# Requirements

## Functional

**FR1:** System shall integrate with Open Library API to search books by title, author, or ISBN

**FR2:** System shall display book search results with cover images, title, author, and page count

**FR3:** System shall allow user to select a book from search results and add it to their reading list

**FR4:** System shall require user to set a deadline date when adding a book to the reading list

**FR5:** System shall display active books in a list view on the main screen

**FR6:** System shall allow user to log current page number for any active book via a quick-tap workflow (tap book → enter page → save)

**FR7:** System shall calculate required pages per day as: (Total Pages - Current Page) ÷ (Days Until Deadline)

**FR8:** System shall calculate actual reading pace as a rolling 7-day average of pages read per day

**FR9:** System shall display both required pace and actual pace with clear labeling

**FR10:** System shall show pages remaining and days remaining for each active book

**FR11:** System shall provide color-coded status indicator:
- Green: Actual pace ≥ Required pace (on track)
- Yellow: Actual pace within 10% of required pace (slightly behind)
- Red: Actual pace >10% below required pace (falling behind)

**FR12:** System shall display a calendar view showing dates when user logged progress

**FR13:** System shall highlight current date and deadline dates on the calendar

**FR14:** System shall persist all book data and reading logs in PostgreSQL database

**FR15:** System shall function as a Progressive Web App (PWA) installable via "Add to Home Screen"

**FR16:** System shall work offline for viewing existing data and logging entries (sync when online)

**FR17:** System shall validate page number inputs (must be numeric, >0, ≤ total pages)

**FR18:** System shall prevent logging page numbers that are less than previously logged page for the same book (can only move forward)

**FR19:** System shall recalculate required pace automatically each day as deadline approaches

**FR20:** System shall cache book metadata from Open Library to reduce API calls and improve performance

## Non Functional

**NFR1:** Page load time shall be <2 seconds on 3G mobile connection

**NFR2:** Log entry save operation shall complete in <1 second

**NFR3:** Application shall be mobile-responsive and fully functional on screen sizes from 320px to 1920px width

**NFR4:** Application shall support last 2 versions of Chrome, Safari, Firefox, and Edge browsers

**NFR5:** Application shall use HTTPS for all communications (enforced by Coolify/PWA requirements)

**NFR6:** Application shall sanitize all user inputs to prevent XSS attacks

**NFR7:** Application shall use parameterized queries or ORM to prevent SQL injection

**NFR8:** Application shall deploy as Docker containers to Coolify infrastructure

**NFR9:** Database shall have automated backup mechanism via Coolify PostgreSQL management

**NFR10:** Application shall respect Open Library API rate limits and implement appropriate caching/retry logic

**NFR11:** Frontend bundle size shall be optimized for mobile (<500KB initial load)

**NFR12:** Application shall handle Open Library API failures gracefully with user-friendly error messages

**NFR13:** PWA service worker shall cache static assets and implement cache-first strategy for offline support

**NFR14:** Application shall be accessible and usable with keyboard navigation for basic workflows

**NFR15:** All REST API endpoints shall validate inputs and return appropriate HTTP status codes and error messages

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