GPT-5.5 Codex reasoning-token clustering may be leading to degraded performance
OpenAI Codex issue (293 HN points): users report GPT-5.5 Codex degrading due to reasoning-token clustering.
Why it matters
- First widely-shared reproducible performance-regression report on GPT-5.5 Codex.
- Lands directly on Zuckerberg's 'agents haven't progressed as quickly' admission from Wednesday.
- Materially affects the enterprise-agent story Amazon, Microsoft, and Anthropic all invested against last week.
- Sets a new procurement signal: token-cluster degradation as a mid-cycle risk category.