issue: Native Function Calling knowledge-base tools fail with `’str’ object has no attribute ‘items’`

该报错发生在 Open WebUI Native Function Calling 模式下,模型调用知识库检索工具( query_knowledge_files 或 kb_exec )时,工具执行器因收到字符串而非预期字典结构而崩溃。优先排查是否启用了 Legacy Function Calling

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