Feature ID: FRD-005
Feature Name: User Authentication & Data Persistence
Related PRD Requirements: REQ-5, REQ-6, REQ-10
Status: Draft
Last Updated: November 11, 2025
Provide secure user account management and reliable data persistence to ensure users can access their personal library, ratings, and preferences from any device and session. This is the foundational infrastructure that enables all other features.
Users trust that their reading data is secure, private, and always available when they return to the app. Simple authentication doesn't create friction while robust data persistence ensures no data loss.
- 95% of users successfully create accounts on first attempt
- Zero data loss during normal operations
- Session persistence allows users to remain logged in for 30 days
- Account creation and login complete within 3 seconds
- Data syncs across devices within 5 seconds of changes
Description: New users must be able to create accounts to access the application.
Inputs:
- Email address (required)
- Password (required, min 8 characters)
- Optional: Display name
- Acceptance of terms of service
Outputs:
- User account created in database
- User automatically logged in
- Welcome message or onboarding flow initiated
- Session token generated
Acceptance Criteria:
- Registration form accessible from homepage
- Email validation: must be valid email format
- Password validation: minimum 8 characters, contains letter and number
- Password strength indicator shown while typing
- Email uniqueness check: error if email already registered
- Confirmation email sent after successful registration (optional for v1)
- User redirected to library/onboarding after registration
- Registration completes within 3 seconds
Edge Cases:
- What if email already exists? → Display: "An account with this email already exists. Try logging in?"
- What if password too weak? → Display specific requirements not met, prevent submission
- What if registration fails? → Display error, allow retry, don't lose entered data
- What if email is invalid format? → Validate on blur, show error before submission
Description: Existing users must be able to securely log in to access their personal data.
Inputs:
- Email address
- Password
- Optional: "Remember me" checkbox
Outputs:
- User authenticated
- Session token generated and stored
- User redirected to library/last viewed page
- Session persists based on "Remember me" selection
Acceptance Criteria:
- Login form accessible from homepage and when session expires
- Email and password fields with appropriate input types
- "Remember me" option to extend session duration
- "Forgot password?" link visible
- Login completes within 3 seconds
- Invalid credentials show clear error: "Invalid email or password"
- Account lockout after 5 failed attempts (security measure)
Edge Cases:
- What if credentials are incorrect? → Display generic error (don't reveal whether email or password is wrong)
- What if account is locked? → Display: "Too many failed attempts. Try again in 15 minutes or reset your password."
- What if login fails due to server error? → Display error, allow retry
- What if session expires while user is active? → Prompt to re-login without losing current work
Description: Users must be able to reset forgotten passwords securely.
Inputs:
- Email address associated with account
- New password (from reset link)
Outputs:
- Password reset email sent
- Reset link valid for 1 hour
- Password updated in database
- User logged in automatically after successful reset
Acceptance Criteria:
- "Forgot password?" link on login page
- Reset form requests email address
- Reset email sent within 1 minute
- Email contains secure, time-limited reset link
- Reset link opens page to enter new password
- New password must meet same requirements as registration
- After successful reset, user logged in automatically
- Old password no longer works
Edge Cases:
- What if email not in system? → Send generic message: "If account exists, reset email sent" (don't reveal account existence)
- What if reset link expired? → Display: "This reset link has expired. Request a new one."
- What if reset link already used? → Display: "This reset link has already been used. Request a new one if needed."
- What if user never receives email? → Provide "Resend" option, check spam folder suggestion
Description: Users must be able to securely log out of their accounts.
Inputs:
- User action: Click logout button
Outputs:
- Session token invalidated
- User redirected to homepage/login page
- Local storage cleared (if applicable)
- Confirmation message: "You've been logged out"
Acceptance Criteria:
- Logout option accessible from header/menu on all pages
- Logout completes immediately (<500ms)
- User cannot access protected pages after logout without re-login
- Clear confirmation that logout succeeded
Edge Cases:
- What if logout request fails? → Retry, if persistent failure clear local session anyway
- What if user has unsaved work? → Warn before logout or auto-save all changes
Description: System must maintain user sessions securely and handle session expiration gracefully.
Inputs:
- Session token (from cookie or local storage)
- User activity
Outputs:
- Active session validated on each request
- Session extended on user activity (if not expired)
- Session expiration handled gracefully
Acceptance Criteria:
- Session duration: 30 days with "Remember me", 24 hours without
- Session auto-extends on user activity (sliding expiration)
- Expired session redirects to login with message: "Your session has expired. Please log in again."
- User's current work is preserved if possible (draft notes, pending changes)
- Session tokens are secure (HttpOnly, Secure flags)
- One session per device (or allow multiple with management)
Edge Cases:
- What if session expires while user is typing? → Preserve unsaved work, prompt re-login, restore after login
- What if user logs in from multiple devices? → Allow, keep sessions independent
- What if session token is compromised? → User can invalidate all sessions from settings
Description: All user data (library, ratings, preferences, notes) must persist reliably between sessions and across devices.
Inputs:
- User actions: add book, rate book, update preferences, etc.
