Add native appearance, screenshot and wallpaper portals

Cargo.lock

@@ -2186,6 +2186,16 @@ dependencies = [
  "weezl",
 ]
 
+[[package]]
+name = "gif"
+version = "0.14.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee8cfcc411d9adbbaba82fb72661cc1bcca13e8bba98b364e62b2dba8f960159"
+dependencies = [
+ "color_quant",
+ "weezl",
+]
+
 [[package]]
 name = "gio-sys"
 version = "0.21.5"
@@ -2921,6 +2931,8 @@ checksum = "85ab80394333c02fe689eaf900ab500fbd0c2213da414687ebf995a65d5a6104"
 dependencies = [
  "bytemuck",
  "byteorder-lite",
+ "color_quant",
+ "gif 0.14.2",
  "image-webp",
  "moxcms",
  "num-traits",
@@ -4883,7 +4895,7 @@ version = "0.45.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a8928798c0a55e03c9ca6c4c6846f76377427d2c1e1f7e6de3c06ae57942df43"
 dependencies = [
- "gif",
+ "gif 0.13.3",
  "image-webp",
  "log",
  "pico-args",
@@ -7402,19 +7414,24 @@ version = "0.1.0"
 dependencies = [
  "dirs",
  "ferese-config",
+ "ferese-ipc",
  "ferese-theme",
  "futures-util",
  "gstreamer",
+ "image",
  "jiff",
  "libc",
  "libcosmic",
  "memmap2 0.9.11",
  "pipewire",
+ "png 0.18.1",
  "serde",
  "serde_json",
  "tempfile",
  "tokio",
+ "url",
  "wayland-client",
+ "wayland-protocols",
  "wayland-protocols-wlr",
  "zbus",
 ]

README.md

@@ -104,6 +104,7 @@ Settings → Shortcuts** to change them or assign gestures to other actions.
 - [Desktop widgets](docs/desktop-widgets.md)
 - [Notifications](docs/notifications.md)
 - [Native locker](docs/locking.md)
+- [Desktop portals and compatibility](docs/portals.md)
 - [Screen sharing and recording](docs/screen-sharing.md)
 
 ## Development

compositor/src/ipc.rs

@@ -341,6 +341,17 @@ impl Ferese {
             "expel" => self.expel_focused_window(),
             "close" => self.close_focused_window(),
             "get-focused-window" => return Ok(self.focused_window_json()),
+            "get-windows" => return Ok(self.windows_json()),
+            "has-client-surfaces" => {
+                let pid = args
+                    .get("pid")
+                    .and_then(Value::as_u64)
+                    .and_then(|pid| u32::try_from(pid).ok())
+                    .ok_or_else(|| {
+                        CommandError::new("invalid_argument", "pid must be an unsigned process ID")
+                    })?;
+                return Ok(json!(self.has_client_surfaces(pid)));
+            }
             "get-workspaces" => return Ok(self.workspaces_json()),
             "get-outputs" => return Ok(self.outputs_json()),
             _ => {
@@ -506,6 +517,64 @@ impl Ferese {
             .unwrap_or(Value::Null)
     }
 
+    fn has_client_surfaces(&self, pid: u32) -> bool {
+        use smithay::reexports::wayland_server::Resource;
+        let belongs_to =
+            |surface: &smithay::reexports::wayland_server::protocol::wl_surface::WlSurface| {
+                surface
+                    .client()
+                    .and_then(|client| client.get_credentials(&self.display_handle).ok())
+                    .is_some_and(|credentials| credentials.pid as u32 == pid)
+            };
+        self.window_ids
+            .keys()
+            .filter_map(|window| window.toplevel())
+            .any(|toplevel| belongs_to(toplevel.wl_surface()))
+            || self.space.outputs().any(|output| {
+                smithay::desktop::layer_map_for_output(output)
+                    .layers()
+                    .any(|layer| belongs_to(layer.wl_surface()))
+            })
+    }
+
+    fn windows_json(&self) -> Value {
+        use smithay::wayland::{compositor::with_states, shell::xdg::XdgToplevelSurfaceData};
+        let mut windows = self
+            .window_ids
+            .iter()
+            .filter_map(|(window, id)| {
+                let toplevel = window.toplevel()?;
+                let (app_id, title) = with_states(toplevel.wl_surface(), |states| {
+                    let attributes = states
+                        .data_map
+                        .get::<XdgToplevelSurfaceData>()
+                        .unwrap()
+                        .lock()
+                        .unwrap();
+                    (
+                        attributes.app_id.clone().unwrap_or_default(),
+                        attributes.title.clone().unwrap_or_default(),
+                    )
+                });
+                let rect = self.visual_rect_for_window(window)?;
+                Some(json!({
+                    "id": id.0,
+                    "app_id": app_id,
+                    "title": title,
+                    "focused": self.focused_window == Some(*id),
+                    "mapped": self.space.element_location(window).is_some(),
+                    "workspace": self.workspaces.workspace_for_window(*id).map(|workspace| workspace.0),
+                    "x": rect.loc.x,
+                    "y": rect.loc.y,
+                    "width": rect.size.w,
+                    "height": rect.size.h,
+                }))
+            })
+            .collect::<Vec<_>>();
+        windows.sort_by_key(|window| window["id"].as_u64());
+        Value::Array(windows)
+    }
+
     fn workspaces_json(&self) -> Value {
         let active = self.workspaces.active_id();
         let workspaces = self

compositor/src/window_rules.rs

@@ -73,7 +73,12 @@ pub fn resolve(
     let mut result = WindowRuleResult::default();
     if matches!(
         app_id.as_deref(),
-        Some("dev.ferese.authentication" | "dev.ferese.screenshare" | "dev.ferese.screenshot")
+        Some(
+            "dev.ferese.authentication"
+                | "dev.ferese.screenshare"
+                | "dev.ferese.screenshot"
+                | "dev.ferese.portaldialog"
+        )
     ) {
         result.floating = Some(true);
     }
@@ -217,6 +222,7 @@ mod tests {
     #[test]
     fn native_dialogs_float_by_default_and_allow_user_overrides() {
         for app_id in [
+            "dev.ferese.PortalDialog",
             "dev.ferese.ScreenShare",
             "dev.ferese.ScreenShare.desktop",
             "dev.ferese.Authentication",

docs/installation.md

@@ -13,7 +13,7 @@ desktop instead of direct access to the graphics device.
 
 Build with **Rust 1.95 or newer**, a C/C++ toolchain, CMake, pkg-config, and the
 native development libraries below. The installer builds Ferese, its shell,
-Settings, command-line tools, locker, polkit agent, and ScreenCast portal together. It does not install system
+Settings, command-line tools, locker, polkit agent, and desktop portal backend together. It does not install system
 packages or enable background services at boot. On systemd systems, the installed
 session helper activates `ferese-session.target` after exporting the compositor's
 Wayland display, and stops it when the shell exits. This keeps
@@ -105,7 +105,7 @@ The installer adds:
 - Commands under `/usr/local/bin/`, including `ferese-session`, `ferese-settings`,
   `feresectl`, `ferese-lock`, `ferese-polkit-agent`, `ferese-screenshot`, and
   `xdg-desktop-portal-ferese`, and `ferese-record`.
-- D-Bus activation and Ferese-specific ScreenCast portal registration.
+- D-Bus activation and Ferese-specific desktop portal registration.
 - A Wayland session entry at `/usr/share/wayland-sessions/ferese.desktop`.
 - A Settings application entry, icons, the default wallpaper, and an example config.
 - `/etc/pam.d/ferese-lock`, using your distribution's authentication stack.

