Seven live e2e tests covering cost-tracking regressions that currently ship
unnoticed: cache-write tokens billed at the cache-creation rate (#34046),
per-component cost_breakdown on the spend row (#31686), cache reads billed at
the cache-read discount on streamed calls (#34812), cache tokens surviving the
anthropic-messages to Responses bridge (#34957), priority-tier rates applied to
input, output and reasoning (#35923, #35925), the per-component response cost
headers summing to the total (#36965), and cost injected into the final usage
frame of an /openai passthrough stream (#36503).
Every test registers its own deployment with a distinct custom rate per
component, so a component billed at the wrong rate cannot pass. The shared
helpers in cost_rows.py encode the one thing the two surfaces disagree on: the
spend row's input_cost is gross of cache while the response's cost-input header
is net of it.
