diff --git a/CHANGELOG.md b/CHANGELOG.md
index b27da79..1e74e6f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 - Optional `config :desktop, :backend, :auto | :wx | :json | :browser` override
 - Menu adapters: `Desktop.Menu.Adapter.Json` and `Desktop.Menu.Adapter.Browser`
 - Public `Desktop.*` APIs unchanged (`Desktop.Window`, `Desktop.Env`, `Desktop.Menu`, etc.)
+- `Desktop.Platform.System.os_description/0` — backend-safe replacement for `:wx_misc.getOsDescription/0` (Wx, Json bridge, Browser)
 - Test suite: `mix test.fast`, `xvfb-run mix test.wx`, `mix test.guard` — see `docs/TEST_PLAN.md`
 - Compile without OTP `:wx`: conditional `erl_src_paths` and `Desktop.Wx` fallbacks (no `wx.hrl` required)
 
diff --git a/guides/faq.md b/guides/faq.md
index d73f0bd..1899dae 100644
--- a/guides/faq.md
+++ b/guides/faq.md
@@ -48,6 +48,8 @@ Inspect what the active backend supports:
 ```elixir
 Desktop.Platform.backend()       # e.g. Desktop.Backend.Wx
 Desktop.Platform.capabilities()  # %{window: true, content: :webview, ...}
+Desktop.Platform.System.locale()
+Desktop.Platform.System.os_description()  # replaces :wx_misc.getOsDescription/0
 ```
 
 | Backend | `window` | `content` | `menu` |
diff --git a/lib/desktop/backend/browser.ex b/lib/desktop/backend/browser.ex
index 97fa2eb..50c2116 100644
--- a/lib/desktop/backend/browser.ex
+++ b/lib/desktop/backend/browser.ex
@@ -45,6 +45,9 @@ defmodule Desktop.Backend.Browser do
   @impl true
   def open_external_url(url), do: Desktop.Impl.HostBrowser.open(url)
 
+  @impl true
+  def os_description, do: nil
+
   @impl true
   def activate_event_active?(_event), do: true
 
diff --git a/lib/desktop/backend/json.ex b/lib/desktop/backend/json.ex
index 88918f7..f8b4f30 100644
--- a/lib/desktop/backend/json.ex
+++ b/lib/desktop/backend/json.ex
@@ -77,6 +77,11 @@ defmodule Desktop.Backend.Json do
     :ok
   end
 
+  @impl true
+  def os_description do
+    Protocol.call(:wx_misc, :getOsDescription, [])
+  end
+
   @impl true
   def activate_event_active?(_event), do: true
 
diff --git a/lib/desktop/backend/wx.ex b/lib/desktop/backend/wx.ex
index 219fbb1..de077cf 100644
--- a/lib/desktop/backend/wx.ex
+++ b/lib/desktop/backend/wx.ex
@@ -75,6 +75,11 @@ defmodule Desktop.Backend.Wx do
     end
   end
 
+  @impl true
+  def os_description do
+    Null.wx_call(:wx_misc, :getOsDescription, [])
+  end
+
   @impl true
   def activate_event_active?(event) do
     if function_exported?(:wxActivateEvent, :getActive, 1) do
diff --git a/lib/desktop/bridge/mock.ex b/lib/desktop/bridge/mock.ex
index 9f154fc..4573b42 100644
--- a/lib/desktop/bridge/mock.ex
+++ b/lib/desktop/bridge/mock.ex
@@ -14,6 +14,7 @@ defmodule Desktop.Bridge.Mock do
   def handle_method([:wx, :getObjectType, [arg]]), do: Keyword.get(arg, :type)
   def handle_method([:wxLocale | _]), do: ~c"en"
   def handle_method([:wx_misc, :launchDefaultBrowser | _]), do: :ok
+  def handle_method([:wx_misc, :getOsDescription | _]), do: ~c"Mock OS"
 
   def handle_method([type, :new | args]),
     do: [id: System.unique_integer([:positive]), type: type, args: args]
diff --git a/lib/desktop/platform/system.ex b/lib/desktop/platform/system.ex
index c53876a..746f893 100644
--- a/lib/desktop/platform/system.ex
+++ b/lib/desktop/platform/system.ex
@@ -17,6 +17,7 @@ defmodule Desktop.Platform.System do
               term()
   @callback wx_available?() :: boolean()
   @callback open_external_url(String.t()) :: :ok
+  @callback os_description() :: String.t() | charlist() | nil
   @callback activate_event_active?(event :: term()) :: boolean()
 
   def init_env, do: impl().init_env()
@@ -32,6 +33,34 @@ defmodule Desktop.Platform.System do
   def wx_available?, do: impl().wx_available?()
   def open_external_url(url), do: Helpers.with_wx_env(fn -> impl().open_external_url(url) end)
 