docs/portals.md

@@ -0,0 +1,80 @@
+# Desktop portals
+
+Applications call the standard `org.freedesktop.portal.Desktop` frontend. Ferese's
+native backend implements desktop integration; GTK remains the fallback for
+standard file, print and application dialogs. Install both backends.
+
+## Native services
+
+- **Settings:** Ferese's color scheme, accent color, contrast preference and
+  reduced-motion setting. Changes are signalled after valid KDL appearance
+  changes; malformed saves leave the last valid preferences intact.
+- **Screenshot:** whole-screen and selected-area PNG captures, plus a screen
+  color picker. Every capture asks for consent. Interactive requests offer area
+  selection. Selection uses `slurp`; captures use Ferese's bounded screenshot IPC.
+  The helper must disappear from the compositor before capture starts.
+- **Wallpaper:** a preview and confirmation, then an atomic configuration update.
+  Desktop and lock-screen wallpaper can be set independently, or together.
+  Ferese copies accepted local images into its own private data directory so
+  temporary portal files can disappear safely. Image bytes and decoded dimensions
+  are bounded. `theme.background.lock-path` overrides the lock-screen image;
+  without it the lock screen follows `theme.background.path`.
+- **ScreenCast:** monitor sharing with a native picker and PipeWire streams.
+  See [screen sharing](screen-sharing.md) for lifetime and recording details.
+
+Native request dialogs use Ferese's theme and are floating windows. Screenshot,
+PickColor and Wallpaper consent dialogs use Wayland parent identifiers to establish
+a transient relationship with the requesting window.
+Cancelling a request or losing the portal frontend terminates its pending helper.
+
+The packaged `ferese-portals.conf` selects these interfaces explicitly. Existing
+user overrides in `~/.config/xdg-desktop-portal/` may take precedence. Install the
+new compositor, backend and preference files together; screenshot synchronization
+requires the updated compositor IPC.
+
+## GNOME compatibility audit
+
+The audit compares the [GNOME backend's registered interfaces](https://github.com/GNOME/xdg-desktop-portal-gnome/blob/main/data/meson.build)
+with the [standard backend D-Bus contracts](https://flatpak.github.io/xdg-desktop-portal/docs/impl-dbus-interfaces.html).
+Matching D-Bus signatures does not establish complete feature parity.
+
+| Interface | Ferese integration |
+| --- | --- |
+| Settings | Native, including appearance change signals |
+| Screenshot | Native screen/area capture and PickColor; true window capture remains missing |
+| Wallpaper | Native desktop, lock-screen and combined targets |
+| ScreenCast | Native monitors; window sources, persistence and richer metadata remain missing |
+| Access, Account, AppChooser, DynamicLauncher, FileChooser, Notification, Print | Delegated to GTK |
+| Background | Missing native application state and background consent |
+| Usb | Missing native device consent |
+| GlobalShortcuts | Missing session-scoped compositor registration and activation signals |
+| RemoteDesktop | Missing authorized input injection and EIS transport |
+| Clipboard | Missing remote-session clipboard transfer |
+| InputCapture | Missing zones, pointer barriers and EIS transport |
+| Lockdown | GTK availability depends on the installed build; no native policy provider |
+| Inhibit | GTK's GNOME-session/ScreenSaver integration does not provide complete Ferese session inhibition |
+
+The frontend supplies additional APIs such as OpenURI, network monitoring,
+document export and permission storage. Adding a similarly named backend service
+is neither required nor sufficient for those APIs.
+
+Do not advertise window capture or input services until the compositor provides
+the corresponding operation. Screen crops include occluding windows and cannot
+serve as isolated window captures. GNOME's remote-input features require native
+compositor/session work, rather than substituting successful empty replies.
+
+## Validation
+
+Build the backend and run unit tests, then check its contracts on a private bus:
+
+```sh
+cargo build --locked -p xdg-desktop-portal-ferese
+cargo test --locked -p xdg-desktop-portal-ferese
+python3 scripts/tests/test_portal_contracts.py
+```
+
+The contract test compares introspection against the installed official backend
+XML, verifies appearance changes and invalid-save retention, and checks that
+sensitive methods reject callers outside the portal frontend. It does not open
+consent dialogs or capture the host desktop. Interactive consent, fractional-scale
+capture, polkit and hotplug still require a live session test.

docs/screen-sharing.md

@@ -47,7 +47,9 @@ The [standard installer](installation.md) builds and installs the backend, its
 D-Bus activation entry, and a Ferese-specific portal preference file. Install
 `pipewire`, a PipeWire session manager such as `wireplumber`,
 `xdg-desktop-portal`, and `xdg-desktop-portal-gtk` using your distribution's package
-manager. The GTK backend supplies other portal interfaces such as file selection.
+manager. The GTK backend supplies standard dialogs such as file selection. Ferese also
+provides native Settings, Screenshot and Wallpaper services; see
+[desktop portals](portals.md).
 The built-in recorder also needs GStreamer’s PipeWire, base, and good plugins
 (`pipewiresrc`, `videoconvert`, `vp8enc`, and `webmmux`). The installation guide
 includes these packages.

feresectl/src/main.rs

@@ -88,8 +88,8 @@ fn parse_args(args: impl IntoIterator<Item = String>) -> Result<(String, Value),
         },
         "toggle-floating" | "toggle-fullscreen" | "toggle-maximized" | "toggle-layout"
         | "toggle-overview" | "cycle-column-width" | "center-column" | "consume" | "expel"
-        | "close" | "get-focused-window" | "get-workspaces" | "get-outputs" | "reload-config"
+        | "close" | "get-focused-window" | "get-windows" | "get-workspaces" | "get-outputs"
-        | "exit" | "request-logout" => {
+        | "reload-config" | "exit" | "request-logout" => {
             if !positional.is_empty() {
                 return Err(format!("{command} does not accept arguments"));
             }
@@ -118,7 +118,7 @@ fn socket_path() -> Result<PathBuf, io::Error> {
 }
 
 fn usage() -> String {
-    "usage: feresectl screenshot [--geometry \"x,y WxH\"]\n       feresectl <focus|move|resize> <direction>\n       feresectl <workspace|move-to-workspace> <index>\n       feresectl <toggle-floating|toggle-maximized|toggle-fullscreen|toggle-layout|toggle-overview>\n       feresectl <cycle-column-width|center-column|consume|expel|close|exit|request-logout>\n       feresectl <get-focused-window|get-workspaces|get-outputs|reload-config>".to_owned()
+    "usage: feresectl screenshot [--geometry \"x,y WxH\"]\n       feresectl <focus|move|resize> <direction>\n       feresectl <workspace|move-to-workspace> <index>\n       feresectl <toggle-floating|toggle-maximized|toggle-fullscreen|toggle-layout|toggle-overview>\n       feresectl <cycle-column-width|center-column|consume|expel|close|exit|request-logout>\n       feresectl <get-focused-window|get-windows|get-workspaces|get-outputs|reload-config>".to_owned()
 }
 
 #[cfg(test)]

packaging/portal/ferese-portals.conf

@@ -1,3 +1,6 @@
 [preferred]
 default=gtk;
 org.freedesktop.impl.portal.ScreenCast=ferese;
+org.freedesktop.impl.portal.Settings=ferese;
+org.freedesktop.impl.portal.Screenshot=ferese;
+org.freedesktop.impl.portal.Wallpaper=ferese;

packaging/portal/ferese.portal

@@ -1,4 +1,4 @@
 [portal]
 DBusName=org.freedesktop.impl.portal.desktop.ferese
-Interfaces=org.freedesktop.impl.portal.ScreenCast;
+Interfaces=org.freedesktop.impl.portal.ScreenCast;org.freedesktop.impl.portal.Settings;org.freedesktop.impl.portal.Screenshot;org.freedesktop.impl.portal.Wallpaper;
 UseIn=Ferese;

portal/Cargo.toml

@@ -14,6 +14,11 @@ name = "ferese-record"
 path = "src/record_main.rs"
 
 [dependencies]
+ferese-ipc = { path = "../crates/ferese-ipc" }
+url = "2.5"
+png = "0.18"
+image = { version = "0.25", default-features = false, features = ["png", "jpeg", "webp", "gif"] }
+tempfile.workspace = true
 ferese-theme = { path = "../crates/ferese-theme" }
 gstreamer = "0.24"
 futures-util = "0.3"
@@ -28,8 +33,6 @@ serde.workspace = true
 serde_json.workspace = true
 tokio = { version = "1", features = ["rt-multi-thread", "macros", "time", "sync", "process", "io-util"] }
 wayland-client.workspace = true
+wayland-protocols = { version = "0.32", features = ["client", "unstable"] }
 wayland-protocols-wlr.workspace = true
 zbus = { version = "5.19.0", default-features = false, features = ["tokio"] }
-
-[dev-dependencies]
-tempfile.workspace = true

portal/src/backend.rs

@@ -25,8 +25,7 @@ use zbus::{
     object_server::SignalEmitter,
     zvariant::{OwnedObjectPath, OwnedValue, Value},
 };
-type Options = HashMap<String, OwnedValue>;
+pub(crate) type Options = HashMap<String, OwnedValue>;
-type Reply = (u32, Options);
 #[derive(Debug)]
 enum StartError {
     Cancelled,
@@ -45,16 +44,16 @@ impl From<&str> for StartError {
 const FRONTEND: &str = "org.freedesktop.portal.Desktop";
 const PATH: &str = "/org/freedesktop/portal/desktop";
 #[derive(Default)]
-struct Cancel {
+pub(crate) struct Cancel {
-    stopped: AtomicBool,
+    pub(crate) stopped: AtomicBool,
     changed: Notify,
 }
 impl Cancel {
-    fn stop(&self) {
+    pub(crate) fn stop(&self) {
         self.stopped.store(true, Ordering::SeqCst);
         self.changed.notify_one();
     }
-    async fn wait(&self) {
+    pub(crate) async fn wait(&self) {
         if !self.stopped.load(Ordering::SeqCst) {
             self.changed.notified().await;
         }
@@ -147,7 +146,10 @@ fn shell_recorder(pid: u32) -> bool {
     parent.is_some_and(|pid| matches_binary(pid, "ferese-shell") == Some(true))
 }
 
