Browser agents built on LLMs can act in web interfaces, yet most remain confined to a single chat surface (e.g., a sidebar). This mismatch with real browsing can increase context-switching and reduce user control. We introduce \textbf{IntentWeave}, a design space of ten spatial paradigms for embedding agentic assistance across a browser, organized as a progressive entry ladder from micro-interventions to dedicated workspaces. We implement IntentWeave as a browser-extension prototype on the Alibaba Cloud website and compare three entry strategies in a within-subjects study (N=16). Workspace-heavy strategies reduced completion time but lowered perceived control; micro-only strategies preserved control but were often insufficient; a mixed sidecar approach achieved the highest satisfaction. We conclude with guidance for escalating and retreating agent surfaces without disrupting user agency.

翻译：基于大型语言模型的浏览器代理可在网页界面中执行操作，但大多数仍局限于单一对话界面（如侧边栏）。这种与现实浏览场景的错位会增加上下文切换负担并降低用户控制感。我们提出\textbf{IntentWeave}设计空间，包含十种将代理辅助嵌入浏览器的空间范式，组织为从微观干预到专用工作区的渐进式入口阶梯。我们以阿里云网站为平台，将IntentWeave实现为浏览器扩展原型，并在受试者内实验（N=16）中比较三种入口策略。重工作区策略虽缩短完成时间，但降低了感知控制权；仅含微观操作的策略虽保留控制力，但往往效力不足；混合式侧车策略取得了最高满意度。最后，我们提出在不损害用户主体性的前提下调整代理界面层级的指导原则。