feat(android): HDR toggle, video-feed stats, landscape lock

- HDR toggle in Settings → Display. Persisted (hdr_enabled, default on); the
  host is advertised HDR only when the toggle is on AND the panel can present
  HDR10 (displaySupportsHdr), so SDR panels never get PQ they'd mis-tone-map.
  The toggle is disabled/greyed on non-HDR displays (ToggleRow gained `enabled`).
- Extend the stats HUD with a video-feed line, e.g.
  "HEVC · 10-bit · HDR (BT.2020 PQ) · 4:2:0". nativeVideoStats now returns 14
  doubles (appends bitDepth, CICP primaries/transfer, chroma_format_idc from the
  negotiated Welcome); older/shorter layouts just omit the line.
- Lock the stream to landscape while streaming (SENSOR_LANDSCAPE), restoring the
  prior orientation on exit. The activity declares configChanges=orientation, so
  it re-lays-out in place with no stream restart; harmless no-op on TV.

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

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

@@ -175,9 +175,9 @@ fun ConnectScreen(settings: Settings, onConnected: (Long) -> Unit) {
         status = "Connecting to $targetHost:$targetPort…"
         discovery.stop() // free the Wi-Fi radio before the stream session
         scope.launch {
-            // Advertise HDR only when this device's display can present it (else the host sends a
-            // proper SDR stream rather than PQ the panel would mis-tone-map).
-            val hdrEnabled = displaySupportsHdr(context)
+            // Advertise HDR only when the user enabled it AND this device's display can present it
+            // (else the host sends a proper SDR stream rather than PQ the panel would mis-tone-map).
+            val hdrEnabled = settings.hdrEnabled && displaySupportsHdr(context)
             // "Automatic" resolves to a concrete pad type from the connected controller's VID/PID
             // (Android exposes no controller-type enum) — parity with the Linux/Apple clients. An
             // explicit choice is passed through unchanged.
@@ -224,7 +224,7 @@ fun ConnectScreen(settings: Settings, onConnected: (Long) -> Unit) {
         status = null
         discovery.stop() // free the Wi-Fi radio before the (parked) stream session
         scope.launch {
-            val hdrEnabled = displaySupportsHdr(context)
+            val hdrEnabled = settings.hdrEnabled && displaySupportsHdr(context)
             val gamepadPref = Gamepad.resolvePref(settings.gamepad)
             // Pin the advertised fingerprint for a discovered host (defence against an impostor while
             // we wait); a manually-typed host has none, so trust-on-first-use.

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

@@ -14,6 +14,13 @@ data class Settings(
     val height: Int = 0,
     val hz: Int = 0,
     val bitrateKbps: Int = 0,
+    /**
+     * Advertise HDR (10-bit BT.2020 PQ) to the host. Default on, but only *effective* on a panel that
+     * can actually present HDR10 (see [displaySupportsHdr]) — on an SDR display HDR is never
+     * advertised regardless, so the host sends a proper 8-bit BT.709 stream rather than PQ the panel
+     * would mis-tone-map. Turning this off forces SDR even on a capable panel.
+     */
+    val hdrEnabled: Boolean = true,
     val compositor: Int = 0,
     val gamepad: Int = 0,
     /** Requested audio channel count: 2 (stereo), 6 (5.1) or 8 (7.1). The host clamps to what it
@@ -40,6 +47,7 @@ class SettingsStore(context: Context) {
         height = prefs.getInt(K_H, 0),
         hz = prefs.getInt(K_HZ, 0),
         bitrateKbps = prefs.getInt(K_BITRATE, 0),
+        hdrEnabled = prefs.getBoolean(K_HDR, true),
         compositor = prefs.getInt(K_COMPOSITOR, 0),
         gamepad = prefs.getInt(K_GAMEPAD, 0),
         audioChannels = prefs.getInt(K_AUDIO_CH, 2),
@@ -54,6 +62,7 @@ class SettingsStore(context: Context) {
             .putInt(K_H, s.height)
             .putInt(K_HZ, s.hz)
             .putInt(K_BITRATE, s.bitrateKbps)
+            .putBoolean(K_HDR, s.hdrEnabled)
             .putInt(K_COMPOSITOR, s.compositor)
             .putInt(K_GAMEPAD, s.gamepad)
             .putInt(K_AUDIO_CH, s.audioChannels)
@@ -68,6 +77,7 @@ class SettingsStore(context: Context) {
         const val K_H = "height"
         const val K_HZ = "hz"
         const val K_BITRATE = "bitrate_kbps"
+        const val K_HDR = "hdr_enabled"
         const val K_COMPOSITOR = "compositor"
         const val K_GAMEPAD = "gamepad"
         const val K_AUDIO_CH = "audio_channels"

