Show HN: DayBreak, a stock brief where the AI never touches the numbers

A developer released DayBreak, a self-hosted morning stock-brief tool for US equities that computes every figure deterministically in TypeScript and uses Google's Gemini only to word a verified fact sheet. DayBreak's guardrail module (src/lib/guard.ts) parses the model's JSON output with Zod and rejects any response containing a number absent from the fact sheet or advisory wording such as "should," "buy," "will rise" or "undervalued," falling back to a deterministic template (src/lib/summarize.ts) if the AI breaks a rule twice. The tool pulls quotes, 5-year daily OHLCV bars, earnings dates, fundamentals and headlines from Financial Modeling Prep, Finnhub and Yahoo Finance with Stooq as a final fallback, caches them in Postgres, and sends a brief only when a watchlist stock moves beyond a default ±3% threshold, has earnings within 7 days, or crosses a custom price level.

A calm, self-hosted morning brief and stock analysis tool for US equities. DayBreak watches your US stock list overnight and sends a short morning note only when something actually happened: a big daily move, upcoming earnings, or a custom watch price crossed. When a stock moves, it explains why by comparing the move against the broader US market SPY , its sector ETF XLK , XLF , etc. , trading volume, and real news headlines. Information only, not financial advice. DayBreak is an opinionated personal tool for US stocks. Every number is computed deterministically in code; the AI only words a verified fact sheet. | Today & Morning Brief | Stock Analysis & Signal Backtest | |---|---| | Paper Ideas Scorecard | Mobile View | |---|---| - Calm Morning Brief Web + Email : Runs on a schedule after the US market close. If nothing on your watchlist moved beyond your threshold default ±3% , has earnings within 7 days, or crossed a custom watch price, it sends a single quiet line with no AI call wasted. - Strict AI Guardrails src/lib/guard.ts : Numbers come from code, never from the AI. Gemini receives a plain-text fact sheet and returns JSON. validateBrief rejects any output containing a number not in the fact sheet, any buy/sell/recommendation wording, or any price prediction. If the AI breaks a rule twice, DayBreak falls back to a deterministic template src/lib/summarize.ts . - "Why Did It Move?" Explainer src/lib/explain.ts : Compares 1D / 1W / 1M returns against SPY and the stock's SPDR Sector ETF XLK , XLF , XLV , XLE , etc. to classify sessions as Market-wide , Sector-wide , Company-specific , or Quiet , paired with 20-day volume ratios and date-matched news headlines. - 5-Year Interactive Chart & Technical Indicators src/lib/indicators.ts : Pure TypeScript calculations for 20/50/200-day SMAs, Golden/Death crosses, Wilder's RSI 14 , MACD 12,26,9 , Bollinger Bands, 30-day annualized volatility, and max drawdown. - Transparent Signal Hints & Per-Stock Backtest src/lib/signal.ts : Computes a -100 to +100 hint score Strong Sell to Strong Buy with every contributing factor and point weight visible, then replays that exact scoring rule across the stock's own stored history 20-day forward returns vs. random-day baseline so you can see whether the signal actually worked on that stock in the past. - Fundamentals & Valuation Context src/lib/fundamentals.ts : Displays Market Cap, P/E Ratio, EPS, Dividend Yield, and Beta cached weekly in Postgres . - Custom Watch Price Levels : Set optional low/high price levels on any stock to get alerted in your morning brief when price crosses your level. - Paper Ideas & Honest Scorecard src/lib/scorecard.ts : Log pretend long/short ideas linked to a morning alert or on your own and track win rate and follow-through before risking real money. - Command Palette Ctrl+K / Cmd+K : Jump directly to any US stock's analysis page, add tickers to your watchlist, trigger a brief, or switch between light and dark frosted-glass themes. 1. Deterministic Data src/lib/market/ : Quotes, 5-year daily OHLCV bars, earnings dates, fundamentals, and headlines are fetched from Financial Modeling Prep FMP , Finnhub , and Yahoo Finance with Stooq as a final fallback and cached in Postgres. 