Amid sociopolitical precarity and denials of social and institutional care, trans people find ways to support each other – named trans care. Alongside nascent HCI work characterising trans care, we conduct focus groups and supplementary participatory speculative design with 17 trans adults in the UK to investigate how trans people use social media to support trans care, and the sociotechnical conditions shaping such care. Based on reflexive thematic analysis and member reflections, we describe how social media support essential community building, identity work, responses to healthcare and legal barriers, everyday care, and resistance work, highlighting sociotechnical tensions animating this care. Simultaneously, we find that algorithmic curation and moderation systematically undermines trans care and exposes trans people to pervasive, yet unpredictable harm. We argue that social media are essential technologies for trans care, yet commercial platforms simultaneously act as precarisation machines, and discuss design orientations for supporting trans people and/alongside trans care.

Decentralised social media (DSM) platforms such as Mastodon offer community-governed alternatives to corporate social networks but place substantial governance burdens on volunteer operators. As interest grows in applying artificial intelligence (AI) to support this work, little is known about whether DSM operators want AI, what roles they consider appropriate, and what governance boundaries they require. We conducted semi-structured interviews with 20 operators across Mastodon, Pixelfed, PeerTube, Lemmy, Pleroma, and Funkwhale, using generative feature probes and speculative scenarios to explore their perceptions of AI. Operators rejected AI as an autonomous actor, instead envisioning it as governance infrastructure that provides contextual intelligence, supports cross-instance coordination, and sustains community and moderator well-being. They also articulated strict boundaries rooted in DSM values, including human accountability, reversibility, transparency, community-centred configuration, and strong data-governance constraints. We contribute empirical insights and design implications for AI compatible with decentralised, federated social media.

Decentralised social media platforms are increasingly being recognised as viable alternatives to their centralised counterparts. Among these, Mastodon stands out as a popular alternative, offering a citizen-powered option distinct from larger and centralised platforms like Twitter/X. However, the future path of Mastodon remains uncertain, particularly in terms of its challenges and the long-term viability of a more citizen-powered internet. In this paper, following a pre-study survey, we conducted semi-structured interviews with 16 Mastodon instance administrators, including those who host instances to support marginalised and stigmatised communities, to understand their motivations and lived experiences of running decentralised social media. Our research indicates that while decentralised social media offers significant potential in supporting the safety, identity and privacy needs of marginalised and stigmatised communities, they also face considerable challenges in content moderation, community building and governance. We emphasise the importance of considering the community's values and diversity when designing future support mechanisms.