feat(android): native mDNS discovery, host naming, touch mouse, stock selects

Discovery: replace the flaky per-OEM NsdManager with the same mdns-sd browse
the Linux/Windows clients use, in the Rust core over JNI and polled by Kotlin
(discovery.rs + nativeDiscovery{Start,Poll,Stop}); Kotlin keeps only the Wi-Fi
MulticastLock + permission UX. IPv4-only (the core can't dial a bare/scoped v6
literal); daemon + fold-thread cleanup on every failure path; field
sanitization so a rogue advert can't corrupt the picker snapshot. Discovery
now starts regardless of NEARBY_WIFI_DEVICES (raw multicast only needs the
MulticastLock) — a denial no longer kills it forever. ParseTxtTest replaced by
ParseRecordTest.

Hosts: hide already-saved hosts from the "Discovered" section (match by
fingerprint, else address:port — mirrors the Apple client); add an optional
Name field to the Add-host sheet and a Rename action on saved cards.

Input: touch -> absolute mouse "direct pointing" like the Apple client — the
host cursor follows the finger (new nativeSendPointerAbs -> MouseMoveAbs). Tap
= left click, two-finger tap = right click, two-finger drag = scroll,
tap-then-drag = left-drag, three-finger tap = HUD toggle.

Settings: revert the dropdowns to the stock ExposedDropdownMenuBox look (a
controller-focus UI will come separately); even out the Add-host field gaps.

Docs updated (CLAUDE.md, client READMEs, docs-site status).

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

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

@@ -67,6 +67,27 @@ object NativeBridge {
     /** Tear down a session handle returned by [nativeConnect]. No-op on `0`. */
     external fun nativeClose(handle: Long)
 
+    // ---- LAN discovery: mDNS browse of `_punktfunk._udp` in Rust (mdns-sd), polled by Kotlin ----
+    // Replaces NsdManager. The caller holds the Wi-Fi MulticastLock for the browse lifetime; raw
+    // multicast *reception* needs it. See io.unom.punktfunk.kit.discovery.HostDiscovery.
+
+    /**
+     * Start browsing `_punktfunk._udp` on the LAN. Returns an opaque discovery handle, or `0` on
+     * failure. Pair with exactly one [nativeDiscoveryStop]. Cheap + non-blocking (spawns the mDNS
+     * daemon + a fold thread).
+     */
+    external fun nativeDiscoveryStart(): Long
+
+    /**
+     * The current resolved-host snapshot for [handle]: newline-joined records, each
+     * `key␟name␟addr␟port␟fp␟pair` (`␟` = U+001F). Empty string = no hosts / `0` handle. Poll ~1 Hz;
+     * cheap (a lock + string build), safe to call on the main thread.
+     */
+    external fun nativeDiscoveryPoll(handle: Long): String
+
+    /** Stop the browse, shut the mDNS daemon down and join its thread. No-op on `0`. */
+    external fun nativeDiscoveryStop(handle: Long)
+
     /**
      * Start the HEVC decode thread rendering onto [surface] (a SurfaceView's surface). Decode runs
      * entirely in Rust (NDK AMediaCodec → ANativeWindow) — no per-frame JNI. No-op if already started.
@@ -108,6 +129,13 @@ object NativeBridge {
     /** Relative mouse move; dx/dy are device-pixel deltas (screen +y down). */
     external fun nativeSendPointerMove(handle: Long, dx: Int, dy: Int)
 
+    /**
+     * Absolute mouse position — the host moves the cursor to (x, y) in a [surfaceWidth]×[surfaceHeight]
+     * pixel space (it normalizes against that size and maps into the output region). Touch
+     * "direct pointing": the cursor jumps to the finger. Parity with the Apple client's absolute touch.
+     */
+    external fun nativeSendPointerAbs(handle: Long, x: Int, y: Int, surfaceWidth: Int, surfaceHeight: Int)
+
     /** One mouse-button transition. button: 1=left 2=middle 3=right 4=X1 5=X2. */
     external fun nativeSendPointerButton(handle: Long, button: Int, down: Boolean)
 

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

@@ -1,17 +1,13 @@
 package io.unom.punktfunk.kit.discovery
 
 import android.content.Context
-import android.net.nsd.NsdManager
-import android.net.nsd.NsdServiceInfo
 import android.net.wifi.WifiManager
-import android.os.Build
+import android.os.Handler
+import android.os.Looper
 import android.util.Log
+import io.unom.punktfunk.kit.NativeBridge
 
