feat(client): device-pick plumbing — GPU enumeration + audio endpoint targeting

The Settings GPU pick existed (adapter → PUNKTFUNK_VK_ADAPTER) but no Linux
shell could enumerate anything to pick: the GTK shell deliberately links no
Vulkan. pf_presenter::vk::list_adapters() reads the physical devices'
marketing names (no surface, discrete first, deduped — the name is the whole
match key in pick_device), surfaced as `punktfunk-session --list-adapters`.

Audio gets the same treatment for the new speaker_device/mic_device settings
(PipeWire node.name; empty = default): session main maps them onto
PUNKTFUNK_AUDIO_SINK/SOURCE — a hand-set env still wins, like the adapter —
and the playback/mic streams pass them as `target.object` (raw key: the
keys::TARGET_OBJECT constant is feature-gated on a newer libpipewire than we
require). pf_client_core::audio::devices() is the registry roundtrip the
pickers read, exposed for debugging as `punktfunk-session --list-audio`.
The WASAPI leg (Windows endpoint IDs) is still to come; the fields are
ignored there.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/session/src/main.rs

@@ -268,19 +268,66 @@ mod session_main {
             )
             .init();
 
+        // `--list-adapters`: print the Vulkan physical devices' marketing names (one per
+        // line, discrete first) for the desktop shells' GPU picker, then exit.
+        if arg_flag("--list-adapters") {
+            return match pf_presenter::vk::list_adapters() {
+                Ok(names) => {
+                    for n in names {
+                        println!("{n}");
+                    }
+                    0
+                }
+                Err(e) => {
+                    eprintln!("list-adapters: {e:#}");
+                    EXIT_PRESENTER_FAILED
+                }
+            };
+        }
+
+        // `--list-audio`: the PipeWire endpoints the settings pickers offer, as
+        // `sink|source<TAB>node.name<TAB>description` lines — a debug window into the
+        // same enumeration the GTK shell probes.
+        #[cfg(target_os = "linux")]
+        if arg_flag("--list-audio") {
+            return match pf_client_core::audio::devices() {
+                Ok((sinks, sources)) => {
+                    for d in sinks {
+                        println!("sink\t{}\t{}", d.name, d.description);
+                    }
+                    for d in sources {
+                        println!("source\t{}\t{}", d.name, d.description);
+                    }
+                    0
+                }
+                Err(e) => {
+                    eprintln!("list-audio: {e:#}");
+                    EXIT_PRESENTER_FAILED
+                }
+            };
+        }
+
         // Before any Vulkan call: make RADV expose its video-decode queue + extensions so the
         // decoder's `auto` path prefers Vulkan Video over VAAPI (Steam Deck, and any gated RADV).
         // Windows drivers (NVIDIA/AMD Adrenalin) expose theirs unconditionally.
         #[cfg(target_os = "linux")]
         enable_radv_video_decode();
 
-        // The Settings GPU pick (the WinUI shell's picker stores the adapter's marketing
-        // name) → the presenter's device selection, unless the user already forced one.
-        // Before any Vulkan call, like the RADV knob (covers --connect and --browse).
-        if std::env::var_os("PUNKTFUNK_VK_ADAPTER").is_none() {
-            let adapter = trust::Settings::load().adapter;
-            if !adapter.is_empty() {
-                std::env::set_var("PUNKTFUNK_VK_ADAPTER", adapter);
+        // The Settings device picks → env, unless the user already forced one by hand:
+        // the GPU (the shells' pickers store the adapter's marketing name) for the
+        // presenter's device selection, and the audio endpoints (PipeWire node names)
+        // for the playback/mic streams' `target.object`. Before any Vulkan call, like
+        // the RADV knob (covers --connect and --browse).
+        {
+            let s = trust::Settings::load();
+            for (var, value) in [
+                ("PUNKTFUNK_VK_ADAPTER", &s.adapter),
+                ("PUNKTFUNK_AUDIO_SINK", &s.speaker_device),
+                ("PUNKTFUNK_AUDIO_SOURCE", &s.mic_device),
+            ] {
+                if std::env::var_os(var).is_none() && !value.is_empty() {
+                    std::env::set_var(var, value);
+                }
             }
         }
 

crates/pf-client-core/src/audio.rs

@@ -20,6 +20,83 @@ const MIC_FRAME: usize = 960;
 
 struct Terminate;
 