-async fn authorize(connection: &Connection, header: &Header<'_>) -> zbus::fdo::Result<String> {
+pub(crate) async fn authorize(
+    connection: &Connection,
+    header: &Header<'_>,
+) -> zbus::fdo::Result<String> {
     let sender = header
         .sender()
         .ok_or_else(|| zbus::fdo::Error::AccessDenied("Missing caller".into()))?;
@@ -155,7 +157,7 @@ async fn authorize(connection: &Connection, header: &Header<'_>) -> zbus::fdo::R
     let owner = dbus.get_name_owner(FRONTEND.try_into().unwrap()).await?;
     if sender.as_str() != owner.as_str() {
         return Err(zbus::fdo::Error::AccessDenied(
-            "Use the ScreenCast desktop portal".into(),
+            "Use the desktop portal".into(),
         ));
     }
     Ok(sender.to_string())
@@ -230,7 +232,7 @@ impl Backend {
         _options: Options,
         #[zbus(connection)] connection: &Connection,
         #[zbus(header)] header: Header<'_>,
-    ) -> zbus::fdo::Result<Reply> {
+    ) -> zbus::fdo::Result<(u32, Options)> {
         let owner = authorize(connection, &header).await?;
         if !session_handle
             .as_str()
@@ -281,7 +283,7 @@ impl Backend {
         options: Options,
         #[zbus(connection)] connection: &Connection,
         #[zbus(header)] header: Header<'_>,
-    ) -> zbus::fdo::Result<Reply> {
+    ) -> zbus::fdo::Result<(u32, Options)> {
         let owner = authorize(connection, &header).await?;
         let settings = source_options(&options);
         let mut sessions = self.sessions.lock().await;
@@ -318,7 +320,7 @@ impl Backend {
         _options: Options,
         #[zbus(connection)] connection: &Connection,
         #[zbus(header)] header: Header<'_>,
-    ) -> zbus::fdo::Result<Reply> {
+    ) -> zbus::fdo::Result<(u32, Options)> {
         let owner = authorize(connection, &header).await?;
         if !handle
             .as_str()
@@ -413,9 +415,9 @@ impl Backend {
         }
     }
 }
-struct Request {
+pub(crate) struct Request {
-    cancel: Arc<Cancel>,
+    pub(crate) cancel: Arc<Cancel>,
-    owner: String,
+    pub(crate) owner: String,
 }
 #[zbus::interface(name = "org.freedesktop.impl.portal.Request")]
 impl Request {
@@ -449,8 +451,12 @@ impl SessionObject {
     async fn closed(emitter: &SignalEmitter<'_>) -> zbus::Result<()>;
 }
 // All helpers die with the service, including a picker awaiting user input.
-fn child_command() -> Result<Command, String> {
+pub(crate) fn child_command() -> Result<Command, String> {
-    let mut command = Command::new(std::env::current_exe().map_err(|e| e.to_string())?);
+    child_command_for(std::env::current_exe().map_err(|e| e.to_string())?)
+}
+
+pub(crate) fn child_command_for(program: impl AsRef<std::ffi::OsStr>) -> Result<Command, String> {
+    let mut command = Command::new(program);
     let parent = std::process::id() as libc::pid_t;
     // SAFETY: only async-signal-safe libc calls run between fork and exec.
     unsafe {
@@ -585,21 +591,24 @@ async fn supervise(mut children: Vec<Child>, cancel: Arc<Cancel>) {
 }
 pub async fn run() -> Result<(), Box<dyn std::error::Error>> {
     let backend = Backend::default();
+    let settings = crate::settings::Settings::new();
+    let requests = crate::desktop::Requests::default();
     let connection = zbus::connection::Builder::session()?
         .name("org.freedesktop.impl.portal.desktop.ferese")?
         .serve_at(PATH, backend.clone())?
+        .serve_at(PATH, settings.clone())?
+        .serve_at(PATH, crate::desktop::Screenshot(requests.clone()))?
+        .serve_at(PATH, crate::desktop::Wallpaper(requests.clone()))?
         .serve_at(
             "/org/ferese/ScreenRecorder",
             RecorderControl(backend.clone()),
         )?
         .build()
         .await?;
+    tokio::spawn(settings.watch(connection.clone()));
     // Frontend death must revoke every stream, even if Session.Close never arrives.
     loop {
         tokio::time::sleep(Duration::from_secs(1)).await;
-        if backend.sessions.lock().await.is_empty() {
-            continue;
-        }
         let owner = match zbus::fdo::DBusProxy::new(&connection).await {
             Ok(proxy) => proxy
                 .get_name_owner(FRONTEND.try_into().unwrap())
@@ -608,6 +617,7 @@ pub async fn run() -> Result<(), Box<dyn std::error::Error>> {
                 .map(|name| name.to_string()),
             Err(_) => None,
         };
+        requests.revoke_stale(owner.as_deref()).await;
         let stale: Vec<_> = backend
             .sessions
             .lock()

portal/src/consent.rs

@@ -0,0 +1,183 @@
+use cosmic::{
+    Element,
+    app::{Core, Settings, Task},
+    iced::{Alignment, Length},
+    widget::{button, column, container, image, row, scrollable},
+};
+use serde::{Deserialize, Serialize};
+use std::io::{Read, Write};
+
+#[derive(Clone, Serialize, Deserialize)]
+pub(crate) struct Prompt {
+    pub title: String,
+    pub description: String,
+    pub accept: String,
+    pub parent: String,
+    pub image: Option<std::path::PathBuf>,
+}
+
+#[derive(Clone, Debug)]
+enum Message {
+    Opened(cosmic::iced::window::Id),
+    Attached(
+        Result<
+            (
+                Option<std::sync::Arc<crate::parent::Parent>>,
+                Result<ferese_theme::material::ModalMaterial, String>,
+            ),
+            String,
+        >,
+    ),
+    Accept,
+    Cancel,
+}
+
+struct Consent {
+    core: Core,
+    prompt: Prompt,
+    material: Option<ferese_theme::material::ModalMaterial>,
+    parent: Option<std::sync::Arc<crate::parent::Parent>>,
+    palette: ferese_theme::Palette,
+    font: cosmic::font::Font,
+    background: cosmic::iced::Color,
+}
+
+pub(crate) fn run() -> Result<(), Box<dyn std::error::Error>> {
+    let mut input = String::new();
+    std::io::stdin()
+        .take(64 * 1024)
+        .read_to_string(&mut input)?;
+    let prompt: Prompt = serde_json::from_str(&input)?;
+    let (theme, font, background, _) = crate::picker::appearance();
+    let height = if prompt.image.is_some() { 430. } else { 220. };
+    cosmic::app::run::<Consent>(
+        Settings::default()
+            .size(cosmic::iced::Size::new(440., height))
+            .client_decorations(false)
+            .transparent(true)
+            .theme(theme)
+            .default_font(font)
+            .default_text_size(14.)
+            .is_daemon(false),
+        (prompt, font, background),
+    )?;
+    Ok(())
+}
+
+impl cosmic::Application for Consent {
+    type Executor = cosmic::executor::Default;
+    type Flags = (Prompt, cosmic::font::Font, cosmic::iced::Color);
+    type Message = Message;
+    const APP_ID: &'static str = "dev.ferese.PortalDialog";
+
+    fn core(&self) -> &Core {
+        &self.core
+    }
+    fn core_mut(&mut self) -> &mut Core {
+        &mut self.core
+    }
+
+    fn init(mut core: Core, (prompt, font, background): Self::Flags) -> (Self, Task<Message>) {
+        core.window.show_headerbar = false;
+        core.window.border_padding = Some(0);
+        core.window.content_container = false;
+        let app = Self {
+            core,
+            prompt,
+            material: None,
+            parent: None,
+            palette: {
+                let document = ferese_config::config_path()
+                    .and_then(|path| std::fs::read_to_string(path).ok())
+                    .and_then(|source| ferese_config::Document::parse(&source).ok());
+                ferese_theme::Palette::from_document(document.as_ref())
+            },
+            font,
+            background,
+        };
+        (app, Task::none())
+    }
+
+    fn subscription(&self) -> cosmic::iced::Subscription<Message> {
+        cosmic::iced::event::listen_with(|event, _, id| match event {
+            cosmic::iced::Event::Window(cosmic::iced::window::Event::Opened { .. }) => {
+                Some(Message::Opened(id))
+            }
+            cosmic::iced::Event::Keyboard(cosmic::iced::keyboard::Event::KeyPressed {
+                key: cosmic::iced::keyboard::Key::Named(cosmic::iced::keyboard::key::Named::Escape),
+                ..
+            }) => Some(Message::Cancel),
+            _ => None,
+        })
+    }
+
+    fn update(&mut self, message: Message) -> Task<Message> {
+        match message {
+            Message::Opened(id) => {
+                let parent = self.prompt.parent.clone();
+                return cosmic::iced::window::run(id, move |window| {
+                    let parent =
+                        crate::parent::Parent::attach(window, &parent)?.map(std::sync::Arc::new);
+                    Ok((
+                        parent,
+                        ferese_theme::material::ModalMaterial::attach(window),
+                    ))
+                })
+                .map(|result| cosmic::Action::App(Message::Attached(result)));
+            }
+            Message::Attached(Ok((parent, material))) => {
+                self.parent = parent;
+                self.material = material.ok();
+            }
+            Message::Attached(Err(error)) => {
+                eprintln!("ferese portal: {error}");
+                return cosmic::iced::exit();
+            }
+            Message::Accept => {
+                println!("true");
+                let _ = std::io::stdout().flush();
+                return cosmic::iced::exit();
+            }
+            Message::Cancel => return cosmic::iced::exit(),
+        }
+        Task::none()
+    }
+
+    fn style(&self) -> Option<cosmic::iced::theme::Style> {
+        Some(self.palette.application_style(if self.material.is_some() {
+            cosmic::iced::Color::TRANSPARENT
+        } else {
+            self.background
+        }))
+    }
+
+    fn view(&self) -> Element<'_, Message> {
+        let text = |value: String| ferese_theme::text(value, self.font);
+        let mut content = column![
+            text(self.prompt.title.clone()).size(22),
+            scrollable(text(self.prompt.description.clone())).height(Length::Fill)
+        ]
+        .spacing(16);
+        if let Some(path) = &self.prompt.image {
+            content = content.push(
+                image(image::Handle::from_path(path))
+                    .height(Length::Fill)
+                    .width(Length::Fill)
+                    .content_fit(cosmic::iced::ContentFit::Contain),
+            );
+        }
+        content = content.push(
+            row![
+                button::custom(text("Cancel".into()))
+                    .class(cosmic::theme::Button::Text)
+                    .on_press(Message::Cancel),
+                button::custom(text(self.prompt.accept.clone()))
+                    .class(ferese_theme::accent_button())
+                    .on_press(Message::Accept)
+            ]
+            .spacing(12)
+            .align_y(Alignment::Center),
+        );
+        container(content).padding(24).width(Length::Fill).into()
+    }
+}

