fix bug area changes for Item do not apply

この issue には説明がありません。

The issue body is empty, providing no details about the bug, the 'Item' model, or what 'area changes' means. A newcomer would need to first explore the codebase to understand the data models and the area management logic. Look for files related to 'Item' and area calculations or updates. Determine what the expected behavior is versus the current bug.

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