Worked on improving the correctness and reliability of hierarchical model simulations in the TuringLang/SSMProblems.jl repository, focusing on state space models and time series analysis using Julia. Addressed a critical bug in the forward simulation process by ensuring the inner model’s initial state is consistently derived from the simulated outer state, and that the outer dynamics step uses the correct initial state. This fix enhanced the fidelity of hierarchical simulations, reduced the risk of incorrect state propagation, and supported more accurate posterior estimation. The solution was validated through targeted tests and code review, strengthening reproducibility and model integrity for future development.