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Nightwatch

Nightwatch is a walking-route app for after dark. Instead of only returning the fastest path, it compares the shortest route against the safest one, scoring paths by streetlight density using the City of Ottawa's Open Data.

Built at CUMSA Hacks (January 2026), where it placed Top 5.

Demo

Live: nightwatch-seven.vercel.app

Features

• Safest vs shortest - one request returns both routes as GeoJSON, with distance, ETA, a safety score, a coverage label and human-readable reasons.
• Streetlight-based scoring - each road segment is scored by lights per 100 m, and the safest path minimizes a safety-adjusted cost instead of raw distance.
• Strict API contracts - Pydantic schemas with nested models validate every request and response.
• Contract tests - pytest integration tests use FastAPI's TestClient to validate the routing endpoints and response schema.
• Interactive map UI - Next.js app with MapLibre map, route comparison, insights and saved-routes screens.
• Demo mode - DEMO_MODE=1 serves mock data for fast, offline-safe demos.

Architecture

flowchart LR
    U[User] --> F["Next.js frontend<br/>MapLibre map"]
    F -- "POST /v1/route/compare" --> A["FastAPI<br/>Pydantic validation"]
    A --> R[Routing service]
    R --> G[("Street graph<br/>NetworkX")]
    R --> S["Safety model<br/>lights per 100 m"]
    L[("Ottawa Open Data<br/>streetlights CSV")] --> S
    S --> R
    R -- "safest + shortest<br/>GeoJSON, score, ETA" --> A
    A --> F

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The shortest path uses Dijkstra on edge length. The safest path uses Dijkstra on a safety-adjusted edge cost derived from streetlight density.

API overview

Base path: /v1 (full contract in shared/api-contract.json). Interactive docs at /docs when running locally.

Method	Endpoint	Description
GET	/v1/health	Health check, returns {"status": "ok"}
POST	/v1/route/compare	Compare the safest and shortest routes between two points

Request body (RouteRequest):

{
  "start": { "lat": 45.4215, "lng": -75.6972 },
  "end": { "lat": 45.4275, "lng": -75.6880 },
  "mode": "night",
  "maxDetour": 15,
  "weights": { "lights": 80, "cameras": 45 },
  "useCctv": false
}

Response (RouteResult): safest and shortest, each a RouteData with geojson, distance_m, eta_min, safety_score, coverage and reasons.

Tech stack

Layer	Technology
Frontend	Next.js 16, React 19, TypeScript, Tailwind CSS 4, MapLibre GL, TanStack Query, Zustand, Framer Motion, GSAP
Backend	Python, FastAPI, Uvicorn, Pydantic v2
Routing and data	NetworkX, pandas, NumPy, SciPy, Ottawa Open Data streetlights
Testing	pytest, FastAPI TestClient, httpx
Deployment	Vercel (frontend), Render (backend)

Project structure

Nightwatch/
├── frontend/                 Next.js app (src/app pages, src/lib API client)
├── backend/
│   ├── app/
│   │   ├── main.py           FastAPI app, CORS, router mounting
│   │   ├── settings.py       Env-driven config (DEMO_MODE, CORS_ORIGINS, PORT)
│   │   ├── api/              Routes and Pydantic schemas
│   │   ├── services/         Router adapter, routing engine, safety model, light store
│   │   └── data/             Ottawa streetlight CSV and graph builder
│   ├── scripts/              Run scripts and data utilities
│   └── tests/                pytest contract tests
├── shared/                   API contract and sample payloads
└── design/                   Design mockups

Getting started

Prerequisites: Python 3.10+ and Node.js 20+.

Backend

cd backend
python3 -m venv .venv
source .venv/bin/activate        # Windows PowerShell: .venv\Scripts\Activate.ps1
pip install -r requirements.txt
DEMO_MODE=0 uvicorn app.main:app --reload --host 127.0.0.1 --port 8000

Or use the helper script, which creates the venv, installs dependencies and starts the server: ./backend/scripts/run_backend.sh (macOS/Linux/WSL) or .\backend\scripts\run_backend.ps1 (Windows).

DEMO_MODE=1 serves mock routes; DEMO_MODE=0 runs the real graph and streetlight scoring. Optional settings are listed in backend/env.example; CORS_ORIGINS is a comma-separated list.

Check it: http://127.0.0.1:8000/v1/health and http://127.0.0.1:8000/docs.

Frontend

cd frontend
cp env.local.example .env.local
npm install
npm run dev

Open http://localhost:3000. The env file sets NEXT_PUBLIC_API_URL (default http://127.0.0.1:8000/), NEXT_PUBLIC_API_PREFIX (/v1) and NEXT_PUBLIC_USE_MOCK.

Running tests

cd backend
pytest tests/

The tests call /v1/health and /v1/route/compare through FastAPI's TestClient and check the response keys and types against the contract.

Deployment

Service	Setting	Value
Render (backend)	Root directory	backend
	Build command	pip install -r requirements.txt
	Start command	uvicorn app.main:app --host 0.0.0.0 --port $PORT
	Env	DEMO_MODE=0, CORS_ORIGINS=<frontend URL>
Vercel (frontend)	Root directory	frontend
	Env	NEXT_PUBLIC_API_URL=<backend URL>, NEXT_PUBLIC_API_PREFIX=/v1, NEXT_PUBLIC_USE_MOCK=false

Design

Team

Built by the Nightwatch team at CUMSA Hacks:

• Saim Hashmi
• Arsh Jameel
• Jadov29
• senuradissa

Author

Saim Hashmi - 4th-year Computer Systems Engineering student at Carleton University. GitHub: @anakafeel