Claude Opus 5.5 Raises Recursive Self-Improvement Stakes

The scary signal is not that Opus 5.5 crossed the RSI threshold—it hasn’t. The bigger shift is that increasingly capable coding agents are becoming part of the frontier-model development loop.

• –METR found incremental gains over Fable 5.1 and judged full AI R&D automation unlikely, while acknowledging meaningful productivity uplift.
• –Anthropic says Claude can complete sprawling migrations, audits, and research experiments with less human intervention.
• –The company’s own warning is fundamentally a governance problem: development speed may outpace safety validation.
• –Developers should treat autonomous coding as supervised infrastructure, with review, sandboxing, audit logs, and rollback controls built in from the start.