feat(xcui): add editor layout persistence validation

new_editor/CMakeLists.txt

@@ -14,6 +14,7 @@ set(NEW_EDITOR_RESOURCE_FILES
 add_library(XCNewEditorLib STATIC
     src/editor/EditorShellAsset.cpp
     src/editor/UIEditorPanelRegistry.cpp
+    src/editor/UIEditorWorkspaceLayoutPersistence.cpp
     src/editor/UIEditorWorkspaceController.cpp
     src/editor/UIEditorWorkspaceModel.cpp
     src/editor/UIEditorWorkspaceSession.cpp

new_editor/include/XCNewEditor/Editor/UIEditorWorkspaceController.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <XCNewEditor/Editor/UIEditorWorkspaceLayoutPersistence.h>
 #include <XCNewEditor/Editor/UIEditorWorkspaceSession.h>
 
 #include <cstdint>
@@ -58,6 +59,23 @@ struct UIEditorWorkspaceControllerValidationResult {
 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;
@@ -79,6 +97,11 @@ public:
     }
 
     UIEditorWorkspaceControllerValidationResult ValidateState() const;
+    UIEditorWorkspaceLayoutSnapshot CaptureLayoutSnapshot() const;
+    UIEditorWorkspaceLayoutOperationResult RestoreLayoutSnapshot(
+        const UIEditorWorkspaceLayoutSnapshot& snapshot);
+    UIEditorWorkspaceLayoutOperationResult RestoreSerializedLayout(
+        std::string_view serializedLayout);
     UIEditorWorkspaceCommandResult Dispatch(const UIEditorWorkspaceCommand& command);
 
 private:
@@ -95,6 +118,10 @@ private:
         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 = {};

new_editor/include/XCNewEditor/Editor/UIEditorWorkspaceLayoutPersistence.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <XCNewEditor/Editor/UIEditorWorkspaceSession.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+
+namespace XCEngine::NewEditor {
+
+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::NewEditor

new_editor/include/XCNewEditor/Editor/UIEditorWorkspaceModel.h

@@ -100,6 +100,14 @@ bool ContainsUIEditorWorkspacePanel(
     const UIEditorWorkspaceModel& workspace,
     std::string_view panelId);
 
+bool AreUIEditorWorkspaceNodesEquivalent(
+    const UIEditorWorkspaceNode& lhs,
+    const UIEditorWorkspaceNode& rhs);
+
+bool AreUIEditorWorkspaceModelsEquivalent(
+    const UIEditorWorkspaceModel& lhs,
+    const UIEditorWorkspaceModel& rhs);
+
 const UIEditorWorkspacePanelState* FindUIEditorWorkspaceActivePanel(
     const UIEditorWorkspaceModel& workspace);
 

new_editor/include/XCNewEditor/Editor/UIEditorWorkspaceSession.h

@@ -53,6 +53,10 @@ UIEditorWorkspaceSessionValidationResult ValidateUIEditorWorkspaceSession(
     const UIEditorWorkspaceModel& workspace,
     const UIEditorWorkspaceSession& session);
 
+bool AreUIEditorWorkspaceSessionsEquivalent(
+    const UIEditorWorkspaceSession& lhs,
+    const UIEditorWorkspaceSession& rhs);
+
 std::vector<UIEditorWorkspaceVisiblePanel> CollectUIEditorWorkspaceVisiblePanels(
     const UIEditorWorkspaceModel& workspace,
     const UIEditorWorkspaceSession& session);