portal/src/desktop.rs

@@ -0,0 +1,727 @@
+use crate::{
+    backend::{Cancel, Options, Request, authorize},
+    consent::Prompt,
+};
+use std::{
+    collections::HashMap,
+    io::Read,
+    os::unix::{fs::PermissionsExt, net::UnixStream},
+    path::{Path, PathBuf},
+    process::Stdio,
+    sync::{Arc, atomic::Ordering},
+    time::Duration,
+};
+use tokio::{io::AsyncWriteExt, sync::Mutex};
+use zbus::{
+    Connection,
+    message::Header,
+    zvariant::{OwnedObjectPath, Value},
+};
+
+const PATH: &str = "/org/freedesktop/portal/desktop";
+const MAX_IMAGE_BYTES: u64 = 128 * 1024 * 1024;
+type Reply = (u32, Options);
+
+#[derive(Clone, Default)]
+pub(crate) struct Requests(Arc<Mutex<HashMap<String, (String, Arc<Cancel>)>>>);
+
+impl Requests {
+    pub(crate) async fn revoke_stale(&self, owner: Option<&str>) {
+        for (request_owner, cancel) in self.0.lock().await.values() {
+            if Some(request_owner.as_str()) != owner {
+                cancel.stop();
+            }
+        }
+    }
+
+    pub(crate) async fn begin(
+        &self,
+        connection: &Connection,
+        header: &Header<'_>,
+        handle: &OwnedObjectPath,
+    ) -> zbus::fdo::Result<Arc<Cancel>> {
+        let owner = authorize(connection, header).await?;
+        if !handle.as_str().starts_with(&format!("{PATH}/request/")) {
+            return Err(zbus::fdo::Error::InvalidArgs("Invalid request path".into()));
+        }
+        let mut pending = self.0.lock().await;
+        if pending.len() >= 8 || pending.contains_key(handle.as_str()) {
+            return Err(zbus::fdo::Error::LimitsExceeded(
+                "Request limit reached".into(),
+            ));
+        }
+        let cancel = Arc::new(Cancel::default());
+        if !connection
+            .object_server()
+            .at(
+                handle,
+                Request {
+                    owner: owner.clone(),
+                    cancel: cancel.clone(),
+                },
+            )
+            .await?
+        {
+            return Err(zbus::fdo::Error::InvalidArgs(
+                "Request already exists".into(),
+            ));
+        }
+        pending.insert(handle.to_string(), (owner, cancel.clone()));
+        Ok(cancel)
+    }
+
+    pub(crate) async fn end(&self, connection: &Connection, handle: &OwnedObjectPath) {
+        self.0.lock().await.remove(handle.as_str());
+        let _ = connection
+            .object_server()
+            .remove::<Request, _>(handle)
+            .await;
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Screenshot(pub(crate) Requests);
+
+#[zbus::interface(name = "org.freedesktop.impl.portal.Screenshot")]
+impl Screenshot {
+    #[zbus(property, name = "version")]
+    fn version(&self) -> u32 {
+        3
+    }
+
+    #[zbus(property)]
+    fn available_targets(&self) -> u32 {
+        1 | 4
+    }
+
+    async fn screenshot(
+        &self,
+        handle: OwnedObjectPath,
+        app_id: String,
+        parent_window: String,
+        options: Options,
+        #[zbus(connection)] connection: &Connection,
+        #[zbus(header)] header: Header<'_>,
+    ) -> zbus::fdo::Result<(u32, Options)> {
+        let cancel = self.0.begin(connection, &header, &handle).await?;
+        let result = tokio::select! {
+            biased;
+            _ = cancel.wait() => (1, Options::new()),
+            result = screenshot(&app_id, &parent_window, &options) => reply(result),
+        };
+        self.0.end(connection, &handle).await;
+        Ok(result)
+    }
+
+    async fn pick_color(
+        &self,
+        handle: OwnedObjectPath,
+        app_id: String,
+        parent_window: String,
+        _options: Options,
+        #[zbus(connection)] connection: &Connection,
+        #[zbus(header)] header: Header<'_>,
+    ) -> zbus::fdo::Result<(u32, Options)> {
+        let cancel = self.0.begin(connection, &header, &handle).await?;
+        let result = tokio::select! {
+            biased;
+            _ = cancel.wait() => (1, Options::new()),
+            result = pick_color(&app_id, &parent_window) => reply(result),
+        };
+        self.0.end(connection, &handle).await;
+        Ok(result)
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Wallpaper(pub(crate) Requests);
+
+#[zbus::interface(name = "org.freedesktop.impl.portal.Wallpaper")]
+impl Wallpaper {
+    #[zbus(name = "SetWallpaperURI")]
+    async fn set_wallpaper_uri(
+        &self,
+        handle: OwnedObjectPath,
+        app_id: String,
+        parent_window: String,
+        uri: String,
+        options: Options,
+        #[zbus(connection)] connection: &Connection,
+        #[zbus(header)] header: Header<'_>,
+    ) -> zbus::fdo::Result<u32> {
+        let cancel = self.0.begin(connection, &header, &handle).await?;
+        let result = tokio::select! {
+            biased;
+            _ = cancel.wait() => 1,
+            result = wallpaper(&app_id, &parent_window, &uri, &options, cancel.clone()) => reply(result).0,
+        };
+        self.0.end(connection, &handle).await;
+        Ok(result)
+    }
+}
+
+pub(crate) fn reply(result: Result<Option<Options>, String>) -> Reply {
+    match result {
+        Ok(Some(values)) => (0, values),
+        Ok(None) => (1, Options::new()),
+        Err(error) => {
+            eprintln!("ferese portal: {error}");
+            (2, Options::new())
+        }
+    }
+}
+
+pub(crate) async fn consent(
+    app: &str,
+    parent: &str,
+    title: &str,
+    description: &str,
+    accept: &str,
+    image: Option<PathBuf>,
+) -> Result<bool, String> {
+    if app.len() > 512 {
+        return Err("Application ID is too long".into());
+    }
+    let prompt = Prompt {
+        parent: parent.into(),
+        title: title.into(),
+        description: if app.is_empty() {
+            description.into()
+        } else {
+            format!("{app}\n{description}")
+        },
+        accept: accept.into(),
+        image,
+    };
+    let mut child = crate::backend::child_command()?
+        .arg("--consent")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::inherit())
+        .kill_on_drop(true)
+        .spawn()
+        .map_err(|error| error.to_string())?;
+    let pid = child.id().ok_or("Missing consent process ID")?;
+    let mut input = child.stdin.take().unwrap();
+    input
+        .write_all(&serde_json::to_vec(&prompt).map_err(|error| error.to_string())?)
+        .await
+        .map_err(|error| error.to_string())?;
+    drop(input);
+    let output = tokio::time::timeout(Duration::from_secs(300), child.wait_with_output())
+        .await
+        .map_err(|_| "Consent timed out")?
+        .map_err(|error| error.to_string())?;
+    if output.status.success() && output.stdout == b"true\n" {
+        wait_for_surface_removal(pid).await?;
+        Ok(true)
+    } else {
+        Ok(false)
+    }
+}
+
+pub(crate) async fn ipc(
+    command: &'static str,
+    args: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    tokio::task::spawn_blocking(move || {
+        let path = std::env::var_os("XDG_RUNTIME_DIR")
+            .map(PathBuf::from)
+            .ok_or("Missing runtime directory")?
+            .join("ferese/control.sock");
+        let mut stream = UnixStream::connect(path).map_err(|error| error.to_string())?;
+        stream
+            .set_read_timeout(Some(Duration::from_secs(15)))
+            .map_err(|error| error.to_string())?;
+        stream
+            .set_write_timeout(Some(Duration::from_secs(2)))
+            .map_err(|error| error.to_string())?;
+        let request = ferese_ipc::Request {
+            version: ferese_ipc::VERSION,
+            id: 1,
+            kind: "command".into(),
+            command: command.into(),
+            args,
+        };
+        ferese_ipc::write_frame(&mut stream, &request).map_err(|error| error.to_string())?;
+        let response: ferese_ipc::Response =
+            ferese_ipc::read_frame(&mut stream).map_err(|error| error.to_string())?;
+        if let Some(error) = response.error {
+            return Err(error.message);
+        }
+        response.result.ok_or("Missing IPC result".into())
