Finmarkets Monitor

Personal browser-based tool for monitoring a single equity position with a tax-overhang exit framework. Generic — works with any single equity ticker supported by Twelve Data.

Stack

• Svelte 5 + TypeScript + Vite
• DuckDB-WASM (OPFS persistence) for storage and analytics (RSI/MACD computed in DuckDB SQL via recursive CTEs and materialised into indicators_rsi / indicators_macd tables)
• Lightweight Charts (TradingView OSS) for visualization
• Twelve Data API for OHLCV (free tier, 800 req/day)

Setup

1. npm install
2. npm run dev
3. Open http://localhost:5173
4. Get a free Twelve Data API key at https://twelvedata.com/
5. Enter it in the Settings panel along with your vest price, shares, and tax rate
6. Click "Refresh data" to pull historical OHLCV
7. Review the Witness Panel and Chart for the current state

Deployment

Live deployment: https://finmarkets-monitor.pages.dev

Deployed to Cloudflare Pages.

One-time setup

You need a Cloudflare account and a Pages project. The first deploy will create the project automatically; subsequent deploys update it.

npx wrangler login   # opens browser for OAuth, one-time

Deploy

npm run deploy           # production deploy (--branch=main)
npm run deploy:preview   # preview deploy (--branch=preview)

The deploy command runs npm run build first, then uploads dist/ to Cloudflare Pages.

DuckDB WASM hosting

The DuckDB-WASM binaries (~40 MB each) are loaded at runtime from jsDelivr's npm mirror (https://cdn.jsdelivr.net/npm/@duckdb/duckdb-wasm/) rather than bundled into the deployed assets. Cloudflare Pages caps individual file uploads at 25 MiB, and the WASM files exceed that.

The version is pinned in src/lib/duckdb.ts (DUCKDB_WASM_VERSION constant) and must be kept in sync with the installed npm package. If you bump @duckdb/duckdb-wasm, also update the constant in duckdb.ts.

Notes

• The Twelve Data API key is stored in browser localStorage, not in the deployed bundle. Each user enters their own key in the Settings panel after the page loads.
• All data lives in the user's browser (DuckDB-WASM + OPFS). No backend, no user accounts, no server-side storage.
• The site is fully static — no Cloudflare Workers Functions, no KV, no D1.

Companion docs

The methodology this app implements lives in:

• ~/docs/finmarkets/monitoring-guide.md — three-phase educational guide
• ~/docs/finmarkets/weekly-review.md — the Sunday checklist template

For honest engineering record of known limitations, conscious tradeoffs, and deferred work, see GAPS.md.

Disclaimers

Educational use only. Not investment, tax, or legal advice. The app applies mechanical rules from the companion docs to live data; it does not replace personal judgment, professional advisors, or your reading of the underlying documents.

Commands

• npm run dev — dev server
• npm run build — production build
• npm run check — type check
• npm test -- --run — run vitest suite

License

Dual-licensed at your option under either:

• Apache License, Version 2.0
• MIT License

SPDX-License-Identifier: Apache-2.0 OR MIT

Copyright © 2026 Tiago Caxias.

Contributions are accepted under both licenses simultaneously. By submitting a contribution you agree to license it under the same Apache-2.0 OR MIT terms as the rest of the project. (This is the same dual-license pattern used by Rust and most crates.)

Bundled and runtime-loaded dependencies

This project bundles or loads the following open-source libraries at runtime, all under permissive licenses compatible with the project's dual-license terms. Full attribution lives in NOTICE.

Build-time tooling (Vite, Svelte compiler, TypeScript, Vitest, Wrangler, etc.) is not redistributed in the deployed application.