Move layout reload policy into platform api

CMakeLists.txt

@@ -212,6 +212,8 @@ target_link_libraries(pp_ui_core
         pp_project_warnings)
 
 add_library(pp_platform_api STATIC
+    src/platform_api/asset_file_load_policy.cpp
+    src/platform_api/asset_file_load_policy.h
     src/platform_api/network_tls_policy.cpp
     src/platform_api/network_tls_policy.h
     src/platform_api/platform_services.cpp
@@ -439,6 +441,7 @@ if(PP_BUILD_APP)
                 pp_project_options
             PRIVATE
                 pp_paint_renderer
+                pp_platform_api
                 pp_renderer_api
                 pp_project_warnings)
         if(TARGET pp_renderer_gl)
@@ -475,6 +478,7 @@ if(PP_BUILD_APP)
                 pp_legacy_ui_core
                 pp_project_options
             PRIVATE
+                pp_platform_api
                 pp_renderer_api
                 pp_project_warnings)
         if(TARGET pp_renderer_gl)

docs/modernization/build-inventory.md

@@ -583,6 +583,11 @@ Known local toolchain state:
   while non-Windows platforms still reach retained platform bridges through
   the debt-tracked adapter isolated in
   `src/platform_legacy/legacy_platform_services.*`.
+- `pp_platform_api` also owns `plan_asset_file_load`, the SDK-free file-load
+  policy consumed by `LayoutManager` for XML layout reload decisions. The
+  helper preserves desktop mtime-based reload behavior and non-desktop
+  already-loaded skip behavior while keeping direct platform guards out of the
+  shared layout parser.
 - `pp_renderer_gl` owns the tested `OpenGlInitialState` startup depth/blend
   policy and dispatch application consumed by `App::init`, tested runtime
   version/vendor/renderer/GLSL string query dispatch, tested default clear
@@ -660,8 +665,8 @@ Known local toolchain state:
   split persistence/runtime dispatch, and malformed startup-plan rejection.
 - `pp_platform_api_tests` covers service dispatch for clipboard read/write,
   empty clipboard writes, cursor visibility, virtual-keyboard visibility,
-  external file display, file sharing, VR lifecycle, and picker callbacks
-  without platform SDK headers or a window.
+  external file display, file sharing, VR lifecycle, layout/asset file load
+  policy, and picker callbacks without platform SDK headers or a window.
 - `pp_app_core_document_cloud_tests` covers cloud upload no-canvas,
   new-document warning, clean publish prompt, and dirty save-before-upload
   decisions, plus cloud browse no-canvas/show-browser and selected-download

docs/modernization/debt.md

@@ -71,6 +71,7 @@ agent or engineer to remove them without reconstructing context from chat.
 | DEBT-0051 | Open | Modernization | Document browser search roots and Browse dialog working-directory picker visibility/path formatting now dispatch through `PlatformServices`, but iOS `Inbox` inclusion and macOS directory picker/display-path behavior still live in `src/platform_legacy/legacy_platform_services.*` | Preserve current iOS document import/browse and desktop browse picker behavior while Apple platform shells are extracted incrementally | `pp_platform_api_tests`; `ctest --preset desktop-fast --build-config Debug`; Apple package smoke once root Apple builds exist | Document browse roots and browse-directory picker/display formatting are owned by injected Apple and desktop `pp_platform_*` services with no legacy adapter branch |
 | DEBT-0052 | Open | Modernization | Native UI/window state saving now dispatches through `PlatformServices`, but macOS execution still lives in `src/platform_legacy/legacy_platform_services.*` and forwards to the retained Objective-C app bridge | Preserve current Windows/macOS UI persistence while platform shells are extracted incrementally | `pp_platform_api_tests`; `ctest --preset desktop-fast --build-config Debug`; Windows app build; Apple package smoke once root Apple builds exist | UI/window state persistence is owned by injected platform services with no legacy adapter branch |
 | DEBT-0053 | Open | Modernization | Prepared-file writable target selection and prepared-file export-dialog policy now dispatch through `PlatformServices`, but iOS/Web target selection still lives in `src/platform_legacy/legacy_platform_services.*` | Preserve mobile/Web export handoff behavior while platform shells are extracted incrementally | `pp_platform_api_tests`; `ctest --preset desktop-fast --build-config Debug`; Windows app build; Apple/Web package smoke once root package builds exist | Prepared-file target selection, export-dialog policy, and save/download handoff are owned by injected platform services with no legacy adapter branch |
+| DEBT-0054 | Open | Modernization | Layout XML file read/reload decisions now consume `pp_platform_api::plan_asset_file_load`, but that helper still encodes the retained compile-time platform policy: Windows/macOS use `stat` mtime reload checks, while other platforms treat already-loaded layouts as successful no-op loads | Preserve current layout hot-reload and mobile/Web single-load behavior while removing platform guards from the shared `LayoutManager` parser | `pp_platform_api_tests`; `ctest --preset desktop-fast --build-config Debug -R pp_platform_api_tests`; Windows app build | Layout reload decisions are owned by injected platform storage/file-watch services or an asset manager boundary with platform-specific file watching removed from compile-time helpers |
 
