feat(android): the client advertises multi-slice tolerance per-decoder

The P0 gating branch deliberately left Android off VIDEO_CAP_MULTI_SLICE
("embedder-set decoder truth") — this is that deferred item, and the P2
slice-pipeline prerequisite. VideoDecoders.multiSliceTolerant() probes the
pick for every advertised codec: tolerant unless any pick is an Amlogic
decoder (the 0.17.0 device-rebooting wedge) or uninspectable (a null pick =
platform default → conservatively single-slice). nativeConnect carries the
bit; the JNI ORs it into the Hello's video_caps beside the panel-truth
HDR bits. Phones (Qualcomm/Exynos) advertise it; the Amlogic TV boxes the
gate exists for never will.

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

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

@@ -49,7 +49,7 @@ suspend fun connectToHost(
             host, port, w, h, hz,
             identity.certPem, identity.privateKeyPem, pinHex,
             settings.bitrateKbps, settings.compositor, gamepadPref,
-            hdrEnabled, settings.audioChannels,
+            hdrEnabled, VideoDecoders.multiSliceTolerant(), settings.audioChannels,
             // What this device can decode (H.264|HEVC always, AV1 when a real decoder exists) +
             // the user's soft codec preference — the host resolves the emitted codec from both.
             VideoDecoders.decodableCodecBits(), settings.preferredCodec(), timeoutMs,

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

@@ -47,6 +47,10 @@ object NativeBridge {
         compositorPref: Int,
         gamepadPref: Int,
         hdrEnabled: Boolean,
+        /** Every decoder this device would use tolerates multi-slice AUs
+         *  ([VideoDecoders.multiSliceTolerant]) — advertises `VIDEO_CAP_MULTI_SLICE`; false keeps
+         *  the host at single-slice frames (the safe pre-0.17 wire shape). */
+        multiSliceOk: Boolean,
         audioChannels: Int,
         /** `quic::CODEC_*` bitfield of codecs this device decodes ([VideoDecoders.decodableCodecBits]);
          *  `0` falls back to H.264|HEVC. The host resolves the emitted codec from this ∩ its GPU. */

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

@@ -53,6 +53,28 @@ object VideoDecoders {
     fun decodableCodecBits(): Int =
         1 or 2 or (if (pickDecoder("video/av01") != null) 4 else 0)
 
+    /**
+     * Whether EVERY decoder this device would use tolerates multi-slice access units — the
+     * `VIDEO_CAP_MULTI_SLICE` advertisement (decoder truth, per the 0.17.0 field regression:
+     * Amlogic HEVC decoders wedge the whole DEVICE on multi-slice frames — Chromecast with
+     * Google TV, onn 4K — which is why Moonlight requests single-slice for every hardware
+     * decoder). We advertise per-family instead: tolerant unless the pick for ANY advertised
+     * codec is an Amlogic decoder or can't be inspected (a null pick = the platform default —
+     * uninspectable, so conservatively single-slice). Probed once at connect time; the host
+     * defaults to >1 slice only toward clients that set the bit.
+     */
+    fun multiSliceTolerant(): Boolean {
+        val mimes = buildList {
+            add("video/avc")
+            add("video/hevc")
+            if (decodableCodecBits() and 4 != 0) add("video/av01")
+        }
+        return mimes.all { mime ->
+            val name = pickDecoder(mime)?.name?.lowercase() ?: return@all false
+            !name.startsWith("omx.amlogic") && !name.startsWith("c2.amlogic")
+        }
+    }
+
     fun pickDecoder(mime: String): DecoderChoice? {
         if (mime.isEmpty()) return null
         val infos = runCatching { MediaCodecList(MediaCodecList.REGULAR_CODECS).codecInfos }

clients/android/native/src/session/connect.rs

@@ -115,6 +115,7 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeConnect<'lo
     compositor_pref: jint,
     gamepad_pref: jint,
     hdr_enabled: jboolean,
+    multi_slice_ok: jboolean,
     audio_channels: jint,
     video_codecs: jint,
     preferred_codec: jint,
@@ -182,11 +183,19 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeConnect<'lo
         // sends a proper 8-bit BT.709 stream rather than PQ the panel would mis-tone-map. AMediaCodec
         // decodes Main10 from the SPS and the decode loop signals the Surface HDR dataspace + static
         // metadata (see crate::decode).
-        if hdr_enabled != 0 {
+        // 10-bit/HDR by panel truth (above) + multi-slice by DECODER truth: Kotlin probes every
+        // decoder this device would use (`VideoDecoders.multiSliceTolerant` — Amlogic wedges the
+        // whole device on multi-slice AUs, the 0.17.0 field regression) and only then may the
+        // host default to >1 slice per frame (its sub-frame readback / the P2 slice pipeline).
+        (if hdr_enabled != 0 {
             punktfunk_core::quic::VIDEO_CAP_10BIT | punktfunk_core::quic::VIDEO_CAP_HDR
         } else {
             0
-        },
+        }) | (if multi_slice_ok != 0 {
+            punktfunk_core::quic::VIDEO_CAP_MULTI_SLICE
+        } else {
+            0
+        }),
         // Requested surround layout (2 = stereo / 6 = 5.1 / 8 = 7.1). The host clamps to what it can
         // capture and echoes the resolved count in `connector.audio_channels`, which drives the
         // decoder + AAudio layout (read in `crate::audio::AudioPlayback::start`). Anything else