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

@@ -94,6 +94,22 @@ fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -
                 options = BITRATE_OPTIONS,
                 selected = s.bitrateKbps,
             ) { kbps -> update(s.copy(bitrateKbps = kbps)) }
+
+            // HDR is only meaningful on a panel that can present HDR10; on an SDR display the toggle
+            // is disabled (and HDR is never advertised regardless) so the host doesn't send PQ the
+            // panel would mis-tone-map. The capability is fixed for the device, so read it once.
+            val hdrCapable = remember { displaySupportsHdr(context) }
+            ToggleRow(
+                title = "HDR",
+                subtitle = if (hdrCapable) {
+                    "Stream 10-bit HDR (BT.2020 PQ) when the host supports it"
+                } else {
+                    "This display can't present HDR10 — streams stay SDR"
+                },
+                checked = s.hdrEnabled && hdrCapable,
+                enabled = hdrCapable,
+                onCheckedChange = { on -> update(s.copy(hdrEnabled = on)) },
+            )
         }
 
         SettingsGroup("Host") {
@@ -181,24 +197,31 @@ private fun SettingsGroup(title: String, content: @Composable ColumnScope.() ->
     }
 }
 
-/** A title + subtitle on the left, a Switch on the right. */
+/** A title + subtitle on the left, a Switch on the right. [enabled] greys out the whole row. */
 @Composable
 private fun ToggleRow(
     title: String,
     subtitle: String,
     checked: Boolean,
     onCheckedChange: (Boolean) -> Unit,
+    enabled: Boolean = true,
 ) {
+    // Dim the labels when disabled so the row reads as inactive (the Switch dims itself).
+    val labelAlpha = if (enabled) 1f else 0.38f
     Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
         Column(Modifier.weight(1f)) {
-            Text(title, style = MaterialTheme.typography.bodyLarge)
+            Text(
+                title,
+                style = MaterialTheme.typography.bodyLarge,
+                color = MaterialTheme.colorScheme.onSurface.copy(alpha = labelAlpha),
+            )
             Text(
                 subtitle,
                 style = MaterialTheme.typography.bodySmall,
-                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = labelAlpha),
             )
         }
-        Switch(checked = checked, onCheckedChange = onCheckedChange)
+        Switch(checked = checked, onCheckedChange = onCheckedChange, enabled = enabled)
     }
 }
 

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

@@ -1,6 +1,7 @@
 package io.unom.punktfunk
 
 import android.Manifest
+import android.content.pm.ActivityInfo
 import android.content.pm.PackageManager
 import android.view.SurfaceHolder
 import android.view.SurfaceView
@@ -102,6 +103,13 @@ fun StreamScreen(handle: Long, micEnabled: Boolean, onDisconnect: () -> Unit) {
             it.systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
             it.hide(WindowInsetsCompat.Type.systemBars())
         }
+        // Lock to landscape while streaming — the host streams a landscape desktop, so pin the device
+        // there (either landscape direction is fine) and stop it rotating to portrait mid-session. The
+        // activity declares configChanges=orientation, so this re-lays out the surface in place without
+        // recreating the activity (no stream restart). On TV (fixed landscape) it's a harmless no-op.
+        // The prior request is captured and restored on the way out.
+        val priorOrientation = activity?.requestedOrientation
+        activity?.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE
         activity?.streamHandle = handle // route hardware keys to this session
         activity?.axisMapper = Gamepad.AxisMapper(handle) // route joystick axes
         // Host→client feedback (rumble + DualSense lightbar/LEDs); poll threads stopped before close.
@@ -114,6 +122,9 @@ fun StreamScreen(handle: Long, micEnabled: Boolean, onDisconnect: () -> Unit) {
             activity?.streamHandle = 0L
             controller?.show(WindowInsetsCompat.Type.systemBars())
             window?.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+            // Release the landscape lock so the rest of the app follows the device/system again.
+            activity?.requestedOrientation =
+                priorOrientation ?: ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED
             // Leaving the stream: stop the mic + audio + decode threads and tear down the session.
             NativeBridge.nativeStopMic(handle)
             NativeBridge.nativeStopAudio(handle)
@@ -314,9 +325,11 @@ fun StreamScreen(handle: Long, micEnabled: Boolean, onDisconnect: () -> Unit) {
 }
 
