whealthy · Wealth Longevity Planner

Client-side planner for modelling lifetime wealth under configurable spending rules, taxes, inflation/real modes, philanthropy, and private commitments. Everything runs locally in the browser—no analytics, no external network calls.

Tech Stack

• Next.js (App Router) + TypeScript
• Tailwind CSS + shadcn/ui primitives
• Zustand (persisted to localStorage) + Zod validation
• Recharts for deterministic and Monte Carlo visualisations
• Vitest + React Testing Library

Features

• Spending rule engine (fixed, % of wealth, guardrails)
• Philanthropy by fixed amount or % of wealth
• Tax drag modelling with public/private yield decomposition
• Private commitments engine (calls, distributions, MOIC)
• One-off inflow/outflow scheduling
• Deterministic and Monte Carlo projections with ruin probability
• Liquidity runway metric based on liquid assets vs next-year needs
• JSON import/export, seed presets, and persisted state

Local Development

npm install
npm run dev

The app is served at http://localhost:3000.

Run the test suite (unit, property, and snapshot tests):

npm run test

Docker

Build and serve the app through Docker:

docker compose up --build

This starts the development server on port 3000. The Dockerfile also supports a production build (npm run build + npm run start).

Project Structure Highlights

• src/lib/ – Zod types, default parameters, simulation and tax models
• src/store/ – Zustand store with persistence helpers
• src/components/ – UI, charts, tables, and parameter forms
• src/app/page.tsx – Planner shell bringing the tabs together
• Dockerfile, docker-compose.yml – containerised local setup

Notes

• CSP locks the app to self-hosted assets only.
• Monte Carlo paths are capped at 2,000 for responsiveness.
• Sequence risk visualisation (5/25/50/75/95 percentiles) accompanies deterministic projections.
• Acceptance baseline: defaults show no deterministic ruin to age 95, liquidity runway displays, Monte Carlo renders when enabled, JSON import/export round-trips parameters.