2. Code-Built Fact Sheet src/lib/facts.ts : All percentages, 52-week range positions, volume ratios, and caution notes are calculated in TypeScript and serialized into a strict fact sheet. 3. Zero-Trust Validation src/lib/guard.ts : The LLM output is parsed with Zod and checked token-by-token. Any invented number, missing symbol, or advisory/predictive phrase "should" , "buy" , "will rise" , "undervalued" , etc. is rejected. Want to explore the UI immediately with demo data? DayBreak includes an embedded Postgres dev runner: npm install npm run dev:db starts embedded Postgres on :5432 and seeds demo@daybreak.local / demo-password-123 Then in a second terminal: SESSION SECRET=demo-secret-at-least-32-characters-long npm run dev Open http://localhost:3000 http://localhost:3000 and sign in with demo@daybreak.local / demo-password-123 . cp .env.example .env fill in your API keys all free tiers work docker compose up -d db start Postgres 16 npm run migrate apply db/schema.sql npm run create-user -- you@example.com 'a-password-of-12+-chars' npm run dev http://localhost:3000 npm run brief run the morning brief job once right now | Variable | Description | |---|---| | DATABASE URL | Postgres connection string postgres://daybreak:...@localhost:5432/daybreak | | SESSION SECRET | 32+ character secret for signing HttpOnly JWT session cookies | | FMP API KEY | Financial Modeling Prep https://site.financialmodelingprep.com/ API key free tier | | FINNHUB API KEY | Finnhub https://finnhub.io/ API key free tier; fallback quotes, fundamentals & news headlines | | GEMINI API KEY | Google Gemini https://aistudio.google.com/ API key free tier; words the morning brief | | SMTP HOST , SMTP PORT , SMTP USER , SMTP PASS , MAIL FROM | Optional SMTP settings e.g., Resend, Postmark, Gmail for morning emails | | BRIEF CRON & BRIEF TZ | Cron schedule for the worker default 0 7 2-6 in Asia/Dubai , after US Mon–Fri close | | MOVE THRESHOLD PCT | Daily % move that triggers a jump/drop alert default 3 | | HEALTHCHECK URL | Optional Healthchecks.io https://healthchecks.io/ dead-man's switch URL | DayBreak is designed to run on a single Ubuntu VPS via Docker Compose or Coolify : docker compose up -d --build docker compose exec web npm run create-user -- you@example.com 'a-password-of-12+-chars' This starts three containers from a single build: - db : Postgres 16 with persistent volume dbdata - web : Next.js 15 server runs idempotent npm run migrate automatically on startup - worker : node-cron scheduler for the daily brief and history sync - Failure Alert : If any step of the morning job fails, worker emails ADMIN EMAIL and pings ${HEALTHCHECK URL}/fail . - Dead-Man's Switch : Pings ${HEALTHCHECK URL}/start and ${HEALTHCHECK URL} on completion so total server outages never go unnoticed. - Health Endpoint : GET /api/health returns HTTP 200 if Postgres is healthy and a brief succeeded within the last 76 hours or 503 otherwise, ready for UptimeRobot / Coolify healthchecks . - Framework : Next.js 15 App Router + React 19, TypeScript - Database : PostgreSQL postgres driver, raw SQL, zero ORM overhead - Styling : Custom frosted-glass CSS with light/dark view transitions & SVG charts src/app/globals.css - Tests : Vitest tests/ npm run dev start Next.js dev server npm test run Vitest unit test suite npm run typecheck run TypeScript compiler check npm run build production Next.js build npm run migrate apply idempotent db/schema.sql npm run brief trigger the morning brief job immediately Contributions are welcome Please read CONTRIBUTING.md https://github.com/XahidEx/DayBreak/blob/main/CONTRIBUTING.md for local setup instructions and project guidelines before opening a pull request. DayBreak is for informational and educational purposes only and does not constitute financial, investment, trading, or legal advice. Signal scores, technical indicators, and backtests describe past price patterns only and cannot predict future market performance. Always do your own research and consult a qualified financial professional before making investment decisions. Released under the MIT License https://github.com/XahidEx/DayBreak/blob/main/LICENSE .