arXiv:2607.17589v2 Announce Type: replace Abstract: Sparse non-uniform array-enabled affine frequency division multiplexing (AFDM) is a promising candidate for integrated sensing and communication (ISAC), while its performance critically depends on accurate target parameter estimation. In this paper, we propose a constrained tensor decomposition-based sensing framework for delay, Doppler, and angle estimation. Specifically, a manifold-constrained alternating least squares algorithm is developed by exploiting the sparse array geometry structure, enabling robust factor matrix extraction and direct angle estimation. In addition, we analyze the uniqueness condition of the tensor decomposition. From the decomposed factor matrices, delays and Doppler shifts are coarsely estimated by pulse compression, and refined by an iterative one dimensional golden-section search.Moreover, the Cram\'er-Rao bound (CRB) is derived to characterize the fundamental performance limit of the considered estimation problem. Finally, simulation results validate the effectiveness of the proposed estimation algorithm.