Teacher agency in English medium instruction classrooms: exploring role perceptions, pedagogical challenges, and language choices

English-medium instruction (EMI) is increasingly adopted in higher education worldwide, often accompanied by English-only policies that pose unique challenges for teachers, especially in multilingual contexts. However, little is known about how EMI teachers exercise agency in navigating these policies in non-Anglophone settings. This study adopts an ecological perspective to investigate how EMI teachers in Bangladesh navigate English-only policies, focusing on their perceptions of role, pedagogical challenges, and agency-mediated language practices. The study utilises semi-structured interviews, classroom observations, and stimulated recall interviews with six EMI teachers to examine their role perceptions, pedagogical challenges, and agency-mediated language practices. Thematic analysis revealed two situated role orientations: content-focused practitioners who reproduced English-only policies, and multilingually aware facilitators who strategically integrated Bangla and multimodal scaffolding resources. Teachers reported interlocking challenges, including inadequate English proficiency, limited training in interactive pedagogy, large classes that constrained participation, and limited formative assessment. Classroom practices ranged along a continuum from policy reproduction to strategic resistance, including spontaneous translanguaging for clarification, humour, participation scaffolding, device-mediated vocabulary support, and trans-semiotizing via visuals and gesture. We argue for context-sensitive EMI policies and discipline-specific professional development that builds multilingual pedagogical content knowledge and expands multimodal scaffolding repertoires.