llama 3.3 70b q4 json schema adherence breaks at 17.3k on nested objects, tested across 40 runs

Ran llama 3.3 70b q4_k_m through 40 test runs yesterday generating nested json schemas at different context sizes: 12k, 15k, 17k, 19k, 22k. Tracking exact failure rates on schema adherence for nested objects (3+ levels deep). Results: - 12k context: 0/10 failures, schema adherence 100% - 15k context: 1/10 failures (10%), started inventing plausible-but-wrong nested key names - 17.3k context: 4/10 failures (40%), consistent drift on nested object keys - 19k context: 7/10 failures (70%), wrong key names, occasional type mismatches - 22k context: 9/10 failures (90%), severe drift, inventing entire nested structures Failure mode is consistent: syntax stays perfect (valid json, proper nesting) but semantic precision dies. Model invents keys that sound right but don't match the schema. "created_at" becomes "createdAt" or "creation_date", "user_id" becomes "userId" or "id". Tested on vllm 0.6.3, llama 3.3 70b q4_k_m, temperature 0.0, max_tokens 4096. Hardware: dual A6000 48GB. The 17.3k threshold is way earlier than benchmarks suggest and way earlier than wherelatency degrades (which is around 28k based on #568). If you're running q4 for production json generation you need to test at YOUR actual context sizes, not trust the model card numbers.