diff --git a/docs/modernization/build-inventory.md b/docs/modernization/build-inventory.md
index 790902f..de0368d 100644
--- a/docs/modernization/build-inventory.md
+++ b/docs/modernization/build-inventory.md
@@ -10,7 +10,7 @@ Keep it updated as platform paths move to shared CMake targets.
 
 | Platform/Target | Current Entrypoint | Notes |
 | --- | --- | --- |
-| Windows desktop | Root `CMakeLists.txt`, preset `windows-msvc-default`; target preset `windows-vs2026-x64` retained for VS 2026 | Raw `.sln/.vcxproj` files removed on 2026-05-31; local machine currently uses Visual Studio 17 2022; `PanoPainter` now links through `pp_platform_windows` and `panopainter_app`, with Windows/vendor link dependencies owned by the platform shell, runtime payload deployment in `cmake/PanoPainterRuntime.cmake`, tested app-level document-open routing plus open/close/save session decisions owned by `pp_app_core`, SDK-free clipboard/cursor/virtual-keyboard service contracts owned by `pp_platform_api`, retained third-party source dependencies contained by `pp_legacy_vendor`, retained asset/file/serialization sources contained by `pp_legacy_assets_io`, retained paint/document/canvas sources contained by `pp_legacy_paint_document`, retained OpenGL runtime sources contained by `pp_legacy_renderer_gl` and folded into `pp_legacy_engine`, retained runtime shell sources contained by `pp_legacy_engine`, retained base UI controls contained by `pp_legacy_ui_core` and folded into `pp_legacy_app`, app orchestration/version metadata owned by `panopainter_app`, and app-specific modal/dialog/panel/canvas workflow nodes owned by `pp_panopainter_ui` |
+| Windows desktop | Root `CMakeLists.txt`, preset `windows-msvc-default`; target preset `windows-vs2026-x64` retained for VS 2026 | Raw `.sln/.vcxproj` files removed on 2026-05-31; local machine currently uses Visual Studio 17 2022; `PanoPainter` now links through `pp_platform_windows` and `panopainter_app`, with Windows/vendor link dependencies owned by the platform shell, runtime payload deployment in `cmake/PanoPainterRuntime.cmake`, tested app-level document-open routing plus open/close/save session decisions owned by `pp_app_core`, SDK-free clipboard/cursor/virtual-keyboard/display/share service contracts owned by `pp_platform_api`, retained third-party source dependencies contained by `pp_legacy_vendor`, retained asset/file/serialization sources contained by `pp_legacy_assets_io`, retained paint/document/canvas sources contained by `pp_legacy_paint_document`, retained OpenGL runtime sources contained by `pp_legacy_renderer_gl` and folded into `pp_legacy_engine`, retained runtime shell sources contained by `pp_legacy_engine`, retained base UI controls contained by `pp_legacy_ui_core` and folded into `pp_legacy_app`, app orchestration/version metadata owned by `panopainter_app`, and app-specific modal/dialog/panel/canvas workflow nodes owned by `pp_panopainter_ui` |
 | Windows AppX | `PanoPainterPackage/Package.appxmanifest`, `.wapproj` referenced by solution | Distribution packaging |
 | macOS | `PanoPainter-OSX/` project files and `Info.plist` | Uses `NSOpenGLView` today |
 | iOS | `PanoPainter/Info.plist`, related Apple sources | Uses OpenGL ES today |
@@ -445,9 +445,10 @@ Known local toolchain state:
   live clipboard get/set requests consume the same contracts before retained
   platform clipboard bridges.
 - `pp_platform_api` exposes the SDK-free `PlatformServices` interface for
-  clipboard text, cursor visibility, and virtual-keyboard visibility; live
-  app execution now reaches retained platform bridges through the
-  debt-tracked legacy adapter in `app_events.cpp`.
+  clipboard text, cursor visibility, virtual-keyboard visibility, external
+  file display, and file sharing; live app execution now reaches retained
+  platform bridges through the debt-tracked legacy adapter in
+  `app_events.cpp`.
 - `pano_cli plan-cloud-upload` exposes `pp_app_core` cloud upload availability,
   new-document warning, publish prompt, and save-before-upload planning as JSON;
   the live cloud upload command consumes the same start contract before
@@ -485,8 +486,9 @@ Known local toolchain state:
   planning before platform cursor callbacks, plus clipboard read/write
   planning before platform clipboard callbacks.
 - `pp_platform_api_tests` covers service dispatch for clipboard read/write,
-  empty clipboard writes, cursor visibility, and virtual-keyboard visibility
-  without platform SDK headers or a window.
+  empty clipboard writes, cursor visibility, virtual-keyboard visibility,
+  external file display, and file sharing 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
diff --git a/docs/modernization/capability-map.md b/docs/modernization/capability-map.md
index 36be5a7..4a1cfa8 100644
--- a/docs/modernization/capability-map.md
+++ b/docs/modernization/capability-map.md
@@ -67,7 +67,7 @@ and validation command.
 | --- | --- | --- | --- |
 | Mouse/keyboard/touch/gestures/cursor | `App`, platform entrypoints | `pp_app_core`, `pp_platform_api`, `pp_platform_*`, app | Cursor visibility decision tests, platform service dispatch tests, synthetic event playback |
 | Wacom pressure | `WacomTablet` | `pp_platform_windows` | Adapter smoke with fallback |