-private const val TAG = "PunktfunkNsd"
-
-/** DNS-SD service type punktfunk hosts advertise (host: `_punktfunk._udp.local.`). */
-const val PUNKTFUNK_SERVICE_TYPE = "_punktfunk._udp"
-const val PUNKTFUNK_PROTO = "punktfunk/1"
+private const val TAG = "PunktfunkMdns"
 
 /** One resolved host fit for the picker. [key] is the stable dedup id. */
 data class DiscoveredHost(
@@ -23,165 +19,115 @@ data class DiscoveredHost(
     val pairingRequired: Boolean = false,
 )
 
-/** Parsed TXT fields. Pure — unit-testable without Android (see ParseTxtTest). */
-data class TxtFields(
-    val proto: String?,
-    val fp: String?,
-    val pair: String?,
-    val id: String?,
-) {
-    val pairingRequired: Boolean get() = pair == "required"
-    val isPunktfunk: Boolean get() = proto == PUNKTFUNK_PROTO
-}
+/** Field separator the native browse uses inside one record (ASCII Unit Separator). */
+private const val FIELD_SEP = '\u001F'
 
 /**
- * Pure TXT parser. NSD hands TXT as a `Map<String, ByteArray?>` (a null/empty value = present-but-
- * empty key). Decode UTF-8; missing keys are null, never an error.
+ * Parse one record from [NativeBridge.nativeDiscoveryPoll] (`key␟name␟addr␟port␟fp␟pair`), or null
+ * if it's malformed. Pure — unit-tested without Android (see ParseRecordTest). The native side
+ * already applied the protocol gate and address selection, so this is just field marshaling.
  */
-fun parseTxt(attrs: Map<String, ByteArray?>): TxtFields {
-    fun s(k: String): String? = attrs[k]?.takeIf { it.isNotEmpty() }?.toString(Charsets.UTF_8)
-    return TxtFields(proto = s("proto"), fp = s("fp"), pair = s("pair"), id = s("id"))
+fun parseHostRecord(record: String): DiscoveredHost? {
+    val f = record.split(FIELD_SEP)
+    if (f.size < 6) return null
+    val addr = f[2]
+    val port = f[3].toIntOrNull() ?: return null
+    if (addr.isBlank() || port !in 1..65535) return null
+    return DiscoveredHost(
+        key = f[0].ifBlank { "$addr:$port" },
+        name = f[1].ifBlank { addr },
+        host = addr,
+        port = port,
+        fingerprint = f[4].ifBlank { null },
+        pairingRequired = f[5] == "required",
+    )
 }
 
 /**
- * Browses `_punktfunk._udp` via NsdManager, resolves each service (the reliable
- * `registerServiceInfoCallback` path on API 34+, legacy `resolveService` on 31–33 where its TXT is
- * often empty), and pushes the live host set to [onChange] (invoked on the main thread).
+ * Browses `_punktfunk._udp` for punktfunk/1 hosts via the native `mdns-sd` core (the same browse the
+ * Linux/Windows clients use), exposed over JNI — *not* `NsdManager`, whose per-OEM system daemon
+ * made discovery "mostly broken". [start] spins up the native browse and polls it ~1 Hz on the main
+ * thread, pushing the live host set to [onChange] (also on the main thread, only when it changes);
+ * [stop] tears it down.
  *
- * Lifecycle: [start] when the picker appears, [stop] when it leaves / on connect — holds a
- * MulticastLock while running (an OEM Wi-Fi power-save hedge). Note: the Android emulator's SLIRP
- * NAT drops multicast, so on the emulator discovery starts but never finds a LAN host.
+ * We hold a Wi-Fi [WifiManager.MulticastLock] for the browse lifetime — raw multicast *reception*
+ * needs it. (The Android emulator's SLIRP NAT drops multicast, so on the emulator discovery starts
+ * but never finds a LAN host — same as before; that's the network, not the API.)
  */
 class HostDiscovery(context: Context) {
     private val appCtx = context.applicationContext
-    private val nsd = appCtx.getSystemService(Context.NSD_SERVICE) as NsdManager
 
     /** Invoked on the main thread whenever the resolved host set changes. */
     var onChange: ((List<DiscoveredHost>) -> Unit)? = null
 
-    private val resolved = LinkedHashMap<String, DiscoveredHost>() // key -> host
+    private val handler = Handler(Looper.getMainLooper())
     private var multicastLock: WifiManager.MulticastLock? = null
-    private var discoveryListener: NsdManager.DiscoveryListener? = null
-    private val infoCallbacks = mutableListOf<NsdManager.ServiceInfoCallback>() // API 34+ registrations
+    private var nativeHandle = 0L
     private var running = false
+    private var last: List<DiscoveredHost> = emptyList()
 