+    })
+    .await
+    .map_err(|error| error.to_string())?
+}
+
+async fn select_geometry(point: bool, windows: Option<String>) -> Result<Option<String>, String> {
+    let mut command = crate::backend::child_command_for("slurp")?;
+    if point {
+        command.arg("-p");
+    }
+    if windows.is_some() {
+        command.arg("-r");
+    }
+    command.stdin(if windows.is_some() {
+        Stdio::piped()
+    } else {
+        Stdio::null()
+    });
+    let mut child = command
+        .stdout(Stdio::piped())
+        .stderr(Stdio::inherit())
+        .kill_on_drop(true)
+        .spawn()
+        .map_err(|error| error.to_string())?;
+    let pid = child.id().ok_or("Missing selection process ID")?;
+    if let Some(windows) = windows {
+        let mut input = child.stdin.take().unwrap();
+        input
+            .write_all(windows.as_bytes())
+            .await
+            .map_err(|error| error.to_string())?;
+        drop(input);
+    }
+    let output = tokio::time::timeout(Duration::from_secs(300), child.wait_with_output())
+        .await
+        .map_err(|_| "Selection timed out")?
+        .map_err(|error| error.to_string())?;
+    if !output.status.success() {
+        return Ok(None);
+    }
+    let geometry = String::from_utf8(output.stdout)
+        .map_err(|error| error.to_string())?
+        .trim()
+        .to_owned();
+    if geometry.len() > 128 || geometry.is_empty() {
+        return Err("Invalid selection".into());
+    }
+    wait_for_surface_removal(pid).await?;
+    Ok(Some(geometry))
+}
+
+async fn wait_for_surface_removal(pid: u32) -> Result<(), String> {
+    for _ in 0..100 {
+        if ipc("has-client-surfaces", serde_json::json!({"pid": pid})).await? == false {
+            return Ok(());
+        }
+        tokio::time::sleep(Duration::from_millis(10)).await;
+    }
+    Err("Screenshot helper is still visible".into())
+}
+
+async fn capture(geometry: Option<String>) -> Result<Vec<u8>, String> {
+    let result = ipc("screenshot", serde_json::json!({"geometry": geometry})).await?;
+    let path = result["path"]
+        .as_str()
+        .ok_or("Missing screenshot path")?
+        .to_owned();
+    tokio::task::spawn_blocking(move || {
+        let file = std::fs::File::open(&path).map_err(|error| error.to_string())?;
+        let _ = std::fs::remove_file(path);
+        let mut bytes = Vec::new();
+        file.take(MAX_IMAGE_BYTES + 1)
+            .read_to_end(&mut bytes)
+            .map_err(|error| error.to_string())?;
+        if bytes.len() as u64 > MAX_IMAGE_BYTES {
+            return Err("Screenshot is too large".into());
+        }
+        Ok(bytes)
+    })
+    .await
+    .map_err(|error| error.to_string())?
+}
+
+async fn screenshot(app: &str, parent: &str, options: &Options) -> Result<Option<Options>, String> {
+    let target = options
+        .get("target")
+        .map(u32::try_from)
+        .transpose()
+        .map_err(|_| "Invalid screenshot target")?
+        .unwrap_or(
+            if options
+                .get("interactive")
+                .map(bool::try_from)
+                .transpose()
+                .map_err(|_| "Invalid interactive hint")?
+                .unwrap_or(false)
+            {
+                4
+            } else {
+                1
+            },
+        );
+    if !matches!(target, 1 | 4) {
+        return Err("Unsupported screenshot target".into());
+    }
+    if !consent(
+        app,
+        parent,
+        "Take a screenshot?",
+        "Allow this app to capture the selected screen content.",
+        "Continue",
+        None,
+    )
+    .await?
+    {
+        return Ok(None);
+    }
+    let geometry = match target {
+        1 => None,
+        4 => {
+            let Some(geometry) = select_geometry(false, None).await? else {
+                return Ok(None);
+            };
+            Some(geometry)
+        }
+        _ => unreachable!(),
+    };
+    let bytes = capture(geometry).await?;
+    let directory = private_directory("screenshots")?;
+    let mut file = tempfile::Builder::new()
+        .prefix("screenshot-")
+        .suffix(".png")
+        .tempfile_in(directory)
+        .map_err(|error| error.to_string())?;
+    std::io::Write::write_all(&mut file, &bytes).map_err(|error| error.to_string())?;
+    let (_, path) = file.keep().map_err(|error| error.to_string())?;
+    Ok(Some(HashMap::from([(
+        "uri".into(),
+        Value::from(file_uri(&path)?)
+            .try_to_owned()
+            .map_err(|error| error.to_string())?,
+    )])))
+}
+
+async fn pick_color(app: &str, parent: &str) -> Result<Option<Options>, String> {
+    if !consent(
+        app,
+        parent,
+        "Pick a screen color?",
+        "Choose a pixel to share its color with this app.",
+        "Choose color",
+        None,
+    )
+    .await?
+    {
+        return Ok(None);
+    }
+    let Some(geometry) = select_geometry(true, None).await? else {
+        return Ok(None);
+    };
+    let bytes = capture(Some(geometry)).await?;
+    let color = png_color(&bytes)?;
+    Ok(Some(HashMap::from([(
+        "color".into(),
+        Value::from(color)
+            .try_to_owned()
+            .map_err(|error| error.to_string())?,
+    )])))
+}
+
+fn png_color(bytes: &[u8]) -> Result<(f64, f64, f64), String> {
+    let mut decoder = png::Decoder::new(std::io::Cursor::new(bytes));
+    decoder.set_transformations(png::Transformations::EXPAND | png::Transformations::STRIP_16);
+    let mut reader = decoder.read_info().map_err(|error| error.to_string())?;
+    let size = reader
+        .output_buffer_size()
+        .filter(|size| *size <= 16 * 1024)
+        .ok_or("Unexpected pixel dimensions")?;
+    let mut pixels = vec![0; size];
+    let info = reader
+        .next_frame(&mut pixels)
+        .map_err(|error| error.to_string())?;
+    if info.width == 0 || info.height == 0 {
+        return Err("Empty image".into());
+    }
+    match info.color_type {
+        png::ColorType::Rgb | png::ColorType::Rgba => Ok((
+            pixels[0] as f64 / 255.,
+            pixels[1] as f64 / 255.,
+            pixels[2] as f64 / 255.,
+        )),
+        _ => Err("Unexpected screenshot pixel format".into()),
+    }
+}
+
+fn private_directory(name: &str) -> Result<PathBuf, String> {
+    let directory = dirs::data_local_dir()
+        .ok_or("Missing data directory")?
+        .join("ferese/portal")
+        .join(name);
+    std::fs::create_dir_all(&directory).map_err(|error| error.to_string())?;
+    std::fs::set_permissions(&directory, std::fs::Permissions::from_mode(0o700))
+        .map_err(|error| error.to_string())?;
+    Ok(directory)
+}
+
+fn file_uri(path: &Path) -> Result<String, String> {
+    url::Url::from_file_path(path)
+        .map(String::from)
+        .map_err(|_| "Invalid file path".into())
+}
+
+fn local_path(uri: &str) -> Result<PathBuf, String> {
+    url::Url::parse(uri)
+        .map_err(|error| error.to_string())?
+        .to_file_path()
+        .map_err(|_| "Wallpaper must be a local file URI".into())
+}
+
+async fn wallpaper(
+    app: &str,
+    parent: &str,
+    uri: &str,
+    options: &Options,
+    cancel: Arc<Cancel>,
+) -> Result<Option<Options>, String> {
+    let target = options
+        .get("set-on")
+        .map(<&str>::try_from)
+        .transpose()
+        .map_err(|_| "Invalid wallpaper target")?
+        .unwrap_or("background");
+    if !matches!(target, "background" | "lockscreen" | "both") {
+        return Err("Unsupported wallpaper target".into());
+    }
+    let input = local_path(uri)?;
+    let preparing = cancel.clone();
+    let file = tokio::task::spawn_blocking(move || prepare_wallpaper(&input, &preparing))
+        .await
+        .map_err(|error| error.to_string())??;
+    if !consent(
+        app,
+        parent,
+        "Change your wallpaper?",
+        "Use this picture as your wallpaper.",
+        "Set wallpaper",
+        Some(file.path().to_path_buf()),
+    )
+    .await?
+    {
+        return Ok(None);
+    }
+    if cancel.stopped.load(Ordering::SeqCst) {
+        return Ok(None);
+    }
