Encode opaque cursors bound to the normalized query
A cursor from one status filter is reused with another and skips records.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Cursor design · Integrity
Estimated field mix
- API design50%
- Security30%
- Database engineering20%
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 logistics platform lists shipments for partner dashboards. Offset pagination duplicates records during updates, while unrestricted filters create expensive database queries.
Setup prerequisites
- Create a local shipment dataset with synthetic tenants, equal timestamps, and concurrent update fixtures.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Bind cursor to tenant, sort, filter digest, and position.
- Validate schema, size, integrity, and expiry.
- Return a stable invalid-cursor problem.
Implementation constraints
- Opaque encoding alone is not integrity protection.
Verification to include
- Continue a matching query.
- Reject tampered, expired, and cross-query cursors.
Deliverables
- Cursor contract.
Rollout and recovery
Version cursors and retain support only for declared compatible versions.
Value of the work
For the engineer: Practice cursor design, query contracts, and consistency/performance tradeoffs.
For the team: Provide predictable list APIs that remain bounded and preserve tenant scope.
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.