Design a superhero incident dispatch system

System Design: Superhero Dispatch (Uber-like) System

Design a system that dispatches superheroes to real-world incidents (e.g., fires, robberies, monster attacks) across a city or globally.

Scenario

• Civilians (or sensors) create incident requests with location and details.
• The platform finds and assigns an appropriate superhero to respond.
• Superheroes continuously publish their live location while available and en route.

Functional requirements

1. Create incident : Accept a new incident with:
   • incident_type (fire/medical/crime/etc.)
   • location (lat/lon)
   • priority (P0–P3)
   • optional constraints (needs flying hero, water powers, max response time)
2. Hero availability : Heroes can go online/offline and set capability metadata.
3. Matching/dispatch :
   • Find a suitable hero near the incident.
   • Prefer shortest ETA while satisfying constraints.
   • Support reassignment if hero rejects/times out.
4. Trip lifecycle : Track states such as CREATED -> MATCHING -> ASSIGNED -> EN_ROUTE -> ARRIVED -> RESOLVED/CANCELED .
5. Real-time updates :
   • Civilians can see assignment + hero ETA.
   • Heroes receive incident details and navigation updates.
6. Reliability : No double-assigning the same hero to two incidents; handle retries/idempotency.

Non-functional requirements

• Low-latency matching (e.g., p95 < 1–2s for common cases).
• High availability; graceful degradation during traffic spikes (e.g., city-wide disaster).
• Scalable location ingestion (large number of frequent hero GPS updates).

What to cover

• APIs (high level)
• Data model and storage choices
• Matching algorithm (including a geospatial index )
• Architecture/services and communication patterns
• Handling failures, race conditions, and hot spots
• Scaling plan (partitioning/sharding, caches, queues/streams)