fix: skill memory keys breaking unrestricted node permissions

Only extend read_keys/write_keys with skill memory keys when the
list was already non-empty (restricted). An empty list means "allow
all" — adding _-prefixed skill keys to an empty list accidentally
activated the permission check and blocked legitimate reads.

core/framework/graph/executor.py

@@ -1831,16 +1831,18 @@ class GraphExecutor:
         # unchanged — empty means "allow all".
         read_keys = list(node_spec.input_keys)
         write_keys = list(node_spec.output_keys)
+        # Only extend lists that were already restricted (non-empty).
+        # Empty means "allow all" — adding keys would accidentally
+        # activate the permission check and block legitimate reads/writes.
         if read_keys or write_keys:
             from framework.skills.defaults import SHARED_MEMORY_KEYS as _skill_keys
 
-            # Also include any _-prefixed keys already written to memory
             existing_underscore = [k for k in memory._data if k.startswith("_")]
             extra_keys = set(_skill_keys) | set(existing_underscore)
             for k in extra_keys:
-                if k not in read_keys:
+                if read_keys and k not in read_keys:
                     read_keys.append(k)
-                if k not in write_keys:
+                if write_keys and k not in write_keys:
                     write_keys.append(k)
 
         scoped_memory = memory.with_permissions(