refactor(new_editor/app): reorganize host structure and add smoke test

new_editor/include/XCEditor/Workspace/UIEditorWindowWorkspaceController.h

@@ -0,0 +1,91 @@
+#pragma once
+
+#include <XCEditor/Workspace/UIEditorWindowWorkspaceModel.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+enum class UIEditorWindowWorkspaceOperationStatus : std::uint8_t {
+    Changed = 0,
+    NoOp,
+    Rejected
+};
+
+struct UIEditorWindowWorkspaceOperationResult {
+    UIEditorWindowWorkspaceOperationStatus status =
+        UIEditorWindowWorkspaceOperationStatus::Rejected;
+    std::string message = {};
+    std::string sourceWindowId = {};
+    std::string targetWindowId = {};
+    std::string panelId = {};
+    std::string activeWindowId = {};
+    std::vector<std::string> windowIds = {};
+};
+
+std::string_view GetUIEditorWindowWorkspaceOperationStatusName(
+    UIEditorWindowWorkspaceOperationStatus status);
+
+class UIEditorWindowWorkspaceController {
+public:
+    UIEditorWindowWorkspaceController() = default;
+    UIEditorWindowWorkspaceController(
+        UIEditorPanelRegistry panelRegistry,
+        UIEditorWindowWorkspaceSet windowSet);
+
+    const UIEditorPanelRegistry& GetPanelRegistry() const {
+        return m_panelRegistry;
+    }
+
+    const UIEditorWindowWorkspaceSet& GetWindowSet() const {
+        return m_windowSet;
+    }
+
+    UIEditorWindowWorkspaceValidationResult ValidateState() const;
+
+    UIEditorWindowWorkspaceOperationResult DetachPanelToNewWindow(
+        std::string_view sourceWindowId,
+        std::string_view sourceNodeId,
+        std::string_view panelId,
+        std::string_view preferredNewWindowId = {});
+
+    UIEditorWindowWorkspaceOperationResult MovePanelToStack(
+        std::string_view sourceWindowId,
+        std::string_view sourceNodeId,
+        std::string_view panelId,
+        std::string_view targetWindowId,
+        std::string_view targetNodeId,
+        std::size_t targetVisibleInsertionIndex);
+
+    UIEditorWindowWorkspaceOperationResult DockPanelRelative(
+        std::string_view sourceWindowId,
+        std::string_view sourceNodeId,
+        std::string_view panelId,
+        std::string_view targetWindowId,
+        std::string_view targetNodeId,
+        UIEditorWorkspaceDockPlacement placement,
+        float splitRatio = 0.5f);
+
+private:
+    UIEditorWindowWorkspaceOperationResult BuildOperationResult(
+        UIEditorWindowWorkspaceOperationStatus status,
+        std::string message,
+        std::string_view sourceWindowId,
+        std::string_view targetWindowId,
+        std::string_view panelId) const;
+
+    std::string MakeUniqueWindowId(std::string_view base) const;
+
+    UIEditorPanelRegistry m_panelRegistry = {};
+    UIEditorWindowWorkspaceSet m_windowSet = {};
+};
+
+UIEditorWindowWorkspaceController BuildDefaultUIEditorWindowWorkspaceController(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace,
+    std::string primaryWindowId = "main-window");
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWindowWorkspaceModel.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <XCEditor/Panels/UIEditorPanelRegistry.h>
+#include <XCEditor/Workspace/UIEditorWorkspaceSession.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWindowWorkspaceState {
+    std::string windowId = {};
+    UIEditorWorkspaceModel workspace = {};
+    UIEditorWorkspaceSession session = {};
+};
+
+struct UIEditorWindowWorkspaceSet {
+    std::string primaryWindowId = {};
+    std::string activeWindowId = {};
+    std::vector<UIEditorWindowWorkspaceState> windows = {};
+};
+
+enum class UIEditorWindowWorkspaceValidationCode : std::uint8_t {
+    None = 0,
+    InvalidPanelRegistry,
+    EmptyWindowId,
+    DuplicateWindowId,
+    MissingPrimaryWindow,
+    MissingActiveWindow,
+    InvalidWorkspace,
+    InvalidSession
