Three endpoints doing the same five seconds of work: one ignores a disconnect, one stops with the caller, one adds a server-side ceiling. Two curl commands reproduce the whole post.

Boolean soup vs discriminated union in one file — including the impossible state the soup happily accepts. Compiles clean under strict.

Two endpoints, one shared counter of database calls. Burst 50 parallel requests at each and watch the classic cache stampede while HybridCache holds at one.

Two tests against real infrastructure in throwaway Docker containers: the NVARCHAR(10) insert that SQLite accepts and SQL Server refuses, and a message round-tripping through actual RabbitMQ.

An Angular app with no zone.js installed at all. A signals counter that just works, next to the setTimeout mutation that changes the value but not the screen — the exact bug the migration order flushes out.