UI+TTS: voice hot-swap + typing dots + emoji stripping

Three tightly-coupled UX fixes the user flagged during live testing.

**Voice hot-swap (Qwen3TtsEngine.setVoice)**: previously a no-op
stub — the spinner callback updated the orb color but the actual
audio kept using Damien's cached prefix/suffix embeddings. Now we
derive the voice id from the WAV basename (elodie.wav → 'elodie'),
look up `<id>_voice_prefix.bin` + `<id>_voice_suffix.bin` in the
model dir, parse their headers, and atomically replace the embedding
arrays so the NEXT synthesized segment uses the new voice. If the
files aren't present we log a clear warning pointing at
prepare_tts_native.py — the hot-swap is wired, but per-voice prefix/
suffix still need to be generated offline and adb-pushed.
KazeiaService.setVoice now forwards to Qwen3TtsEngine in addition to
the Chatterbox branch.

**Emoji stripping**: the model loves closing on "😊" and it was
reaching TTS as a standalone segment that synthesized a fraction of
a second of junk. KazeiaPipeline.speakText now runs each sentence
through stripNonSpeakable before enqueueing — drops Unicode emoji /
dingbat / pictograph / flag blocks plus variation selectors and
zero-width joiners, then trims. Empty-after-strip sentences are
skipped entirely. The chat bubble still shows the original text
(with emojis) — only the audio path drops them.

**Typing dots indicator**: while LLM is done but TTS synthesis is
still running (~3–5 s for the first segment), the Kazeia bubble now
shows an animated ". / .. / ..." cycle at 400 ms cadence instead of
sitting empty. The moment the first segment actually starts playing,
the cycle cancels, the bubble resets to empty, and the existing
word-by-word reveal takes over. A defensive finally block also
cancels the job when no segment ever fires (e.g. all-emoji reply).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

kazeia-android/app/src/main/java/com/kazeia/service/KazeiaPipeline.kt

@@ -164,7 +164,14 @@ class KazeiaPipeline {
             if (qwen != null) {
                 qwen.onSegmentPlaying = onSegmentPlaying
                 qwen.startStreamingSession()
-                val streamer = com.kazeia.tts.SentenceStreamer { s -> qwen.enqueueSentence(s) }
+                val streamer = com.kazeia.tts.SentenceStreamer { raw ->
+                    // Strip emoji / non-speakable pictographs before TTS
+                    // so a standalone "😊" doesn't become its own noisy
+                    // segment. The chat bubble keeps the original text —
+                    // only the audio path sees the cleaned version.
+                    val spoken = stripNonSpeakable(raw).trim()
+                    if (spoken.isNotEmpty()) qwen.enqueueSentence(spoken)
+                }
                 streamer.append(text)
                 streamer.flush()
                 qwen.endStreamingSession()
@@ -183,6 +190,41 @@ class KazeiaPipeline {
         _messages.value = _messages.value + msg
     }
 
+    /**
+     * Drop emoji + dingbat + pictographic characters so the TTS engine
+     * doesn't try to synthesize them. Covers the main Unicode emoji
+     * blocks (Miscellaneous Symbols, Dingbats, Emoticons, Transport,
+     * Supplemental Symbols and Pictographs, etc.) plus variation
+     * selectors and zero-width joiners that tag emoji sequences.
+     * Keeps everything in the Basic Latin / Latin-1 / Latin Extended
+     * ranges + common French punctuation untouched.
+     */
+    private fun stripNonSpeakable(text: String): String {
+        val sb = StringBuilder(text.length)
+        var i = 0
+        while (i < text.length) {
+            val cp = text.codePointAt(i)
+            val skip = when {
+                cp in 0x2600..0x27BF -> true              // misc symbols + dingbats
+                cp in 0x1F300..0x1F5FF -> true            // pictographs
+                cp in 0x1F600..0x1F64F -> true            // emoticons
+                cp in 0x1F680..0x1F6FF -> true            // transport
+                cp in 0x1F700..0x1F77F -> true            // alchemical
+                cp in 0x1F780..0x1F7FF -> true            // geometric extended
+                cp in 0x1F800..0x1F8FF -> true            // supplemental arrows-c
+                cp in 0x1F900..0x1F9FF -> true            // supplemental pictographs
+                cp in 0x1FA00..0x1FAFF -> true            // symbols & pictographs extended-A
+                cp == 0x200D -> true                       // zero-width joiner
+                cp in 0xFE00..0xFE0F -> true              // variation selectors
+                cp in 0x1F1E6..0x1F1FF -> true            // regional indicators (flags)
+                else -> false
+            }
+            if (!skip) sb.appendCodePoint(cp)
+            i += Character.charCount(cp)
+        }
+        return sb.toString()
+    }
+
     fun log(msg: String) {
         Log.i(TAG, msg)
         val time = java.text.SimpleDateFormat("HH:mm:ss.SSS", java.util.Locale.FRANCE)