+};
+
+struct UIEditorWindowWorkspaceValidationResult {
+    UIEditorWindowWorkspaceValidationCode code = UIEditorWindowWorkspaceValidationCode::None;
+    std::string message = {};
+
+    [[nodiscard]] bool IsValid() const {
+        return code == UIEditorWindowWorkspaceValidationCode::None;
+    }
+};
+
+UIEditorWindowWorkspaceSet BuildDefaultUIEditorWindowWorkspaceSet(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace,
+    std::string primaryWindowId = "main-window");
+
+const UIEditorWindowWorkspaceState* FindUIEditorWindowWorkspaceState(
+    const UIEditorWindowWorkspaceSet& windowSet,
+    std::string_view windowId);
+
+UIEditorWindowWorkspaceState* FindMutableUIEditorWindowWorkspaceState(
+    UIEditorWindowWorkspaceSet& windowSet,
+    std::string_view windowId);
+
+UIEditorWindowWorkspaceValidationResult ValidateUIEditorWindowWorkspaceSet(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWindowWorkspaceSet& windowSet);
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceCompose.h

@@ -0,0 +1,107 @@
+#pragma once
+
+#include <XCEditor/Panels/UIEditorPanelContentHost.h>
+#include <XCEditor/Panels/UIEditorPanelRegistry.h>
+#include <XCEditor/Viewport/UIEditorViewportShell.h>
+#include <XCEditor/Workspace/UIEditorWorkspaceSession.h>
+#include <XCEditor/Docking/UIEditorDockHost.h>
+
+#include <XCEngine/UI/DrawData.h>
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWorkspacePanelPresentationModel {
+    std::string panelId = {};
+    UIEditorPanelPresentationKind kind = UIEditorPanelPresentationKind::Placeholder;
+    UIEditorViewportShellModel viewportShellModel = {};
+};
+
+struct UIEditorWorkspacePanelPresentationState {
+    std::string panelId = {};
+    UIEditorViewportShellState viewportShellState = {};
+};
+
+struct UIEditorWorkspaceComposeState {
+    UIEditorPanelContentHostState contentHostState = {};
+    std::vector<UIEditorWorkspacePanelPresentationState> panelStates = {};
+};
+
+struct UIEditorWorkspaceViewportComposeRequest {
+    std::string panelId = {};
+    ::XCEngine::UI::UIRect bounds = {};
+    UIEditorViewportShellRequest viewportShellRequest = {};
+};
+
+struct UIEditorWorkspaceComposeRequest {
+    Widgets::UIEditorDockHostLayout dockHostLayout = {};
+    UIEditorPanelContentHostRequest contentHostRequest = {};
+    std::vector<UIEditorWorkspaceViewportComposeRequest> viewportRequests = {};
+};
+
+struct UIEditorWorkspaceViewportComposeFrame {
+    std::string panelId = {};
+    ::XCEngine::UI::UIRect bounds = {};
+    UIEditorViewportShellModel viewportShellModel = {};
+    UIEditorViewportShellFrame viewportShellFrame = {};
+};
+
+struct UIEditorWorkspaceComposeFrame {
+    Widgets::UIEditorDockHostLayout dockHostLayout = {};
+    UIEditorPanelContentHostFrame contentHostFrame = {};
+    std::vector<UIEditorWorkspaceViewportComposeFrame> viewportFrames = {};
+};
+
+const UIEditorWorkspacePanelPresentationModel* FindUIEditorWorkspacePanelPresentationModel(
+    const std::vector<UIEditorWorkspacePanelPresentationModel>& presentations,
+    std::string_view panelId);
+
+const UIEditorWorkspacePanelPresentationState* FindUIEditorWorkspacePanelPresentationState(
+    const UIEditorWorkspaceComposeState& state,
+    std::string_view panelId);
+
+const UIEditorWorkspaceViewportComposeRequest* FindUIEditorWorkspaceViewportPresentationRequest(
+    const UIEditorWorkspaceComposeRequest& request,
+    std::string_view panelId);
+
+const UIEditorWorkspaceViewportComposeFrame* FindUIEditorWorkspaceViewportPresentationFrame(
+    const UIEditorWorkspaceComposeFrame& frame,
+    std::string_view panelId);
+
+UIEditorWorkspaceComposeRequest ResolveUIEditorWorkspaceComposeRequest(
+    const ::XCEngine::UI::UIRect& bounds,
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    const std::vector<UIEditorWorkspacePanelPresentationModel>& presentations,