new_editor/src/editor/UIEditorWorkspaceController.cpp

@@ -6,57 +6,6 @@ namespace XCEngine::NewEditor {
 
 namespace {
 
-bool AreWorkspaceNodesEquivalent(
-    const UIEditorWorkspaceNode& lhs,
-    const UIEditorWorkspaceNode& rhs) {
-    if (lhs.kind != rhs.kind ||
-        lhs.nodeId != rhs.nodeId ||
-        lhs.splitAxis != rhs.splitAxis ||
-        lhs.splitRatio != rhs.splitRatio ||
-        lhs.selectedTabIndex != rhs.selectedTabIndex ||
-        lhs.panel.panelId != rhs.panel.panelId ||
-        lhs.panel.title != rhs.panel.title ||
-        lhs.panel.placeholder != rhs.panel.placeholder ||
-        lhs.children.size() != rhs.children.size()) {
-        return false;
-    }
-
-    for (std::size_t index = 0; index < lhs.children.size(); ++index) {
-        if (!AreWorkspaceNodesEquivalent(lhs.children[index], rhs.children[index])) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
-bool AreWorkspaceModelsEquivalent(
-    const UIEditorWorkspaceModel& lhs,
-    const UIEditorWorkspaceModel& rhs) {
-    return lhs.activePanelId == rhs.activePanelId &&
-        AreWorkspaceNodesEquivalent(lhs.root, rhs.root);
-}
-
-bool AreWorkspaceSessionsEquivalent(
-    const UIEditorWorkspaceSession& lhs,
-    const UIEditorWorkspaceSession& rhs) {
-    if (lhs.panelStates.size() != rhs.panelStates.size()) {
-        return false;
-    }
-
-    for (std::size_t index = 0; index < lhs.panelStates.size(); ++index) {
-        const UIEditorPanelSessionState& lhsState = lhs.panelStates[index];
-        const UIEditorPanelSessionState& rhsState = rhs.panelStates[index];
-        if (lhsState.panelId != rhsState.panelId ||
-            lhsState.open != rhsState.open ||
-            lhsState.visible != rhsState.visible) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
 std::vector<std::string> CollectVisiblePanelIds(
     const UIEditorWorkspaceModel& workspace,
     const UIEditorWorkspaceSession& session) {
@@ -106,6 +55,20 @@ std::string_view GetUIEditorWorkspaceCommandStatusName(UIEditorWorkspaceCommandS
     return "Unknown";
 }
 
+std::string_view GetUIEditorWorkspaceLayoutOperationStatusName(
+    UIEditorWorkspaceLayoutOperationStatus status) {
+    switch (status) {
+    case UIEditorWorkspaceLayoutOperationStatus::Changed:
+        return "Changed";
+    case UIEditorWorkspaceLayoutOperationStatus::NoOp:
+        return "NoOp";
+    case UIEditorWorkspaceLayoutOperationStatus::Rejected:
+        return "Rejected";
+    }
+
+    return "Unknown";
+}
+
 UIEditorWorkspaceController::UIEditorWorkspaceController(
     UIEditorPanelRegistry panelRegistry,
     UIEditorWorkspaceModel workspace,
@@ -148,6 +111,10 @@ UIEditorWorkspaceControllerValidationResult UIEditorWorkspaceController::Validat
     return {};
 }
 
+UIEditorWorkspaceLayoutSnapshot UIEditorWorkspaceController::CaptureLayoutSnapshot() const {
+    return BuildUIEditorWorkspaceLayoutSnapshot(m_workspace, m_session);
+}
+
 UIEditorWorkspaceCommandResult UIEditorWorkspaceController::BuildResult(
     const UIEditorWorkspaceCommand& command,
     UIEditorWorkspaceCommandStatus status,
@@ -162,6 +129,17 @@ UIEditorWorkspaceCommandResult UIEditorWorkspaceController::BuildResult(
     return result;
 }
 
+UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::BuildLayoutOperationResult(
+    UIEditorWorkspaceLayoutOperationStatus status,
+    std::string message) const {
+    UIEditorWorkspaceLayoutOperationResult result = {};
+    result.status = status;
+    result.message = std::move(message);
+    result.activePanelId = m_workspace.activePanelId;
+    result.visiblePanelIds = CollectVisiblePanelIds(m_workspace, m_session);
+    return result;
+}
+
 UIEditorWorkspaceCommandResult UIEditorWorkspaceController::FinalizeMutation(
     const UIEditorWorkspaceCommand& command,
     bool changed,
@@ -197,6 +175,71 @@ const UIEditorPanelDescriptor* UIEditorWorkspaceController::FindPanelDescriptor(
     return FindUIEditorPanelDescriptor(m_panelRegistry, panelId);
 }
 
+UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::RestoreLayoutSnapshot(
+    const UIEditorWorkspaceLayoutSnapshot& snapshot) {
+    const UIEditorPanelRegistryValidationResult registryValidation =
+        ValidateUIEditorPanelRegistry(m_panelRegistry);
+    if (!registryValidation.IsValid()) {
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::Rejected,
+            "Panel registry invalid: " + registryValidation.message);
+    }
+
+    const UIEditorWorkspaceValidationResult workspaceValidation =
+        ValidateUIEditorWorkspace(snapshot.workspace);
+    if (!workspaceValidation.IsValid()) {
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::Rejected,
+            "Layout workspace invalid: " + workspaceValidation.message);
+    }
+
+    const UIEditorWorkspaceSessionValidationResult sessionValidation =
+        ValidateUIEditorWorkspaceSession(m_panelRegistry, snapshot.workspace, snapshot.session);
+    if (!sessionValidation.IsValid()) {
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::Rejected,
+            "Layout session invalid: " + sessionValidation.message);
+    }
+
+    if (AreUIEditorWorkspaceModelsEquivalent(m_workspace, snapshot.workspace) &&
+        AreUIEditorWorkspaceSessionsEquivalent(m_session, snapshot.session)) {
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::NoOp,
+            "Current state already matches the requested layout snapshot.");
+    }
+
+    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
+    const UIEditorWorkspaceSession previousSession = m_session;
+    m_workspace = snapshot.workspace;
+    m_session = snapshot.session;
+
+    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
+    if (!validation.IsValid()) {
+        m_workspace = previousWorkspace;
+        m_session = previousSession;
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::Rejected,
+            "Restored layout produced invalid controller state: " + validation.message);
+    }
+
+    return BuildLayoutOperationResult(
+        UIEditorWorkspaceLayoutOperationStatus::Changed,
+        "Layout restored.");
+}
+
+UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::RestoreSerializedLayout(
+    std::string_view serializedLayout) {
+    const UIEditorWorkspaceLayoutLoadResult loadResult =
+        DeserializeUIEditorWorkspaceLayoutSnapshot(m_panelRegistry, serializedLayout);
+    if (!loadResult.IsValid()) {
+        return BuildLayoutOperationResult(
+            UIEditorWorkspaceLayoutOperationStatus::Rejected,
+            "Serialized layout rejected: " + loadResult.message);
+    }
+
+    return RestoreLayoutSnapshot(loadResult.snapshot);
+}
+
 UIEditorWorkspaceCommandResult UIEditorWorkspaceController::Dispatch(
     const UIEditorWorkspaceCommand& command) {
     const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
@@ -326,8 +369,8 @@ UIEditorWorkspaceCommandResult UIEditorWorkspaceController::Dispatch(
             previousSession);
 
     case UIEditorWorkspaceCommandKind::ResetWorkspace:
-        if (AreWorkspaceModelsEquivalent(m_workspace, m_baselineWorkspace) &&
-            AreWorkspaceSessionsEquivalent(m_session, m_baselineSession)) {
+        if (AreUIEditorWorkspaceModelsEquivalent(m_workspace, m_baselineWorkspace) &&
+            AreUIEditorWorkspaceSessionsEquivalent(m_session, m_baselineSession)) {
             return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Workspace already matches the baseline state.");
         }
 

