Anthropic's Enterprise ZDR isolation is under scrutiny after cross-account context appeared in a user's coding session, exposing the fragility of runtime-layer data boundaries. Statistical analysis of 390,000 GPT-5.5 Codex responses reveals anomalous 516-token reasoning clusters consistent with hidden budget caps, degrading complex-task performance while keeping simple-task metrics intact. The UK AISI publishes the empirical case for a missing disclosure standard: without a compute budget appendix, every frontier agent task-horizon benchmark is an apples-to-oranges comparison.