feat(android): native display resolution + Settings screen

The connect mode was hardcoded to 720p60 — violating the "native client resolution, no
scaling" invariant. Derive the device's real display mode (landscape, long edge = width) and
add a Settings screen to tune the stream, mirroring the Linux/Apple clients.

- crates/punktfunk-android: nativeConnect gains bitrateKbps + compositorPref + gamepadPref
  (CompositorPref/GamepadPref wire bytes via from_u8); these were hardcoded Auto/Auto/0.
- app/Settings.kt: Settings (width/height/hz/bitrate/compositor/gamepad; 0 = native/auto) +
  a SharedPreferences store + nativeDisplayMode (Display.mode, landscape-swapped) +
  effectiveMode + the UI option tables.
- app/SettingsScreen.kt: dropdowns for resolution / refresh / bitrate / compositor / controller.
- MainActivity: App owns the settings + a Settings screen; ConnectScreen resolves the effective
  mode (Native = the display), shows it on the Connect button, and threads the prefs through
  nativeConnect.

Mic + codec selection deferred (mic uplink isn't wired yet; the decoder is HEVC-only).

Verified live (emulator pf_phone -> home-worker-2): default -> host mode=2400x1080@60 (the
emulator's native display, was 720p); Settings 1920x1080 + 20 Mbps + DualSense -> host
mode=1920x1080, requested_kbps=20000, gamepad=dualsense (host created a UHID DualSense).
Settings persist across screens; pinned reconnect stays silent.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/android/app/src/main/kotlin/io/unom/punktfunk/MainActivity.kt

@@ -137,11 +137,9 @@ class MainActivity : ComponentActivity() {
     }
 }
 
-/** Scaffold mode requested from the host (WxH@Hz). TODO: derive from the display. */
-private val REQUEST_MODE = Triple(1280, 720, 60)
-
 private sealed interface Screen {
     data object Connect : Screen
+    data object Settings : Screen
     data class Stream(val handle: Long) : Screen
 }
 
@@ -163,15 +161,27 @@ private data class PendingTrust(
 
 @Composable
 private fun App() {
+    val context = LocalContext.current
+    val settingsStore = remember { SettingsStore(context) }
+    var settings by remember { mutableStateOf(settingsStore.load()) }
     var screen by remember { mutableStateOf<Screen>(Screen.Connect) }
     when (val s = screen) {
-        Screen.Connect -> ConnectScreen(onConnected = { handle -> screen = Screen.Stream(handle) })
+        Screen.Connect -> ConnectScreen(
+            settings = settings,
+            onConnected = { handle -> screen = Screen.Stream(handle) },
+            onOpenSettings = { screen = Screen.Settings },
+        )
+        Screen.Settings -> SettingsScreen(
+            initial = settings,
+            onChange = { settings = it; settingsStore.save(it) },
+            onBack = { screen = Screen.Connect },
+        )
         is Screen.Stream -> StreamScreen(s.handle, onDisconnect = { screen = Screen.Connect })
     }
 }
 
 @Composable
-private fun ConnectScreen(onConnected: (Long) -> Unit) {
+private fun ConnectScreen(settings: Settings, onConnected: (Long) -> Unit, onOpenSettings: () -> Unit) {
     val scope = rememberCoroutineScope()
     val context = LocalContext.current
     var host by remember { mutableStateOf("") }
@@ -179,7 +189,8 @@ private fun ConnectScreen(onConnected: (Long) -> Unit) {
     var connecting by remember { mutableStateOf(false) }
     var status by remember { mutableStateOf<String?>(null) }
     val abi = remember { runCatching { NativeBridge.abiVersion() }.getOrDefault(-1) }
-    val (w, h, hz) = REQUEST_MODE
+    // The host streams at exactly this mode; "Native" settings resolve from the device display.
+    val (w, h, hz) = settings.effectiveMode(context)
 
     // mDNS discovery scoped to this screen; NsdManager callbacks arrive on the main thread, so the
     // onChange callback can set Compose state directly. (Emulator SLIRP drops multicast → empty.)
@@ -225,6 +236,7 @@ private fun ConnectScreen(onConnected: (Long) -> Unit) {
                 NativeBridge.nativeConnect(
                     targetHost, targetPort, w, h, hz,
                     id.certPem, id.privateKeyPem, pinHex ?: "",
+                    settings.bitrateKbps, settings.compositor, settings.gamepad,
                 )
             }
             connecting = false
@@ -311,6 +323,7 @@ private fun ConnectScreen(onConnected: (Long) -> Unit) {
             enabled = !connecting && host.isNotBlank() && port.isNotBlank(),
             onClick = { connect(host.trim(), port.toInt()) },
         ) { Text(if (connecting) "Connecting…" else "Connect  ($w×$h@$hz)") }
+        TextButton(enabled = !connecting, onClick = onOpenSettings) { Text("Settings") }
         status?.let {
             Spacer(Modifier.height(12.dp))
             Text(it, style = MaterialTheme.typography.bodySmall)

