Worked on the marimo-team/marimo repository to address a threading-related issue affecting ProgressBar reliability during concurrent executions. Focused on a targeted bug fix in Python, the developer ensured that ExecutionContext.output is properly propagated into the mo.Thread context, allowing ProgressBar to flush output correctly across threads. This internal change, implemented with threading and context management skills, restored accurate progress reporting for users running long-running or multi-threaded tasks. The solution was delivered as a minimal, low-risk update with no impact on the public API, demonstrating careful scoping and effective collaboration through code review and co-authorship in the pull request process.