The run detail tab, route, query hook, and query key say usage. Every
read of input_tokens, output_tokens, total_tokens, reasoning_tokens,
cache_read_tokens, cache_write_tokens, and total_usd_micros moves to
usage.tokens and usage.cost, with lib/usage.ts replacing lib/billing.ts:
totalTokens sums the five buckets, and costSourceTag names a cost that
the provider reported or that was summed from differently sourced parts.
The Usage tab and the stage popover show that tag next to such a cost.
Test fixtures build a Usage through makeUsage; the failing set of the
web tests is unchanged from main (the same 13 environment failures).
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
