fix(tools): keep memory tool available when fcntl is unavailable

tests/tools/test_memory_tool_import_fallback.py

@@ -0,0 +1,31 @@
+"""Regression tests for memory-tool import fallbacks."""
+
+import builtins
+import importlib
+import sys
+
+from tools.registry import registry
+
+
+def test_memory_tool_imports_without_fcntl(monkeypatch, tmp_path):
+    original_import = builtins.__import__
+
+    def fake_import(name, globals=None, locals=None, fromlist=(), level=0):
+        if name == "fcntl":
+            raise ImportError("simulated missing fcntl")
+        return original_import(name, globals, locals, fromlist, level)
+
+    registry.deregister("memory")
+    monkeypatch.delitem(sys.modules, "tools.memory_tool", raising=False)
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    memory_tool = importlib.import_module("tools.memory_tool")
+    monkeypatch.setattr(memory_tool, "get_memory_dir", lambda: tmp_path)
+
+    store = memory_tool.MemoryStore(memory_char_limit=200, user_char_limit=200)
+    store.load_from_disk()
+    result = store.add("memory", "fact learned during import fallback test")
+
+    assert memory_tool.fcntl is None
+    assert registry.get_entry("memory") is not None
+    assert result["success"] is True