clients/android/app/src/main/kotlin/io/unom/punktfunk/Settings.kt

@@ -0,0 +1,125 @@
+package io.unom.punktfunk
+
+import android.content.Context
+
+/**
+ * User-tunable stream settings, persisted in `SharedPreferences`. A `0` resolution/refresh means
+ * "native display mode" (resolved at connect time from [nativeDisplayMode]); `0` bitrate means the
+ * host's default. [compositor]/[gamepad] are the `CompositorPref`/`GamepadPref` wire bytes the host
+ * understands (0 = Auto). Mirrors the Linux/Apple clients' settings.
+ */
+data class Settings(
+    val width: Int = 0,
+    val height: Int = 0,
+    val hz: Int = 0,
+    val bitrateKbps: Int = 0,
+    val compositor: Int = 0,
+    val gamepad: Int = 0,
+)
+
+/** Loads/saves [Settings] in the app-private `punktfunk_settings` prefs. */
+class SettingsStore(context: Context) {
+    private val prefs =
+        context.applicationContext.getSharedPreferences("punktfunk_settings", Context.MODE_PRIVATE)
+
+    fun load(): Settings = Settings(
+        width = prefs.getInt(K_W, 0),
+        height = prefs.getInt(K_H, 0),
+        hz = prefs.getInt(K_HZ, 0),
+        bitrateKbps = prefs.getInt(K_BITRATE, 0),
+        compositor = prefs.getInt(K_COMPOSITOR, 0),
+        gamepad = prefs.getInt(K_GAMEPAD, 0),
+    )
+
+    fun save(s: Settings) {
+        prefs.edit()
+            .putInt(K_W, s.width)
+            .putInt(K_H, s.height)
+            .putInt(K_HZ, s.hz)
+            .putInt(K_BITRATE, s.bitrateKbps)
+            .putInt(K_COMPOSITOR, s.compositor)
+            .putInt(K_GAMEPAD, s.gamepad)
+            .apply()
+    }
+
+    private companion object {
+        const val K_W = "width"
+        const val K_H = "height"
+        const val K_HZ = "hz"
+        const val K_BITRATE = "bitrate_kbps"
+        const val K_COMPOSITOR = "compositor"
+        const val K_GAMEPAD = "gamepad"
+    }
+}
+
+/**
+ * The device's native display mode as a landscape `(width, height, hz)` — the long edge is the
+ * width, since we stream a desktop. Falls back to 1920×1080@60 if the display can't be read.
+ * [context] must be a visual (Activity) context.
+ */
+fun nativeDisplayMode(context: Context): Triple<Int, Int, Int> {
+    // getDisplay() throws on a non-visual context rather than returning null — guard it.
+    val display = runCatching { context.display }.getOrNull() ?: return Triple(1920, 1080, 60)
+    val mode = display.mode
+    val w = mode.physicalWidth
+    val h = mode.physicalHeight
+    val hz = mode.refreshRate.toInt().coerceAtLeast(1)
+    return Triple(maxOf(w, h), minOf(w, h), hz)
+}
+
+/** Resolve [Settings] (with its 0=native placeholders) to the concrete mode to request. */
+fun Settings.effectiveMode(context: Context): Triple<Int, Int, Int> {
+    val native = nativeDisplayMode(context)
+    val w = if (width > 0) width else native.first
+    val h = if (height > 0) height else native.second
+    val hz = if (hz > 0) hz else native.third
+    return Triple(w, h, hz)
+}
+
+// ---- UI option tables (value, label). The first entry is always the "auto/native" default. ----
+
+/** (width, height, label). `(0,0)` = native display. */
+val RESOLUTION_OPTIONS = listOf(
+    Triple(0, 0, "Native display"),
+    Triple(1280, 720, "1280 × 720"),
+    Triple(1920, 1080, "1920 × 1080"),
+    Triple(2560, 1440, "2560 × 1440"),
+    Triple(3840, 2160, "3840 × 2160"),
+)
+
+/** (hz, label). `0` = native refresh. */
+val REFRESH_OPTIONS = listOf(
+    0 to "Native",
+    30 to "30 Hz",
+    60 to "60 Hz",
+    90 to "90 Hz",
+    120 to "120 Hz",
+    144 to "144 Hz",
+    165 to "165 Hz",
+    240 to "240 Hz",
+)
+
+/** (kbps, label). `0` = host default. */
+val BITRATE_OPTIONS = listOf(
+    0 to "Automatic",
+    10_000 to "10 Mbps",
+    20_000 to "20 Mbps",
+    50_000 to "50 Mbps",
+    100_000 to "100 Mbps",
+)
+
+/** index = CompositorPref wire byte. */
+val COMPOSITOR_OPTIONS = listOf(
+    "Automatic",
+    "KWin (KDE Plasma)",
+    "wlroots (Sway / Hyprland)",
+    "Mutter (GNOME)",
+    "gamescope",
+)
+
+/** index = GamepadPref wire byte. */
+val GAMEPAD_OPTIONS = listOf(
+    "Automatic",
+    "Xbox 360",
+    "DualSense",
+)