+    const Widgets::UIEditorDockHostState& dockHostState = {},
+    const Widgets::UIEditorDockHostMetrics& dockHostMetrics = {},
+    const Widgets::UIEditorViewportSlotMetrics& viewportMetrics = {});
+
+UIEditorWorkspaceComposeFrame UpdateUIEditorWorkspaceCompose(
+    UIEditorWorkspaceComposeState& state,
+    const ::XCEngine::UI::UIRect& bounds,
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    const std::vector<UIEditorWorkspacePanelPresentationModel>& presentations,
+    const std::vector<::XCEngine::UI::UIInputEvent>& inputEvents,
+    const Widgets::UIEditorDockHostState& dockHostState = {},
+    const Widgets::UIEditorDockHostMetrics& dockHostMetrics = {},
+    const Widgets::UIEditorViewportSlotMetrics& viewportMetrics = {});
+
+std::vector<std::string> CollectUIEditorWorkspaceComposeExternalBodyPanelIds(
+    const UIEditorWorkspaceComposeFrame& frame);
+
+void AppendUIEditorWorkspaceCompose(
+    ::XCEngine::UI::UIDrawList& drawList,
+    const UIEditorWorkspaceComposeFrame& frame,
+    const Widgets::UIEditorDockHostPalette& dockHostPalette = {},
+    const Widgets::UIEditorDockHostMetrics& dockHostMetrics = {},
+    const Widgets::UIEditorViewportSlotPalette& viewportPalette = {},
+    const Widgets::UIEditorViewportSlotMetrics& viewportMetrics = {});
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceController.h

@@ -0,0 +1,156 @@
+#pragma once
+
+#include <XCEditor/Workspace/UIEditorWorkspaceLayoutPersistence.h>
+#include <XCEditor/Workspace/UIEditorWorkspaceSession.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+enum class UIEditorWorkspaceCommandKind : std::uint8_t {
+    OpenPanel = 0,
+    ClosePanel,
+    ShowPanel,
+    HidePanel,
+    ActivatePanel,
+    ResetWorkspace
+};
+
+enum class UIEditorWorkspaceCommandStatus : std::uint8_t {
+    Changed = 0,
+    NoOp,
+    Rejected
+};
+
+struct UIEditorWorkspaceCommand {
+    UIEditorWorkspaceCommandKind kind = UIEditorWorkspaceCommandKind::ActivatePanel;
+    std::string panelId = {};
+};
+
+struct UIEditorWorkspaceCommandResult {
+    UIEditorWorkspaceCommandKind kind = UIEditorWorkspaceCommandKind::ActivatePanel;
+    UIEditorWorkspaceCommandStatus status = UIEditorWorkspaceCommandStatus::Rejected;
+    std::string panelId = {};
+    std::string message = {};
+    std::string activePanelId = {};
+    std::vector<std::string> visiblePanelIds = {};
+};
+
+enum class UIEditorWorkspaceControllerValidationCode : std::uint8_t {
+    None = 0,
+    InvalidPanelRegistry,
+    InvalidWorkspace,
+    InvalidWorkspaceSession
+};
+
+struct UIEditorWorkspaceControllerValidationResult {
+    UIEditorWorkspaceControllerValidationCode code =
+        UIEditorWorkspaceControllerValidationCode::None;
+    std::string message = {};
+
+    [[nodiscard]] bool IsValid() const {
+        return code == UIEditorWorkspaceControllerValidationCode::None;
+    }
+};
+
+std::string_view GetUIEditorWorkspaceCommandKindName(UIEditorWorkspaceCommandKind kind);
+std::string_view GetUIEditorWorkspaceCommandStatusName(UIEditorWorkspaceCommandStatus status);
+
+enum class UIEditorWorkspaceLayoutOperationStatus : std::uint8_t {
+    Changed = 0,
+    NoOp,
+    Rejected
+};
+
+struct UIEditorWorkspaceLayoutOperationResult {
+    UIEditorWorkspaceLayoutOperationStatus status =
+        UIEditorWorkspaceLayoutOperationStatus::Rejected;
+    std::string message = {};
+    std::string activePanelId = {};
+    std::vector<std::string> visiblePanelIds = {};
+};
+
+std::string_view GetUIEditorWorkspaceLayoutOperationStatusName(
+    UIEditorWorkspaceLayoutOperationStatus status);
+
+class UIEditorWorkspaceController {
+public:
+    UIEditorWorkspaceController() = default;
+    UIEditorWorkspaceController(
+        UIEditorPanelRegistry panelRegistry,
+        UIEditorWorkspaceModel workspace,
+        UIEditorWorkspaceSession session);
