Topic
The harness and meta-harness layers that own the agent loop, context, tools and session, spanning opinionated products and programmable substrates.
OpenAI's Codex harness is now Apache-2.0 and Pi is MIT. That means the comparison can be run directly instead of inferred from a leaked bundle. The three loops agree about the middle and diverge at the edges.
Reality
Microsoft reports Qwen3.5-9B going from 41.8% to 56.4% on SWE-bench Verified using 6K examples. The load-bearing change is who owns the agent loop, and what the service boundary costs.
Reality
Headlong is Apache-2.0, so a team can read the loop before running it. What nobody can read is a benchmark, and the shared thought stream is also the privacy problem.
Reality
NestMux's author documents the plumbing: HOME redirected per pane, one git worktree each, and a resource panel that has to guess which process belongs to whom.
Reality
latent.space argues models and harnesses improved together, and that models keep swallowing the harness. If so, most scaffolding you write is scheduled for deletion. Permissions are not.
Reality