clients/android/app/src/main/kotlin/io/unom/punktfunk/SettingsScreen.kt

@@ -0,0 +1,125 @@
+package io.unom.punktfunk
+
+import androidx.activity.compose.BackHandler
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ExposedDropdownMenuBox
+import androidx.compose.material3.ExposedDropdownMenuAnchorType
+import androidx.compose.material3.ExposedDropdownMenuDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.dp
+
+/**
+ * Stream settings. Edits are persisted immediately via [onChange]; [onBack] returns to the connect
+ * screen. Resolution/refresh "Native" resolve from the device display at connect time.
+ */
+@Composable
+fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -> Unit) {
+    var s by remember { mutableStateOf(initial) }
+    val context = LocalContext.current
+    fun update(next: Settings) {
+        s = next
+        onChange(next)
+    }
+
+    BackHandler(onBack = onBack)
+
+    Column(
+        modifier = Modifier.fillMaxSize().verticalScroll(rememberScrollState()).padding(24.dp),
+        verticalArrangement = Arrangement.spacedBy(16.dp),
+    ) {
+        Text("Settings", style = MaterialTheme.typography.headlineMedium)
+
+        val (nw, nh, nhz) = nativeDisplayMode(context)
+        SettingDropdown(
+            label = "Resolution",
+            options = RESOLUTION_OPTIONS.map { (w, h, lbl) ->
+                (w to h) to (if (w == 0) "$lbl ($nw × $nh)" else lbl)
+            },
+            selected = s.width to s.height,
+        ) { (w, h) -> update(s.copy(width = w, height = h)) }
+
+        SettingDropdown(
+            label = "Refresh rate",
+            options = REFRESH_OPTIONS.map { (hz, lbl) -> hz to (if (hz == 0) "$lbl (${nhz} Hz)" else lbl) },
+            selected = s.hz,
+        ) { hz -> update(s.copy(hz = hz)) }
+
+        SettingDropdown(
+            label = "Bitrate",
+            options = BITRATE_OPTIONS,
+            selected = s.bitrateKbps,
+        ) { kbps -> update(s.copy(bitrateKbps = kbps)) }
+
+        SettingDropdown(
+            label = "Compositor (virtual-display host backend)",
+            options = COMPOSITOR_OPTIONS.mapIndexed { i, lbl -> i to lbl },
+            selected = s.compositor,
+        ) { c -> update(s.copy(compositor = c)) }
+
+        SettingDropdown(
+            label = "Controller type",
+            options = GAMEPAD_OPTIONS.mapIndexed { i, lbl -> i to lbl },
+            selected = s.gamepad,
+        ) { g -> update(s.copy(gamepad = g)) }
+
+        Spacer(Modifier.height(8.dp))
+        TextButton(onClick = onBack) { Text("Done") }
+    }
+}
+
+/** A labelled read-only dropdown over [options] (value → label); calls [onSelect] on a pick. */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun <T> SettingDropdown(
+    label: String,
+    options: List<Pair<T, String>>,
+    selected: T,
+    onSelect: (T) -> Unit,
+) {
+    var expanded by remember { mutableStateOf(false) }
+    val selectedLabel = options.firstOrNull { it.first == selected }?.second
+        ?: options.firstOrNull()?.second.orEmpty()
+    ExposedDropdownMenuBox(expanded = expanded, onExpandedChange = { expanded = it }) {
+        OutlinedTextField(
+            value = selectedLabel,
+            onValueChange = {},
+            readOnly = true,
+            label = { Text(label) },
+            trailingIcon = { ExposedDropdownMenuDefaults.TrailingIcon(expanded = expanded) },
+            modifier = Modifier
+                .menuAnchor(ExposedDropdownMenuAnchorType.PrimaryNotEditable)
+                .fillMaxWidth(),
+        )
+        ExposedDropdownMenu(expanded = expanded, onDismissRequest = { expanded = false }) {
+            options.forEach { (value, lbl) ->
+                DropdownMenuItem(
+                    text = { Text(lbl) },
+                    onClick = {
+                        onSelect(value)
+                        expanded = false
+                    },
+                )
+            }
+        }
+    }
+}

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/NativeBridge.kt

@@ -27,7 +27,10 @@ object NativeBridge {
     /**
      * Connect, presenting [certPem]/[keyPem] (both empty = anonymous) and pinning [pinHex] (empty =
      * trust-on-first-use — read [nativeHostFingerprint] after; else 64-hex host SHA-256, mismatch →
-     * `0`). Returns an opaque session handle, or `0` on failure. Pair with exactly one [nativeClose].
+     * `0`). [width]/[height]/[refreshHz] are the requested virtual-output mode (the host streams at
+     * exactly this); [bitrateKbps] 0 = host default; [compositorPref]/[gamepadPref] are the
+     * `CompositorPref`/`GamepadPref` wire bytes (0 = Auto). Returns an opaque session handle, or `0`
+     * on failure. Pair with exactly one [nativeClose].
      */
     external fun nativeConnect(
         host: String,
@@ -38,6 +41,9 @@ object NativeBridge {
         certPem: String,
         keyPem: String,
         pinHex: String,
+        bitrateKbps: Int,
+        compositorPref: Int,
+        gamepadPref: Int,
     ): Long
 
     /** 64-hex SHA-256 of the cert the host presented on [handle]; valid after a successful connect. */