new_editor/src/editor/UIEditorWorkspaceLayoutPersistence.cpp

@@ -0,0 +1,497 @@
+#include <XCNewEditor/Editor/UIEditorWorkspaceLayoutPersistence.h>
+
+#include <iomanip>
+#include <limits>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace XCEngine::NewEditor {
+
+namespace {
+
+constexpr std::string_view kLayoutHeader = "XCUI_EDITOR_WORKSPACE_LAYOUT";
+constexpr int kLayoutVersion = 1;
+
+struct LayoutLine {
+    std::size_t number = 0u;
+    std::string text = {};
+};
+
+UIEditorWorkspaceLayoutLoadResult MakeLoadError(
+    UIEditorWorkspaceLayoutLoadCode code,
+    std::string message) {
+    UIEditorWorkspaceLayoutLoadResult result = {};
+    result.code = code;
+    result.message = std::move(message);
+    return result;
+}
+
+bool HasTrailingTokens(std::istringstream& stream) {
+    stream >> std::ws;
+    return !stream.eof();
+}
+
+std::string MakeLinePrefix(const LayoutLine& line) {
+    return "Line " + std::to_string(line.number) + ": ";
+}
+
+bool ParseBinaryFlag(
+    std::istringstream& stream,
+    const LayoutLine& line,
+    int& outValue,
+    UIEditorWorkspaceLayoutLoadResult& outError,
+    UIEditorWorkspaceLayoutLoadCode code,
+    std::string_view fieldName) {
+    if (!(stream >> outValue) || (outValue != 0 && outValue != 1)) {
+        outError = MakeLoadError(
+            code,
+            MakeLinePrefix(line) + std::string(fieldName) + " must be encoded as 0 or 1.");
+        return false;
+    }
+
+    return true;
+}
+
+bool ParseNodeLine(
+    const LayoutLine& line,
+    std::string& outTag,
+    std::istringstream& outStream) {
+    outStream = std::istringstream(line.text);
+    return static_cast<bool>(outStream >> outTag);
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseNodeRecursive(
+    const std::vector<LayoutLine>& lines,
+    std::size_t& index,
+    UIEditorWorkspaceNode& outNode);
+
+std::string SerializeAxis(UIEditorWorkspaceSplitAxis axis) {
+    return axis == UIEditorWorkspaceSplitAxis::Vertical ? "vertical" : "horizontal";
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseAxis(
+    std::string_view text,
+    UIEditorWorkspaceSplitAxis& outAxis,
+    const LayoutLine& line) {
+    if (text == "horizontal") {
+        outAxis = UIEditorWorkspaceSplitAxis::Horizontal;
+        return {};
+    }
+
+    if (text == "vertical") {
+        outAxis = UIEditorWorkspaceSplitAxis::Vertical;
+        return {};
+    }
+
+    return MakeLoadError(
+        UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+        MakeLinePrefix(line) + "split axis must be \"horizontal\" or \"vertical\".");
+}
+
+void SerializeNodeRecursive(
+    const UIEditorWorkspaceNode& node,
+    std::ostringstream& stream) {
+    switch (node.kind) {
+    case UIEditorWorkspaceNodeKind::Panel:
+        stream << "node_panel "
+               << std::quoted(node.nodeId) << ' '
+               << std::quoted(node.panel.panelId) << ' '
+               << std::quoted(node.panel.title) << ' '
+               << (node.panel.placeholder ? 1 : 0) << '\n';
+        return;
+
+    case UIEditorWorkspaceNodeKind::TabStack:
+        stream << "node_tabstack "
+               << std::quoted(node.nodeId) << ' '
+               << node.selectedTabIndex << ' '
+               << node.children.size() << '\n';
+        for (const UIEditorWorkspaceNode& child : node.children) {
+            SerializeNodeRecursive(child, stream);
+        }
+        return;
+
+    case UIEditorWorkspaceNodeKind::Split:
+        stream << "node_split "
+               << std::quoted(node.nodeId) << ' '
+               << std::quoted(SerializeAxis(node.splitAxis)) << ' '
+               << std::setprecision(std::numeric_limits<float>::max_digits10)
+               << node.splitRatio << '\n';
+        for (const UIEditorWorkspaceNode& child : node.children) {
+            SerializeNodeRecursive(child, stream);
+        }
+        return;
+    }
+}
+
+std::vector<LayoutLine> CollectNonEmptyLines(std::string_view serializedLayout) {
+    std::vector<LayoutLine> lines = {};
+    std::istringstream stream{ std::string(serializedLayout) };
+    std::string text = {};
+    std::size_t lineNumber = 0u;
+    while (std::getline(stream, text)) {
+        ++lineNumber;
+        if (!text.empty() && text.back() == '\r') {
+            text.pop_back();
+        }
+
+        const std::size_t first = text.find_first_not_of(" \t");
+        if (first == std::string::npos) {
+            continue;
+        }
+
+        lines.push_back({ lineNumber, text });
+    }
+
+    return lines;
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseHeader(const LayoutLine& line) {
+    std::istringstream stream(line.text);
+    std::string header = {};
+    int version = 0;
+    if (!(stream >> header >> version) || HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidHeader,
+            MakeLinePrefix(line) + "invalid layout header.");
+    }
+
+    if (header != kLayoutHeader) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidHeader,
+            MakeLinePrefix(line) + "layout header magic is invalid.");
+    }
+
+    if (version != kLayoutVersion) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::UnsupportedVersion,
+            MakeLinePrefix(line) + "unsupported layout version " + std::to_string(version) + ".");
+    }
+
+    return {};
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseActiveRecord(
