2025-09 monthly summary for google/closure-compiler: Delivered a focused feature to enhance diagnostics for JSC_IMPORT_ASSIGN errors by including the definition location of the imported symbol. The change refines the error message format and updates the report function arguments to carry this additional context, enabling developers to pinpoint the source of improper assignments more quickly. This strengthens developer productivity and reduces time-to-resolution for import-related issues, contributing to more reliable builds. Demonstrated skills in debugging diagnostics, error reporting pipelines, and working with a large, mature codebase. Tech stack touched: JavaScript, Closure Compiler diagnostic framework, and commit-based development workflow.