Compile-time AST scanner that warns when a ctest body uses operations that aren't routed through Lockstep's controller. Bare send, bare receive, Process.send_after, GenServer.call, Task.async, and similar will silently break the controlled schedule -- better to warn at compile time than have the user wonder why nothing reproduces.

False positives (your project genuinely defines MyMod.send/2 and the linter flags send/2 calls) can be silenced by qualifying the call (Kernel.send(...)) or by importing nothing.