+
+    const UIEditorPanelRegistry& GetPanelRegistry() const {
+        return m_panelRegistry;
+    }
+
+    const UIEditorWorkspaceModel& GetWorkspace() const {
+        return m_workspace;
+    }
+
+    const UIEditorWorkspaceSession& GetSession() const {
+        return m_session;
+    }
+
+    UIEditorWorkspaceControllerValidationResult ValidateState() const;
+    UIEditorWorkspaceLayoutSnapshot CaptureLayoutSnapshot() const;
+    UIEditorWorkspaceLayoutOperationResult RestoreLayoutSnapshot(
+        const UIEditorWorkspaceLayoutSnapshot& snapshot);
+    UIEditorWorkspaceLayoutOperationResult RestoreSerializedLayout(
+        std::string_view serializedLayout);
+    UIEditorWorkspaceLayoutOperationResult SetSplitRatio(
+        std::string_view nodeId,
+        float splitRatio);
+    UIEditorWorkspaceLayoutOperationResult ReorderTab(
+        std::string_view nodeId,
+        std::string_view panelId,
+        std::size_t targetVisibleInsertionIndex);
+    UIEditorWorkspaceLayoutOperationResult MoveTabToStack(
+        std::string_view sourceNodeId,
+        std::string_view panelId,
+        std::string_view targetNodeId,
+        std::size_t targetVisibleInsertionIndex);
+    UIEditorWorkspaceLayoutOperationResult DockTabRelative(
+        std::string_view sourceNodeId,
+        std::string_view panelId,
+        std::string_view targetNodeId,
+        UIEditorWorkspaceDockPlacement placement,
+        float splitRatio = 0.5f);
+    UIEditorWorkspaceCommandResult Dispatch(const UIEditorWorkspaceCommand& command);
+
+private:
+    UIEditorWorkspaceCommandResult BuildResult(
+        const UIEditorWorkspaceCommand& command,
+        UIEditorWorkspaceCommandStatus status,
+        std::string message) const;
+
+    UIEditorWorkspaceCommandResult FinalizeMutation(
+        const UIEditorWorkspaceCommand& command,
+        bool changed,
+        std::string changedMessage,
+        std::string unexpectedFailureMessage,
+        const UIEditorWorkspaceModel& previousWorkspace,
+        const UIEditorWorkspaceSession& previousSession);
+
+    UIEditorWorkspaceLayoutOperationResult BuildLayoutOperationResult(
+        UIEditorWorkspaceLayoutOperationStatus status,
+        std::string message) const;
+
+    const UIEditorPanelDescriptor* FindPanelDescriptor(std::string_view panelId) const;
+
+    UIEditorPanelRegistry m_panelRegistry = {};
+    UIEditorWorkspaceModel m_baselineWorkspace = {};
+    UIEditorWorkspaceSession m_baselineSession = {};
+    UIEditorWorkspaceModel m_workspace = {};
+    UIEditorWorkspaceSession m_session = {};
+};
+
+UIEditorWorkspaceController BuildDefaultUIEditorWorkspaceController(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace);
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceInteraction.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <XCEditor/Docking/UIEditorDockHostInteraction.h>
+#include <XCEditor/Workspace/UIEditorWorkspaceCompose.h>
+
+#include <XCEngine/UI/Types.h>
+
+#include <string>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWorkspaceInteractionModel {
+    std::vector<UIEditorWorkspacePanelPresentationModel> workspacePresentations = {};
+};
+
+struct UIEditorWorkspaceInteractionState {
+    UIEditorDockHostInteractionState dockHostInteractionState = {};
+    UIEditorWorkspaceComposeState composeState = {};
+};
+
+struct UIEditorWorkspaceInteractionResult {
+    bool consumed = false;
+    bool requestPointerCapture = false;
+    bool releasePointerCapture = false;
+    bool viewportInteractionChanged = false;
+    std::string viewportPanelId = {};
+    UIEditorViewportInputBridgeFrame viewportInputFrame = {};
+    UIEditorDockHostInteractionResult dockHostResult = {};
+};
+
+struct UIEditorWorkspaceInteractionFrame {
+    UIEditorDockHostInteractionFrame dockHostFrame = {};