+    const LayoutLine& line,
+    std::string& outActivePanelId) {
+    std::istringstream stream(line.text);
+    std::string tag = {};
+    if (!(stream >> tag) || tag != "active" ||
+        !(stream >> std::quoted(outActivePanelId)) ||
+        HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::MissingActiveRecord,
+            MakeLinePrefix(line) + "active record must be `active \"panel-id\"`.");
+    }
+
+    return {};
+}
+
+UIEditorWorkspaceLayoutLoadResult ParsePanelNode(
+    std::istringstream& stream,
+    const LayoutLine& line,
+    UIEditorWorkspaceNode& outNode) {
+    std::string nodeId = {};
+    std::string panelId = {};
+    std::string title = {};
+    int placeholderValue = 0;
+    if (!(stream >> std::quoted(nodeId) >> std::quoted(panelId) >> std::quoted(title))) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            MakeLinePrefix(line) + "panel node record is malformed.");
+    }
+
+    UIEditorWorkspaceLayoutLoadResult boolParse = {};
+    if (!ParseBinaryFlag(
+            stream,
+            line,
+            placeholderValue,
+            boolParse,
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            "placeholder")) {
+        return boolParse;
+    }
+
+    if (HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            MakeLinePrefix(line) + "panel node record contains trailing tokens.");
+    }
+
+    outNode = BuildUIEditorWorkspacePanel(
+        std::move(nodeId),
+        std::move(panelId),
+        std::move(title),
+        placeholderValue != 0);
+    return {};
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseTabStackNode(
+    const std::vector<LayoutLine>& lines,
+    std::size_t& index,
+    std::istringstream& stream,
+    const LayoutLine& line,
+    UIEditorWorkspaceNode& outNode) {
+    std::string nodeId = {};
+    std::size_t selectedTabIndex = 0u;
+    std::size_t childCount = 0u;
+    if (!(stream >> std::quoted(nodeId) >> selectedTabIndex >> childCount) ||
+        HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            MakeLinePrefix(line) + "tab stack node record is malformed.");
+    }
+
+    outNode = {};
+    outNode.kind = UIEditorWorkspaceNodeKind::TabStack;
+    outNode.nodeId = std::move(nodeId);
+    outNode.selectedTabIndex = selectedTabIndex;
+    outNode.children.reserve(childCount);
+    for (std::size_t childIndex = 0; childIndex < childCount; ++childIndex) {
+        UIEditorWorkspaceNode child = {};
+        UIEditorWorkspaceLayoutLoadResult childResult = ParseNodeRecursive(lines, index, child);
+        if (!childResult.IsValid()) {
+            return childResult;
+        }
+        outNode.children.push_back(std::move(child));
+    }
+
+    return {};
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseSplitNode(
+    const std::vector<LayoutLine>& lines,
+    std::size_t& index,
+    std::istringstream& stream,
+    const LayoutLine& line,
+    UIEditorWorkspaceNode& outNode) {
+    std::string nodeId = {};
+    std::string axisText = {};
+    float splitRatio = 0.0f;
+    if (!(stream >> std::quoted(nodeId) >> std::quoted(axisText) >> splitRatio) ||
+        HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            MakeLinePrefix(line) + "split node record is malformed.");
+    }
+
+    UIEditorWorkspaceSplitAxis axis = UIEditorWorkspaceSplitAxis::Horizontal;
+    if (UIEditorWorkspaceLayoutLoadResult axisResult = ParseAxis(axisText, axis, line);
+        !axisResult.IsValid()) {
+        return axisResult;
+    }
+
+    UIEditorWorkspaceNode primary = {};
+    UIEditorWorkspaceNode secondary = {};
+    if (UIEditorWorkspaceLayoutLoadResult primaryResult = ParseNodeRecursive(lines, index, primary);
+        !primaryResult.IsValid()) {
+        return primaryResult;
+    }
+
+    if (UIEditorWorkspaceLayoutLoadResult secondaryResult = ParseNodeRecursive(lines, index, secondary);
+        !secondaryResult.IsValid()) {
+        return secondaryResult;
+    }
+
+    outNode = BuildUIEditorWorkspaceSplit(
+        std::move(nodeId),
+        axis,
+        splitRatio,
+        std::move(primary),
+        std::move(secondary));
+    return {};
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseNodeRecursive(
+    const std::vector<LayoutLine>& lines,
+    std::size_t& index,
+    UIEditorWorkspaceNode& outNode) {
+    if (index >= lines.size()) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::UnexpectedEndOfInput,
+            "Unexpected end of input while parsing workspace nodes.");
+    }
+
+    const LayoutLine& line = lines[index++];
+    std::istringstream stream = {};
+    std::string tag = {};
+    if (!ParseNodeLine(line, tag, stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+            MakeLinePrefix(line) + "workspace node record is empty.");
+    }
+
+    if (tag == "node_panel") {
+        return ParsePanelNode(stream, line, outNode);
+    }
+
+    if (tag == "node_tabstack") {
+        return ParseTabStackNode(lines, index, stream, line, outNode);
+    }
+
+    if (tag == "node_split") {
+        return ParseSplitNode(lines, index, stream, line, outNode);
+    }
+
+    return MakeLoadError(
+        UIEditorWorkspaceLayoutLoadCode::InvalidNodeRecord,
+        MakeLinePrefix(line) + "unknown workspace node tag '" + tag + "'.");
+}
+
+UIEditorWorkspaceLayoutLoadResult ParseSessionRecord(