+/// A selectable PipeWire endpoint for the settings pickers.
+#[derive(Clone, Debug)]
+pub struct AudioDevice {
+    /// `node.name` — the stable key the streams target via `target.object`.
+    pub name: String,
+    /// `node.description` — the human label the picker shows.
+    pub description: String,
+}
+
+/// Enumerate audio endpoints: `(sinks, sources)`. One registry roundtrip on a private
+/// mainloop (a few ms against a live PipeWire); no daemon errors out and the caller
+/// simply shows no pickers.
+pub fn devices() -> Result<(Vec<AudioDevice>, Vec<AudioDevice>)> {
+    use pipewire as pw;
+    use std::cell::RefCell;
+    use std::rc::Rc;
+
+    static PW_INIT: std::sync::Once = std::sync::Once::new();
+    PW_INIT.call_once(pw::init);
+
+    let mainloop = pw::main_loop::MainLoopRc::new(None).context("pw MainLoop")?;
+    let context = pw::context::ContextRc::new(&mainloop, None).context("pw Context")?;
+    let core = context
+        .connect_rc(None)
+        .context("pw connect (is PipeWire running in this session?)")?;
+    let registry = core.get_registry_rc().context("pw registry")?;
+
+    let found: Rc<RefCell<(Vec<AudioDevice>, Vec<AudioDevice>)>> = Rc::default();
+    let _reg_listener = registry
+        .add_listener_local()
+        .global({
+            let found = found.clone();
+            move |g| {
+                let Some(props) = g.props else { return };
+                let sink = match props.get("media.class") {
+                    Some("Audio/Sink") => true,
+                    Some("Audio/Source") => false,
+                    _ => return,
+                };
+                let Some(name) = props.get("node.name") else {
+                    return;
+                };
+                let description = props
+                    .get("node.description")
+                    .or_else(|| props.get("node.nick"))
+                    .unwrap_or(name)
+                    .to_string();
+                let dev = AudioDevice {
+                    name: name.to_string(),
+                    description,
+                };
+                let mut f = found.borrow_mut();
+                if sink { &mut f.0 } else { &mut f.1 }.push(dev);
+            }
+        })
+        .register();
+
+    // The registry replays existing globals asynchronously; one core sync marks the
+    // point they've all been delivered — quit the loop there.
+    let pending = core.sync(0).context("pw sync")?;
+    let _core_listener = core
+        .add_listener_local()
+        .done({
+            let mainloop = mainloop.clone();
+            move |_, seq| {
+                if seq == pending {
+                    mainloop.quit();
+                }
+            }
+        })
+        .register();
+    mainloop.run();
+
+    let result = found.borrow().clone();
+    Ok(result)
+}
+
 pub struct AudioPlayer {
     pcm_tx: SyncSender<Vec<f32>>,
     /// Drained chunk Vecs coming back from the PipeWire consumer for reuse (the pool half
@@ -118,20 +195,26 @@ fn pw_thread(
         move |_| mainloop.quit()
     });
 
-    let stream = pw::stream::StreamBox::new(
-        &core,
-        "punktfunk-client",
-        properties! {
-            *pw::keys::MEDIA_TYPE       => "Audio",
-            *pw::keys::MEDIA_CATEGORY   => "Playback",
-            *pw::keys::MEDIA_ROLE       => "Game",
-            *pw::keys::NODE_NAME        => "punktfunk-client",
-            *pw::keys::NODE_DESCRIPTION => "Punktfunk Stream",
-            // ~5 ms quantum (one Opus frame) keeps the ring — and so the latency — small.
-            *pw::keys::NODE_LATENCY     => "240/48000",
-        },
-    )
-    .context("pw Stream")?;
+    let mut props = properties! {
+        *pw::keys::MEDIA_TYPE       => "Audio",
+        *pw::keys::MEDIA_CATEGORY   => "Playback",
+        *pw::keys::MEDIA_ROLE       => "Game",
+        *pw::keys::NODE_NAME        => "punktfunk-client",
+        *pw::keys::NODE_DESCRIPTION => "Punktfunk Stream",
+        // ~5 ms quantum (one Opus frame) keeps the ring — and so the latency — small.
+        *pw::keys::NODE_LATENCY     => "240/48000",
+    };
+    // The Settings speaker pick (session main maps `Settings::speaker_device` here);
+    // unset/empty = PipeWire's default routing.
+    if let Ok(target) = std::env::var("PUNKTFUNK_AUDIO_SINK") {
+        if !target.is_empty() {
+            // Raw key: the `keys::TARGET_OBJECT` constant is feature-gated on a newer
+            // libpipewire than we require; the wire name is stable.
+            props.insert("target.object", target);
+        }
+    }
+    let stream =
+        pw::stream::StreamBox::new(&core, "punktfunk-client", props).context("pw Stream")?;
 
     let ud = PlayerData {
         rx: pcm_rx,
@@ -316,18 +399,23 @@ fn mic_thread(
         move |_| mainloop.quit()
     });
 
