Give support a safe reservation incident view
Support needs to explain why an order lost its hold. The current workaround is database access that exposes customer addresses and permits accidental stock edits.
- Focused work estimate
- 2h + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Read models · Least privilege · Operational communication
Estimated field mix
- Backend40%
- Security30%
- Privacy engineering30%
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 sells bicycle parts from East and West warehouses. Cart reservations last ten minutes, payment callbacks arrive late, and warehouse counts occasionally need correction. The exercise has no real orders or payment integration.
Setup prerequisites
- Relational modeling
- Concurrent API requests
- State transitions
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- STOCK-101 · Return available stock for a specific warehouse
- STOCK-102 · Define legal reservation transitions
- STOCK-103 · Reserve the last unit atomically
- STOCK-104 · Replay checkout retries without extending a hold
- STOCK-105 · Decide the winner when payment and expiry arrive together
- STOCK-107 · Apply a stock count correction with an explicit shortage
Acceptance criteria
- Show reservation transitions, expiry, warehouse, and exception reason for one authorized order.
- Exclude addresses, payment payloads, and write controls.
- Distinguish a late payment exception from a normal expiry in readable text.
Implementation constraints
- The view is diagnostic only; corrective actions remain separate audited commands.
Verification to include
- Inspect committed, expired, and shortage examples.
- Deny another retailer and assert sensitive fields are absent.
Deliverables
- Support projection and a three-case incident walkthrough
Rollout and recovery
Grant read access to the synthetic support role; revoke the route permission to rollback.
Value of the work
For the engineer: Practice inventory invariants and timed state transitions while balancing customer experience with operational repair.
For the team: Inspect an engineer's handling of overselling, delayed callbacks, warehouse boundaries, and reversible schema changes.
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.