autodesk/DocumentAutomation/docs/word-com-lifecycle.md

Word COM lifecycle

Word is resolved late-bound through Word.Application; the Word PIA and office.dll are not required at application load time. Each service owns one serial StaWordQueue, and every Word job runs on its dedicated STA thread with Visible=false and alerts disabled. The service opens a working copy, performs one operation, updates fields, repaginates, saves, closes the Document, quits the Application, and releases owned COM proxies in finally.

The prototype does not run as a Windows Service, does not kill unrelated WINWORD.EXE processes, and does not execute macros. Integration tests compare process IDs before and after each job and verify that no newly-created Word process remains.