We present a design framework for friendship-supportive youth social media, derived from a synthesis of five empirical studies with 331 youth participants (ages 13--25) using interviews, co-design, surveys, diary studies, and a field deployment. Iterative analysis of 209 design-relevant data points identified three pillars: \textit{Sense of Social Understanding} (interaction norms, interaction cues and scaffolding, social accountability and governance), \textit{Sense of Place} (third place and community, boundaries and personal spaces, shared presence), and \textit{Sense of Identity Alignment} (identity currency, identity plurality, relational identity signals). The framework maps nine design spaces through which platforms can support the conditions under which youth friendships form, deepen, and are maintained. It offers a shared vocabulary for locating contributions, comparing design interventions, and identifying under-explored areas for future work.

翻译：我们提出一个面向青少年友谊支持的社交媒体设计框架，该框架基于五项实证研究的综合成果，涉及331名青少年参与者（年龄13-25岁），采用了访谈、协同设计、问卷、日记研究和现场部署等方法。通过对209个与设计相关的数据点进行迭代分析，确定了三大支柱：社交理解感（互动规范、互动线索与支架、社交问责与治理）、场所感（第三场所与社区、边界与个人空间、共享在场）以及身份认同对齐感（身份货币、身份多元性、关系身份信号）。该框架映射出九个设计空间，平台可通过这些空间支持青少年友谊形成、深化和维持的条件。它为定位研究成果、比较设计干预措施以及识别未来研究的未充分探索领域提供了共享术语。