Claude Opus 5.5 Beats Codex’s 28-Day Resets

The sharper takeaway is about sustained output, not model hype: developers care whether an agent finishes meaningful work before limits, resets, or supervision become the bottleneck.

• –Opus 5.5 is built for sprawling coding jobs and Anthropic reports major improvements on migrations, audits, and agentic benchmarks.
• –OpenAI’s 28-day challenge creates goodwill when resets restore access, but resets do not necessarily improve task quality or reliability.
• –The comparison highlights a shift toward measuring useful work per day, dollar, and session rather than raw model capability.
• –This remains an anecdotal comparison; harness, effort level, project complexity, and quota policies can materially change the result.
• –Developers should test both models on the same repository and track completion rate, rework, latency, and spend.