 ## Closed Debt
 

docs/modernization/roadmap.md

@@ -650,6 +650,9 @@ file display, file sharing, recording file cleanup, live asset/layout reload
 policy, diagnostic stacktrace/crash hooks, SonarPen availability/startup,
 VR mode start/stop,
 image/file/save-file pickers, and directory pickers.
+It also owns the SDK-free layout/asset file load policy helper used by
+`LayoutManager`, so XML layout hot-reload timestamp checks no longer live in
+the shared UI parser.
 Windows installs an injected `WindowsPlatformServices` implementation from
 `src/platform_windows/windows_platform_services.*` in `pp_platform_windows`;
 other platforms still route through the debt-tracked legacy fallback adapter
@@ -786,6 +789,9 @@ guards from `App::rec_clear`.
 The UI loop now asks `PlatformServices` whether live shader/layout reloading
 should run, preserving the previous Windows/macOS reload behavior while removing
 the direct `(_WIN32 || __OSX__)` guard from `App::ui_thread_main`.
+Layout XML reload read/skip decisions now go through `pp_platform_api` as well,
+preserving desktop mtime-based reloads and non-desktop single-load behavior
+while removing the direct Windows/macOS guard from `LayoutManager::load`.
 `App::stacktrace` and `App::crash_test` now dispatch through `PlatformServices`,
 with Windows retaining the debug-break crash hook and the legacy adapter
 preserving Apple stacktrace/crash and Android crash-test behavior.
@@ -1766,6 +1772,7 @@ Results:
   collection policy dispatch, network TLS verification policy dispatch,
   default network TLS policy coverage, PPBR export data-directory policy
   dispatch, SonarPen availability/startup dispatch, VR lifecycle dispatch,
+  layout/asset file load policy coverage,
   live asset/layout reload policy dispatch,
   diagnostic hook dispatch, per-frame platform hook dispatch, picker callback
   dispatch, and prepared-file save/download callback dispatch. The live Windows

src/layout.cpp

@@ -5,6 +5,7 @@
 #include "node.h"
 #include "node_border.h"
 #include "layout.h"
+#include "platform_api/asset_file_load_policy.h"
 
 void LayoutManager::unload()
 {
@@ -22,17 +23,13 @@ void LayoutManager::create()
 bool LayoutManager::load(const char* path)
 {
     auto abs_path = Asset::absolute(path);
-#if _WIN32 || __OSX__
-    struct stat tmp_info;
-    if (stat(abs_path.c_str(), &tmp_info) != 0)
-        return false;
-    if (tmp_info.st_mtime <= m_file_info.st_mtime)
-        return false;
-    m_file_info = tmp_info;
-#else
-    if (m_loaded)
-        return true; // already loaded
-#endif // __ANDROID__
+    const auto file_load = pp::platform::plan_asset_file_load(
+        abs_path,
+        m_loaded,
+        m_file_last_write_time);
+    if (!file_load.should_read_file)
+        return file_load.skipped_load_result;
+    m_file_last_write_time = file_load.last_write_time;
 
     if (!m_layouts.empty() && on_reloading)
         on_reloading();

