fix: single-flight object_info build (prevents concurrent-build hang)

The off-loop (threaded) build introduced a concurrency bug: ComfyUI's
cache_helper is a global, so a manual refresh (R) fired while a rebuild was
still running started a SECOND build; when the first finished it cleared the
shared cache_helper, making the second re-walk the CIFS mount per-node = hang.

Now an asyncio lock serialises builds: concurrent object_info requests wait for
the in-flight build and serve its result instead of starting another. Verified:
3 concurrent requests -> exactly one build.

Docs: note that Quick refresh detects changes by directory mtime, which network
mounts (cache=loose CIFS) can report stale/coarse, so it may miss a brand-new
file -- use Full refresh for just-added models.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -41,7 +41,7 @@ from the **`Extensions`** menu (and the command palette):
 | Mode | What it does | Speed |
 |------|--------------|-------|
 | ⚡ **Quick refresh** | Re-walks only the folders whose timestamp **changed** since the last scan; reuses the cache for the rest. Catches new / removed / renamed files. | Fast on local disks; **~2× faster** on a slow network mount (it still has to stat every folder to find which changed). |
-| 🔄 **Full refresh** | Clears ComfyUI's folder cache and re-walks **everything**. Catches moves/deletes anywhere. | Slowest (the original behaviour). |
+| 🔄 **Full refresh** | Clears ComfyUI's folder cache and re-walks **everything**, ignoring timestamps. Catches moves/deletes anywhere. **Use this for files you *just* added.** | Slowest (the original behaviour). |
 | ➕ **Register new file…** | You give it the path(s) of the file(s) you just added; it appends them to the cache with **no folder walk**. | Instant disk-wise — only the `object_info` rebuild remains. |
 
 Also available:
@@ -55,6 +55,12 @@ Also available:
 > so it's as slow as a Full refresh that one time; every Quick refresh after that
 > is incremental. The index is saved to `./cache/scan_snapshot.json`.
 
+> **Network mounts (CIFS/SMB/NFS):** Quick refresh detects changes by directory
+> timestamp, which network filesystems can report with a delay or coarse
+> resolution (e.g. a `cache=loose` CIFS mount), so it may *occasionally miss a
+> brand-new file*. If a just-added model doesn't show up after a Quick refresh,
+> use **Full refresh** — it re-walks everything and doesn't rely on timestamps.
+
 Whichever mode you pick, the button shows a "refreshing…" toast and normal loads
 stay instant.
 

__init__.py

@@ -415,6 +415,12 @@ _node_info_resolved = False
 # Live build progress, surfaced at /tenaciousload/status for the loading overlay.
 _build_state = {"building": False, "started": 0.0, "done": 0, "total": 0, "last_ms": 0, "last_bytes": 0}
 
+# Single-flight: only ONE object_info build may run at a time. ComfyUI's
+# cache_helper is a global, so two concurrent builds (e.g. a manual refresh
+# fired during a rebuild) corrupt it and the second build re-walks the network
+# mount per-node = a hang. Concurrent requests wait on this and serve the result.
+_build_lock = asyncio.Lock()
+
 
 def _resolve_node_info_fn():
     """Pull ComfyUI's own `node_info` closure off the /object_info route, so the
@@ -514,12 +520,18 @@ async def _object_info_cache_mw(request, handler):
         return _serve_cached(request)
 
     # MISS / refresh: build in a worker thread so a slow folder-walk does not
-    # freeze the event loop. Falls back to the normal in-loop handler.
+    # freeze the event loop. Single-flight via _build_lock — a concurrent
+    # request (e.g. a manual refresh during a rebuild) waits here and then serves
+    # the fresh result instead of starting a second, conflicting build.
+    async with _build_lock:
+        # another request may have finished the build while we waited for the lock
+        if "nocache" not in request.query and _mem["raw"] is not None:
+            return _serve_cached(request)
         raw = await _build_object_info_off_loop()
         if raw is not None:
             _store(raw)
             return _serve_cached(request)
-
+        # off-loop build unavailable -> in-loop handler (still under the lock)
         resp = await handler(request)
         try:
             body = getattr(resp, "body", None)