Which way up, given today?
Search a trail, and ProbablyThisWay scores every mapped route against today's weather, daylight, distance and climb with TypeSafe AI's Jev model. Then it replays the best eligible route on 3D terrain and shows you why.
Recommended route
Summit LoopRanks highest among eligible routes. Its 48-minute estimate leaves daylight to spare.
Live session
Route signal
From a place name to a reasoned route.
Unknown facts stay unknown. The model scores; a deterministic policy decides; the interface shows every step.
Search a trail
OpenStreetMap is searched by name and location. A place can resolve to its trail lines or up to eight named branches nearby.
Take a snapshot
Route geometry and known facts are stored, with current conditions from Open-Meteo at the trailhead, refreshed every five minutes.
Score every candidate
Jev weighs weather, daylight, distance, duration, climb, exposure, pace, fatigue and data quality, returning a score, confidence and probabilities.
Apply the policy
Ineligible routes are removed by rule. The highest scoring eligible route wins. Jev never makes the final pick on its own.
Show the evidence
Shared inputs, every score, policy checks and exclusions stay on screen. Structured evidence, not hidden reasoning.
Replay the route
A marker walks the route across Cesium 3D terrain while the model-to-policy stages replay beside it.
Some routes are never an option.
Before any score counts, the policy excludes routes the data says you shouldn't take. If nothing is eligible, the app says so plainly and tells you to check official guidance.
Routes marked as illegal trails are excluded.
Closed routes never reach scoring.
Restricted access, or any prohibitive restriction, removes a route.
Without an OpenRouter key, or if Jev returns something invalid, a clearly labelled deterministic baseline takes over.
No database, no Docker, no keys needed to start.
Node 22 and a WebGL browser are enough. Add an OpenRouter key to switch from the baseline to Jev. For production, Docker Compose adds PostgreSQL and Nginx.
# clone and install git clone https://github.com/shivamshinde123/ProbablyThisWay.git cd ProbablyThisWay && npm install # optional: enable Jev (~typesafe/jev-latest) cp .env.example .env # OPENROUTER_API_KEY=… npm run dev # open http://localhost:5173 and try # "Newton Hill, Worcester, MA, USA"
React 19, TypeScript, Vite, CesiumJS
Node.js 22, Fastify, Zod
TypeSafe AI Jev via OpenRouter's Decisions API
OpenStreetMap, Open-Meteo, PostgreSQL 17
Decision support, not a safety guarantee. ProbablyThisWay is an experiment, not a navigation system. Always check official trail guidance, closures, weather alerts and posted signs before you hike.