Emergency App
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**Purpose**: Handle situations where the assigned field team is unavailable on survey or installation day — find backup teams or reschedule.

Responsibilities
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- Log emergency events (team unavailable for scheduled survey or installation)
- Search for available backup teams in the same zone
- Create emergency assignments to backup teams
- Manage priority rescheduling when no backup is available
- Track emergency resolution

Dependencies
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- **accounts** — Team availability checks, Central Ops handlers
- **surveys** — Emergency events linked to surveys
- **installations** — Emergency events linked to installations

Key Models
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- **EmergencyEvent** — Records that a team is unavailable for a scheduled job. Links to either a Survey or an Installation (exactly one, enforced by constraint). Tracks resolution status.
- **BackupSearch** — Log of each team checked during the backup search process. Records whether the team was available.
- **EmergencyAssignment** — When a backup team is found, records the reassignment with outcome tracking.
- **PriorityReschedule** — When no backup is found, records the new date/time offered to the customer and their confirmation status.

Business Rules
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- An emergency can only be linked to one survey OR one installation, never both, never neither.
- Backup search checks teams in the same zone first, then adjacent zones.
- Only teams with ``is_available=True`` and matching ``team_type`` (survey or installation) are considered.
- If no backup is found within the zone, a priority reschedule is created.
- Priority reschedules require customer confirmation — the new date is proposed, not imposed.
- Emergency events must be resolved (either reassigned or rescheduled) within 4 hours of creation.
- All emergency events are flagged on the Central Ops dashboard for immediate attention.