Rehearse recovery from a vendor schema change
The vendor replaces quantity with availableQuantity in its next API version. Demonstrate that the connector fails visibly, can resume with a new adapter, and preserves the old run history.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- API evolution · Contract testing · Incident recovery
Estimated field mix
- Integrations60%
- Quality engineering20%
- Site reliability20%
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 retailer receives stock from two vendor warehouses. The vendor API paginates snapshots and emits change events, but retries and deleted products have caused unexplained stock drift. Work against a local vendor simulator.
Setup prerequisites
- Create a local vendor API simulator with cursor pages and stock events.
- Use synthetic tenants, SKUs, and warehouse records; no vendor account is required.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- SYNC-101 · Validate vendor stock records at the adapter boundary
- SYNC-102 · Map vendor items without assuming SKUs are globally unique
- SYNC-103 · Resume a paginated snapshot from the last committed page
- SYNC-104 · Ignore stale stock events while retaining their delivery record
- SYNC-106 · Distinguish a discontinued item from an item missing on one page
- SYNC-107 · Produce a stock drift report before applying corrections
- SYNC-108 · Apply an approved reconciliation plan only if stock is unchanged
- SYNC-105 · Stop concurrent refreshes from multiplying vendor requests
- SYNC-109 · Surface a stale connector without logging vendor payloads
Acceptance criteria
- Unexpected required-field changes stop affected ingestion without defaulting stock values.
- A versioned adapter can be selected per connector after contract fixtures pass.
- Recovery resumes from a compatible checkpoint or starts a new snapshot with an explicit reason.
Implementation constraints
- Keep both schema fixtures local and versioned.
- Do not reinterpret an old cursor under an incompatible API version.
Verification to include
- Switch the simulator schema mid-run and confirm no corrupt stock or silent success.
- Upgrade the adapter, reconcile a complete new snapshot, and reproduce the documented recovery path.
Deliverables
- Schema-change contract cases and connector recovery runbook
Rollout and recovery
Canary the new adapter on one synthetic connector; revert adapter selection and pause writes if contract errors recur.
Value of the work
For the engineer: Practice external contracts, cursor recovery, mapping conflicts, and reconciliation under partial failure.
For the team: Inspect whether integration changes protect inventory correctness and give operators a clear recovery path.
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.