode_UIGate(t *testing.T) {
 	handler := serverTool.Handler(deps)
 
 	t.Run("UI client without _ui_submitted returns form message", func(t *testing.T) {
-		request := createMCPRequestWithSession(t, "Visual Studio Code - Insiders", map[string]any{
+		request := createMCPRequestWithSession(t, ClientNameVSCodeInsiders, true, map[string]any{
 			"method": "create",
 			"owner":  "owner",
 			"repo":   "repo",
@@ -972,7 +971,7 @@ func Test_IssueWrite_InsidersMode_UIGate(t *testing.T) {
 	})
 
 	t.Run("UI client with _ui_submitted executes directly", func(t *testing.T) {
-		request := createMCPRequestWithSession(t, "Visual Studio Code - Insiders", map[string]any{
+		request := createMCPRequestWithSession(t, ClientNameVSCodeInsiders, true, map[string]any{
 			"method":        "create",
 			"owner":         "owner",
 			"repo":          "repo",

pkg/github/minimal_types.go

@@ -278,8 +278,38 @@ type MinimalProjectStatusUpdate struct {
 	Creator    *MinimalUser `json:"creator,omitempty"`
 }
 
+// MinimalPullRequestReview is the trimmed output type for pull request review objects to reduce verbosity.
+type MinimalPullRequestReview struct {
+	ID                int64        `json:"id"`
+	State             string       `json:"state"`
+	Body              string       `json:"body,omitempty"`
+	HTMLURL           string       `json:"html_url"`
+	User              *MinimalUser `json:"user,omitempty"`
+	CommitID          string       `json:"commit_id,omitempty"`
+	SubmittedAt       string       `json:"submitted_at,omitempty"`
+	AuthorAssociation string       `json:"author_association,omitempty"`
+}
+
 // Helper functions
 
+func convertToMinimalPullRequestReview(review *github.PullRequestReview) MinimalPullRequestReview {
+	m := MinimalPullRequestReview{
+		ID:                review.GetID(),
+		State:             review.GetState(),
+		Body:              review.GetBody(),
+		HTMLURL:           review.GetHTMLURL(),
+		User:              convertToMinimalUser(review.GetUser()),
+		CommitID:          review.GetCommitID(),
+		AuthorAssociation: review.GetAuthorAssociation(),
+	}
+
+	if review.SubmittedAt != nil {
+		m.SubmittedAt = review.SubmittedAt.Format(time.RFC3339)
+	}
+
+	return m
+}
+
 func convertToMinimalIssue(issue *github.Issue) MinimalIssue {
 	m := MinimalIssue{
 		Number:            issue.GetNumber(),

pkg/github/pullrequests.go

@@ -455,12 +455,12 @@ func GetPullRequestReviews(ctx context.Context, client *github.Client, deps Tool
 		}
 	}
 
-	r, err := json.Marshal(reviews)
-	if err != nil {
-		return nil, fmt.Errorf("failed to marshal response: %w", err)
+	minimalReviews := make([]MinimalPullRequestReview, 0, len(reviews))
+	for _, review := range reviews {
+		minimalReviews = append(minimalReviews, convertToMinimalPullRequestReview(review))
 	}
 
-	return utils.NewToolResultText(string(r)), nil
+	return MarshalledTextResult(minimalReviews), nil
 }
 
 // PullRequestWriteUIResourceURI is the URI for the create_pull_request tool's MCP App UI resource.
@@ -538,7 +538,7 @@ 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/pullrequests_test.go

@@ -1990,18 +1990,18 @@ func Test_GetPullRequestReviews(t *testing.T) {
 			textContent := getTextResult(t, result)
 