+    let (_, path) = file.keep().map_err(|error| error.to_string())?;
+    if let Err(error) = update_wallpaper(&path, target) {
+        let _ = std::fs::remove_file(path);
+        return Err(error);
+    }
+    Ok(Some(Options::new()))
+}
+
+fn prepare_wallpaper(input: &Path, cancel: &Cancel) -> Result<tempfile::NamedTempFile, String> {
+    use std::os::unix::fs::OpenOptionsExt;
+    let input = std::fs::OpenOptions::new()
+        .read(true)
+        .custom_flags(libc::O_NONBLOCK)
+        .open(input)
+        .map_err(|error| error.to_string())?;
+    if !input
+        .metadata()
+        .map_err(|error| error.to_string())?
+        .is_file()
+    {
+        return Err("Wallpaper must be a regular file".into());
+    }
+    let directory = private_directory("wallpapers")?;
+    let mut file = tempfile::Builder::new()
+        .prefix("wallpaper-")
+        .tempfile_in(directory)
+        .map_err(|error| error.to_string())?;
+    let mut input = input.take(MAX_IMAGE_BYTES + 1);
+    let mut size = 0u64;
+    let mut buffer = [0; 64 * 1024];
+    loop {
+        if cancel.stopped.load(Ordering::SeqCst) {
+            return Err("Wallpaper request cancelled".into());
+        }
+        let bytes = input.read(&mut buffer).map_err(|error| error.to_string())?;
+        if bytes == 0 {
+            break;
+        }
+        size += bytes as u64;
+        if size > MAX_IMAGE_BYTES {
+            return Err("Wallpaper is too large".into());
+        }
+        std::io::Write::write_all(&mut file, &buffer[..bytes])
+            .map_err(|error| error.to_string())?;
+    }
+    if size == 0 {
+        return Err("Wallpaper is empty".into());
+    }
+    let reader = image::ImageReader::open(file.path())
+        .map_err(|error| error.to_string())?
+        .with_guessed_format()
+        .map_err(|error| error.to_string())?;
+    let (width, height) = reader
+        .into_dimensions()
+        .map_err(|error| error.to_string())?;
+    if width == 0
+        || height == 0
+        || width > 16384
+        || height > 16384
+        || u64::from(width) * u64::from(height) > MAX_IMAGE_BYTES / 4
+    {
+        return Err("Wallpaper dimensions exceed the image limit".into());
+    }
+    let mut reader = image::ImageReader::open(file.path())
+        .map_err(|error| error.to_string())?
+        .with_guessed_format()
+        .map_err(|error| error.to_string())?;
+    let mut limits = image::Limits::default();
+    limits.max_alloc = Some(MAX_IMAGE_BYTES);
+    reader.limits(limits);
+    reader.decode().map_err(|error| error.to_string())?;
+    Ok(file)
+}
+
+fn update_wallpaper(image: &Path, target: &str) -> Result<(), String> {
+    let path = ferese_config::config_path().ok_or("Missing config path")?;
+    edit_wallpaper(&path, image, target)
+}
+
+fn edit_wallpaper(path: &Path, image: &Path, target: &str) -> Result<(), String> {
+    let source = match std::fs::read_to_string(&path) {
+        Ok(source) => source,
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => String::new(),
+        Err(error) => return Err(error.to_string()),
+    };
+    let mut document =
+        ferese_config::Document::parse(&source).map_err(|error| error.to_string())?;
+    if target == "background" && document.get("theme.background.lock_path").is_none() {
+        let old = document
+            .get("theme.background.path")
+            .and_then(serde_json::Value::as_str)
+            .unwrap_or(ferese_config::default_wallpaper())
+            .to_owned();
+        document
+            .set("theme.background.lock_path", old.into())
+            .map_err(|error| error.to_string())?;
+    }
+    if target != "lockscreen" {
+        document
+            .set(
+                "theme.background.path",
+                image.to_string_lossy().into_owned().into(),
+            )
+            .map_err(|error| error.to_string())?;
+    }
+    if target != "background" {
+        document
+            .set(
+                "theme.background.lock_path",
+                image.to_string_lossy().into_owned().into(),
+            )
+            .map_err(|error| error.to_string())?;
+    }
+    let parent = path.parent().ok_or("Invalid config path")?;
+    std::fs::create_dir_all(parent).map_err(|error| error.to_string())?;
+    let mut temp = tempfile::NamedTempFile::new_in(parent).map_err(|error| error.to_string())?;
+    std::io::Write::write_all(&mut temp, document.to_string().as_bytes())
+        .map_err(|error| error.to_string())?;
+    temp.as_file()
+        .sync_all()
+        .map_err(|error| error.to_string())?;
+    if std::fs::read_to_string(&path).unwrap_or_default() != source {
+        return Err("Configuration changed; please try again".into());
+    }
+    temp.persist(path).map_err(|error| error.to_string())?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn local_uris_preserve_special_characters_and_reject_network_paths() {
+        let path = Path::new("/tmp/wallpaper #1_日本.png");
+        assert_eq!(local_path(&file_uri(path).unwrap()).unwrap(), path);
+        for uri in [
+            "https://example.com/a.png",
+            "file://example.com/a.png",
+            "not a URI",
+        ] {
+            assert!(local_path(uri).is_err());
+        }
+    }
+
+    #[test]
+    fn pixel_color_is_normalized_rgb() {
+        let mut bytes = Vec::new();
+        let mut encoder = png::Encoder::new(&mut bytes, 1, 1);
+        encoder.set_color(png::ColorType::Rgba);
+        encoder.set_depth(png::BitDepth::Eight);
+        encoder
+            .write_header()
+            .unwrap()
+            .write_image_data(&[255, 128, 0, 255])
+            .unwrap();
+        assert_eq!(png_color(&bytes).unwrap(), (1., 128. / 255., 0.));
+    }
+
+    #[test]
+    fn wallpaper_targets_preserve_independent_paths_and_other_settings() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("config.kdl");
+        std::fs::write(&path, "// Keep my settings\ntheme { background { path \"/old.png\"; }; }; commands { terminal \"foot\"; }\n").unwrap();
+        edit_wallpaper(&path, Path::new("/desktop.png"), "background").unwrap();
+        let document =
+            ferese_config::Document::parse(&std::fs::read_to_string(&path).unwrap()).unwrap();
+        assert_eq!(
+            document.get("theme.background.path").unwrap(),
+            "/desktop.png"
+        );
+        assert_eq!(
+            document.get("theme.background.lock_path").unwrap(),
+            "/old.png"
+        );
+        assert!(
+            std::fs::read_to_string(&path)
+                .unwrap()
+                .contains("Keep my settings")
+        );
+        edit_wallpaper(&path, Path::new("/lock.png"), "lockscreen").unwrap();
+        let document =
+            ferese_config::Document::parse(&std::fs::read_to_string(&path).unwrap()).unwrap();
+        assert_eq!(
+            document.get("theme.background.path").unwrap(),
+            "/desktop.png"
+        );
+        assert_eq!(
+            document.get("theme.background.lock_path").unwrap(),
+            "/lock.png"
+        );
+        edit_wallpaper(&path, Path::new("/both.png"), "both").unwrap();
+        let document =
+            ferese_config::Document::parse(&std::fs::read_to_string(&path).unwrap()).unwrap();
+        assert_eq!(document.get("theme.background.path").unwrap(), "/both.png");
+        assert_eq!(
+            document.get("theme.background.lock_path").unwrap(),
+            "/both.png"
+        );
+        assert_eq!(
+            document.get("commands.terminal").unwrap(),
+            &serde_json::json!(["foot"])
+        );
+    }
+
+    #[test]
+    fn wallpaper_rejects_nonregular_files_and_cancellation_before_copy() {
+        let dir = tempfile::tempdir().unwrap();
+        assert!(prepare_wallpaper(dir.path(), &Cancel::default()).is_err());
+        let path = dir.path().join("image");
+        std::fs::write(&path, [0u8; 32]).unwrap();
+        let cancel = Cancel::default();
+        cancel.stop();
+        assert!(
+            prepare_wallpaper(&path, &cancel)
+                .unwrap_err()
+                .contains("cancelled")
+        );
+    }
+}

