@network-harness/executor-cli

An executor that is a command line -- the shape every coding harness already has. pi and claude are two rows of this in executors.yml, not two packages: what differs between them is argv, not machinery.

What the seam needs from a subprocess is small: a prompt in, text out, a way to stop it, and a record of what happened. Everything here is about the ways a subprocess fails to be that.

• The prompt goes in on stdin by default, because that is the only route with no length limit and no quoting. file and args are there for commands that insist.
• stdout is the answer; stderr is kept beside it in the turn's artifact directory, along with the prompt, because a human reading a trace afterwards needs what the model was told and not only what it said.
• Nothing is inherited that was not named. A model's process is the least trusted thing in the node, and the parent's environment is where a token lives.
• Output past a bound is a runaway process rather than an answer, and the command is killed.
• The command runs in its own process group, so stopping it reaches the whole tree rather than a shell that already forked the real work.