getSqlForDurableStore throws SiaxError(DEPENDENCY_UNAVAILABLE, httpStatus 503,
retryable) when a money-bearing store would fall back to an in-memory Map in a
production runtime (the durable-store guard). The /api/0pt/* surface already
maps it via src/http/siax-error-response.ts; the seven legacy routes outside
the middleware matcher did not — the documented 503 leaked as Next's opaque
500 with no body.
- app/api/siax-error-mapping.ts: shared isSiaxError + siaxErrorResponseForLegacy
- orders (POST/GET), orders/[id] (GET/PATCH), subscriptions (GET/POST),
payments/deposit, payments/release, admin/metrics: try/catch -> mapper,
each route's own typed error contract preserved (idempotency conflict 409 etc.)
- webhooks/stripe: store outage -> 503 received:false reason:store_unavailable
so Stripe's delivery retry path stays open (never a silent received:true)
- tests/api/legacy-routes-siax-error-mapping.test.ts: pins the 503 + body
admin