hold-bac feature flag

Author: mattdholloway

pkg/github/projects.go

@@ -30,6 +30,14 @@ const (
 // in favor of the consolidated project tools.
 const FeatureFlagConsolidatedProjects = "remote_mcp_consolidated_projects"
 
+// FeatureFlagHoldBackLegacyProjects allows users to keep the old individual project tools
+// even after FeatureFlagConsolidatedProjects is enabled. This provides a transition period
+// for users who need more time to migrate to the consolidated tools.
+//
+// Deprecated: This flag will be removed in a future release. Users should migrate to
+// the consolidated project tools (projects_list, projects_get, projects_write).
+const FeatureFlagHoldBackLegacyProjects = "remote_mcp_holdback_legacy_projects"
+
 // Method constants for consolidated project tools
 const (
 	projectsMethodListProjects      = "list_projects"
@@ -160,6 +168,7 @@ func ListProjects(t translations.TranslationHelperFunc) inventory.ServerTool {
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -251,6 +260,7 @@ func GetProject(t translations.TranslationHelperFunc) inventory.ServerTool {
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -360,6 +370,7 @@ func ListProjectFields(t translations.TranslationHelperFunc) inventory.ServerToo
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -455,6 +466,7 @@ func GetProjectField(t translations.TranslationHelperFunc) inventory.ServerTool
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -594,6 +606,7 @@ func ListProjectItems(t translations.TranslationHelperFunc) inventory.ServerTool
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -703,6 +716,7 @@ func GetProjectItem(t translations.TranslationHelperFunc) inventory.ServerTool {
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -817,6 +831,7 @@ func AddProjectItem(t translations.TranslationHelperFunc) inventory.ServerTool {
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -932,6 +947,7 @@ func UpdateProjectItem(t translations.TranslationHelperFunc) inventory.ServerToo
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 
@@ -1021,6 +1037,7 @@ func DeleteProjectItem(t translations.TranslationHelperFunc) inventory.ServerToo
 		},
 	)
 	tool.FeatureFlagDisable = FeatureFlagConsolidatedProjects
+	tool.FeatureFlagHoldBack = FeatureFlagHoldBackLegacyProjects
 	return tool
 }
 

pkg/inventory/filters.go

@@ -38,13 +38,18 @@ func (r *Inventory) checkFeatureFlag(ctx context.Context, flagName string) bool
 // isFeatureFlagAllowed checks if an item passes feature flag filtering.
 // - If FeatureFlagEnable is set, the item is only allowed if the flag is enabled
 // - If FeatureFlagDisable is set, the item is excluded if the flag is enabled
-func (r *Inventory) isFeatureFlagAllowed(ctx context.Context, enableFlag, disableFlag string) bool {
+// - If FeatureFlagHoldBack is set and enabled, it overrides FeatureFlagDisable (keeps tool available)
+func (r *Inventory) isFeatureFlagAllowed(ctx context.Context, enableFlag, disableFlag, holdBackFlag string) bool {
 	// Check enable flag - item requires this flag to be on
 	if enableFlag != "" && !r.checkFeatureFlag(ctx, enableFlag) {
 		return false
 	}
 	// Check disable flag - item is excluded if this flag is on
 	if disableFlag != "" && r.checkFeatureFlag(ctx, disableFlag) {
+		// Check if hold-back flag overrides the disable
+		if holdBackFlag != "" && r.checkFeatureFlag(ctx, holdBackFlag) {
+			return true // Hold-back keeps tool enabled during transition
+		}
 		return false
 	}
 	return true
@@ -70,7 +75,7 @@ func (r *Inventory) isToolEnabled(ctx context.Context, tool *ServerTool) bool {
 		}
 	}
 	// 2. Check feature flags
-	if !r.isFeatureFlagAllowed(ctx, tool.FeatureFlagEnable, tool.FeatureFlagDisable) {
+	if !r.isFeatureFlagAllowed(ctx, tool.FeatureFlagEnable, tool.FeatureFlagDisable, tool.FeatureFlagHoldBack) {
 		return false
 	}
 	// 3. Check read-only filter (applies to all tools)
@@ -130,7 +135,7 @@ func (r *Inventory) AvailableResourceTemplates(ctx context.Context) []ServerReso
 	for i := range r.resourceTemplates {
 		res := &r.resourceTemplates[i]
 		// Check feature flags
-		if !r.isFeatureFlagAllowed(ctx, res.FeatureFlagEnable, res.FeatureFlagDisable) {
+		if !r.isFeatureFlagAllowed(ctx, res.FeatureFlagEnable, res.FeatureFlagDisable, res.FeatureFlagHoldBack) {
 			continue
 		}
 		if r.isToolsetEnabled(res.Toolset.ID) {
@@ -157,7 +162,7 @@ func (r *Inventory) AvailablePrompts(ctx context.Context) []ServerPrompt {
 	for i := range r.prompts {
 		prompt := &r.prompts[i]
 		// Check feature flags
-		if !r.isFeatureFlagAllowed(ctx, prompt.FeatureFlagEnable, prompt.FeatureFlagDisable) {
+		if !r.isFeatureFlagAllowed(ctx, prompt.FeatureFlagEnable, prompt.FeatureFlagDisable, prompt.FeatureFlagHoldBack) {
 			continue
 		}
 		if r.isToolsetEnabled(prompt.Toolset.ID) {

pkg/inventory/prompts.go

@@ -14,6 +14,9 @@ type ServerPrompt struct {
 	// FeatureFlagDisable specifies a feature flag that, when enabled, causes this prompt
 	// to be omitted. Used to disable prompts when a feature flag is on.
 	FeatureFlagDisable string
+	// FeatureFlagHoldBack specifies a feature flag that, when enabled, overrides
+	// FeatureFlagDisable and keeps the prompt available during a transition period.
+	FeatureFlagHoldBack string
 }
 
