This prospective observational study aims to characterize dynamic changes in the tumor microenvironment of patients with esophageal squamous cell carcinoma receiving standard neoadjuvant chemotherapy combined with immunotherapy followed by surgical resection. Paired tumor tissue samples will be collected before treatment and at surgery, and peripheral blood samples may also be collected when feasible. Single-cell RNA sequencing and spatial transcriptomics will be used to evaluate changes in cellular composition, transcriptional states, and spatial organization within the tumor microenvironment and to explore their associations with pathological response.