Design a provider cutover with in-flight payment ownership
Switching all traffic at once would send old payment lookups to the new provider.
- Focused work estimate
- 6h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Migration design · Distributed consistency
Estimated field mix
- System design50%
- Integrations30%
- Distributed systems20%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional software vendor changes payment providers. Its application must tolerate unknown outcomes, signed callbacks, refunds, and inconsistent settlement reports.
Setup prerequisites
- Create a local payment-provider double and synthetic orders; use test-only signatures and execute no financial transactions.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- BBILL-101 · Map provider payment states to explicit order transitions
- BBILL-102 · Bind payment creation retries to one local operation
- BBILL-103 · Verify callback signatures before trusting event fields
- BBILL-104 · Apply duplicate and out-of-order payment callbacks idempotently
- BBILL-105 · Reconcile unknown creation outcomes by operation identity
- BBILL-106 · Represent partial refunds without rewriting original payment facts
- BBILL-107 · Import settlement rows with source-file provenance
- BBILL-108 · Explain settlement discrepancies without automatic repair
Acceptance criteria
- Pin each operation to its original provider.
- Define new-operation routing and rollback conditions.
- Rehearse callbacks and refunds crossing the cutover boundary.
Implementation constraints
- Compare adapter complexity and reconciliation burden explicitly.
Verification to include
- Complete an old-provider payment after cutover.
- Roll back new routing without reassigning existing operations.
Deliverables
- Cutover decision record and rehearsal.
Rollout and recovery
Change only new-operation routing; retain both adapters until old obligations finish.
Value of the work
For the engineer: Practice idempotent integrations, state reconciliation, and provider migration.
For the team: Provide a reviewable adapter design that protects order consistency and recovery.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.