+  @doc """
+  Returns a human-readable OS / device description string.
+
+  Replaces direct `:wx_misc.getOsDescription/0` calls so apps work on all
+  backends (Wx, Json/mobile bridge, Browser). Returns `nil` when unavailable.
+  """
+  def os_description do
+    raw =
+      Helpers.with_wx_env(fn ->
+        case impl().os_description() do
+          desc when is_binary(desc) -> desc
+          desc when is_list(desc) -> List.to_string(desc)
+          _ -> nil
+        end
+      end)
+
+    case raw do
+      nil ->
+        nil
+
+      str ->
+        case String.trim(str) do
+          "" -> nil
+          trimmed -> trimmed
+        end
+    end
+  end
+
   def activate_event_active?(event),
     do: Helpers.with_wx_env(fn -> impl().activate_event_active?(event) end)
 
diff --git a/test/desktop/backend/browser_test.exs b/test/desktop/backend/browser_test.exs
index 49c09f6..3e013e9 100644
--- a/test/desktop/backend/browser_test.exs
+++ b/test/desktop/backend/browser_test.exs
@@ -37,6 +37,7 @@ defmodule Desktop.Backend.BrowserTest do
     assert :ok = Browser.set_env(nil)
     assert Browser.get_env() == nil
     assert Browser.locale() == nil
+    assert Browser.os_description() == nil
     refute Browser.wx_available?()
   end
 end
diff --git a/test/desktop/backend/json_test.exs b/test/desktop/backend/json_test.exs
index 9545256..04e5297 100644
--- a/test/desktop/backend/json_test.exs
+++ b/test/desktop/backend/json_test.exs
@@ -27,6 +27,11 @@ defmodule Desktop.Backend.JsonTest do
     assert Json.locale() == "en"
   end
 
+  test "T-JSN: os_description via bridge RPC" do
+    assert Json.os_description() == ~c"Mock OS"
+    assert Desktop.Platform.System.os_description() == "Mock OS"
+  end
+
   test "T-JSN: new frame handle shape" do
     wx = Transport.ensure_started()
 
diff --git a/test/desktop/backend/wx_test.exs b/test/desktop/backend/wx_test.exs
index 6bed0db..5fb6260 100644
--- a/test/desktop/backend/wx_test.exs
+++ b/test/desktop/backend/wx_test.exs
@@ -39,4 +39,9 @@ defmodule Desktop.Backend.WxTest do
     result = Wx.locale()
     assert result == nil or is_binary(result)
   end
+
+  test "T-WX: os_description via Platform.System" do
+    result = Desktop.Platform.System.os_description()
+    assert result == nil or is_binary(result)
+  end
 end
diff --git a/test/desktop/platform_system_test.exs b/test/desktop/platform_system_test.exs
new file mode 100644
index 0000000..d6ecb71
--- /dev/null
+++ b/test/desktop/platform_system_test.exs
@@ -0,0 +1,43 @@
+defmodule Desktop.Platform.SystemTest do
+  use ExUnit.Case, async: false
+
+  alias Desktop.Platform.System, as: PlatformSystem
+
+  defmodule StubBackend do
+    # Minimal stand-in: Platform.System.os_description/0 uses with_wx_env/1, which may
+    # call set_env/1 when Desktop.Env is up.
+    def set_env(_env), do: :ok
+    def os_description, do: Process.get(:stub_os_description)
+  end
+
+  setup do
+    previous = Application.get_env(:desktop, :backend, :auto)
+    Application.put_env(:desktop, :backend, StubBackend)
+
+    on_exit(fn ->
+      Application.put_env(:desktop, :backend, previous)
+      Process.delete(:stub_os_description)
+    end)
+
+    :ok
+  end
+
+  test "os_description normalizes charlist and binary" do
+    Process.put(:stub_os_description, ~c"Mock OS")
+    assert PlatformSystem.os_description() == "Mock OS"
+
+    Process.put(:stub_os_description, "Linux Desktop")
+    assert PlatformSystem.os_description() == "Linux Desktop"
+  end
+
+  test "os_description trims blank values to nil" do
+    Process.put(:stub_os_description, "   ")
+    assert PlatformSystem.os_description() == nil
+
+    Process.put(:stub_os_description, ~c"")
+    assert PlatformSystem.os_description() == nil
+
+    Process.put(:stub_os_description, nil)
+    assert PlatformSystem.os_description() == nil
+  end
+end
diff --git a/test/desktop/regression/beam_wx_calls_test.exs b/test/desktop/regression/beam_wx_calls_test.exs
index 8a5d1ad..3de0832 100644
--- a/test/desktop/regression/beam_wx_calls_test.exs
+++ b/test/desktop/regression/beam_wx_calls_test.exs
@@ -31,6 +31,11 @@ defmodule Desktop.Regression.BeamWxCallsTest do
     assert Json.locale() == "en"
   end
 
+  test "os_description uses bridge RPC not OTP :wx_misc" do
+    assert Json.os_description() == ~c"Mock OS"
+    assert PlatformSystem.os_description() == "Mock OS"
+  end
+
   test "open_external_url on Json uses bridge RPC" do
     assert :ok = Json.open_external_url("https://example.com")
     assert :ok = PlatformSystem.open_external_url("https://example.com")
diff --git a/test/support/guard_platform_abstraction.exs b/test/support/guard_platform_abstraction.exs
index 5001b23..3b2ba0c 100644
--- a/test/support/guard_platform_abstraction.exs
+++ b/test/support/guard_platform_abstraction.exs
@@ -17,7 +17,9 @@ forbidden_patterns = [
   {~r/ensure_wx_env/,
    "use Desktop.Platform.Helpers.with_wx_env/1 via Platform facades, not ensure_wx_env"},
   {~r/:wxLocale\.getSystemLanguage\s*\(/,
-   "Json/mobile: pass :getSystemLanguage as a bridge atom to Protocol, never :wxLocale.getSystemLanguage/0"}
+   "Json/mobile: pass :getSystemLanguage as a bridge atom to Protocol, never :wxLocale.getSystemLanguage/0"},
+  {~r/:wx_misc\.getOsDescription\s*\(/,
+   "use Desktop.Platform.System.os_description/0 instead of :wx_misc.getOsDescription/0"}
 ]
 
 violations =