-| Clipboard/file picker/share/display | `App` platform methods | `pp_app_core`, `pp_platform_api`, `pp_platform_*` | Clipboard read/write, share saved-path, picked-path, and display-file decision tests, platform service dispatch tests, platform smoke or mocked service |
+| Clipboard/file picker/share/display | `App` platform methods | `pp_app_core`, `pp_platform_api`, `pp_platform_*` | Clipboard read/write, share saved-path, picked-path, and display-file decision tests, platform service display/share dispatch tests, picker callback tests, platform smoke or mocked service |
 | Virtual keyboard | `App`, platform entrypoints | `pp_app_core`, `pp_platform_api`, `pp_platform_*` | Keyboard visibility decision tests, platform service dispatch tests, platform smoke |
 | OpenVR desktop | `HMD`, `Vive`, `app_vr` | `pp_platform_vr`, app | Compile gate and mocked pose tests |
 | Quest/OVR | Android Quest files | `pp_platform_android_quest` | Compile/package gate |
diff --git a/docs/modernization/debt.md b/docs/modernization/debt.md
index b71b433..3d3c970 100644
--- a/docs/modernization/debt.md
+++ b/docs/modernization/debt.md
@@ -35,7 +35,7 @@ agent or engineer to remove them without reconstructing context from chat.
 | DEBT-0014 | Open | Modernization | `windows-clangcl-asan` now configures as a headless Ninja/clang-cl preset and uses the release MSVC runtime required by ASan, but local builds still fail because installed clang-cl 18.1.8 is paired with VS 2026-preview STL headers that require Clang 20 or newer | Sanitizer validation should be local and repeatable, but this machine's compiler/header pairing is incompatible | `cmake --fresh --preset windows-clangcl-asan`; `cmake --build --preset windows-clangcl-asan --target pp_foundation` | Install/use Clang 20+ with the VS 2026 STL, or point the preset at a compatible VS 2022 toolchain, then make `platform-build.ps1 -Presets windows-clangcl-asan` pass for the headless matrix |
 | DEBT-0015 | Open | Modernization | Cursor visibility requests now consume pure `pp_app_core` planning through `pano_cli plan-cursor-visibility`, but live cursor execution still reaches retained Win32/macOS platform bridges from `App::show_cursor` and `App::hide_cursor` | Keep canvas cursor behavior stable while platform shells are extracted incrementally | `pp_app_core_document_platform_io_tests`; `pano_cli plan-cursor-visibility --visible`; `ctest --preset desktop-fast --build-config Debug` | Cursor visibility execution is owned by `pp_platform_*` services and live app code depends on an injected platform interface instead of direct singleton/platform calls |
 | DEBT-0016 | Open | Modernization | Clipboard get/set requests now consume pure `pp_app_core` planning through `pano_cli plan-clipboard-read` and `pano_cli plan-clipboard-write`, but live clipboard execution still reaches retained Win32/Apple/Android platform bridges from `App::clipboard_get_text` and `App::clipboard_set_text` | Keep picker/color text clipboard behavior stable while platform shells are extracted incrementally | `pp_app_core_document_platform_io_tests`; `pano_cli plan-clipboard-write --text #ff00aa`; `ctest --preset desktop-fast --build-config Debug` | Clipboard execution is owned by `pp_platform_*` services and live app code depends on an injected platform interface instead of direct singleton/platform calls |
-| DEBT-0017 | Open | Modernization | `App::clipboard_get_text`, `App::clipboard_set_text`, `App::show_cursor`, `App::hide_cursor`, `App::showKeyboard`, and `App::hideKeyboard` now call the SDK-free `pp::platform::PlatformServices` interface, but the live implementation is still a legacy adapter in `app_events.cpp` that forwards to retained Win32/Apple/Android bridge functions | Preserve behavior while moving platform execution behind a testable service boundary before platform shell implementations are injected | `pp_platform_api_tests`; `pp_app_core_document_platform_io_tests`; `ctest --preset desktop-fast --build-config Debug`; `powershell -ExecutionPolicy Bypass -File scripts\automation\package-smoke.ps1 -Preset windows-msvc-default -Configuration Debug` | Replace the `app_events.cpp` legacy adapter with injected `pp_platform_*` service implementations owned by each platform shell |
+| DEBT-0017 | Open | Modernization | `App::clipboard_get_text`, `App::clipboard_set_text`, `App::show_cursor`, `App::hide_cursor`, `App::showKeyboard`, `App::hideKeyboard`, `App::display_file`, and `App::share_file` now call the SDK-free `pp::platform::PlatformServices` interface, but the live implementation is still a legacy adapter in `app_events.cpp` that forwards to retained Win32/Apple/Android bridge functions and retained no-op branches | Preserve behavior while moving platform execution behind a testable service boundary before platform shell implementations are injected | `pp_platform_api_tests`; `pp_app_core_document_platform_io_tests`; `ctest --preset desktop-fast --build-config Debug`; `powershell -ExecutionPolicy Bypass -File scripts\automation\package-smoke.ps1 -Preset windows-msvc-default -Configuration Debug` | Replace the `app_events.cpp` legacy adapter with injected `pp_platform_*` service implementations owned by each platform shell |
 
 ## Closed Debt
 
diff --git a/docs/modernization/roadmap.md b/docs/modernization/roadmap.md
index cf3ea73..95d0b62 100644
--- a/docs/modernization/roadmap.md
+++ b/docs/modernization/roadmap.md
@@ -469,10 +469,11 @@ cursor bridges continue.
 app-core clipboard text decisions used by live clipboard get/set requests
 before retained platform clipboard bridges continue.
 `pp_platform_api` now owns a headless `PlatformServices` interface for
-clipboard text, cursor visibility, and virtual-keyboard visibility. Live app
-clipboard/cursor/keyboard execution routes through a debt-tracked legacy
-adapter in `app_events.cpp`, so behavior is preserved while later platform
-shell implementations can replace direct bridge calls.
+clipboard text, cursor visibility, virtual-keyboard visibility, external file
+display, and file sharing. Live app clipboard/cursor/keyboard/display/share
+execution routes through a debt-tracked legacy adapter in `app_events.cpp`, so
+behavior is preserved while later platform shell implementations can replace
+direct bridge calls.
 `pano_cli plan-cloud-upload` exposes the app-core cloud upload decision used by
 the live cloud upload command for missing-canvas, new-document warning, publish
 prompt, and dirty-document save-before-upload states before legacy UI, canvas,
@@ -985,9 +986,10 @@ Results:
   clipboard decisions as JSON, including empty write text.
 - `pp_platform_api_tests` passed, covering the SDK-free `PlatformServices`
   interface for clipboard read/write, empty clipboard writes, cursor
-  visibility dispatch, and virtual-keyboard visibility dispatch. The live app
-  now consumes this interface through the legacy platform adapter for
-  clipboard/cursor/keyboard execution.
+  visibility dispatch, virtual-keyboard visibility dispatch, external file
+  display dispatch, and file sharing dispatch. The live app now consumes this
+  interface through the legacy platform adapter for
+  clipboard/cursor/keyboard/display/share execution.
 - `panopainter_validate_shaders` passed, validating 25 shader programs and 7
   shader includes for stage markers and include graph integrity.
 - `pp_renderer_gl_capabilities_tests` passed on default MSVC, vcpkg-headless,
diff --git a/src/app_events.cpp b/src/app_events.cpp
index 6e026ff..b9d887d 100644
--- a/src/app_events.cpp
+++ b/src/app_events.cpp
@@ -120,6 +120,36 @@ public:
         displayKeyboard(visible);
 #else
         (void)visible;
+#endif
+    }
+
+    void display_file(std::string_view path) override
+    {
+        const std::string value(path);
+#ifdef __IOS__
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [App::I->ios_view display_file:value];
+        });
+#elif __OSX__
+        [[NSWorkspace sharedWorkspace] openFile:[NSString stringWithUTF8String:value.c_str()]];
+#else
+        (void)value;
+#endif
+    }
+
+    void share_file(std::string_view path) override
+    {
+        const std::string value(path);
+#ifdef __IOS__
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [App::I->ios_view share_file:[NSString stringWithUTF8String:value.c_str()]];
+        });
+#elif __OSX__
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [App::I->osx_view share_file:[NSString stringWithUTF8String:value.c_str()]];
+        });
+#else
+        (void)value;
 #endif
     }
 };
@@ -398,24 +428,7 @@ void App::display_file(std::string path)
     if (pp::app::plan_display_file(path) == pp::app::DisplayFileAction::ignore_empty_path)
         return;
 
