Killian Courvoisier developed a conflict-handling enhancement for the cozy/cozy-client repository, focusing on improving file operation predictability for client integrations. He introduced the FailOnConflict option to the moveToCozy method, enabling explicit failure with an HTTP 409 status when file conflicts occur, rather than relying on automatic file renaming. This approach aligns cozy-client’s behavior with NextcloudFileCollection, supporting clearer conflict resolution semantics for developers. Killian implemented this feature using JavaScript within a full stack development context, demonstrating a targeted and thoughtful solution to a nuanced integration challenge. The work reflects a focused contribution with depth in conflict management logic.