Fix 0-output inference causing dropped audio return

Root cause: gradio.Server infers output components from the function's
return-type annotation. The endpoints had none, and
'from __future__ import annotations' stringified what little existed,
so Gradio inferred 0 outputs and discarded the return ('Output
components: []') — the JS client then got undefined.

- Remove 'from __future__ import annotations' so annotations resolve to
real type objects
- Restore FileData returns with explicit -> tuple[FileData, str] and
-> tuple[FileData, FileData, str] annotations (proven docs pattern)
- Drop the /rendered dict route; render_wav uses tempfile FileData again
- JS: accept obj.url || obj.path || string for the audio handle

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

app.py

@@ -1,9 +1,8 @@
-from __future__ import annotations
-
 import logging
 import os
 import re
 import sys
+import tempfile
 import threading
 import time
 from dataclasses import dataclass
@@ -39,6 +38,7 @@ sys.path.insert(0, str(RUNTIME))
 sys.path.insert(0, str(ROOT))
 
 from gradio import Server
+from gradio.data_classes import FileData
 
 # Register ONNX Runtime / model asset MIME types. Windows (and some containers)
 # do not map these by default, and FileResponse would otherwise serve the
@@ -280,22 +280,17 @@ def validate(
     return text, float(speed), float(variation), float(pitch_steps), int(seed)
 
 
-WAV_STORE = ROOT / "rendered"
-WAV_STORE.mkdir(exist_ok=True)
-WAV_URL = "/rendered"
-
-
-def render_wav(sample_rate: int, samples: np.ndarray) -> dict:
-    """Persist PCM16 samples to a WAV and return a serializable file handle.
+def render_wav(sample_rate: int, samples: np.ndarray) -> FileData:
+    """Persist PCM16 samples to a WAV and return a Gradio FileData handle.
 
-    @app.api() endpoints return JSON to the JS client, so we hand back a plain
-    dict (url + filename) rather than a FileData object whose shape depends on
-    Gradio's component serialization.
+    The return-type annotation is what tells gradio.Server which output
+    component to serialize, so the JS client receives a {url, ...} blob
+    rather than the function's return value being dropped.
     """
-    name = f"{int(time.perf_counter() * 1000)}_{os.getpid()}.wav"
-    out_path = WAV_STORE / name
-    sf.write(str(out_path), samples, sample_rate, subtype="PCM_16")
-    return {"url": f"{WAV_URL}/{name}", "filename": name}
+    handle, out_path = tempfile.mkstemp(suffix=".wav", prefix="inflect_")
+    os.close(handle)
+    sf.write(out_path, samples, sample_rate, subtype="PCM_16")
+    return FileData(path=out_path)
 
 
 @app.api(concurrency_limit=1)
@@ -307,7 +302,7 @@ def synthesize(
     variation: float,
     pitch_steps: float,
     seed: int,
-):
+) -> tuple[FileData, str]:
     text, speed, variation, pitch_steps, seed = validate(
         text, speed, variation, pitch_steps, seed
     )
@@ -337,7 +332,7 @@ def compare(
     variation: float,
     pitch_steps: float,
     seed: int,
-):
+) -> tuple[FileData, FileData, str]:
     text, speed, variation, pitch_steps, seed = validate(
         text, speed, variation, pitch_steps, seed
     )
@@ -374,14 +369,6 @@ async def _cross_origin_isolation(request, call_next):
     return response
 
 
-@app.get(WAV_URL + "/{name}")
-async def serve_rendered_wav(name: str):
-    full = (WAV_STORE / name).resolve()
-    if not full.is_file() or full.parent != WAV_STORE.resolve():
-        return HTMLResponse("Not found", status_code=404)
-    return FileResponse(str(full), media_type="audio/wav")
-
-
 @app.get(STATIC_URL + "/{path:path}")
 async def serve_web_runtime(path: str):
     full = (WEB_RUNTIME / path).resolve()

index.html

@@ -643,7 +643,7 @@ async function doGenerate(){
   try{
     const c=await getClient(); const res=await c.predict("/synthesize",{ ...inputs(), model_name: activeModel() });
     const fileObj=res.data[0]; const statusText=res.data[1]||"Done.";
-    const url=fileObj.url; if(!url) throw new Error("server returned no audio url");
+    const url=(fileObj && (fileObj.url || fileObj.path)) || (typeof fileObj==="string"?fileObj:""); if(!url) throw new Error("server returned no audio url");
     const buf=await fetchArray(url); const blobUrl=wavBlobUrl(buf); const decoded=await decodeWav(buf);
     const text=$("text").value; const chunks=splitText(text); const timings=chunkTimings(chunks,decoded.duration);
     const samples=decoded.getChannelData(0);
@@ -669,7 +669,7 @@ async function doCompare(){
       ["micro",microObj,"micro-dur","micro-now","micro-seek","micro-dl","micro-ph",cmpCanvas.micro],
       ["nano",nanoObj,"nano-dur","nano-now","nano-seek","nano-dl","nano-ph",cmpCanvas.nano],
     ]){
-      const url=obj.url; if(!url) throw new Error(`server returned no ${key} url`);
+      const url=(obj && (obj.url || obj.path)) || (typeof obj==="string"?obj:""); if(!url) throw new Error(`server returned no ${key} url`);
       const buf=await fetchArray(url); const blobUrl=wavBlobUrl(buf); const decoded=await decodeWav(buf); const samples=decoded.getChannelData(0);
       $(dlId).href=blobUrl; $(durId).textContent=fmtTime(decoded.duration); $(seekId).value="0"; $(seekId).disabled=false;
       drawMini(cv,samples,0);