'Harness' now means the loop above Claude Code

Developers on r/ClaudeAI split the meaning of 'harness' into two layers, per a 167-upvote thread with 79 comments.

The split matters because it locates the real engineering work outside Claude Code and Codex, in the custom loop that supervises them. One Anthropic team runs 8 to 10 concurrent projects through exactly that kind of loop.

Answers in the thread describe the inner harness as the coding assistant itself, Claude Code or Codex. The outer harness is a separate system a developer builds around it, one that retries failures, sequences tasks, and decides what to hand off next.

A quoted Anthropic newsletter excerpt describes one version of that outer loop. Two lead agents restart each other on failure and delegate to tech-lead or PM agents across those same 8 to 10 concurrent projects.

Temporal shipped its own answer on August 20. Its Agent Harness product doesn't replace Claude Code or Codex. It wraps durability around whichever inner harness a team already runs, per the announcement.

Infrastructure vendors are learning to pitch the outer loop instead of the coding assistant itself. Temporal won't be the last vendor to try it. The next mover will likely price durability by agent count, the same math behind the 8-10 concurrent projects one Anthropic team already runs.