+    UIEditorWorkspaceComposeFrame composeFrame = {};
+    UIEditorWorkspaceInteractionResult result = {};
+};
+
+UIEditorWorkspaceInteractionFrame UpdateUIEditorWorkspaceInteraction(
+    UIEditorWorkspaceInteractionState& state,
+    UIEditorWorkspaceController& controller,
+    const ::XCEngine::UI::UIRect& bounds,
+    const UIEditorWorkspaceInteractionModel& model,
+    const std::vector<::XCEngine::UI::UIInputEvent>& inputEvents,
+    const Widgets::UIEditorDockHostMetrics& dockHostMetrics = {},
+    const Widgets::UIEditorViewportSlotMetrics& viewportMetrics = {});
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceLayoutPersistence.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <XCEditor/Workspace/UIEditorWorkspaceSession.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWorkspaceLayoutSnapshot {
+    UIEditorWorkspaceModel workspace = {};
+    UIEditorWorkspaceSession session = {};
+};
+
+enum class UIEditorWorkspaceLayoutLoadCode : std::uint8_t {
+    None = 0,
+    InvalidPanelRegistry,
+    EmptyInput,
+    InvalidHeader,
+    UnsupportedVersion,
+    MissingActiveRecord,
+    UnexpectedEndOfInput,
+    InvalidNodeRecord,
+    InvalidSessionRecord,
+    InvalidWorkspace,
+    InvalidWorkspaceSession
+};
+
+struct UIEditorWorkspaceLayoutLoadResult {
+    UIEditorWorkspaceLayoutLoadCode code = UIEditorWorkspaceLayoutLoadCode::None;
+    std::string message = {};
+    UIEditorWorkspaceLayoutSnapshot snapshot = {};
+
+    [[nodiscard]] bool IsValid() const {
+        return code == UIEditorWorkspaceLayoutLoadCode::None;
+    }
+};
+
+UIEditorWorkspaceLayoutSnapshot BuildUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session);
+
+bool AreUIEditorWorkspaceLayoutSnapshotsEquivalent(
+    const UIEditorWorkspaceLayoutSnapshot& lhs,
+    const UIEditorWorkspaceLayoutSnapshot& rhs);
+
+std::string SerializeUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorWorkspaceLayoutSnapshot& snapshot);
+
+UIEditorWorkspaceLayoutLoadResult DeserializeUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorPanelRegistry& panelRegistry,
+    std::string_view serializedLayout);
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceModel.h

@@ -0,0 +1,192 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWorkspaceSession;
+
+enum class UIEditorWorkspaceNodeKind : std::uint8_t {
+    Panel = 0,
+    TabStack,
+    Split
+};
+
+enum class UIEditorWorkspaceSplitAxis : std::uint8_t {
+    Horizontal = 0,
+    Vertical
+};
+
+enum class UIEditorWorkspaceDockPlacement : std::uint8_t {
+    Center = 0,
+    Left,
+    Right,
+    Top,
+    Bottom
+};
+
+struct UIEditorWorkspacePanelState {
+    std::string panelId = {};
+    std::string title = {};
+    bool placeholder = false;
+};
+
+struct UIEditorWorkspaceNode {
+    UIEditorWorkspaceNodeKind kind = UIEditorWorkspaceNodeKind::Panel;
+    std::string nodeId = {};
+    UIEditorWorkspaceSplitAxis splitAxis = UIEditorWorkspaceSplitAxis::Horizontal;
+    float splitRatio = 0.5f;
+    std::size_t selectedTabIndex = 0u;
+    UIEditorWorkspacePanelState panel = {};
+    std::vector<UIEditorWorkspaceNode> children = {};
+};
+
+struct UIEditorWorkspaceModel {
+    UIEditorWorkspaceNode root = {};
+    std::string activePanelId = {};
+};
+
+enum class UIEditorWorkspaceValidationCode : std::uint8_t {
+    None = 0,
+    EmptyNodeId,
+    InvalidSplitChildCount,
+    InvalidSplitRatio,
+    EmptyTabStack,
+    InvalidSelectedTabIndex,
+    NonPanelTabChild,
+    EmptyPanelId,
+    EmptyPanelTitle,
+    DuplicatePanelId,
+    InvalidActivePanelId
+};
+
+struct UIEditorWorkspaceValidationResult {
+    UIEditorWorkspaceValidationCode code = UIEditorWorkspaceValidationCode::None;
+    std::string message = {};
+
+    [[nodiscard]] bool IsValid() const {
+        return code == UIEditorWorkspaceValidationCode::None;
+    }
+};
+
