Show dispatchers how old each vehicle position is
A van’s last position remains bright green after its device disconnects. Dispatch assigns a nearby job using a point that is twenty minutes old.
- Focused work estimate
- 1h 15m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Time handling · Real-time UX · State modeling
Estimated field mix
- Real-time systems60%
- Frontend40%
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
The fictional Cedar delivery depot dispatches vans through a browser map and accessible list. Synthetic telemetry arrives through a gateway with device sequence numbers. This is operational fleet software practice; no real driver tracking, employee scoring, or routing safety guarantee is part of the project.
Setup prerequisites
- Synthetic vehicle telemetry with device sessions and sequence numbers
- Dispatch assignment and authorized region API contracts
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Map and list expose last accepted fix time and age.
- Positions move through configured fresh, stale, and unknown states without requiring a new event.
- Device timestamps outside the allowed clock-skew range cannot make a position appear indefinitely fresh.
Implementation constraints
- Use a controllable clock and text labels as well as visual styling.
Verification to include
- Advance the clock past both freshness thresholds and verify map/list agreement.
- Send a future-dated fix and disconnect the stream; no false current label remains.
Deliverables
- Position freshness policy and fake-clock UI checks
Rollout and recovery
Release age labels before assignment features; disable freshness coloring if timestamp authority is uncertain.
Value of the work
For the engineer: Practice geospatial boundaries, stream ordering, snapshot recovery, and concurrent operational commands.
For the team: Inspect whether a developer keeps dispatch decisions grounded in current authorized data and exposes uncertainty during outages.
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.