kazeia-android/app/src/main/java/com/kazeia/service/KazeiaService.kt

@@ -628,6 +628,16 @@ class KazeiaService : Service() {
         if (chatterbox != null) {
             chatterbox.setVoice(voicePath)
             log("Voice set to: $voicePath")
+            return
+        }
+        val qwen = tts as? com.kazeia.tts.Qwen3TtsEngine
+        if (qwen != null) {
+            // Hot-swap prefix/suffix embeddings — no model reload. Takes
+            // effect from the NEXT synthesized segment (current in-flight
+            // one, if any, finishes with the old voice since the arrays
+            // are already in its closure).
+            qwen.setVoice(voicePath)
+            log("Voice set to: $voicePath")
         }
     }
 
@@ -1241,18 +1251,36 @@ class KazeiaService : Service() {
                 // the continuous-listening mic loop drops frames and we
                 // don't feed our own speaker output back into STT.
                 _pipelineState.value = PipelineState.Speaking
-                // Create an empty KAZEIA bubble up-front so the per-sentence
-                // reveal has somewhere to append to, but the text stays
-                // empty until TTS audio for the first sentence starts —
-                // matching the "conversation" feel the user asked for
-                // (read-as-you-hear, not read-then-hear).
-                val bubble = ChatMessage(role = ChatMessage.Role.KAZEIA, text = "")
+                // Create a KAZEIA bubble up-front. Until the first TTS
+                // segment actually starts playing the bubble shows an
+                // animated "." → ".." → "..." typing indicator so the
+                // user knows Kazeia is thinking/synthesising; once the
+                // first segment plays the dots are cleared and the
+                // per-sentence word reveal takes over.
+                val bubble = ChatMessage(role = ChatMessage.Role.KAZEIA, text = ".")
                 addMessage(bubble)
                 val revealScope = kotlinx.coroutines.CoroutineScope(kotlinx.coroutines.Dispatchers.Default)
                 var revealedSoFar = ""
                 val revealJobs = mutableListOf<kotlinx.coroutines.Job>()
+                val firstSegmentSeen = java.util.concurrent.atomic.AtomicBoolean(false)
+                val typingJob = revealScope.launch {
+                    var tick = 0
+                    while (!firstSegmentSeen.get()) {
+                        val dots = ".".repeat(1 + (tick % 3))   // . → .. → ...
+                        updateMessageText(bubble.id, dots)
+                        tick++
+                        kotlinx.coroutines.delay(400)
+                    }
+                }
                 try {
                     pipeline.speakText(responseText) { sentence, durationMs, envelope, spectrogram ->
+                        // First segment: stop the typing indicator and
+                        // reset the bubble to empty so the word reveal
+                        // doesn't collide with the dots.
+                        if (firstSegmentSeen.compareAndSet(false, true)) {
+                            try { typingJob.cancel() } catch (_: Exception) {}
+                            updateMessageText(bubble.id, "")
+                        }
                         // Push the envelope + spectrogram to the
                         // visualizer at the same moment the MediaPlayer
                         // starts playing so the orb reacts to this
@@ -1293,6 +1321,11 @@ class KazeiaService : Service() {
                     revealJobs.forEach { try { it.join() } catch (_: Exception) {} }
                     updateMessageText(bubble.id, responseText)
                 } finally {
+                    // Defensive: cancel the typing dots in case no
+                    // segment ever fired (e.g. the response was entirely
+                    // emojis and got stripped empty).
+                    firstSegmentSeen.set(true)
+                    try { typingJob.cancel() } catch (_: Exception) {}
                     _pipelineState.value = if (_isListening.value)
                         PipelineState.Listening else PipelineState.Idle
                     // If we're going back to mic listening, the VAD loop