-#ifdef __IOS__
-    dispatch_async(dispatch_get_main_queue(), ^{
-        [ios_view display_file:path];
-    });
-#elif __OSX__
-    [[NSWorkspace sharedWorkspace] openFile:[NSString stringWithUTF8String:path.c_str()]];
-//    dispatch_async(dispatch_get_main_queue(), ^{
-//        std::string path = [osx_view pick_file];
-//        if (!path.empty())
-//            callback(path);
-//    });
-#elif __ANDROID__
-    //displayKeyboard(and_app, false);
-#elif _WIN32
-//    std::string path = win32_open_file();
-//    if (!path.empty())
-//        callback(path);
-#endif
+    legacy_platform_services().display_file(path);
 }
 
 void App::share_file(std::string path)
@@ -426,18 +439,7 @@ void App::share_file(std::string path)
         message_box("Sharing failed", "Please save the document before sharing it.");
         return;
     }
-#ifdef __IOS__
-    dispatch_async(dispatch_get_main_queue(), ^{
-        [ios_view share_file:[NSString stringWithUTF8String:path.c_str()]];
-    });
-#elif __OSX__
-    dispatch_async(dispatch_get_main_queue(), ^{
-        [osx_view share_file:[NSString stringWithUTF8String:path.c_str()]];
-    });
-#elif __ANDROID__
-#elif _WIN32
-    // not implemented
-#endif
+    legacy_platform_services().share_file(path);
 }
 
 bool App::mouse_down(int button, float x, float y, float pressure, kEventSource source, bool eraser)
diff --git a/src/platform_api/platform_services.h b/src/platform_api/platform_services.h
index 2ff1346..3a642dc 100644
--- a/src/platform_api/platform_services.h
+++ b/src/platform_api/platform_services.h
@@ -13,6 +13,8 @@ public:
     [[nodiscard]] virtual bool set_clipboard_text(std::string_view text) = 0;
     virtual void set_cursor_visible(bool visible) = 0;
     virtual void set_virtual_keyboard_visible(bool visible) = 0;
+    virtual void display_file(std::string_view path) = 0;
+    virtual void share_file(std::string_view path) = 0;
 };
 
 }
diff --git a/tests/platform_api/platform_services_tests.cpp b/tests/platform_api/platform_services_tests.cpp
index 00b2352..f4fdb78 100644
--- a/tests/platform_api/platform_services_tests.cpp
+++ b/tests/platform_api/platform_services_tests.cpp
@@ -39,12 +39,28 @@ public:
         keyboard_visible = visible;
     }
 
+    void display_file(std::string_view path) override
+    {
+        ++display_file_requests;
+        displayed_path.assign(path);
+    }
+
+    void share_file(std::string_view path) override
+    {
+        ++share_file_requests;
+        shared_path.assign(path);
+    }
+
     int clipboard_reads = 0;
     int clipboard_writes = 0;
     int cursor_updates = 0;
     int keyboard_updates = 0;
+    int display_file_requests = 0;
+    int share_file_requests = 0;
     bool cursor_visible = false;
     bool keyboard_visible = false;
+    std::string displayed_path;
+    std::string shared_path;
 
 private:
     std::string clipboard_value_;
@@ -88,6 +104,20 @@ void platform_services_dispatch_visibility_updates(pp::tests::Harness& harness)
     PP_EXPECT(harness, !fake.keyboard_visible);
 }
 
+void platform_services_dispatch_file_actions(pp::tests::Harness& harness)
+{
+    FakePlatformServices fake("unused");
+    pp::platform::PlatformServices& services = fake;
+
+    services.display_file("D:/Paint/export.png");
+    services.share_file("D:/Paint/demo.ppi");
+
+    PP_EXPECT(harness, fake.display_file_requests == 1);
+    PP_EXPECT(harness, fake.share_file_requests == 1);
+    PP_EXPECT(harness, fake.displayed_path == "D:/Paint/export.png");
+    PP_EXPECT(harness, fake.shared_path == "D:/Paint/demo.ppi");
+}
+
 }
 
 int main()
@@ -96,5 +126,6 @@ int main()
     harness.run("platform services dispatch clipboard reads and writes", platform_services_dispatch_clipboard_reads_and_writes);
     harness.run("platform services preserve empty clipboard writes", platform_services_preserve_empty_clipboard_writes);
     harness.run("platform services dispatch visibility updates", platform_services_dispatch_visibility_updates);
+    harness.run("platform services dispatch file actions", platform_services_dispatch_file_actions);
     return harness.finish();
 }