AI writing assistants can reduce effort and improve fluency, but they may also weaken writers' sense of authorship. We study this tension with an ownership-aware co-writing editor that offers on-demand, sentence-level suggestions and tests two common design choices: persona-based coaching and style personalization. In an online study (N=176), participants completed three professional writing tasks: an email without AI help, a proposal with generic AI suggestions, and a cover letter with persona-based coaching, while half received suggestions tailored to a brief sample of their prior writing. Across the two AI-assisted tasks, psychological ownership dropped relative to unassisted writing (about 0.85-1.0 points on a 7-point scale), even as cognitive load decreased (about 0.9 points) and quality ratings stayed broadly similar overall. Persona coaching did not prevent the ownership decline. Style personalization partially restored ownership (about +0.43) and increased AI incorporation in text (+5 percentage points). We distill five design patterns: on-demand initiation, micro-suggestions, voice anchoring, audience scaffolds, and point-of-decision provenance, to guide authorship-preserving writing tools.

翻译：AI写作助手能够减少写作负担并提升表达流畅度，但也可能削弱写作者的作者身份认同感。我们通过一款具备所有权意识的协同写作编辑器研究这一矛盾，该编辑器提供按需的句子级建议，并测试了两种常见设计选择：基于角色的写作指导和风格个性化。在一项在线研究（N=176）中，参与者完成了三项专业写作任务：无需AI协助的电子邮件撰写、使用通用AI建议的方案撰写，以及采用基于角色指导的求职信撰写，其中半数参与者获得了根据其先前写作简短样本定制的建议。在两项AI辅助任务中，相较于无协助写作，参与者的心理所有权感均出现下降（在7分量表上约降低0.85-1.0分），尽管认知负荷有所减轻（约降低0.9分）且文本质量评分总体保持相近。角色指导未能阻止所有权感下降。风格个性化部分恢复了所有权感（约提升0.43分），并提高了文本对AI建议的采纳率（+5个百分点）。我们提炼出五项设计模式：按需启动、微建议、声音锚定、读者支架和决策点溯源，以指导构建能够维护作者身份的写作工具。