portal/src/main.rs

@@ -1,6 +1,10 @@
 mod backend;
 mod capture;
+mod consent;
+mod desktop;
+mod parent;
 mod picker;
+mod settings;
 mod stream;
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
@@ -16,6 +20,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             Ok(())
         }
         [flag] if flag == "--picker" => picker::run(),
+        [flag] if flag == "--consent" => consent::run(),
         [] => tokio::runtime::Runtime::new()?.block_on(backend::run()),
         _ => Err("Usage: xdg-desktop-portal-ferese [--sources]".into()),
     }

portal/src/parent.rs

@@ -0,0 +1,119 @@
+use wayland_client::{
+    Connection, Dispatch, Proxy, QueueHandle, delegate_noop,
+    globals::{GlobalListContents, registry_queue_init},
+    protocol::{wl_registry, wl_surface},
+};
+use wayland_protocols::xdg::foreign::zv2::client::{
+    zxdg_imported_v2::{self, ZxdgImportedV2},
+    zxdg_importer_v2::ZxdgImporterV2,
+};
+
+#[derive(Debug)]
+pub(crate) struct Parent {
+    connection: Connection,
+    imported: ZxdgImportedV2,
+    importer: ZxdgImporterV2,
+}
+
+impl Parent {
+    pub(crate) fn attach(
+        window: &dyn cosmic::iced::window::Window,
+        parent: &str,
+    ) -> Result<Option<Self>, String> {
+        use cosmic::iced::window::raw_window_handle::{RawDisplayHandle, RawWindowHandle};
+        if parent.is_empty() {
+            return Ok(None);
+        }
+        let handle = parent
+            .strip_prefix("wayland:")
+            .filter(|handle| !handle.is_empty() && handle.len() <= 4096)
+            .ok_or("Unsupported portal parent window identifier")?;
+        let display = window.display_handle().map_err(|error| error.to_string())?;
+        let surface = window.window_handle().map_err(|error| error.to_string())?;
+        let (RawDisplayHandle::Wayland(display), RawWindowHandle::Wayland(surface)) =
+            (display.as_raw(), surface.as_raw())
+        else {
+            return Err("Portal parenting requires Wayland".into());
+        };
+        // The window lends live handles; the borrowed backend never owns the display.
+        let backend = unsafe {
+            wayland_client::backend::Backend::from_foreign_display(display.display.as_ptr().cast())
+        };
+        let connection = Connection::from_backend(backend);
+        let id = unsafe {
+            wayland_client::backend::ObjectId::from_ptr(
+                wl_surface::WlSurface::interface(),
+                surface.surface.as_ptr().cast(),
+            )
+        }
+        .map_err(|error| error.to_string())?;
+        let surface =
+            wl_surface::WlSurface::from_id(&connection, id).map_err(|error| error.to_string())?;
+        let (globals, mut queue) =
+            registry_queue_init::<State>(&connection).map_err(|error| error.to_string())?;
+        let qh = queue.handle();
+        let importer = globals
+            .bind::<ZxdgImporterV2, _, _>(&qh, 1..=1, ())
+            .map_err(|error| error.to_string())?;
+        let imported = importer.import_toplevel(handle.into(), &qh, ());
+        let mut state = State::default();
+        queue
+            .roundtrip(&mut state)
+            .map_err(|error| error.to_string())?;
+        if state.invalid {
+            imported.destroy();
+            importer.destroy();
+            let _ = connection.flush();
+            return Err("Portal parent window no longer exists".into());
+        }
+        imported.set_parent_of(&surface);
+        connection.flush().map_err(|error| error.to_string())?;
+        Ok(Some(Self {
+            connection,
+            imported,
+            importer,
+        }))
+    }
+}
+
+impl Drop for Parent {
+    fn drop(&mut self) {
+        self.imported.destroy();
+        self.importer.destroy();
+        let _ = self.connection.flush();
+    }
+}
+
+#[derive(Default)]
+struct State {
+    invalid: bool,
+}
+
+impl Dispatch<wl_registry::WlRegistry, GlobalListContents> for State {
+    fn event(
+        _: &mut Self,
+        _: &wl_registry::WlRegistry,
+        _: wl_registry::Event,
+        _: &GlobalListContents,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+    ) {
+    }
+}
+
+impl Dispatch<ZxdgImportedV2, ()> for State {
+    fn event(
+        state: &mut Self,
+        _: &ZxdgImportedV2,
+        event: zxdg_imported_v2::Event,
+        _: &(),
+        _: &Connection,
+        _: &QueueHandle<Self>,
+    ) {
+        if matches!(event, zxdg_imported_v2::Event::Destroyed) {
+            state.invalid = true;
+        }
+    }
+}
+
+delegate_noop!(State: ignore ZxdgImporterV2);

portal/src/picker.rs

@@ -258,7 +258,7 @@ impl Picker {
     }
 }
 
-fn appearance() -> (
+pub(crate) fn appearance() -> (
     cosmic::Theme,
     cosmic::font::Font,
     cosmic::iced::Color,

portal/src/settings.rs

@@ -0,0 +1,191 @@
+use ferese_config::Document;
+use ferese_theme::Palette;
+use std::{collections::HashMap, sync::Arc, time::Duration};
+use tokio::sync::RwLock;
+use zbus::{
+    Connection,
+    object_server::SignalEmitter,
+    zvariant::{OwnedValue, Value},
+};
+
+const APPEARANCE: &str = "org.freedesktop.appearance";
+const PATH: &str = "/org/freedesktop/portal/desktop";
+type Values = HashMap<String, HashMap<String, OwnedValue>>;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct Appearance {
+    scheme: u32,
+    accent: (f64, f64, f64),
+    reduced_motion: u32,
+}
+
+impl Appearance {
+    fn from_document(document: Option<&Document>) -> Self {
+        let palette = Palette::from_document(document);
+        let animations = document
+            .and_then(|document| document.get("animations.enabled"))
+            .and_then(serde_json::Value::as_bool)
+            .unwrap_or(true);
+        Self {
+            scheme: if ferese_theme::luminance(palette.sidebar) > 0.5 {
+                2
+            } else {
+                1
+            },
+            accent: (
+                palette.accent.r as f64,
+                palette.accent.g as f64,
+                palette.accent.b as f64,
+            ),
+            reduced_motion: u32::from(
+                !animations
+                    || document
+                        .and_then(|doc| doc.get("animations.reduced_motion"))
+                        .and_then(serde_json::Value::as_bool)
+                        .unwrap_or(false),
+            ),
+        }
+    }
+
+    fn values(self) -> HashMap<String, OwnedValue> {
+        HashMap::from([
+            ("color-scheme".into(), self.scheme.into()),
+            (
+                "accent-color".into(),
+                Value::from(self.accent).try_to_owned().unwrap(),
+            ),
+            ("contrast".into(), 0u32.into()),
+            ("reduced-motion".into(), self.reduced_motion.into()),
+        ])
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Settings(Arc<RwLock<Appearance>>);
+
+impl Settings {
+    pub(crate) fn new() -> Self {
+        Self(Arc::new(RwLock::new(
+            load().unwrap_or_else(|| Appearance::from_document(None)),
+        )))
+    }
+
+    pub(crate) async fn watch(self, connection: Connection) {
+        let emitter = SignalEmitter::new(&connection, PATH).unwrap();
+        loop {
+            tokio::time::sleep(Duration::from_secs(1)).await;
+            let Some(next) = load() else { continue };
+            let mut current = self.0.write().await;
+            if *current == next {
+                continue;
+            }
+            let previous = current.values();
+            *current = next;
+            drop(current);
+            for (key, value) in next.values() {
+                if previous.get(&key) != Some(&value) {
+                    let _ = Self::setting_changed(&emitter, APPEARANCE, &key, value).await;
+                }
+            }
+        }
+    }
+}
+
+#[zbus::interface(name = "org.freedesktop.impl.portal.Settings")]
+impl Settings {
+    #[zbus(property, name = "version")]
+    fn version(&self) -> u32 {
+        1
+    }
+
+    async fn read_all(&self, namespaces: Vec<String>) -> Values {
+        if matches_namespace(&namespaces, APPEARANCE) {
+            HashMap::from([(APPEARANCE.into(), self.0.read().await.values())])
+        } else {
+            HashMap::new()
+        }
+    }
+
+    async fn read(&self, namespace: &str, key: &str) -> zbus::fdo::Result<OwnedValue> {
+        if namespace == APPEARANCE {
+            if let Some(value) = self.0.read().await.values().remove(key) {
+                return Ok(value);
+            }
+        }
+        Err(zbus::fdo::Error::InvalidArgs("Unknown setting".into()))
+    }
+
+    #[zbus(signal)]
+    async fn setting_changed(
+        emitter: &SignalEmitter<'_>,
+        namespace: &str,
+        key: &str,
+        value: OwnedValue,
+    ) -> zbus::Result<()>;
+}
+
+fn matches_namespace(filters: &[String], namespace: &str) -> bool {
+    filters.is_empty()
+        || filters.iter().any(|filter| {
+            filter.is_empty()
+                || filter == namespace
+                || filter.strip_suffix(".*").is_some_and(|prefix| {
+                    namespace
+                        .strip_prefix(prefix)
+                        .is_some_and(|suffix| suffix.starts_with('.'))
+                })
+        })
+}
+
+fn load() -> Option<Appearance> {
+    let path = ferese_config::config_path()?;
+    let source = match std::fs::read_to_string(path) {
+        Ok(source) if source.len() <= 1024 * 1024 => source,
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
+            return Some(Appearance::from_document(None));
+        }
+        _ => return None,
+    };
+    let document = Document::parse(&source).ok()?;
+    Some(Appearance::from_document(Some(&document)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn namespaces_support_only_trailing_section_wildcards() {
+        for filter in [
+            "",
+            "org.freedesktop.appearance",
+            "org.freedesktop.*",
+            "org.*",
+        ] {
+            assert!(matches_namespace(&[filter.into()], APPEARANCE));
+        }
+        for filter in [
+            "org.freedesktop*",
+            "org.*.appearance",
+            "org.freedesktop.appearance.*",
+            "other",
+        ] {
+            assert!(!matches_namespace(&[filter.into()], APPEARANCE));
+        }
+        assert!(matches_namespace(&[], APPEARANCE));
+    }
+
+    #[test]
+    fn reports_ferese_theme_and_reduced_motion() {
+        let doc = Document::parse("theme { colors { surface-base \"#ffffff\"; accent \"#ff8000\"; }; }; animations { enabled #false; }").unwrap();
+        let appearance = Appearance::from_document(Some(&doc));
+        assert_eq!(appearance.scheme, 2);
+        assert_eq!(appearance.reduced_motion, 1);
+        assert_eq!(appearance.accent.0, 1.);
+        assert_eq!(appearance.accent.2, 0.);
+        assert_eq!(
+            u32::try_from(appearance.values().remove("contrast").unwrap()).unwrap(),
+            0
+        );
+    }
+}

