Add debug logging to cache lookup

server.py

@@ -280,6 +280,42 @@ async def root():
     return HOME_HTML
 
 
+@app.get("/debug/cache/{content_hash}")
+async def debug_cache(content_hash: str):
+    """Debug endpoint to check cache status for a content hash."""
+    import os
+
+    result = {
+        "content_hash": content_hash,
+        "cache_dir": str(cache_manager.cache_dir),
+        "nodes_dir": str(cache_manager.cache.cache_dir),
+        "in_content_index": content_hash in cache_manager._content_index,
+        "node_id_from_index": cache_manager._content_index.get(content_hash),
+    }
+
+    # Check various locations
+    locations = {
+        "legacy_direct": cache_manager.cache_dir / content_hash,
+        "nodes_dir": cache_manager.cache.cache_dir / content_hash,
+    }
+
+    for name, path in locations.items():
+        result[f"{name}_path"] = str(path)
+        result[f"{name}_exists"] = path.exists()
+        if path.exists() and path.is_dir():
+            result[f"{name}_contents"] = [f.name for f in path.iterdir()]
+
+    # Check if artdag cache has it
+    result["artdag_cache_get"] = str(cache_manager.cache.get(content_hash))
+
+    # Check via cache_manager
+    found_path = cache_manager.get_by_content_hash(content_hash)
+    result["cache_manager_path"] = str(found_path) if found_path else None
+    result["has_content"] = cache_manager.has_content(content_hash)
+
+    return result
+
+
 @app.post("/runs", response_model=RunStatus)
 async def create_run(request: RunRequest, username: str = Depends(get_required_user)):
     """Start a new rendering run. Requires authentication."""