 /**
- * The live stats overlay — mirrors the Apple client's HUD. Reads the 10-double layout from
+ * The live stats overlay — mirrors the Apple client's HUD. Reads the 14-double layout from
  * [NativeBridge.nativeVideoStats]:
- * `[fps, mbps, latP50Ms, latP95Ms, latValid, skew, w, h, hz, dropped]`.
+ * `[fps, mbps, latP50Ms, latP95Ms, latValid, skew, w, h, hz, dropped, bitDepth, colorPrimaries,
+ * colorTransfer, chromaFormatIdc]`. The trailing four (present on a current native lib) describe the
+ * negotiated video feed and render as a codec/depth/colour/chroma line; older layouts just omit it.
  */
 @Composable
 internal fun StatsOverlay(s: DoubleArray, modifier: Modifier = Modifier) {
@@ -338,6 +351,14 @@ internal fun StatsOverlay(s: DoubleArray, modifier: Modifier = Modifier) {
             fontFamily = FontFamily.Monospace,
             fontSize = 12.sp,
         )
+        videoFeedLine(s)?.let { feed ->
+            Text(
+                feed,
+                color = Color.White,
+                fontFamily = FontFamily.Monospace,
+                fontSize = 12.sp,
+            )
+        }
         if (latValid) {
             val tag = if (skew) "" else " (same-host)"
             Text(
@@ -357,3 +378,31 @@ internal fun StatsOverlay(s: DoubleArray, modifier: Modifier = Modifier) {
         }
     }
 }
+
+/**
+ * Format the negotiated video-feed descriptor from the trailing four stats doubles
+ * `[bitDepth, colorPrimaries, colorTransfer, chromaFormatIdc]`, e.g.
+ * `HEVC · 10-bit · HDR (BT.2020 PQ) · 4:2:0`. Returns `null` on a pre-video-feed layout (< 14 doubles)
+ * so the overlay simply omits the line. The codes are CICP / H.273: transfer 16 = PQ, 18 = HLG (else
+ * SDR); primaries 9 = BT.2020, 1 = BT.709; chroma_format_idc 1 = 4:2:0, 2 = 4:2:2, 3 = 4:4:4. The
+ * Android decoder is always HEVC (`video/hevc`).
+ */
+private fun videoFeedLine(s: DoubleArray): String? {
+    if (s.size < 14) return null
+    val bitDepth = s[10].toInt()
+    val primaries = s[11].toInt()
+    val transfer = s[12].toInt()
+    val chromaIdc = s[13].toInt()
+    val depthLabel = if (bitDepth > 0) "$bitDepth-bit" else "8-bit"
+    val (dynamicRange, colorSpace) = when (transfer) {
+        16 -> "HDR" to "BT.2020 PQ"
+        18 -> "HDR" to "BT.2020 HLG"
+        else -> "SDR" to if (primaries == 9) "BT.2020" else "BT.709"
+    }
+    val chromaLabel = when (chromaIdc) {
+        3 -> "4:4:4"
+        2 -> "4:2:2"
+        else -> "4:2:0"
+    }
+    return "HEVC · $depthLabel · $dynamicRange ($colorSpace) · $chromaLabel"
+}