-    @Synchronized
-    fun start() {
-        if (running) return
-        running = true
-        acquireMulticastLock()
-        val listener = makeDiscoveryListener()
-        discoveryListener = listener
-        runCatching {
-            nsd.discoverServices(PUNKTFUNK_SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, listener)
-        }.onFailure {
-            Log.e(TAG, "discoverServices failed", it)
-            stop()
+    private val poll = object : Runnable {
+        override fun run() {
+            if (!running) return
+            val hosts = snapshot()
+            if (hosts != last) {
+                last = hosts
+                onChange?.invoke(hosts)
+            }
+            handler.postDelayed(this, POLL_MS)
         }
     }
 
-    @Synchronized
-    fun stop() {
-        if (!running) return
-        running = false
-        discoveryListener?.let { runCatching { nsd.stopServiceDiscovery(it) } }
-        discoveryListener = null
-        if (Build.VERSION.SDK_INT >= 34) {
-            for (cb in infoCallbacks) runCatching { nsd.unregisterServiceInfoCallback(cb) }
+    fun start() {
+        if (running) return
+        acquireMulticastLock()
+        val h = runCatching { NativeBridge.nativeDiscoveryStart() }
+            .onFailure { Log.e(TAG, "nativeDiscoveryStart threw", it) }
+            .getOrDefault(0L)
+        if (h == 0L) {
+            Log.e(TAG, "native mDNS discovery failed to start")
+            releaseMulticastLock()
+            return
         }
-        infoCallbacks.clear()
+        nativeHandle = h
+        running = true
+        last = emptyList()
+        handler.post(poll)
+    }
+
+    fun stop() {
+        if (!running && nativeHandle == 0L) return
+        running = false
+        handler.removeCallbacks(poll)
+        val h = nativeHandle
+        nativeHandle = 0L
+        if (h != 0L) runCatching { NativeBridge.nativeDiscoveryStop(h) }
+            .onFailure { Log.e(TAG, "nativeDiscoveryStop threw", it) }
         releaseMulticastLock()
-        resolved.clear()
+        last = emptyList()
         onChange?.invoke(emptyList())
     }
 
