synthetic-cache-write._expectations.md (synthetic)

All files in this directory are synthetic test data, not extracts from real sessions. Test cache_write>0, absent from M0 native Codex samples, where this field was always zero. The shape follows Codex 0.155.0-alpha.16.3.

Scenario and expectations

• One call: input=1000, cached=400, cache_write=100, output=50, reasoning=10, total=1050. The snapshot matches these values; reconciliation=matched.
• Mapping: input_cache_write=100 (reported); input_uncached=1000−400−100= 500 (derived); input_total=1000 (reported); total_tokens=1050 (derived), source_total=1050 (reported).
• This synthetic sample alone defines the cache_write⊆input assumption. If real data contradicts it, producing uncached<0, record a diagnostic rather than truncating the value.