scripts/tests/test_portal_contracts.py

@@ -0,0 +1,125 @@
+"""Check native portal wire contracts on a private bus without touching the desktop."""
+import os
+from pathlib import Path
+import signal
+import subprocess
+import sys
+import tempfile
+import time
+import unittest
+import xml.etree.ElementTree as ET
+
+REPO = Path(__file__).resolve().parents[2]
+BINARY = REPO / os.environ.get("FERESE_TEST_PORTAL_BINARY", "target/debug/xdg-desktop-portal-ferese")
+NAME = "org.freedesktop.impl.portal.desktop.ferese"
+PATH = "/org/freedesktop/portal/desktop"
+
+
+class NativePortalContracts(unittest.TestCase):
+    def test_private_bus_contracts(self):
+        result = subprocess.run(["dbus-run-session", "--", sys.executable, __file__, "--private"],
+                                capture_output=True, text=True, timeout=45)
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+
+
+def private_bus_checks():
+    import gi
+    gi.require_version("Gio", "2.0")
+    from gi.repository import Gio, GLib
+
+    bus = Gio.bus_get_sync(Gio.BusType.SESSION, None)
+
+    def call(interface, method, parameters, signature=None, destination=NAME):
+        return bus.call_sync(destination, PATH, interface, method, parameters,
+                             GLib.VariantType.new(signature) if signature else None,
+                             Gio.DBusCallFlags.NO_AUTO_START, 5000, None).unpack()
+
+    with tempfile.TemporaryDirectory(prefix="ferese-portal-contracts-") as directory:
+        root = Path(directory)
+        config = root / "ferese/config.kdl"
+        config.parent.mkdir()
+        config.write_text('theme { colors { surface-base "#ffffff"; accent "#ff8000"; }; }; animations { reduced-motion #true; }\n')
+        log = (root / "backend.log").open("w")
+        process = subprocess.Popen([str(BINARY)], env=dict(os.environ, XDG_CONFIG_HOME=directory),
+                                   stdout=log, stderr=log, start_new_session=True)
+        try:
+            deadline = time.monotonic() + 15
+            while True:
+                try:
+                    xml, = call("org.freedesktop.DBus.Introspectable", "Introspect", None, "(s)")
+                    break
+                except GLib.Error:
+                    if time.monotonic() > deadline:
+                        raise AssertionError((root / "backend.log").read_text())
+                    time.sleep(0.05)
+            node = ET.fromstring(xml)
+            for name in ("ScreenCast", "Settings", "Screenshot", "Wallpaper"):
+                interface = node.find(f"interface[@name='org.freedesktop.impl.portal.{name}']")
+                assert interface is not None, name
+                expected = ET.parse(f"/usr/share/dbus-1/interfaces/org.freedesktop.impl.portal.{name}.xml").getroot().find("interface")
+                for member in expected:
+                    if member.tag not in ("method", "signal", "property"):
+                        continue
+                    actual = interface.find(f"{member.tag}[@name='{member.attrib['name']}']")
+                    assert actual is not None, (name, member.tag, member.attrib["name"])
+                    if member.tag == "property":
+                        assert actual.attrib["type"] == member.attrib["type"]
+                    else:
+                        def types(element, direction):
+                            return [arg.attrib["type"] for arg in element.findall("arg")
+                                    if arg.attrib.get("direction", "out" if element.tag == "signal" else "in") == direction]
+                        assert types(actual, "in") == types(member, "in"), (name, member.attrib["name"], "in")
+                        assert types(actual, "out") == types(member, "out"), (name, member.attrib["name"], types(actual, "out"), types(member, "out"))
+            values, = call("org.freedesktop.impl.portal.Settings", "ReadAll", GLib.Variant("(as)", ([],)), "(a{sa{sv}})")
+            appearance = values["org.freedesktop.appearance"]
+            assert appearance["color-scheme"] == 2 and appearance["reduced-motion"] == 1, appearance
+            assert appearance["accent-color"][0] == 1. and appearance["accent-color"][2] == 0., appearance
+            result, = call("org.freedesktop.impl.portal.Settings", "ReadAll", GLib.Variant("(as)", (["other.*"],)), "(a{sa{sv}})")
+            assert result == {}
+            try:
+                call("org.freedesktop.impl.portal.Settings", "Read", GLib.Variant("(ss)", ("org.freedesktop.appearance", "missing")))
+                raise AssertionError("Unknown Settings key succeeded")
+            except GLib.Error as error:
+                assert "InvalidArgs" in str(error)
+
+            params = GLib.Variant("(ossa{sv})", (PATH + "/request/test/screenshot", "org.test.App", "", {"target": GLib.Variant("u", 99)}))
+            try:
+                call("org.freedesktop.impl.portal.Screenshot", "Screenshot", params)
+                raise AssertionError("Untrusted backend caller succeeded")
+            except GLib.Error:
+                pass
+            request_name = bus.call_sync("org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus", "RequestName",
+                                         GLib.Variant("(su)", ("org.freedesktop.portal.Desktop", 0)), GLib.VariantType.new("(u)"),
+                                         Gio.DBusCallFlags.NONE, 5000, None).unpack()[0]
+            assert request_name == 1
+            response, values = call("org.freedesktop.impl.portal.Screenshot", "Screenshot", params, "(ua{sv})")
+            assert response == 2 and values == {}
+
+            signals = []
+            subscription = bus.signal_subscribe(NAME, "org.freedesktop.impl.portal.Settings", "SettingChanged", PATH,
+                                                None, Gio.DBusSignalFlags.NONE, lambda *args: signals.append(args[-1].unpack()))
+            temporary = config.with_suffix(".tmp")
+            temporary.write_text('theme { colors { surface-base "#111111"; accent "#0080ff"; }; }; animations { enabled #false; }\n')
+            temporary.replace(config)
+            deadline = time.monotonic() + 5
+            while time.monotonic() < deadline and not any(signal[1] == "color-scheme" for signal in signals):
+                GLib.MainContext.default().iteration(False)
+                time.sleep(0.02)
+            assert any(signal[1] == "color-scheme" and signal[2] == 1 for signal in signals), signals
+            assert any(signal[1] == "accent-color" for signal in signals), signals
+            config.write_text('theme { broken')
+            time.sleep(1.2)
+            scheme, = call("org.freedesktop.impl.portal.Settings", "Read", GLib.Variant("(ss)", ("org.freedesktop.appearance", "color-scheme")))
+            assert scheme == 1, scheme
+            bus.signal_unsubscribe(subscription)
+        finally:
+            os.killpg(process.pid, signal.SIGTERM)
+            process.wait(timeout=5)
+            log.close()
+
+
+if __name__ == "__main__":
+    if sys.argv[1:] == ["--private"]:
+        private_bus_checks()
+    else:
+        unittest.main()

shell/ferese-lock/src/appearance.rs

@@ -30,7 +30,8 @@ impl Appearance {
         };
         let palette = ferese_theme::Palette::from_document(doc.as_ref());
         let font = string("theme.typography.font_family", "Inter");
-        let path = string("theme.background.path", ferese_config::default_wallpaper());
+        let background = string("theme.background.path", ferese_config::default_wallpaper());
+        let path = string("theme.background.lock_path", &background);
         let path = if let Some(tail) = path.strip_prefix("~/") {
             std::env::var("HOME")
                 .map(|home| format!("{home}/{tail}"))