Yes, what's preventing the LLM from running myCommand > /tmp/out_someHash.txt ; tail out_someHash.txt and then greping or tailing around /tmp/out_someHash.txt on failure?
A lot of the time this behaviour is probably right. But it's annoyingly hard to steer it to handle this correctly. I've had it do this even with make targets where the makefile itself makes clear the dependencies means it could trust the cached (in a file) results if it just runs make <target>. Instead I regularly find it reading the Makefile and running the commands manually to work around the dependency management.