codex 0.133.0 emits two token-accounting fields at top level that
we previously dropped:
cached_input_tokens — subset of input_tokens that hit the prompt
cache (cheaper, but still counted in
input_tokens per OpenAI Responses API
semantics)
reasoning_output_tokens — separately reported billable thinking
tokens on reasoning-capable models
Map cached_input_tokens to message.Usage.CacheReadTokens and subtract
it from InputTokens. message.Usage.Add() sums InputTokens and
CacheReadTokens as peers, so the uncached residual goes in
InputTokens — matches the anthropic provider's convention and keeps
cumulative usage tracking arithmetically correct.
Fold reasoning_output_tokens into OutputTokens for accurate cost
tracking. The top-level peer positioning (vs nested in
output_tokens_details) implies a separately counted billable
quantity, not a subset of output_tokens.
Defensive clamp at zero in case a future codex build reports
cached > input due to schema drift. Includes a verbatim regression
guard against the live 2026-05-22 codex 0.133.0 output to catch
schema changes early.
vikingowl
1606d19366