-    private fun publish() {
-        onChange?.invoke(resolved.values.sortedBy { it.name.lowercase() })
-    }
-
-    private fun makeDiscoveryListener() = object : NsdManager.DiscoveryListener {
-        override fun onDiscoveryStarted(type: String) {
-            Log.d(TAG, "discovery started: $type")
-        }
-        override fun onDiscoveryStopped(type: String) {
-            Log.d(TAG, "discovery stopped: $type")
-        }
-        override fun onStartDiscoveryFailed(type: String, code: Int) {
-            Log.e(TAG, "start discovery failed: $code")
-            runCatching { nsd.stopServiceDiscovery(this) }
-        }
-        override fun onStopDiscoveryFailed(type: String, code: Int) {
-            Log.e(TAG, "stop discovery failed: $code")
-        }
-
-        override fun onServiceFound(info: NsdServiceInfo) {
-            Log.d(TAG, "found: ${info.serviceName}")
-            resolve(info)
-        }
-        override fun onServiceLost(info: NsdServiceInfo) {
-            Log.d(TAG, "lost: ${info.serviceName}")
-            // onServiceLost carries no TXT, so drop by the instance-name fallback key only.
-            if (resolved.remove(info.serviceName) != null) publish()
-        }
-    }
-
-    private fun resolve(found: NsdServiceInfo) {
-        if (Build.VERSION.SDK_INT >= 34) resolveViaCallback(found) else resolveViaLegacy(found)
-    }
-
-    private fun resolveViaCallback(found: NsdServiceInfo) {
-        val cb = object : NsdManager.ServiceInfoCallback {
-            override fun onServiceUpdated(info: NsdServiceInfo) = ingest(info)
-            override fun onServiceLost() {}
-            override fun onServiceInfoCallbackRegistrationFailed(code: Int) {
-                Log.e(TAG, "ServiceInfoCallback reg failed: $code")
-            }
-            override fun onServiceInfoCallbackUnregistered() {}
-        }
-        runCatching {
-            nsd.registerServiceInfoCallback(found, appCtx.mainExecutor, cb)
-            infoCallbacks.add(cb)
-        }.onFailure { Log.e(TAG, "registerServiceInfoCallback failed", it) }
-    }
-
-    private fun resolveViaLegacy(found: NsdServiceInfo) {
-        // A ResolveListener can't be reused — allocate one per resolve. TXT may be empty pre-34.
-        val listener = object : NsdManager.ResolveListener {
-            override fun onServiceResolved(info: NsdServiceInfo) = ingest(info)
-            override fun onResolveFailed(info: NsdServiceInfo, code: Int) {
-                Log.e(TAG, "resolve failed: $code")
-            }
-        }
-        runCatching { nsd.resolveService(found, listener) }
-            .onFailure { Log.e(TAG, "resolveService failed", it) }
-    }
-
-    @Suppress("DEPRECATION") // info.host is deprecated at API 34 (replaced by hostAddresses)
-    private fun ingest(info: NsdServiceInfo) {
-        val txt = parseTxt(info.attributes)
-        // Reject an incompatible protocol IF the host advertised one; tolerate empty TXT (pre-34).
-        if (txt.proto != null && !txt.isPunktfunk) {
-            Log.d(TAG, "skip non-punktfunk proto=${txt.proto}")
-            return
-        }
-        val ip = (if (Build.VERSION.SDK_INT >= 34) info.hostAddresses.firstOrNull() else info.host)
-            ?.hostAddress ?: return
-        val key = txt.id?.takeIf { it.isNotBlank() } ?: info.serviceName
-        resolved[key] = DiscoveredHost(
-            key = key,
-            name = info.serviceName.removeSuffix("."),
-            host = ip,
-            port = info.port,
-            fingerprint = txt.fp,
-            pairingRequired = txt.pairingRequired,
-        )
-        Log.d(TAG, "resolved: ${resolved[key]}")
-        publish()
+    private fun snapshot(): List<DiscoveredHost> {
+        val h = nativeHandle
+        if (h == 0L) return emptyList()
+        // getOrNull (not getOrDefault): the JNI returns a platform String!, so a (near-impossible)
+        // native null is a *success* value here — coalesce it so the main-thread poll can't NPE.
+        val blob = runCatching { NativeBridge.nativeDiscoveryPoll(h) }
+            .onFailure { Log.e(TAG, "nativeDiscoveryPoll threw", it) }
+            .getOrNull() ?: ""
+        if (blob.isEmpty()) return emptyList()
+        return blob.split('\n')
+            .filter { it.isNotBlank() }
+            .mapNotNull { parseHostRecord(it) }
+            .associateBy { it.key } // dedup by stable key (id, or addr:port)
+            .values
+            .sortedBy { it.name.lowercase() }
     }
 
     private fun acquireMulticastLock() {
         val wifi = appCtx.getSystemService(Context.WIFI_SERVICE) as WifiManager
-        multicastLock = wifi.createMulticastLock("punktfunk-nsd").apply {
+        multicastLock = wifi.createMulticastLock("punktfunk-mdns").apply {
             setReferenceCounted(true)
             runCatching { acquire() }
         }
@@ -191,4 +137,8 @@ class HostDiscovery(context: Context) {
         multicastLock?.takeIf { it.isHeld }?.let { runCatching { it.release() } }
         multicastLock = null
     }
+
+    private companion object {
+        const val POLL_MS = 1000L
+    }
 }

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

@@ -50,6 +50,12 @@ class KnownHostStore(context: Context) {
         prefs.edit().remove(key(address, port)).apply()
     }
 
+    /** Set a saved host's display name, keeping its pin + paired flag. No-op if not saved. */
+    fun rename(address: String, port: Int, newName: String) {
+        val h = get(address, port) ?: return
+        save(h.copy(name = newName))
+    }
+
     /** All trusted hosts, name-sorted — backs the saved-hosts list. */
     fun all(): List<KnownHost> =
         prefs.all.values.mapNotNull { (it as? String)?.let(::parse) }.sortedBy { it.name.lowercase() }

clients/android/kit/src/test/kotlin/io/unom/punktfunk/kit/discovery/ParseRecordTest.kt