+struct UIEditorWorkspaceVisiblePanel {
+    std::string panelId = {};
+    std::string title = {};
+    bool active = false;
+    bool placeholder = false;
+};
+
+UIEditorWorkspaceModel BuildDefaultEditorShellWorkspaceModel();
+
+UIEditorWorkspaceNode BuildUIEditorWorkspacePanel(
+    std::string nodeId,
+    std::string panelId,
+    std::string title,
+    bool placeholder = false);
+
+UIEditorWorkspaceNode BuildUIEditorWorkspaceSingleTabStack(
+    std::string nodeId,
+    std::string panelId,
+    std::string title,
+    bool placeholder = false);
+
+UIEditorWorkspaceNode BuildUIEditorWorkspaceTabStack(
+    std::string nodeId,
+    std::vector<UIEditorWorkspaceNode> panels,
+    std::size_t selectedTabIndex = 0u);
+
+UIEditorWorkspaceNode BuildUIEditorWorkspaceSplit(
+    std::string nodeId,
+    UIEditorWorkspaceSplitAxis axis,
+    float splitRatio,
+    UIEditorWorkspaceNode primary,
+    UIEditorWorkspaceNode secondary);
+
+UIEditorWorkspaceValidationResult ValidateUIEditorWorkspace(
+    const UIEditorWorkspaceModel& workspace);
+
+UIEditorWorkspaceModel CanonicalizeUIEditorWorkspaceModel(
+    UIEditorWorkspaceModel workspace);
+
+std::vector<UIEditorWorkspaceVisiblePanel> CollectUIEditorWorkspaceVisiblePanels(
+    const UIEditorWorkspaceModel& workspace);
+
+bool ContainsUIEditorWorkspacePanel(
+    const UIEditorWorkspaceModel& workspace,
+    std::string_view panelId);
+
+const UIEditorWorkspaceNode* FindUIEditorWorkspaceNode(
+    const UIEditorWorkspaceModel& workspace,
+    std::string_view nodeId);
+
+bool AreUIEditorWorkspaceNodesEquivalent(
+    const UIEditorWorkspaceNode& lhs,
+    const UIEditorWorkspaceNode& rhs);
+
+bool AreUIEditorWorkspaceModelsEquivalent(
+    const UIEditorWorkspaceModel& lhs,
+    const UIEditorWorkspaceModel& rhs);
+
+const UIEditorWorkspacePanelState* FindUIEditorWorkspaceActivePanel(
+    const UIEditorWorkspaceModel& workspace);
+
+bool TryActivateUIEditorWorkspacePanel(
+    UIEditorWorkspaceModel& workspace,
+    std::string_view panelId);
+
+bool TrySetUIEditorWorkspaceSplitRatio(
+    UIEditorWorkspaceModel& workspace,
+    std::string_view nodeId,
+    float splitRatio);
+
+bool TryReorderUIEditorWorkspaceTab(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    std::string_view nodeId,
+    std::string_view panelId,
+    std::size_t targetVisibleInsertionIndex);
+
+bool TryExtractUIEditorWorkspaceVisiblePanelNode(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    std::string_view sourceNodeId,
+    std::string_view panelId,
+    UIEditorWorkspaceNode& extractedPanel);
+
+bool TryInsertUIEditorWorkspacePanelNodeToStack(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    UIEditorWorkspaceNode panelNode,
+    std::string_view targetNodeId,
+    std::size_t targetVisibleInsertionIndex);
+
+bool TryDockUIEditorWorkspacePanelNodeRelative(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    UIEditorWorkspaceNode panelNode,
+    std::string_view targetNodeId,
+    UIEditorWorkspaceDockPlacement placement,
+    float splitRatio = 0.5f);
+
+bool TryMoveUIEditorWorkspaceTabToStack(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    std::string_view sourceNodeId,
+    std::string_view panelId,
+    std::string_view targetNodeId,
+    std::size_t targetVisibleInsertionIndex);
+
+bool TryDockUIEditorWorkspaceTabRelative(
+    UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session,
+    std::string_view sourceNodeId,
+    std::string_view panelId,
+    std::string_view targetNodeId,
+    UIEditorWorkspaceDockPlacement placement,
+    float splitRatio = 0.5f);
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceSession.h

@@ -0,0 +1,98 @@
+#pragma once
+
+#include <XCEditor/Panels/UIEditorPanelRegistry.h>
+#include <XCEditor/Workspace/UIEditorWorkspaceModel.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorPanelSessionState {
