Dasemu
1dae56415c
React + Vite frontend with a local-JSON-backed API (Vite middleware) for tracking portfolio holdings, contributions/withdrawals, recurring contribution plans, and a forecast chart comparing the portfolio's real value against a same-contributions S&P 500 benchmark. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
59 lines
2.4 KiB
Markdown
59 lines
2.4 KiB
Markdown
# Investment Visualizer
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A personal investment dashboard: track contributions, see asset allocation, and
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compare your portfolio's performance against the S&P 500.
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## Stack
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- **Frontend**: React + TypeScript + Vite, charts with Recharts.
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- **Backend**: a small REST API implemented as a Vite dev-server middleware
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(`server/apiPlugin.ts`) backed by local JSON files in `data/`. No database,
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no separate process — `npm run dev` starts both.
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- **Data**: everything lives under `data/*.json`. The API layer
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(`src/api/client.ts`) is the only place that knows the data lives in local
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files — swapping it for a real backend later means only changing that file.
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## Data model (`data/`)
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- `portfolio.json` — current holdings snapshot (values, asset class, region,
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RV/RF allocation).
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- `history.json` — periodic total-account-value snapshots, used to compute
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time-weighted return (TWR). Add more snapshots over time for a more accurate
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performance line.
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- `contributions.json` — the movements ledger (external contributions/
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withdrawals plus internal fund subscriptions/redemptions) and recurring
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contribution plans (weekly/monthly/etc.) used to project future cash flows.
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- `settings.json` — portfolio inception date, forecast horizon (years), and
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the assumed annual return used for the projected part of the chart
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(historical TWR-derived or a manual assumption).
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- `sp500.json` — cached daily S&P 500 closes, refreshed with:
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```bash
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node scripts/fetch-sp500.mjs
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```
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## Performance methodology
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- **Portfolio return**: simplified chain-linked time-weighted return (TWR)
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computed from `history.json` snapshots and external cash flows in
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`contributions.json`. Internal fund subscriptions/redemptions net to zero on
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total account value and don't affect it.
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- **S&P 500 line**: percentage change of the index since the portfolio's
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inception date, for an apples-to-apples "who's outperforming whom"
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comparison against the portfolio's TWR line.
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- **Forecast segment**: continues the portfolio line past today using either
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the historical annualized TWR or a manual rate, applied to the current value
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plus projected future contributions from active recurring plans.
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- **0% baseline**: cumulative net contributions (actual + projected) with no
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investment return at all — the reference line for "what if it just sat in
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cash."
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## Development
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```bash
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npm install
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npm run dev
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```
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This starts Vite (frontend + local JSON API) on http://localhost:5173.
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