refund.sx — refund as a second flow-on-sx flow (request -> approve -> settle)
with two suspension points (approval = human/policy decision, settle =
provider). refund-begin! records :refund-requested and suspends at approval;
refund-approve! advances to settle; refund-settle! records :refunded
(idempotent) and completes; refund-reject! records :refund-rejected and cancels.
Only :refunded moves the books. Reuses order.sx flow helpers. Completes the
Phase 5 backlog. Total 278/278 across 17 suites.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
giles
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