 			// Unmarshal and verify the result
-			var returnedReviews []*github.PullRequestReview
+			var returnedReviews []MinimalPullRequestReview
 			err = json.Unmarshal([]byte(textContent.Text), &returnedReviews)
 			require.NoError(t, err)
 			assert.Len(t, returnedReviews, len(tc.expectedReviews))
 			for i, review := range returnedReviews {
+				assert.Equal(t, tc.expectedReviews[i].GetID(), review.ID)
+				assert.Equal(t, tc.expectedReviews[i].GetState(), review.State)
+				assert.Equal(t, tc.expectedReviews[i].GetBody(), review.Body)
 				require.NotNil(t, tc.expectedReviews[i].User)
 				require.NotNil(t, review.User)
-				assert.Equal(t, tc.expectedReviews[i].GetID(), review.GetID())
-				assert.Equal(t, tc.expectedReviews[i].GetState(), review.GetState())
-				assert.Equal(t, tc.expectedReviews[i].GetBody(), review.GetBody())
-				assert.Equal(t, tc.expectedReviews[i].GetUser().GetLogin(), review.GetUser().GetLogin())
-				assert.Equal(t, tc.expectedReviews[i].GetHTMLURL(), review.GetHTMLURL())
+				assert.Equal(t, tc.expectedReviews[i].GetUser().GetLogin(), review.User.Login)
+				assert.Equal(t, tc.expectedReviews[i].GetHTMLURL(), review.HTMLURL)
 			}
 		})
 	}
@@ -2185,7 +2185,7 @@ func Test_CreatePullRequest_InsidersMode_UIGate(t *testing.T) {
 	handler := serverTool.Handler(deps)
 
 	t.Run("UI client without _ui_submitted returns form message", func(t *testing.T) {
-		request := createMCPRequestWithSession(t, "Visual Studio Code", map[string]any{
+		request := createMCPRequestWithSession(t, ClientNameVSCodeInsiders, true, map[string]any{
 			"owner": "owner",
 			"repo":  "repo",
 			"title": "Test PR",
@@ -2200,7 +2200,7 @@ func Test_CreatePullRequest_InsidersMode_UIGate(t *testing.T) {
 	})
 
 	t.Run("UI client with _ui_submitted executes directly", func(t *testing.T) {
-		request := createMCPRequestWithSession(t, "Visual Studio Code", map[string]any{
+		request := createMCPRequestWithSession(t, ClientNameVSCodeInsiders, true, map[string]any{
 			"owner":         "owner",
 			"repo":          "repo",
 			"title":         "Test PR",

pkg/github/ui_capability.go

@@ -1,27 +1,32 @@
 package github
 
-import "github.com/modelcontextprotocol/go-sdk/mcp"
+import (
+	"context"
 
-// uiSupportedClients lists client names (from ClientInfo.Name) known to
-// support MCP Apps UI rendering.
-//
-// This is a temporary workaround until the Go SDK adds an Extensions field
-// to ClientCapabilities (see https://github.com/modelcontextprotocol/go-sdk/issues/777).
-// Once that lands, detection should use capabilities.extensions instead.
-var uiSupportedClients = map[string]bool{
-	"Visual Studio Code - Insiders": true,
-	"Visual Studio Code":            true,
-}
+	ghcontext "github.com/github/github-mcp-server/pkg/context"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+// mcpAppsExtensionKey is the capability extension key that clients use to
+// advertise MCP Apps UI support.
+const mcpAppsExtensionKey = "io.modelcontextprotocol/ui"
 
 // 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 context first (set by HTTP/stateless servers from stored
+// session capabilities), then falls back to the go-sdk Session (for stdio).
+func clientSupportsUI(ctx context.Context, req *mcp.CallToolRequest) bool {
+	// Check context first (works for HTTP/stateless servers)
+	if supported, ok := ghcontext.HasUISupport(ctx); ok {
+		return supported
 	}
-	params := req.Session.InitializeParams()
-	if params == nil || params.ClientInfo == nil {
-		return false
+	// Fall back to go-sdk session (works for stdio/stateful servers)
+	if req != nil && req.Session != nil {
+		params := req.Session.InitializeParams()
+		if params != nil && params.Capabilities != nil {
+			_, hasUI := params.Capabilities.Extensions[mcpAppsExtensionKey]
+			return hasUI
+		}
 	}
-	return uiSupportedClients[params.ClientInfo.Name]
+	return false
 }