Amid mounting environmental pressures and tightening resource constraints in China’s cities, advancing zero-waste city initiatives has become a critical avenue for sustainable urban governance. Zero-waste cities not only improve environmental quality but also enhance resource recycling and foster innovative urban governance models. This study develops an evolutionary game model that incorporates prospect theory to examine the strategic interactions between provincial and local governments. The results show that: (1) each side’s subjective perception of gains and losses significantly shapes its willingness to cooperate; (2) incentives and penalties exert asymmetric effects over the course of policy evolution: subsidies matter most during initiation, penalties are pivotal for overcoming resistance in the transition phase, and non-material incentives become increasingly important as the governance system matures; (3) zero-waste city development follows a three-stage evolutionary trajectory, moving from pilot programs to self-sustaining local governance. Using numerical simulations, this research further assesses how key parameters affect the strategic choices of both levels of government, generating policy-relevant insights for municipal solid waste management and intergovernmental cooperation in zero-waste city governance.

Toxic metal pollution in farmland soils has become a critical environmental issue threatening land security and agricultural sustainability. This study develops an evolutionary game model involving the government, enterprises, the public, and environmental public-interest organizations to analyze the dynamic interactions underlying multi-actor governance. By combining equilibrium analysis with numerical simulations, the study examines the conditions for collaborative governance and the effects of key parameters on the system’s evolution. The results reveal a stage-based trajectory: weak regulation and limited participation in the early stage lead to persistent illegal discharge; strengthened government intervention and rising social participation in the transitional stage promote more coordinated supervision, although enterprises may still behave non-compliantly; in the mature stage, favorable cost–benefit conditions induce enterprises to adopt compliant treatment, reducing reliance on continuous external oversight. Further analysis shows that effective incentive and deterrence mechanisms are essential for activating multi-actor responses, while enterprises’ strategies are mainly driven by pollution-control costs, expected returns, and potential losses, and social participation depends on monitoring costs, expected benefits, and government support. Initial strategy distributions have limited influence on long-term outcomes. These findings provide policy-relevant insights for improving institutional design and strengthening collaborative governance in the management of toxic metal pollution in China’s farmland soils.