Test agent TTS routing in settings layer

Signed-off-by: John Tennant <jtennant@squareup.com>

desktop/src-tauri/src/huddle/agent_tts_routing_tests.rs

@@ -0,0 +1,26 @@
+use super::{enqueue_agent_tts_text, normalize_agent_tts_text, MAX_TTS_TEXT_LEN};
+
+#[tokio::test]
+async fn assistant_plain_text_routes_unchanged_into_voice_pipeline_boundary() {
+    let (sender, receiver) = std::sync::mpsc::channel();
+    let text = "A newly submitted assistant reply.".to_string();
+
+    enqueue_agent_tts_text(text.clone(), move |queued| {
+        sender.send(queued).map_err(|error| error.to_string())
+    })
+    .await
+    .expect("route assistant text");
+
+    assert_eq!(receiver.recv().expect("queued text"), text);
+}
+
+#[test]
+fn assistant_text_truncation_is_unicode_safe_before_voice_routing() {
+    let input = "🦀".repeat(MAX_TTS_TEXT_LEN + 1);
+    let output = normalize_agent_tts_text(input);
+    assert_eq!(
+        output.chars().count(),
+        MAX_TTS_TEXT_LEN + "... message truncated.".chars().count()
+    );
+    assert!(output.ends_with("... message truncated."));
+}

desktop/src-tauri/src/huddle/mod.rs

@@ -825,6 +825,25 @@ pub fn get_model_status(_state: State<'_, AppState>) -> Result<models::VoiceMode
 /// ~2000 chars ≈ 1–2 minutes of speech. Longer messages are truncated.
 const MAX_TTS_TEXT_LEN: usize = 2000;
 
+fn normalize_agent_tts_text(text: String) -> String {
+    if text.chars().count() > MAX_TTS_TEXT_LEN {
+        let mut truncated: String = text.chars().take(MAX_TTS_TEXT_LEN).collect();
+        truncated.push_str("... message truncated.");
+        truncated
+    } else {
+        text
+    }
+}
+
+async fn enqueue_agent_tts_text<F>(text: String, enqueue: F) -> Result<(), String>
+where
+    F: FnOnce(String) -> Result<(), String> + Send + 'static,
+{
+    tokio::task::spawn_blocking(move || enqueue(text))
+        .await
+        .map_err(|error| format!("TTS enqueue task failed: {error}"))?
+}
+
 /// Called by the WebView when it receives an incoming agent kind:9 message.
 /// Lazily starts the TTS pipeline if models are ready but the pipeline hasn't
 /// been created yet (e.g. models finished downloading after huddle started).
@@ -834,13 +853,7 @@ const MAX_TTS_TEXT_LEN: usize = 2000;
 pub async fn speak_agent_message(text: String, state: State<'_, AppState>) -> Result<(), String> {
     // Truncate oversized messages — agents shouldn't monologue in a voice huddle.
     // Use char count (not byte length) to avoid panicking on multi-byte UTF-8.
-    let text = if text.chars().count() > MAX_TTS_TEXT_LEN {
-        let mut truncated: String = text.chars().take(MAX_TTS_TEXT_LEN).collect();
-        truncated.push_str("... message truncated.");
-        truncated
-    } else {
-        text
-    };
+    let text = normalize_agent_tts_text(text);
 
     let needs_pipeline = {
         let hs = state.huddle()?;
@@ -869,15 +882,17 @@ pub async fn speak_agent_message(text: String, state: State<'_, AppState>) -> Re
     let Some(sender) = sender else {
         return Ok(());
     };
-    tokio::task::spawn_blocking(move || {
+    enqueue_agent_tts_text(text, move |text| {
         sender
             .send(text)
             .map_err(|error| format!("TTS queue closed while waiting to enqueue: {error}"))
     })
     .await
-    .map_err(|error| format!("TTS enqueue task failed: {error}"))?
 }
 
+#[cfg(test)]
+mod agent_tts_routing_tests;
+
 /// Add an agent to the active huddle.
 ///
 /// Steps: