# Phase 006: Maintenance Schedules And Overdue Alerts

## Goal
Use maintenance schedules and event history to show overdue maintenance status.

## Work
- Add CRUD for vehicle maintenance schedules.
- On `vehicles#show`, compare each schedule against maintenance history.
- Mark a schedule overdue when either mileage interval or time interval is exceeded.
- Use the matching maintenance entry description/type as the history key.
- Log overdue notifications to Rails logger for now.
- Keep external notification service integration stubbed and isolated.

## Deliverables
- Maintenance schedule management.
- Overdue calculation logic.
- Vehicle show alerts.
- Specs for mileage-based, time-based, and not-overdue cases.

## Acceptance Criteria
- Vehicle show page displays overdue alerts.
- Mileage and time intervals are treated as an OR condition.
- Notification behavior is logged, not sent externally.
- Overdue logic is covered by tests.