Boundary freedom in higher spin gravity

We investigate new boundary conditions in three-dimensional asymptotically Anti-de Sitter gravity coupled to higher-spin fields, allowing for arbitrary boundary degrees of freedom. This generalization gives rise to an enlarged algebra of asymptotic charges and predicts novel anomalies in the dual field theory, whose physical origin is traced to corner ambiguities in the symplectic structure. We also prescribe a smooth flat limit, thereby extending these anomalous higher-spin effects to asymptotically flat spacetimes.