+    std::string panelId = {};
+    bool open = true;
+    bool visible = true;
+};
+
+struct UIEditorWorkspaceSession {
+    std::vector<UIEditorPanelSessionState> panelStates = {};
+};
+
+enum class UIEditorWorkspaceSessionValidationCode : std::uint8_t {
+    None = 0,
+    MissingPanelState,
+    UnknownPanelId,
+    DuplicatePanelId,
+    ClosedPanelVisible,
+    NonHideablePanelHidden,
+    NonCloseablePanelClosed,
+    InvalidActivePanelId
+};
+
+struct UIEditorWorkspaceSessionValidationResult {
+    UIEditorWorkspaceSessionValidationCode code = UIEditorWorkspaceSessionValidationCode::None;
+    std::string message = {};
+
+    [[nodiscard]] bool IsValid() const {
+        return code == UIEditorWorkspaceSessionValidationCode::None;
+    }
+};
+
+UIEditorWorkspaceSession BuildDefaultUIEditorWorkspaceSession(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace);
+
+const UIEditorPanelSessionState* FindUIEditorPanelSessionState(
+    const UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+UIEditorWorkspaceSessionValidationResult ValidateUIEditorWorkspaceSession(
+    const UIEditorPanelRegistry& panelRegistry,
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session);
+
+bool AreUIEditorWorkspaceSessionsEquivalent(
+    const UIEditorWorkspaceSession& lhs,
+    const UIEditorWorkspaceSession& rhs);
+
+std::vector<UIEditorWorkspaceVisiblePanel> CollectUIEditorWorkspaceVisiblePanels(
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session);
+
+const UIEditorWorkspacePanelState* FindUIEditorWorkspaceActivePanel(
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session);
+
+bool TryOpenUIEditorWorkspacePanel(
+    const UIEditorPanelRegistry& panelRegistry,
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+bool TryCloseUIEditorWorkspacePanel(
+    const UIEditorPanelRegistry& panelRegistry,
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+bool TryShowUIEditorWorkspacePanel(
+    const UIEditorPanelRegistry& panelRegistry,
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+bool TryHideUIEditorWorkspacePanel(
+    const UIEditorPanelRegistry& panelRegistry,
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+bool TryActivateUIEditorWorkspacePanel(
+    const UIEditorPanelRegistry& panelRegistry,
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view panelId);
+
+} // namespace XCEngine::UI::Editor

new_editor/include/XCEditor/Workspace/UIEditorWorkspaceTransfer.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <XCEditor/Workspace/UIEditorWorkspaceSession.h>
+
+namespace XCEngine::UI::Editor {
+
+struct UIEditorWorkspaceExtractedPanel {
+    UIEditorWorkspaceNode panelNode = {};
+    UIEditorPanelSessionState sessionState = {};
+};
+
+bool TryExtractUIEditorWorkspaceVisiblePanel(
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    std::string_view sourceNodeId,
+    std::string_view panelId,
+    UIEditorWorkspaceExtractedPanel& extractedPanel);
+
+UIEditorWorkspaceModel BuildUIEditorDetachedWorkspaceFromExtractedPanel(
+    std::string rootNodeId,
+    UIEditorWorkspaceExtractedPanel extractedPanel);
+
+UIEditorWorkspaceSession BuildUIEditorDetachedWorkspaceSessionFromExtractedPanel(
+    UIEditorWorkspaceExtractedPanel extractedPanel);
+
+bool TryInsertExtractedUIEditorWorkspacePanelToStack(
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    UIEditorWorkspaceExtractedPanel extractedPanel,
+    std::string_view targetNodeId,
+    std::size_t targetVisibleInsertionIndex);
+
+bool TryDockExtractedUIEditorWorkspacePanelRelative(
+    UIEditorWorkspaceModel& workspace,
+    UIEditorWorkspaceSession& session,
+    UIEditorWorkspaceExtractedPanel extractedPanel,
+    std::string_view targetNodeId,
+    UIEditorWorkspaceDockPlacement placement,
+    float splitRatio = 0.5f);
+
+} // namespace XCEngine::UI::Editor