+    const LayoutLine& line,
+    UIEditorPanelSessionState& outState) {
+    std::istringstream stream(line.text);
+    std::string tag = {};
+    int openValue = 0;
+    int visibleValue = 0;
+    if (!(stream >> tag) || tag != "session" ||
+        !(stream >> std::quoted(outState.panelId))) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidSessionRecord,
+            MakeLinePrefix(line) + "session record must start with `session`.");
+    }
+
+    UIEditorWorkspaceLayoutLoadResult boolParse = {};
+    if (!ParseBinaryFlag(
+            stream,
+            line,
+            openValue,
+            boolParse,
+            UIEditorWorkspaceLayoutLoadCode::InvalidSessionRecord,
+            "open")) {
+        return boolParse;
+    }
+
+    if (!ParseBinaryFlag(
+            stream,
+            line,
+            visibleValue,
+            boolParse,
+            UIEditorWorkspaceLayoutLoadCode::InvalidSessionRecord,
+            "visible")) {
+        return boolParse;
+    }
+
+    if (HasTrailingTokens(stream)) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidSessionRecord,
+            MakeLinePrefix(line) + "session record contains trailing tokens.");
+    }
+
+    outState.open = openValue != 0;
+    outState.visible = visibleValue != 0;
+    return {};
+}
+
+} // namespace
+
+UIEditorWorkspaceLayoutSnapshot BuildUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorWorkspaceModel& workspace,
+    const UIEditorWorkspaceSession& session) {
+    UIEditorWorkspaceLayoutSnapshot snapshot = {};
+    snapshot.workspace = workspace;
+    snapshot.session = session;
+    return snapshot;
+}
+
+bool AreUIEditorWorkspaceLayoutSnapshotsEquivalent(
+    const UIEditorWorkspaceLayoutSnapshot& lhs,
+    const UIEditorWorkspaceLayoutSnapshot& rhs) {
+    return AreUIEditorWorkspaceModelsEquivalent(lhs.workspace, rhs.workspace) &&
+        AreUIEditorWorkspaceSessionsEquivalent(lhs.session, rhs.session);
+}
+
+std::string SerializeUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorWorkspaceLayoutSnapshot& snapshot) {
+    std::ostringstream stream = {};
+    stream << kLayoutHeader << ' ' << kLayoutVersion << '\n';
+    stream << "active " << std::quoted(snapshot.workspace.activePanelId) << '\n';
+    SerializeNodeRecursive(snapshot.workspace.root, stream);
+    for (const UIEditorPanelSessionState& state : snapshot.session.panelStates) {
+        stream << "session "
+               << std::quoted(state.panelId) << ' '
+               << (state.open ? 1 : 0) << ' '
+               << (state.visible ? 1 : 0) << '\n';
+    }
+    return stream.str();
+}
+
+UIEditorWorkspaceLayoutLoadResult DeserializeUIEditorWorkspaceLayoutSnapshot(
+    const UIEditorPanelRegistry& panelRegistry,
+    std::string_view serializedLayout) {
+    const UIEditorPanelRegistryValidationResult registryValidation =
+        ValidateUIEditorPanelRegistry(panelRegistry);
+    if (!registryValidation.IsValid()) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidPanelRegistry,
+            "Panel registry invalid: " + registryValidation.message);
+    }
+
+    const std::vector<LayoutLine> lines = CollectNonEmptyLines(serializedLayout);
+    if (lines.empty()) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::EmptyInput,
+            "Serialized layout input is empty.");
+    }
+
+    if (UIEditorWorkspaceLayoutLoadResult headerResult = ParseHeader(lines.front());
+        !headerResult.IsValid()) {
+        return headerResult;
+    }
+
+    if (lines.size() < 2u) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::MissingActiveRecord,
+            "Serialized layout is missing the active panel record.");
+    }
+
+    UIEditorWorkspaceLayoutSnapshot snapshot = {};
+    if (UIEditorWorkspaceLayoutLoadResult activeResult =
+            ParseActiveRecord(lines[1], snapshot.workspace.activePanelId);
+        !activeResult.IsValid()) {
+        return activeResult;
+    }
+
+    std::size_t index = 2u;
+    if (UIEditorWorkspaceLayoutLoadResult rootResult =
+            ParseNodeRecursive(lines, index, snapshot.workspace.root);
+        !rootResult.IsValid()) {
+        return rootResult;
+    }
+
+    snapshot.session.panelStates.clear();
+    while (index < lines.size()) {
+        UIEditorPanelSessionState state = {};
+        if (UIEditorWorkspaceLayoutLoadResult stateResult =
+                ParseSessionRecord(lines[index], state);
+            !stateResult.IsValid()) {
+            return stateResult;
+        }
+        snapshot.session.panelStates.push_back(std::move(state));
+        ++index;
+    }
+
+    if (UIEditorWorkspaceValidationResult workspaceValidation =
+            ValidateUIEditorWorkspace(snapshot.workspace);
+        !workspaceValidation.IsValid()) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidWorkspace,
+            workspaceValidation.message);
+    }
+
+    if (UIEditorWorkspaceSessionValidationResult sessionValidation =
+            ValidateUIEditorWorkspaceSession(panelRegistry, snapshot.workspace, snapshot.session);
+        !sessionValidation.IsValid()) {
+        return MakeLoadError(
+            UIEditorWorkspaceLayoutLoadCode::InvalidWorkspaceSession,
+            sessionValidation.message);
+    }
+
+    UIEditorWorkspaceLayoutLoadResult result = {};
+    result.snapshot = std::move(snapshot);
+    return result;
+}
+
+} // namespace XCEngine::NewEditor

