Fix runtime dependency and model placement

app.py

@@ -100,6 +100,15 @@ _comfy_ready = False
 _nodes_ready = False
 
 
+def _ffmpeg_exe() -> str:
+    exe = shutil.which("ffmpeg")
+    if exe:
+        return exe
+    import imageio_ffmpeg
+
+    return imageio_ffmpeg.get_ffmpeg_exe()
+
+
 def _run(cmd: list[str], cwd: pathlib.Path | None = None, check: bool = True) -> subprocess.CompletedProcess:
     print("[setup]", " ".join(cmd), flush=True)
     return subprocess.run(cmd, cwd=str(cwd) if cwd else None, check=check)
@@ -178,6 +187,36 @@ def _link_or_copy(src: pathlib.Path, dest: pathlib.Path) -> None:
     shutil.copy2(src, dest)
 
 
+def _download_to_dest(repo: str, file_path: str, dest: pathlib.Path, token: str | None) -> None:
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    if dest.exists() and not dest.is_symlink():
+        return
+    if dest.is_symlink():
+        dest.unlink()
+
+    filename = pathlib.Path(file_path).name
+    subfolder = str(pathlib.Path(file_path).parent)
+    downloaded = pathlib.Path(
+        hf_hub_download(
+            repo_id=repo,
+            filename=filename,
+            subfolder=None if subfolder == "." else subfolder,
+            local_dir=str(dest.parent),
+            token=token,
+        )
+    )
+
+    if downloaded.resolve() == dest.resolve():
+        return
+    if dest.exists() or dest.is_symlink():
+        dest.unlink()
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    try:
+        os.replace(downloaded, dest)
+    except OSError:
+        _link_or_copy(downloaded, dest)
+
+
 def _ensure_models(progress: gr.Progress | None = None) -> None:
     token = os.environ.get("HF_TOKEN") or os.environ.get("HUGGINGFACE_HUB_TOKEN")
     for index, item in enumerate(DOWNLOADS):
@@ -187,15 +226,7 @@ def _ensure_models(progress: gr.Progress | None = None) -> None:
             continue
         if progress:
             progress(index / len(DOWNLOADS), desc=f"downloading {item['label']}")
-        filename = pathlib.Path(item["file"]).name
-        subfolder = str(pathlib.Path(item["file"]).parent)
-        cached = hf_hub_download(
-            repo_id=item["repo"],
-            filename=filename,
-            subfolder=None if subfolder == "." else subfolder,
-            token=token,
-        )
-        _link_or_copy(pathlib.Path(cached), dest)
+        _download_to_dest(item["repo"], item["file"], dest, token)
 
 
 def _init_comfy_nodes() -> None:
@@ -492,7 +523,7 @@ def generate(
         out_path = out_dir / "output.mp4"
         rc = subprocess.run(
             [
-                "ffmpeg",
+                _ffmpeg_exe(),
                 "-y",
                 "-i",
                 result,

requirements.txt

@@ -1,4 +1,4 @@
---extra-index-url https://download.pytorch.org/whl/cu126
+--extra-index-url https://download.pytorch.org/whl/cu128
 torch==2.8.0
 torchvision==0.23.0
 torchaudio==2.8.0