Cost: before, during, after
Quote and cap before, the cap riding the run, actuals next to the quote after.
The full treatment — principles, the ledger schema, capacity and usage probes, billing classes, model-per-task economics, and our own books — is Cost management. The shape in three sentences:
Before. Every order carries a per-run quote and a cap derived as 2× the quote; the
composer refuses to compose a dispatch nobody priced, and saphan fleet headroom /
saphan fleet usage answer "can we afford to start this now, and where" mechanically —
reports, never dispatches.
During. The cap rides the run (vendor-enforced where the backend supports it, post-hoc compared where it does not — stated honestly per backend), and the wall clock is the engine's own unconditional backstop.
After. Every run's actuals land in the record next to the quote: saphan cost <stream> for the stream's money, saphan ledger show / export for the fleet's, refusals
ledgered as zero-cost rows with reasons — what the system would not do is part of the
account of what it did.