dea5b84af0
The test parks the removed child in PostStop (ShutdownGate) to hold the retired-but-not-terminated window open, but PostStop abandons a shutdown after DefaultShutdownTimeout (5 s). Under a loaded suite run more than 5 s can pass between the stop and the host processing the stale burst; the child then terminates, the host forgets it on Terminated, and the burst sent AS it is forwarded and re-retained. Reproduced deterministically with a 6 s sleep before the burst. Not a production path: a terminated actor cannot send. DriverHostActor gains a childShutdownTimeout test seam (last parameter, passed to DriverInstanceActor.Props). The test raises it to 5 min, asserts the child was really stopped (ShutdownCount) before the burst, checks the premise as a positive control (no Terminated by the time the fence has passed), and expects Terminated once the gate is released. With an 8 s sleep before the burst the fixed test passes.