-    let stream = pw::stream::StreamBox::new(
-        &core,
-        "punktfunk-mic-capture",
-        properties! {
-            *pw::keys::MEDIA_TYPE       => "Audio",
-            *pw::keys::MEDIA_CATEGORY   => "Capture",
-            *pw::keys::MEDIA_ROLE       => "Communication",
-            *pw::keys::NODE_NAME        => "punktfunk-mic-capture",
-            *pw::keys::NODE_DESCRIPTION => "Punktfunk Microphone",
-        },
-    )
-    .context("pw mic Stream")?;
+    let mut props = properties! {
+        *pw::keys::MEDIA_TYPE       => "Audio",
+        *pw::keys::MEDIA_CATEGORY   => "Capture",
+        *pw::keys::MEDIA_ROLE       => "Communication",
+        *pw::keys::NODE_NAME        => "punktfunk-mic-capture",
+        *pw::keys::NODE_DESCRIPTION => "Punktfunk Microphone",
+    };
+    // The Settings microphone pick (`Settings::mic_device` via session main).
+    if let Ok(target) = std::env::var("PUNKTFUNK_AUDIO_SOURCE") {
+        if !target.is_empty() {
+            // Raw key: the `keys::TARGET_OBJECT` constant is feature-gated on a newer
+            // libpipewire than we require; the wire name is stable.
+            props.insert("target.object", target);
+        }
+    }
+    let stream = pw::stream::StreamBox::new(&core, "punktfunk-mic-capture", props)
+        .context("pw mic Stream")?;
 
     let ud = MicData {
         connector: connector.clone(),

crates/pf-client-core/src/trust.rs

@@ -544,6 +544,16 @@ pub struct Settings {
     /// "Invert scroll direction"). Default off = the host scrolls the way this machine does.
     #[serde(default)]
     pub invert_scroll: bool,
+    /// Playback endpoint for stream audio — on Linux the PipeWire `node.name` the
+    /// playback stream targets (`target.object`); empty = the session default (the
+    /// Apple client's Speaker picker). The session maps it onto `PUNKTFUNK_AUDIO_SINK`.
+    /// Ignored on Windows until the WASAPI endpoint leg exists.
+    #[serde(default)]
+    pub speaker_device: String,
+    /// Capture endpoint for the mic uplink (same semantics as `speaker_device`;
+    /// `PUNKTFUNK_AUDIO_SOURCE`).
+    #[serde(default)]
+    pub mic_device: String,
     /// Match-window resolution policy (design/midstream-resolution-resize.md D1): the
     /// stream mode follows the session window — the connect asks for the window's pixel
     /// size and a mid-session resize renegotiates the host's virtual display + encoder
@@ -634,6 +644,8 @@ impl Default for Settings {
             library_enabled: false,
             auto_wake: true,
             invert_scroll: false,
+            speaker_device: String::new(),
+            mic_device: String::new(),
             match_window: false,
             last_window_w: 0,
             last_window_h: 0,

crates/pf-presenter/src/vk/mod.rs

@@ -33,6 +33,8 @@ mod reconfig;
 mod resources;
 mod setup;
 
+pub use setup::list_adapters;
+
 /// One presenter iteration's video input.
 pub enum FrameInput<'a> {
     /// No new frame — re-composite the retained video image (expose/resize).

crates/pf-presenter/src/vk/setup.rs

@@ -497,6 +497,52 @@ impl Presenter {
     }
 }
 
+/// The physical devices' marketing names — the shells' GPU-picker source
+/// (`punktfunk-session --list-adapters`). No surface and no logical device; discrete
+/// GPUs first (mirroring `pick_device`'s tie-break), duplicates collapsed (the name is
+/// the whole `PUNKTFUNK_VK_ADAPTER` match key, so a second identical card adds nothing).
+/// Same 1.3 instance the presenter creates, so the list matches what streaming sees.
+pub fn list_adapters() -> Result<Vec<String>> {
+    let entry = unsafe { ash::Entry::load() }.context("libvulkan not loadable")?;
+    let app_name = CString::new("punktfunk-session").unwrap();
+    let app_info = vk::ApplicationInfo::default()
+        .application_name(&app_name)
+        .api_version(vk::API_VERSION_1_3);
+    let instance = unsafe {
+        entry.create_instance(
+            &vk::InstanceCreateInfo::default().application_info(&app_info),
+            None,
+        )
+    }
+    .context("vkCreateInstance")?;
+    let mut ranked: Vec<(u8, String)> = unsafe { instance.enumerate_physical_devices() }?
+        .into_iter()
+        .map(|d| {
+            let props = unsafe { instance.get_physical_device_properties(d) };
+            let rank = match props.device_type {
+                vk::PhysicalDeviceType::DISCRETE_GPU => 0u8,
+                vk::PhysicalDeviceType::INTEGRATED_GPU => 1,
+                _ => 2,
+            };
+            let name = props
+                .device_name_as_c_str()
+                .map(|c| c.to_string_lossy().into_owned())
+                .unwrap_or_default();
+            (rank, name)
+        })
+        .filter(|(_, n)| !n.is_empty())
+        .collect();
+    unsafe { instance.destroy_instance(None) };
+    ranked.sort_by_key(|(r, _)| *r); // stable: enumeration order within each tier
+    let mut names: Vec<String> = Vec::new();
+    for (_, n) in ranked {
+        if !names.contains(&n) {
+            names.push(n);
+        }
+    }
+    Ok(names)
+}
+
 /// First physical device with a queue family that does graphics + present here;
 /// `PUNKTFUNK_VK_DEVICE=<index>` overrides on multi-GPU boxes.
 fn pick_device(