Inspect existing native Codex threads, queue messages, resume conversations, or coordinate bounded fan-out while preserving verified identities and delivery semantics. Use for Codex thread messaging and handoffs, not general application development.
Design, review and implement C# 15 unions and closed hierarchies in .NET 11 code. Use for union declarations, custom [Union] types, exhaustive matching, default/null handling and union serialization. Do not upgrade earlier frameworks or replace working inheritance merely because unions exist.
Choose and implement explicit test, class or assembly ownership for MSTest fixtures. Use for shared input files, expensive setup, failure cleanup, parallel consumers and removing repeated fixture lifecycle wiring.