Fix HF Spaces startup: restore spaces import + clear stale cache placeholders

- import spaces at top level (was missing, caused NameError on @spaces.GPU)
- restore sys.unraisablehook for asyncio GC bug suppression
- remove stale placeholder files before snapshot_download to prevent
[Errno 20] Not a directory errors on re-deploy

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

image_generator.py

@@ -20,39 +20,50 @@ if not hasattr(torch, "xpu"):
 
 IS_HF_SPACE = os.environ.get("SPACE_ID") is not None
 
+if IS_HF_SPACE:
+    import spaces
+    import sys, threading, asyncio
+
+    # Suppress Python 3.10 asyncio GC bug (Invalid file descriptor: -1)
+    _orig_unraisable = sys.unraisablehook
+    def _unraisable_hook(args):
+        if args.exc_type is ValueError and "Invalid file descriptor" in str(args.exc_value):
+            return
+        _orig_unraisable(args)
+    sys.unraisablehook = _unraisable_hook
+
 # ---------------------------------------------------------------------------
 # Persistent storage cache — survives sleep/restart on HF Spaces
 # ---------------------------------------------------------------------------
-# Enable in Space Settings → Storage (mount at /data).
-# HF_HOME env var can also be set manually in Space Settings → Variables,
-# but this block handles it automatically when /data is present.
 if IS_HF_SPACE and os.path.isdir("/data"):
     _cache_dir = "/data/hf_cache"
     os.makedirs(_cache_dir, exist_ok=True)
     os.environ.setdefault("HF_HOME", _cache_dir)
     print(f"Persistent cache active → {_cache_dir}")
 
-    # Pre-download model at startup so the first @spaces.GPU call is fast.
-    # /data survives sleep/restart — download only happens once.
-    import threading, asyncio
-    from huggingface_hub import snapshot_download
-
-    _hf_token    = os.environ.get("HF_TOKEN") or os.environ.get("HUGGING_FACE_HUB_TOKEN")
-    _model_id    = "black-forest-labs/FLUX.2-klein-4B"
+    # Clean up any stale placeholder files left by a previous failed download
+    # (huggingface_hub creates placeholder files that block re-download)
     _model_cache = os.path.join(_cache_dir, "models--black-forest-labs--FLUX.2-klein-4B")
+    for _placeholder in [_model_cache, f"{_model_cache}/blobs", f"{_model_cache}/refs",
+                         f"{_model_cache}/snapshots"]:
+        if os.path.isfile(_placeholder):
+            os.remove(_placeholder)
+            print(f"Removed stale placeholder: {_placeholder}")
 
     if os.path.isdir(_model_cache):
         print(f"✅ FLUX.2-klein-4B already cached — skipping download")
     else:
         print(f"Downloading FLUX.2-klein-4B to persistent cache…")
         try:
+            from huggingface_hub import snapshot_download
+            _hf_token = os.environ.get("HF_TOKEN") or os.environ.get("HUGGING_FACE_HUB_TOKEN")
             _result = {}
             def _download():
                 loop = asyncio.new_event_loop()
                 asyncio.set_event_loop(loop)
                 try:
                     snapshot_download(
-                        _model_id,
+                        "black-forest-labs/FLUX.2-klein-4B",
                         cache_dir=_cache_dir,
                         token=_hf_token,
                         ignore_patterns=["*.msgpack", "*.h5", "flax_model*"],