Social media is central to how young people maintain relationships, develop identity, and access communities, yet dominant platform designs often leave youth feeling disempowered rather than supported. My dissertation argues that youth social media design is shaped by three forms of problem-space misattunement. \textit{Conceptual misattunement} occurs when the language of ``social media'' anchors participants to existing platforms' interaction templates. I address this through a Fictional Inquiry design workshop that frees youth from preconceived notions of social media by having them brainstorm ways to ``magically connect with remote wizard friends'' rather than ideas for ``social media.'' \textit{Definitional misattunement} occurs when researchers define what ``better'' means on youth's behalf. I address this through a Discord-based asynchronous community that supports youth-led collective inquiry. \textit{Evaluative misattunement} occurs when participants are asked to judge static or hypothetical designs. I address this through an ego-anchored, LLM-agent simulation sandbox. Together, these studies develop youth-grounded criteria and design directions for relationally supportive social media.

翻译：社交网络是青少年维系人际关系、发展自我认同以及融入社群的核心渠道，然而主流平台的设计往往使青少年感到被压制而非获得支持。我的博士论文认为，青少年社交媒体设计受三种问题空间失调的塑造。**概念失调**表现为“社交网络”这一词汇将参与者锚定于现有平台的交互模板。我通过虚构探究设计工作坊解决此问题——让青少年围绕“与远程巫师朋友建立神奇联结”进行头脑风暴，而非构思“社交网络”方案，从而使其摆脱对社交媒体的先入之见。**定义失调**发生于研究者代青少年定义何为“更好”时。我通过基于Discord的异步社群来应对，该社群支持青少年主导的集体探究。**评估失调**出现于参与者被要求评估静态或假设性设计时。我通过以自我锚定的LLM智能体模拟沙盒来应对。这些研究共同构建了基于青少年视角的关系支持型社交媒体的评价标准与设计方向。