Test seams and fixtures

Four seams, highest first (docs/SPEC.md → Testing Decisions):

1. HTTP surface of the bridge with in-memory Engine, provider, PSP, Mailer, a settable Clock and a SQLite file: apps/pressline/tests/*.test.ts through tests/harness.ts. Full flows, idempotent and out-of-order webhooks, Demo Mode, every CLI action, every Reconciliation step. Playwright drives the Storefront pages on the same seam (pnpm e2e).
2. Adapter contract tests against recorded fixtures: tests/printful-adapter.test.ts, stripe-adapter.test.ts, resend-adapter.test.ts replay tests/fixtures/<provider>/*.json (file name = URL path with / → _).
3. Render helper by PNG headers: packages/render/tests, one suite against both backends.
4. Conformance suite: packages/conformance/tests against a fake Engine; the sample Engine runs the real suite in-process.

No module-level tests of the ledger; a test asserts what a caller can observe.

pnpm verify runs format, lint, typecheck, ADR check, tests and builds; CI runs the same plus the e2e job and the platform builds. Maintainers re-record fixtures from the live APIs with pnpm --filter pressline fixtures:refresh (needs PRINTFUL_TOKEN and a test-mode STRIPE_SECRET_KEY) and review the diff; the nightly live smoke (test:live) is what tells us an API changed shape.

Architecture model

The C4 views in the Architecture section are rendered from docs/architecture/*.c4, a LikeC4 model reviewed like any other code. pnpm --filter pressline-docs architecture:dev previews it with hot reload. pnpm verify runs likec4 validate on it and the model test suite in apps/docs/tests, which checks that every workspace is drawn or named, that every ADR link resolves and the load-bearing ADRs are all linked, that every container and component has a technology, and that no title or description spells a domain name. Element names come from CONTEXT.md; a box that encodes an ADR links to it.