kazeia-android/app/src/main/java/com/kazeia/tts/Qwen3TtsEngine.kt

@@ -608,8 +608,53 @@ class Qwen3TtsEngine(
 
     override fun isLoaded(): Boolean = loaded
 
+    /**
+     * Hot-swap the speaker prefix/suffix embeddings used for voice
+     * conditioning. [voicePath] is a WAV path like
+     * `/…/voix/elodie.wav` — we derive the voice id from its basename
+     * and look for matching `<id>_voice_prefix.bin` + `<id>_voice_suffix.bin`
+     * in the model dir. If both files exist they replace the current
+     * [damienVoicePrefix] / [damienVoiceSuffix] arrays so the next
+     * segment generated uses the new voice. If either file is missing
+     * we log a warning and keep the current voice — per-voice
+     * prefix/suffix files are offline-generated via
+     * scripts/prepare_tts_native.py; run once per voice WAV and
+     * `adb push` into the model dir to enable.
+     *
+     * Thread-safety: the arrays are read by the synth worker on
+     * Dispatchers.IO; replacing a reference via a volatile var is
+     * atomic on the JVM so a mid-segment replacement just takes
+     * effect on the next segment boundary.
+     */
     fun setVoice(voicePath: String) {
-        nlog("Voice: $voicePath")
+        val modelDir = "/data/local/tmp/kazeia/models/qwen3-tts-npu"
+        val id = java.io.File(voicePath).nameWithoutExtension.lowercase()
+        val prefixFile = java.io.File("$modelDir/${id}_voice_prefix.bin")
+        val suffixFile = java.io.File("$modelDir/${id}_voice_suffix.bin")
+        if (!prefixFile.exists() || !suffixFile.exists()) {
+            nlog("Voice '$id' not available (missing ${prefixFile.name} or ${suffixFile.name}); keeping current voice. " +
+                "Run scripts/prepare_tts_native.py with this WAV to generate the files.")
+            return
+        }
+        try {
+            val pBytes = prefixFile.readBytes()
+            val pHead = java.nio.ByteBuffer.wrap(pBytes).order(java.nio.ByteOrder.LITTLE_ENDIAN)
+            val nPref = pHead.int; val dimPref = pHead.int
+            if (dimPref != TALKER_DIM) throw IllegalStateException("prefix dim $dimPref != $TALKER_DIM")
+            val newPrefix = Array(nPref) { FloatArray(TALKER_DIM).also { arr -> for (j in 0 until TALKER_DIM) arr[j] = pHead.float } }
+
+            val sBytes = suffixFile.readBytes()
+            val sHead = java.nio.ByteBuffer.wrap(sBytes).order(java.nio.ByteOrder.LITTLE_ENDIAN)
+            val nSuf = sHead.int; val dimSuf = sHead.int
+            if (dimSuf != TALKER_DIM) throw IllegalStateException("suffix dim $dimSuf != $TALKER_DIM")
+            val newSuffix = Array(nSuf) { FloatArray(TALKER_DIM).also { arr -> for (j in 0 until TALKER_DIM) arr[j] = sHead.float } }
+
+            damienVoicePrefix = newPrefix
+            damienVoiceSuffix = newSuffix
+            nlog("Voice switched to '$id' ($nPref prefix + $nSuf suffix embeds)")
+        } catch (e: Exception) {
+            nlog("Voice swap failed for '$id': ${e.message}")
+        }
     }
 
     override suspend fun synthesize(text: String, language: String): TtsResult {