 // NewServerPrompt creates a new ServerPrompt with toolset metadata.

pkg/inventory/registry_test.go

@@ -1077,6 +1077,56 @@ func TestFeatureFlagBoth(t *testing.T) {
 	}
 }
 
+func TestFeatureFlagHoldBack(t *testing.T) {
+	// Tool with disable flag and hold-back flag (simulates legacy tool during consolidation)
+	legacyTool := mockToolWithFlags("legacy_tool", "toolset1", true, "", "consolidation_flag")
+	legacyTool.FeatureFlagHoldBack = "holdback_flag"
+
+	tools := []ServerTool{
+		mockTool("always_available", "toolset1", true),
+		legacyTool,
+	}
+
+	// Consolidation OFF, hold-back OFF -> legacy tool available (normal operation)
+	checkerAllOff := func(_ context.Context, _ string) (bool, error) { return false, nil }
+	regAllOff := NewBuilder().SetTools(tools).WithToolsets([]string{"all"}).WithFeatureChecker(checkerAllOff).Build()
+	availableAllOff := regAllOff.AvailableTools(context.Background())
+	if len(availableAllOff) != 2 {
+		t.Fatalf("Expected 2 tools when both flags off, got %d", len(availableAllOff))
+	}
+
+	// Consolidation ON, hold-back OFF -> legacy tool excluded (migrated to new tools)
+	checkerConsolidationOnly := func(_ context.Context, flag string) (bool, error) {
+		return flag == "consolidation_flag", nil
+	}
+	regConsolidationOnly := NewBuilder().SetTools(tools).WithToolsets([]string{"all"}).WithFeatureChecker(checkerConsolidationOnly).Build()
+	availableConsolidationOnly := regConsolidationOnly.AvailableTools(context.Background())
+	if len(availableConsolidationOnly) != 1 {
+		t.Fatalf("Expected 1 tool when consolidation on but holdback off, got %d", len(availableConsolidationOnly))
+	}
+	if availableConsolidationOnly[0].Tool.Name != "always_available" {
+		t.Errorf("Expected always_available, got %s", availableConsolidationOnly[0].Tool.Name)
+	}
+
+	// Consolidation ON, hold-back ON -> legacy tool available (user opted to hold back)
+	checkerBothOn := func(_ context.Context, _ string) (bool, error) { return true, nil }
+	regBothOn := NewBuilder().SetTools(tools).WithToolsets([]string{"all"}).WithFeatureChecker(checkerBothOn).Build()
+	availableBothOn := regBothOn.AvailableTools(context.Background())
+	if len(availableBothOn) != 2 {
+		t.Fatalf("Expected 2 tools when both consolidation and holdback on, got %d", len(availableBothOn))
+	}
+
+	// Consolidation OFF, hold-back ON -> legacy tool available (hold-back has no effect when consolidation off)
+	checkerHoldbackOnly := func(_ context.Context, flag string) (bool, error) {
+		return flag == "holdback_flag", nil
+	}
+	regHoldbackOnly := NewBuilder().SetTools(tools).WithToolsets([]string{"all"}).WithFeatureChecker(checkerHoldbackOnly).Build()
+	availableHoldbackOnly := regHoldbackOnly.AvailableTools(context.Background())
+	if len(availableHoldbackOnly) != 2 {
+		t.Fatalf("Expected 2 tools when only holdback on, got %d", len(availableHoldbackOnly))
+	}
+}
+
 func TestFeatureFlagError(t *testing.T) {
 	tools := []ServerTool{
 		mockToolWithFlags("needs_flag", "toolset1", true, "my_feature", ""),

pkg/inventory/resources.go

@@ -22,6 +22,9 @@ type ServerResourceTemplate struct {
 	// FeatureFlagDisable specifies a feature flag that, when enabled, causes this resource
 	// to be omitted. Used to disable resources when a feature flag is on.
 	FeatureFlagDisable string
+	// FeatureFlagHoldBack specifies a feature flag that, when enabled, overrides
+	// FeatureFlagDisable and keeps the resource available during a transition period.
+	FeatureFlagHoldBack string
 }
 
 // HasHandler returns true if this resource has a handler function.

pkg/inventory/server_tool.go

@@ -64,6 +64,12 @@ type ServerTool struct {
 	// to be omitted. Used to disable tools when a feature flag is on.
 	FeatureFlagDisable string
 
+	// FeatureFlagHoldBack specifies a feature flag that, when enabled, overrides
+	// FeatureFlagDisable and keeps the tool available. This allows users to "hold back"
+	// on a deprecation by opting to keep the old tools during a transition period.
+	// Used during tool consolidation to give users time to migrate.
+	FeatureFlagHoldBack string
+
 	// Enabled is an optional function called at build/filter time to determine
 	// if this tool should be available. If nil, the tool is considered enabled
 	// (subject to FeatureFlagEnable/FeatureFlagDisable checks).