clients/android/app/src/test/kotlin/io/unom/punktfunk/screenshots/ShotScenes.kt

@@ -186,9 +186,11 @@ internal fun StreamScene() {
                 Brush.linearGradient(listOf(Color(0xFF2A1E5C), Color(0xFF0E1B3D), Color(0xFF06122B))),
             ),
     ) {
-        // [fps, mbps, latP50, latP95, latValid, skew, w, h, hz, dropped]
+        // [fps, mbps, latP50, latP95, latValid, skew, w, h, hz, dropped,
+        //  bitDepth, colorPrimaries, colorTransfer, chromaFormatIdc] — the last four = a 10-bit
+        //  BT.2020 PQ (HDR) 4:2:0 feed, so the HUD renders its video-feed line.
         StatsOverlay(
-            doubleArrayOf(238.0, 921.4, 1.3, 2.1, 1.0, 1.0, 5120.0, 1440.0, 240.0, 0.0),
+            doubleArrayOf(238.0, 921.4, 1.3, 2.1, 1.0, 1.0, 5120.0, 1440.0, 240.0, 0.0, 10.0, 9.0, 16.0, 1.0),
             Modifier.align(Alignment.TopStart).padding(12.dp),
         )
     }

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

@@ -103,9 +103,12 @@ object NativeBridge {
 
     /**
      * Drain ~1 s of live decode stats for the on-stream HUD, or `null` when no decode thread runs.
-     * Returns 10 doubles:
-     * `[fps, mbps, latP50Ms, latP95Ms, latValid, skewCorrected, width, height, refreshHz, framesDropped]`
-     * (the two flags are 1.0/0.0). Poll ~1 Hz; each call resets the measurement window.
+     * Returns 14 doubles:
+     * `[fps, mbps, latP50Ms, latP95Ms, latValid, skewCorrected, width, height, refreshHz, framesDropped,
+     * bitDepth, colorPrimaries, colorTransfer, chromaFormatIdc]`
+     * (the two flags are 1.0/0.0; the trailing four describe the negotiated video feed — bit depth
+     * 8/10, CICP primaries/transfer, and the HEVC chroma_format_idc 1=4:2:0 / 3=4:4:4). Poll ~1 Hz;
+     * each call resets the measurement window.
      */
     external fun nativeVideoStats(handle: Long): DoubleArray?
 

clients/android/native/src/session.rs

@@ -409,11 +409,13 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeStopVideo(
 }
 
 /// `NativeBridge.nativeVideoStats(handle): DoubleArray?` — drain ~1 s of decode stats for the HUD.
-/// Returns 10 doubles
-/// `[fps, mbps, latP50Ms, latP95Ms, latValid, skewCorrected, width, height, refreshHz, framesDropped]`
-/// (the two flags are 1.0/0.0), or `null` when no decode thread is running. Poll ~1 Hz from the UI;
-/// each call resets the measurement window. Not android-gated — pure `jni` + connector reads, so it
-/// links on the host build too (Kotlin only ever calls it on device).
+/// Returns 14 doubles
+/// `[fps, mbps, latP50Ms, latP95Ms, latValid, skewCorrected, width, height, refreshHz, framesDropped,
+/// bitDepth, colorPrimaries, colorTransfer, chromaFormatIdc]`
+/// (the two flags are 1.0/0.0; the trailing four describe the negotiated video feed — see below), or
+/// `null` when no decode thread is running. Poll ~1 Hz from the UI; each call resets the measurement
+/// window. Not android-gated — pure `jni` + connector reads, so it links on the host build too
+/// (Kotlin only ever calls it on device).
 #[no_mangle]
 pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeVideoStats(
     env: JNIEnv,
@@ -431,7 +433,8 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeVideoStats(
             None => return std::ptr::null_mut(), // not streaming → no stats
         };
         let mode = h.client.mode();
-        let buf: [f64; 10] = [
+        let color = h.client.color;
+        let buf: [f64; 14] = [
             snap.fps,
             snap.mbps,
             snap.lat_p50_ms,
@@ -442,6 +445,14 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeVideoStats(
             mode.height as f64,
             mode.refresh_hz as f64,
             h.client.frames_dropped() as f64,
+            // Video-feed properties the host resolved at the handshake (Welcome): encode bit depth
+            // (8 / 10), the CICP colour primaries + transfer code points (Kotlin maps these to a
+            // colour-space / HDR label — transfer 16 = PQ, 18 = HLG ⇒ HDR), and the HEVC
+            // chroma_format_idc (1 = 4:2:0, 3 = 4:4:4). Static for the session unless renegotiated.
+            h.client.bit_depth as f64,
+            color.primaries as f64,
+            color.transfer as f64,
+            h.client.chroma_format as f64,
         ];
         let arr = match env.new_double_array(buf.len() as jsize) {
             Ok(a) => a,