Enforce 300-char synthesis limit

Add a live n/300 counter (red when over) that disables Generate past the
limit, plus a server-side gr.Error guard so API/MCP callers can't bypass
it. Replaces the silent text_input[:300] truncation.

app.py

@@ -108,6 +108,7 @@ LANGUAGE_CONFIG = {
 LANGUAGE_CHOICES = [('en', 'English'), ('ar', 'Arabic'), ('da', 'Danish'), ('de', 'German'), ('el', 'Greek'), ('es', 'Spanish'), ('fi', 'Finnish'), ('fr', 'French'), ('he', 'Hebrew'), ('hi', 'Hindi'), ('it', 'Italian'), ('ja', 'Japanese'), ('ko', 'Korean'), ('ms', 'Malay'), ('nl', 'Dutch'), ('no', 'Norwegian'), ('pl', 'Polish'), ('pt', 'Portuguese'), ('ru', 'Russian'), ('sv', 'Swedish'), ('sw', 'Swahili'), ('tr', 'Turkish'), ('zh', 'Chinese')]
 DEFAULT_LANGUAGE = 'en'
 FIXED_LANGUAGE_ID = None
+MAX_CHARS = 300
 
 EXAMPLES = [
         ['Last month, we reached a new milestone with two billion views on our YouTube channel.', 'https://storage.googleapis.com/chatterbox-demo-samples/mtl_prompts/en_f1.flac', 'en', 0.5, 0.8, 0, 0.5],
@@ -135,6 +136,20 @@ def on_language_change(language_id: str, current_ref_wav: str | None, current_te
     return default_audio_for_ui(language_id), default_text_for_ui(language_id)
 
 
+def update_char_count(text: str):
+    """Live character-count feedback for the synthesis box.
+
+    Returns two values wired to outputs=[char_count, run_btn]:
+      1. counter_md    -> "n / MAX_CHARS", turned red once over the limit
+      2. button_update -> disables Generate while over the limit
+    (The server still rejects over-limit text; disabling is the visible cue.)
+    """
+    n = len(text or "")
+    over = n > MAX_CHARS
+    counter_md = f"<span style='color:#e11'>{n} / {MAX_CHARS}</span>" if over else f"{n} / {MAX_CHARS}"
+    return counter_md, gr.update(interactive=not over)
+
+
 def get_or_load_model():
     global MODEL
     if MODEL is None:
@@ -170,6 +185,8 @@ def generate_tts_audio(
     cfgw_input: float = 0.5,
 ):
     """Generate speech from text with optional reference audio styling."""
+    if len(text_input) > MAX_CHARS:
+        raise gr.Error(f"Text exceeds {MAX_CHARS} characters ({len(text_input)}). Please shorten it.")
     current_model = get_or_load_model()
     device = current_model.device
     if seed_num_input != 0:
@@ -185,7 +202,7 @@ def generate_tts_audio(
     }
     if chosen_prompt:
         generate_kwargs["audio_prompt_path"] = chosen_prompt
-    wav = current_model.generate(text_input[:300], **generate_kwargs)
+    wav = current_model.generate(text_input, **generate_kwargs)
     return (current_model.sr, wav.squeeze(0).cpu().numpy())
 
 
@@ -206,9 +223,10 @@ with gr.Blocks() as demo:
         with gr.Column():
             text = gr.Textbox(
                 value=default_text_for_ui(DEFAULT_LANGUAGE),
-                label="Text to synthesize (max chars 300)",
+                label=f"Text to synthesize (max {MAX_CHARS} chars)",
                 max_lines=5,
             )
+            char_count = gr.Markdown(f"{len(default_text_for_ui(DEFAULT_LANGUAGE))} / {MAX_CHARS}")
             ref_wav = gr.Audio(
                 sources=["upload", "microphone"],
                 type="filepath",
@@ -237,6 +255,7 @@ with gr.Blocks() as demo:
 
     inputs = [text, ref_wav, language, exaggeration, temp, seed_num, cfg_weight]
     run_btn.click(fn=generate_tts_audio, inputs=inputs, outputs=[audio_output])
+    text.change(fn=update_char_count, inputs=[text], outputs=[char_count, run_btn])
 
     gr.Examples(
         examples=EXAMPLES,