new_editor/src/editor/UIEditorWorkspaceModel.cpp

@@ -205,6 +205,37 @@ UIEditorWorkspaceValidationResult ValidateNodeRecursive(
 
 } // namespace
 
+bool AreUIEditorWorkspaceNodesEquivalent(
+    const UIEditorWorkspaceNode& lhs,
+    const UIEditorWorkspaceNode& rhs) {
+    if (lhs.kind != rhs.kind ||
+        lhs.nodeId != rhs.nodeId ||
+        lhs.splitAxis != rhs.splitAxis ||
+        lhs.splitRatio != rhs.splitRatio ||
+        lhs.selectedTabIndex != rhs.selectedTabIndex ||
+        lhs.panel.panelId != rhs.panel.panelId ||
+        lhs.panel.title != rhs.panel.title ||
+        lhs.panel.placeholder != rhs.panel.placeholder ||
+        lhs.children.size() != rhs.children.size()) {
+        return false;
+    }
+
+    for (std::size_t index = 0; index < lhs.children.size(); ++index) {
+        if (!AreUIEditorWorkspaceNodesEquivalent(lhs.children[index], rhs.children[index])) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool AreUIEditorWorkspaceModelsEquivalent(
+    const UIEditorWorkspaceModel& lhs,
+    const UIEditorWorkspaceModel& rhs) {
+    return lhs.activePanelId == rhs.activePanelId &&
+        AreUIEditorWorkspaceNodesEquivalent(lhs.root, rhs.root);
+}
+
 UIEditorWorkspaceModel BuildDefaultEditorShellWorkspaceModel() {
     const UIEditorPanelRegistry registry = BuildDefaultEditorShellPanelRegistry();
     const UIEditorPanelDescriptor& rootPanel =

new_editor/src/editor/UIEditorWorkspaceSession.cpp

@@ -198,57 +198,6 @@ void NormalizeWorkspaceSession(
     TryActivateUIEditorWorkspacePanel(workspace, targetActivePanelId);
 }
 
-bool AreWorkspaceNodesEquivalent(
-    const UIEditorWorkspaceNode& lhs,
-    const UIEditorWorkspaceNode& rhs) {
-    if (lhs.kind != rhs.kind ||
-        lhs.nodeId != rhs.nodeId ||
-        lhs.splitAxis != rhs.splitAxis ||
-        lhs.splitRatio != rhs.splitRatio ||
-        lhs.selectedTabIndex != rhs.selectedTabIndex ||
-        lhs.panel.panelId != rhs.panel.panelId ||
-        lhs.panel.title != rhs.panel.title ||
-        lhs.panel.placeholder != rhs.panel.placeholder ||
-        lhs.children.size() != rhs.children.size()) {
-        return false;
-    }
-
-    for (std::size_t index = 0; index < lhs.children.size(); ++index) {
-        if (!AreWorkspaceNodesEquivalent(lhs.children[index], rhs.children[index])) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
-bool AreWorkspaceModelsEquivalent(
-    const UIEditorWorkspaceModel& lhs,
-    const UIEditorWorkspaceModel& rhs) {
-    return lhs.activePanelId == rhs.activePanelId &&
-        AreWorkspaceNodesEquivalent(lhs.root, rhs.root);
-}
-
-bool AreWorkspaceSessionsEquivalent(
-    const UIEditorWorkspaceSession& lhs,
-    const UIEditorWorkspaceSession& rhs) {
-    if (lhs.panelStates.size() != rhs.panelStates.size()) {
-        return false;
-    }
-
-    for (std::size_t index = 0; index < lhs.panelStates.size(); ++index) {
-        const UIEditorPanelSessionState& lhsState = lhs.panelStates[index];
-        const UIEditorPanelSessionState& rhsState = rhs.panelStates[index];
-        if (lhsState.panelId != rhsState.panelId ||
-            lhsState.open != rhsState.open ||
-            lhsState.visible != rhsState.visible) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
 } // namespace
 
