Abstract This study examines the nature and dynamics of student engagement in synchronous French for Specific Purposes (FSP) at the University of Batna 1 (Algeria), within the context of post-COVID-19 digital transformations. Grounded in a systemic approach, the study draws on the multidimensional engagement theory and the Community of Inquiry framework. It also incorporates the interactionist perspective on language learning and conceptualizes withdrawal as a systemic regulator. The research employs an adapted and validated version of the Live Online Classes Engagement Scale (LOCES) with 144 undergraduate economics students. The results reveal high overall engagement (M = 3.91/5), a finding that is counterintuitive given contextual constraints. The analysis highlights a clear hierarchy of dimensions: instructional engagement (M = 4.25) and behavioral engagement (M = 4.05) constitute a core, while social, emotional, and technological dimensions act as moderators. The withdrawal dimension emerges as an integrated antagonistic regulator, negatively correlated with all positive forms of engagement (r from -.37 to -.57) and loading negatively onto a single latent factor (-.704). Correlations and confirmatory factor analysis suggest that positive forms of engagement mutually reinforce each other, whereas withdrawal signals latent disinvestment. These findings, rooted in the Algerian university context, highlight the systemic nature of engagement and emphasize the importance of active pedagogical practices and institutional vigilance regarding withdrawal signals. Keywords: Student engagement, withdrawal, synchronous online FSP, Algerian higher education, Live Online Classes Engagement Scale (LOCES).