src/layout.h

@@ -1,9 +1,11 @@
 #pragma once
 
+#include <cstdint>
+
 class LayoutManager
 {
     std::string m_path;
-    struct stat m_file_info { 0 };
+    std::int64_t m_file_last_write_time = 0;
 public:
     std::map<uint16_t, std::shared_ptr<class Node>> m_layouts;
     bool m_loaded = false;

src/platform_api/asset_file_load_policy.cpp

@@ -0,0 +1,33 @@
+#include "platform_api/asset_file_load_policy.h"
+
+#include <string>
+#include <sys/stat.h>
+
+namespace pp::platform {
+
+AssetFileLoadDecision plan_asset_file_load(
+    std::string_view absolute_path,
+    bool already_loaded,
+    std::int64_t previous_last_write_time)
+{
+#if defined(_WIN32) || defined(__OSX__)
+    struct stat file_info {};
+    const std::string path(absolute_path);
+    if (stat(path.c_str(), &file_info) != 0)
+        return { false, false, previous_last_write_time };
+
+    const auto current_last_write_time = static_cast<std::int64_t>(file_info.st_mtime);
+    if (current_last_write_time <= previous_last_write_time)
+        return { false, false, previous_last_write_time };
+
+    return { true, true, current_last_write_time };
+#else
+    if (already_loaded)
+        return { false, true, previous_last_write_time };
+
+    (void)absolute_path;
+    return { true, true, previous_last_write_time };
+#endif
+}
+
+}

src/platform_api/asset_file_load_policy.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <cstdint>
+#include <string_view>
+
+namespace pp::platform {
+
+struct AssetFileLoadDecision {
+    bool should_read_file = true;
+    bool skipped_load_result = true;
+    std::int64_t last_write_time = 0;
+};
+
+[[nodiscard]] AssetFileLoadDecision plan_asset_file_load(
+    std::string_view absolute_path,
+    bool already_loaded,
+    std::int64_t previous_last_write_time);
+
+}

tests/platform_api/platform_services_tests.cpp

@@ -1,8 +1,11 @@
 #include "test_harness.h"
 
+#include "platform_api/asset_file_load_policy.h"
 #include "platform_api/network_tls_policy.h"
 #include "platform_api/platform_services.h"
 
+#include <filesystem>
+#include <fstream>
 #include <string>
 #include <string_view>
 #include <utility>
@@ -757,6 +760,36 @@ void default_network_tls_policy_matches_build_target(pp::tests::Harness& harness
 #endif
 }
 
+void asset_file_load_policy_preserves_platform_reload_behavior(pp::tests::Harness& harness)
+{
+    const auto temp_path = std::filesystem::temp_directory_path()
+        / "panopainter-platform-api-file-policy.xml";
+    {
+        std::ofstream file(temp_path);
+        file << "<layouts />";
+    }
+
+    const auto first_load = pp::platform::plan_asset_file_load(
+        temp_path.string(),
+        false,
+        0);
+    PP_EXPECT(harness, first_load.should_read_file);
+    PP_EXPECT(harness, first_load.skipped_load_result);
+
+    const auto repeated_load = pp::platform::plan_asset_file_load(
+        temp_path.string(),
+        true,
+        first_load.last_write_time);
+    PP_EXPECT(harness, !repeated_load.should_read_file);
+#if defined(_WIN32) || defined(__OSX__)
+    PP_EXPECT(harness, !repeated_load.skipped_load_result);
+#else
+    PP_EXPECT(harness, repeated_load.skipped_load_result);
+#endif
+
+    std::filesystem::remove(temp_path);
+}
+
 void platform_services_dispatch_ppbr_export_directory_policy(pp::tests::Harness& harness)
 {
     FakePlatformServices fake("unused");
@@ -833,6 +866,9 @@ int main()
         platform_services_dispatch_document_export_collection_policy);
     harness.run("platform services dispatch network tls policy", platform_services_dispatch_network_tls_policy);
     harness.run("default network tls policy matches build target", default_network_tls_policy_matches_build_target);
+    harness.run(
+        "asset file load policy preserves platform reload behavior",
+        asset_file_load_policy_preserves_platform_reload_behavior);
     harness.run(
         "platform services dispatch ppbr export directory policy",
         platform_services_dispatch_ppbr_export_directory_policy);