Add MCP App form deferral opt-out · github/github-mcp-server@a217a7f · GitHub
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connor4312Copilot
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SamMorrowDrums
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Add MCP App form deferral opt-out
Allow clients to keep MCP App views enabled while making form-backed write tools execute directly when explicitly configured. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
1 parent b8bfb49 commit a217a7f

6 files changed

Lines changed: 91 additions & 5 deletions

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‎docs/server-configuration.md‎

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‎pkg/github/feature_flags.go‎

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@@ -5,6 +5,10 @@ import "slices"
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// MCPAppsFeatureFlag is the feature flag name for MCP Apps (interactive UI forms).
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const MCPAppsFeatureFlag = "remote_mcp_ui_apps"
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// MCPAppsDisableFormDeferralFeatureFlag disables handing write-tool calls off
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// to MCP App forms while preserving MCP Apps UI metadata and result views.
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const MCPAppsDisableFormDeferralFeatureFlag = "mcp_apps_disable_form_deferral"
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// FeatureFlagCSVOutput is the feature flag name for CSV output on list tools.
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const FeatureFlagCSVOutput = "csv_output"
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@@ -37,6 +41,7 @@ const FeatureFlagFieldsParam = "fields_param"
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// This is the single source of truth for which flags are user-controllable.
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var AllowedFeatureFlags = []string{
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MCPAppsFeatureFlag,
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MCPAppsDisableFormDeferralFeatureFlag,
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FeatureFlagCSVOutput,
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FeatureFlagIFCLabels,
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FeatureFlagIssuesGranular,

‎pkg/github/feature_flags_test.go‎

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@@ -155,6 +155,11 @@ func TestResolveFeatureFlags(t *testing.T) {
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enabledFeatures: []string{MCPAppsFeatureFlag},
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expectedFlags: []string{MCPAppsFeatureFlag},
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},
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{
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name: "MCP Apps form deferral can be disabled directly",
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enabledFeatures: []string{MCPAppsDisableFormDeferralFeatureFlag},
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expectedFlags: []string{MCPAppsDisableFormDeferralFeatureFlag},
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},
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{
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name: "fields param is not enabled by default",
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enabledFeatures: nil,
@@ -183,6 +188,12 @@ func TestResolveFeatureFlags(t *testing.T) {
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insidersMode: true,
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unexpectedFlags: []string{FeatureFlagIFCLabels},
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},
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{
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name: "insiders mode does not disable MCP Apps form deferral",
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enabledFeatures: nil,
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insidersMode: true,
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unexpectedFlags: []string{MCPAppsDisableFormDeferralFeatureFlag},
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},
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{
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name: "ifc_labels can be directly enabled",
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enabledFeatures: []string{FeatureFlagIFCLabels},

‎pkg/github/ui_capability.go‎

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@@ -63,13 +63,15 @@ func hasNonFormParams(args map[string]any, formParams map[string]struct{}) bool
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// shared by the form-backed write tools (create_pull_request,
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// update_pull_request, issue_write). It reports whether a call should be handed
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// off to its MCP App form instead of executing now: defer only when MCP Apps
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// are enabled, the client can render UI, the call is not itself a form
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// submission, and every supplied parameter can be represented by the form
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// (formParams is the tool's form-parameter allowlist). When it returns false
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// the handler executes directly; the host may still render the tool's view,
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// which renders the result rather than an input form.
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// are enabled, form deferral has not been disabled, the client can render UI,
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// the call is not itself a form submission, and every supplied parameter can
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// be represented by the form (formParams is the tool's form-parameter
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// allowlist). When it returns false the handler executes directly; the host may
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// still render the tool's view, which renders the result rather than an input
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// form.
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func shouldDeferToForm(ctx context.Context, deps ToolDependencies, req *mcp.CallToolRequest, args map[string]any, formParams map[string]struct{}) bool {
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return deps.IsFeatureEnabled(ctx, MCPAppsFeatureFlag) &&
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!deps.IsFeatureEnabled(ctx, MCPAppsDisableFormDeferralFeatureFlag) &&
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clientSupportsUI(ctx, req) &&
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!uiSubmitted(args) &&
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!hasNonFormParams(args, formParams)

‎pkg/github/ui_capability_test.go‎

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@@ -85,3 +85,48 @@ func Test_clientSupportsUI_fromContext(t *testing.T) {
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assert.False(t, clientSupportsUI(context.Background(), nil))
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})
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}
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func Test_shouldDeferToForm_featureFlags(t *testing.T) {
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t.Parallel()
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ctx := ghcontext.WithUISupport(context.Background(), true)
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args := map[string]any{"owner": "octocat"}
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formParams := map[string]struct{}{"owner": {}}
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tests := []struct {
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name string
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enabledFlags []string
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want bool
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}{
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{
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name: "MCP Apps enabled defers to form",
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enabledFlags: []string{MCPAppsFeatureFlag},
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want: true,
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},
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{
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name: "form deferral disabled executes directly",
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enabledFlags: []string{
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MCPAppsFeatureFlag,
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MCPAppsDisableFormDeferralFeatureFlag,
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},
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want: false,
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},
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{
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name: "form deferral opt-out does not enable MCP Apps",
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enabledFlags: []string{MCPAppsDisableFormDeferralFeatureFlag},
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want: false,
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},
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{
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name: "MCP Apps disabled executes directly",
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want: false,
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},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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deps := BaseDeps{featureChecker: featureCheckerFor(tc.enabledFlags...)}
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assert.Equal(t, tc.want, shouldDeferToForm(ctx, deps, nil, args, formParams))
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})
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}
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}

‎pkg/http/server_test.go‎

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