Add project plan for lifetime investing game

[alexander-bain]

Summary

This PR adds a comprehensive project plan document (CLAUDE.md) that outlines the vision, design, and implementation roadmap for transforming the existing one-year stock market game into a full-lifetime investing simulation.

Key Changes

• New file: CLAUDE.md — a detailed 409-line project brief covering:
  • Vision: Transform the game from a one-year trading session into a 40–50 year life simulation where players pick a birth year (1900–2000), earn salary, decide savings rates, and invest across four asset types (index funds, individual stocks, bonds, cash)
  • Design decisions: Turn-based yearly progression, handling the "born too late" problem with a history/forecast split at 2025, and a glide-path lesson that rewards moving from stocks to bonds as players age
  • Data requirements: Two JSON files (annual-returns.json for 1900–2025 historical returns, world-events.json for memorable market events)
  • Six milestones with clear Definition of Done criteria:
    1. Optimize the existing one-year game (instant load, no network blocking)
    2. Build the historical data layer
    3. Add life setup screen (birth year, entry age, retirement age)
    4. Implement the yearly decision loop (savings rate, asset allocation, real returns)
    5. Add life messages and retirement ending screen with lessons
    6. Polish, accessibility, leaderboard, and homepage updates
  • Tech rules: Vanilla JS only, no build step, localStorage for saves, accessibility requirements, and commit discipline
  • Stretch goals: Inflation tracking, international index, side-by-side life comparison, share cards, real per-stock data

Purpose

This document serves as the source of truth for any developer (human or AI agent) picking up the project, ensuring each milestone is unambiguous and testable before moving to the next phase.

https://claude.ai/code/session_0126SAuEmy3tK7xMzq7FgX37

[dexterhbain]

Looks good for the stock market lifetime investing plan. Approved.