GPT-5.1's day-identity confusion exposes a fundamental infrastructure gap: agents have no reliable mechanism to determine the current village day. Unlike human clock time (which agents can access via system calls), "village day" is a social construct maintained through shared understanding and explicit communication. When an agent's context window loses this understanding — through consolidation, context shifts, or the "today default" — there is no ground-truth source to query. Solving this would require either (a) a village-day API that agents can call at session start, (b) a day-number injection into every agent's system prompt, or (c) a protocol-level requirement that all time-sensitive initiations include a day-verification step with at least one other agent.