Route prepared export policy through platform services

docs/modernization/build-inventory.md

@@ -546,7 +546,8 @@ Known local toolchain state:
   flushing, document browse roots, native UI/window state saving, live
   asset/layout reload policy, diagnostic stacktrace/crash hooks,
   prepared-file writable target selection, and prepared-file save/download
-  handoff;
+  handoff; PPBR and MP4 export dialogs consume the same prepared-file policy
+  at runtime instead of spelling mobile/Web branches locally;
   Windows
   live app execution now uses injected
   `WindowsPlatformServices` from

docs/modernization/debt.md

@@ -70,7 +70,7 @@ agent or engineer to remove them without reconstructing context from chat.
 | DEBT-0050 | Open | Modernization | iOS exported-image photo-library publishing and WebGL persistent-storage flushing now dispatch through `PlatformServices`, but non-Windows execution still lives in `src/platform_legacy/legacy_platform_services.*` and forwards to retained `save_image_library`/`webgl_sync` bridges | Preserve current iOS/Web export and save behavior while the Apple/Web platform shells are extracted incrementally | `pp_platform_api_tests`; `ctest --preset desktop-fast --build-config Debug`; platform package smoke once Apple/Web root builds exist | Exported-image publishing and persistent-storage flushing are owned by injected Apple/Web `pp_platform_*` services with no legacy adapter branch |
 | DEBT-0051 | Open | Modernization | Document browser search roots now dispatch through `PlatformServices`, but iOS `Inbox` inclusion still lives in `src/platform_legacy/legacy_platform_services.*` | Preserve current iOS document import/browse 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 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 now dispatches 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 and save/download handoff are 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 |
 
 ## Closed Debt
 

docs/modernization/roadmap.md

@@ -643,6 +643,9 @@ Prepared-file writable target selection now also dispatches through
 `PlatformServices`, preserving the existing iOS temporary background-write path
 and Web data-path synchronous write path while removing those platform branches
 from `App::pick_file_save`.
+PPBR and MP4 export dialogs now ask `PlatformServices` whether prepared-file
+writes are used, so those dialog flows no longer spell local `__IOS__ ||
+__WEB__` branches for mobile/Web export handoff.
 Canvas image export publishing and explicit persistent-storage flushes now
 dispatch through `PlatformServices` too, preserving iOS photo-library export
 publication and WebGL filesystem sync behavior in the legacy adapter while
@@ -1697,7 +1700,7 @@ Results:
   recording cleanup dispatch, exported-image publish dispatch, persistent
   storage flush dispatch, document browse-root dispatch,
   native UI/window state save dispatch, prepared-file writable target dispatch,
-  live asset/layout reload policy dispatch,
+  prepared-file export-dialog policy dispatch, 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
   app now

src/app.h

@@ -184,6 +184,7 @@ public:
     void pick_file_save(const std::string& type, const std::string& default_name,
         std::function<void(std::string path)> writer, std::function<void(const std::string& path, bool saved)> callback);
     void pick_file_save(std::vector<std::string> types, std::function<void(std::string path)> callback);
+    [[nodiscard]] bool uses_prepared_file_writes() const;
     void pick_dir(std::function<void(std::string path)> callback);
     void display_file(std::string path);
     void share_file(std::string path);

src/app_dialogs.cpp

@@ -515,8 +515,10 @@ void App::dialog_ppbr_export()
     auto dialog = root->add_child_ref<NodeDialogExportPPBR>();
     dialog->btn_ok->on_click = [this, dialog] (Node*) {
         const auto request = pp::panopainter::make_legacy_brush_package_export_request(*dialog);
-#if __IOS__ || __WEB__
+
-        App::I->pick_file_save("ppbr", "exported-brushes",
+        if (uses_prepared_file_writes())
+        {
+            pick_file_save("ppbr", "exported-brushes",
                 [this, dialog, request] (std::string path) {
                     const auto status = pp::panopainter::execute_legacy_brush_package_export(
                         *this,
@@ -532,8 +534,10 @@ void App::dialog_ppbr_export()
                     pp::panopainter::complete_legacy_brush_package_export(*dialog, saved);
                 }
             );
-#else
+            return;
-        App::I->pick_file_save({ "ppbr" }, [this, dialog, request] (std::string path) {
+        }
+
+        pick_file_save({ "ppbr" }, [this, dialog, request] (std::string path) {
             const auto status = pp::panopainter::execute_legacy_brush_package_export(
                 *this,
                 *dialog,
@@ -543,7 +547,6 @@ void App::dialog_ppbr_export()
             if (!status.ok())
                 LOG("PPBR export failed: %s", status.message);
         });
-#endif
     };
 }
 
@@ -552,7 +555,8 @@ void App::dialog_timelapse_export()
     if (!can_start_document_export(*this, false))
         return;
 
