Agent harness overhead becomes a real cost line — Jul 13

Two engineering teardowns this week land on the same lesson: coding-agent costs are being decided by system-prompt bloat and prompt-caching configuration, not model sticker prices. Systima measures Claude Code's hidden 33,000-token baseline against OpenCode's leaner scaffolding, while Ploy's real production migration to GPT-5.6 shows 2.2x speed and 27% lower cost once a caching bug got fixed. Meanwhile a viral Hacker News thread pushes for AI content labeling, a sign the disclosure debate is starting in developer communities before it reaches regulation.