GPT‑5.5 Codex clusters at 516 tokens, causing code‑gen regression
OpenAI’s internal telemetry shows GPT‑5.5 Codex responses clustering at exactly 516 reasoning tokens, with spikes at 1034 and 1552. This fixed‑token pattern coincides with a sharp drop in average reasoning‑token usage and a measurable regression in complex refactoring and multi‑file code generation. The anomaly suggests a hidden budgeting or truncation mechanism affecting performance.