 UIEditorWorkspaceSession BuildDefaultUIEditorWorkspaceSession(
@@ -348,6 +297,26 @@ UIEditorWorkspaceSessionValidationResult ValidateUIEditorWorkspaceSession(
     return {};
 }
 
+bool AreUIEditorWorkspaceSessionsEquivalent(
+    const UIEditorWorkspaceSession& lhs,
+    const UIEditorWorkspaceSession& rhs) {
+    if (lhs.panelStates.size() != rhs.panelStates.size()) {
+        return false;
+    }
+
+    for (std::size_t index = 0; index < lhs.panelStates.size(); ++index) {
+        const UIEditorPanelSessionState& lhsState = lhs.panelStates[index];
+        const UIEditorPanelSessionState& rhsState = rhs.panelStates[index];
+        if (lhsState.panelId != rhsState.panelId ||
+            lhsState.open != rhsState.open ||
+            lhsState.visible != rhsState.visible) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 std::vector<UIEditorWorkspaceVisiblePanel> CollectUIEditorWorkspaceVisiblePanels(
     const UIEditorWorkspaceModel& workspace,
     const UIEditorWorkspaceSession& session) {
@@ -391,8 +360,8 @@ bool TryOpenUIEditorWorkspacePanel(
     state->open = true;
     state->visible = true;
     NormalizeWorkspaceSession(panelRegistry, workspace, session, panelId);
-    return !AreWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
-        !AreWorkspaceSessionsEquivalent(sessionBefore, session);
+    return !AreUIEditorWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
+        !AreUIEditorWorkspaceSessionsEquivalent(sessionBefore, session);
 }
 
 bool TryCloseUIEditorWorkspacePanel(
@@ -412,8 +381,8 @@ bool TryCloseUIEditorWorkspacePanel(
     state->open = false;
     state->visible = false;
     NormalizeWorkspaceSession(panelRegistry, workspace, session, {});
-    return !AreWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
-        !AreWorkspaceSessionsEquivalent(sessionBefore, session);
+    return !AreUIEditorWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
+        !AreUIEditorWorkspaceSessionsEquivalent(sessionBefore, session);
 }
 
 bool TryShowUIEditorWorkspacePanel(
@@ -432,8 +401,8 @@ bool TryShowUIEditorWorkspacePanel(
 
     state->visible = true;
     NormalizeWorkspaceSession(panelRegistry, workspace, session, panelId);
-    return !AreWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
-        !AreWorkspaceSessionsEquivalent(sessionBefore, session);
+    return !AreUIEditorWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
+        !AreUIEditorWorkspaceSessionsEquivalent(sessionBefore, session);
 }
 
 bool TryHideUIEditorWorkspacePanel(
@@ -452,8 +421,8 @@ bool TryHideUIEditorWorkspacePanel(
 
     state->visible = false;
     NormalizeWorkspaceSession(panelRegistry, workspace, session, {});
-    return !AreWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
-        !AreWorkspaceSessionsEquivalent(sessionBefore, session);
+    return !AreUIEditorWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
+        !AreUIEditorWorkspaceSessionsEquivalent(sessionBefore, session);
 }
 
 bool TryActivateUIEditorWorkspacePanel(
@@ -469,8 +438,8 @@ bool TryActivateUIEditorWorkspacePanel(
     }
 
     NormalizeWorkspaceSession(panelRegistry, workspace, session, panelId);
-    return !AreWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
-        !AreWorkspaceSessionsEquivalent(sessionBefore, session);
+    return !AreUIEditorWorkspaceModelsEquivalent(workspaceBefore, workspace) ||
+        !AreUIEditorWorkspaceSessionsEquivalent(sessionBefore, session);
 }
 
 } // namespace XCEngine::NewEditor