@@ -0,0 +1,62 @@
+package io.unom.punktfunk.kit.discovery
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Pure JVM test of the native-record parser (`key␟name␟addr␟port␟fp␟pair`), the Kotlin half of the
+ * discovery JNI seam. No Android types. Run: `./gradlew :kit:testDebugUnitTest`.
+ */
+class ParseRecordTest {
+    private val s = '\u001F' // field separator (must match the Rust side, discovery.rs FIELD_SEP)
+
+    private fun rec(vararg f: String) = f.joinToString(s.toString())
+
+    @Test
+    fun parsesFullRecord() {
+        val fp = "a".repeat(64)
+        val h = parseHostRecord(rec("host-123", "home-worker-2", "192.168.1.70", "9777", fp, "required"))!!
+        assertEquals("host-123", h.key)
+        assertEquals("home-worker-2", h.name)
+        assertEquals("192.168.1.70", h.host)
+        assertEquals(9777, h.port)
+        assertEquals(fp, h.fingerprint)
+        assertTrue(h.pairingRequired)
+    }
+
+    @Test
+    fun optionalPairingAndEmptyFingerprint() {
+        val h = parseHostRecord(rec("id", "name", "10.0.0.5", "9777", "", "optional"))!!
+        assertNull(h.fingerprint)
+        assertEquals(false, h.pairingRequired)
+    }
+
+    @Test
+    fun emptyKeyFallsBackToAddrPort() {
+        // Host advertised no `id` TXT → the native side leaves the key blank; we synthesize addr:port.
+        val h = parseHostRecord(rec("", "name", "10.0.0.5", "9777", "", "required"))!!
+        assertEquals("10.0.0.5:9777", h.key)
+    }
+
+    @Test
+    fun emptyNameFallsBackToAddr() {
+        val h = parseHostRecord(rec("k", "", "10.0.0.5", "9777", "", "optional"))!!
+        assertEquals("10.0.0.5", h.name)
+    }
+
+    @Test
+    fun rejectsTooFewFields() {
+        assertNull(parseHostRecord("only${'\u001F'}three${'\u001F'}fields"))
+        assertNull(parseHostRecord(""))
+    }
+
+    @Test
+    fun rejectsBadPortOrAddress() {
+        assertNull(parseHostRecord(rec("k", "n", "10.0.0.5", "notaport", "", "required")))
+        assertNull(parseHostRecord(rec("k", "n", "10.0.0.5", "0", "", "required")))
+        assertNull(parseHostRecord(rec("k", "n", "10.0.0.5", "70000", "", "required")))
+        assertNull(parseHostRecord(rec("k", "n", "", "9777", "", "required")))
+    }
+}

clients/android/kit/src/test/kotlin/io/unom/punktfunk/kit/discovery/ParseTxtTest.kt

@@ -1,63 +0,0 @@
-package io.unom.punktfunk.kit.discovery
-
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertNull
-import org.junit.Assert.assertTrue
-import org.junit.Test
-
-/** Pure JVM test of the mDNS TXT parser (no Android types). Run: `./gradlew :kit:testDebugUnitTest`. */
-class ParseTxtTest {
-    private fun b(s: String): ByteArray = s.toByteArray(Charsets.UTF_8)
-
-    @Test
-    fun parsesFullRecord() {
-        val fp = "a".repeat(64)
-        val t = parseTxt(
-            mapOf(
-                "proto" to b("punktfunk/1"),
-                "fp" to b(fp),
-                "pair" to b("required"),
-                "id" to b("host-123"),
-            ),
-        )
-        assertEquals("punktfunk/1", t.proto)
-        assertEquals(fp, t.fp)
-        assertEquals("host-123", t.id)
-        assertTrue(t.isPunktfunk)
-        assertTrue(t.pairingRequired)
-    }
-
-    @Test
-    fun optionalPairingAndMissingKeys() {
-        val t = parseTxt(mapOf("proto" to b("punktfunk/1"), "pair" to b("optional")))
-        assertFalse(t.pairingRequired)
-        assertNull(t.fp)
-        assertNull(t.id)
-    }
-
-    @Test
-    fun emptyMapYieldsAllNull() {
-        val t = parseTxt(emptyMap())
-        assertNull(t.proto)
-        assertNull(t.fp)
-        assertNull(t.pair)
-        assertNull(t.id)
-        assertFalse(t.isPunktfunk)
-        assertFalse(t.pairingRequired)
-    }
-
-    @Test
-    fun nullAndEmptyValuesTreatedAsAbsent() {
-        // NSD delivers present-but-empty TXT keys as null / empty ByteArray.
-        val t = parseTxt(mapOf("fp" to null, "id" to ByteArray(0), "proto" to b("punktfunk/1")))
-        assertNull(t.fp)
-        assertNull(t.id)
-        assertTrue(t.isPunktfunk)
-    }
-
-    @Test
-    fun nonPunktfunkProtoIsNotAccepted() {
-        assertFalse(parseTxt(mapOf("proto" to b("moonlight/7"))).isPunktfunk)
-    }
-}