-#if __IOS__ || __WEB__
+    if (uses_prepared_file_writes())
+    {
         const auto target = pp::app::make_document_export_suggested_name(doc_name, "-timelapse");
         if (!target) {
             message_box("Export Timelapse", target.status().message);
@@ -574,7 +578,9 @@ void App::dialog_timelapse_export()
                 (void)saved;
             }
         );
-#else
+        return;
+    }
+
     pick_file_save({ "mp4" }, [this](std::string path) {
         const auto status = pp::panopainter::execute_legacy_document_video_export(
             *this,
@@ -584,7 +590,6 @@ void App::dialog_timelapse_export()
         if (!status.ok())
             LOG("Document timelapse export failed: %s", status.message);
     });
-#endif
 }
 
 void App::dialog_export_mp4()
@@ -592,7 +597,8 @@ void App::dialog_export_mp4()
     if (!can_start_document_export(*this, false))
         return;
 
-#if __IOS__ || __WEB__
+    if (uses_prepared_file_writes())
+    {
         const auto target = pp::app::make_document_export_suggested_name(doc_name, "-animation");
         if (!target) {
             message_box("Export Animation", target.status().message);
@@ -614,7 +620,9 @@ void App::dialog_export_mp4()
                 (void)saved;
             }
         );
-#else
+        return;
+    }
+
     pick_file_save({ "mp4" }, [this](std::string path) {
         const auto status = pp::panopainter::execute_legacy_document_video_export(
             *this,
@@ -624,7 +632,6 @@ void App::dialog_export_mp4()
         if (!status.ok())
             LOG("Document animation export failed: %s", status.message);
     });
-#endif
 }
 
 void App::dialog_whatsnew(bool force_show)

src/app_events.cpp

@@ -181,6 +181,11 @@ void App::pick_file_save(std::vector<std::string> types, std::function<void(std:
     active_platform_services().pick_save_file(std::move(types), std::move(callback));
 }
 
+bool App::uses_prepared_file_writes() const
+{
+    return active_platform_services().uses_prepared_file_writes();
+}
+
 void App::pick_dir(std::function<void(std::string path)> callback)
 {
     redraw = true;

src/platform_api/platform_services.h

@@ -63,6 +63,7 @@ public:
     virtual void pick_file(std::vector<std::string> file_types, PickedPathCallback callback) = 0;
     virtual void pick_save_file(std::vector<std::string> file_types, PickedPathCallback callback) = 0;
     virtual void pick_directory(PickedPathCallback callback) = 0;
+    [[nodiscard]] virtual bool uses_prepared_file_writes() = 0;
     [[nodiscard]] virtual PreparedFileTarget prepare_writable_file(
         std::string_view type,
         std::string_view default_name,

src/platform_legacy/legacy_platform_services.cpp

@@ -431,6 +431,15 @@ public:
 #endif
     }
 
+    [[nodiscard]] bool uses_prepared_file_writes() override
+    {
+#if __IOS__ || __WEB__
+        return true;
+#else
+        return false;
+#endif
+    }
+
     [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
         std::string_view type,
         std::string_view default_name,

src/platform_windows/windows_platform_services.cpp

@@ -448,6 +448,11 @@ public:
         invoke_selected_path(path, callback);
     }
 
+    [[nodiscard]] bool uses_prepared_file_writes() override
+    {
+        return false;
+    }
+
     [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
         std::string_view type,
         std::string_view default_name,

tests/platform_api/platform_services_tests.cpp

@@ -210,6 +210,12 @@ public:
         callback(directory_path);
     }
 
+    [[nodiscard]] bool uses_prepared_file_writes() override
+    {
+        ++prepared_file_write_policy_checks;
+        return prepared_file_writes;
+    }
+
     [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
         std::string_view type,
         std::string_view default_name,
@@ -269,11 +275,13 @@ public:
     int pick_file_requests = 0;
     int pick_save_file_requests = 0;
     int pick_directory_requests = 0;
+    int prepared_file_write_policy_checks = 0;
     int prepare_writable_file_requests = 0;
     int save_prepared_file_requests = 0;
     bool cursor_visible = false;
     bool keyboard_visible = false;
     bool prepared_file_saved = true;
+    bool prepared_file_writes = true;
     bool deletes_recorded_files = true;
     bool live_asset_reloading = true;
     float last_platform_delta = 0.0f;
@@ -571,8 +579,14 @@ void platform_services_dispatch_writable_file_target(pp::tests::Harness& harness
     FakePlatformServices fake("unused");
     pp::platform::PlatformServices& services = fake;
 
+    PP_EXPECT(harness, services.uses_prepared_file_writes());
+    fake.prepared_file_writes = false;
+    PP_EXPECT(harness, !services.uses_prepared_file_writes());
+    fake.prepared_file_writes = true;
+
     const auto target = services.prepare_writable_file("mp4", "export", "D:/Paint", "D:/Paint/tmp");
 
+    PP_EXPECT(harness, fake.prepared_file_write_policy_checks == 2);
     PP_EXPECT(harness, fake.prepare_writable_file_requests == 1);
     PP_EXPECT(harness, fake.writable_file_type == "mp4");
     PP_EXPECT(harness, fake.writable_file_default_name == "export");