- User data from database
Outputs:
- Changes saved to database immediately
- Data synced across user's devices
- Data retrieved on login from any device
Acceptance Criteria:
- All changes auto-save (no manual save button)
- Data saves complete within 1 second
- Save failures display clear error and allow retry
- Data loads on login within 2 seconds
- User sees same data on all devices after sync
- Offline changes queue for sync when connection restored (optional for v1)
Edge Cases:
- What if save fails? → Display error, queue for retry, show pending state
- What if user edits same data from two devices simultaneously? → Last write wins (or conflict resolution in v2)
- What if database is unavailable? → Show error, queue changes, sync when available
- What if data loads slowly? → Show loading skeleton, don't block other UI
Description: Users must be able to view and update basic account information.
Inputs:
- User profile/settings page access
- Updated information (email, password, display name)
Outputs:
- Current account information displayed
- Updates saved to database
- Confirmation of changes
Acceptance Criteria:
- Settings/profile page accessible from header/menu
- Display current: email, display name, account created date
- Allow updates to: password, display name
- Email change requires re-verification (optional for v1)
- Password change requires current password confirmation
- Changes save immediately with confirmation
Edge Cases:
- What if user changes email to one already in use? → Display error: "This email is already registered"
- What if password change fails validation? → Show specific requirements not met
- What if update fails? → Display error, allow retry, don't lose entered data
Description: Users must be able to delete their accounts and all associated data (optional for v1, recommended for compliance).
Inputs:
- User action: Request account deletion
- Confirmation (password or explicit "Delete my account" text)
Outputs:
- Account marked for deletion or immediately deleted
- All user data removed from database
- User logged out
- Confirmation email sent
Acceptance Criteria:
- Account deletion option in settings (clearly labeled, separate from other actions)
- Requires strong confirmation (password + checkbox or typing "DELETE")
- Warning message about permanent data loss
- Grace period of 7-30 days before permanent deletion (optional)
- User can cancel deletion during grace period (optional)
- After deletion, user cannot log in with old credentials
Edge Cases:
- What if user deletes account accidentally? → Grace period allows recovery
- What if deletion fails? → Display error, allow retry, don't partially delete data
- What if user has active subscription or paid features? → Handle refund/cancellation first (not applicable for v1)
User Entity:
id(unique identifier, UUID)email(unique, required)passwordHash(bcrypt or similar, required)displayName(optional)createdDate(timestamp)lastLoginDate(timestamp)accountStatus(active, locked, deleted)emailVerified(boolean, optional for v1)
Session Entity:
sessionToken(unique, secure random string)userId(links to User)createdDate(timestamp)expiresDate(timestamp)lastActivityDate(timestamp)deviceInfo(optional: browser, OS, IP)
Associated Data (linked by userId):
- Books (from FRD-001)
- Ratings and Notes (from FRD-003)
- Preferences (from FRD-003)
- Recommendation history (from FRD-004, optional)
Requirements:
- Passwords must be hashed with bcrypt or Argon2 (never stored plaintext)
- Session tokens must be cryptographically random and unpredictable
- Sensitive data transmitted over HTTPS only
- Database access restricted by user ID (row-level security)
- Regular backups of user data
Layout:
- Email input field
- Password input field with show/hide toggle
- Password strength indicator
- Display name field (optional)
- Terms of service checkbox
- "Create Account" button
- Link to login page ("Already have an account? Log in")
Layout:
- Email input field
- Password input field with show/hide toggle
- "Remember me" checkbox
- "Log In" button
- "Forgot password?" link
- Link to registration page ("Don't have an account? Sign up")
Pages:
- Request reset: Email input, submit button
- Check email: Confirmation message
- Reset form: New password input, strength indicator, submit button
- Success: Confirmation, redirect to app
Sections:
- Account Information: email, display name (editable)
- Change Password: current password, new password fields
- Account Actions: Delete account button (with warning)
- Created date (read-only)
- Registration: complete within 3 seconds
- Login: complete within 3 seconds
- Password reset email: sent within 1 minute
- Data save: complete within 1 second
- Data load on login: complete within 2 seconds
- Logout: complete within 500ms
Scenarios:
- Email already exists: "An account with this email already exists. Try logging in?"
- Invalid email format: "Please enter a valid email address"
- Weak password: "Password must be at least 8 characters with letters and numbers"
- Network error: "Unable to create account. Please try again."
Scenarios:
- Invalid credentials: "Invalid email or password"
- Account locked: "Too many failed attempts. Try again in 15 minutes or reset your password."
- Network error: "Unable to log in. Please try again."
Scenario: Session expires while user is active
Behavior:
- Preserve unsaved work in memory or local storage
- Display modal: "Your session has expired. Please log in again."
- After re-login, restore user to current page with preserved work
Scenario: Failed to save user data
Behavior:
- Display: "Unable to save changes. Please try again."
- Provide retry button
- Queue changes for automatic retry
- Show pending/unsaved indicator
Scenarios:
- Email not found: "If an account exists, a reset email has been sent" (generic for security)
- Expired link: "This reset link has expired. Request a new one."
- Invalid token: "This reset link is invalid. Request a new one."
Requirements:
- Minimum 8 characters
- Must contain letters and numbers (optional: symbols, mixed case)
- Stored as bcrypt hash (cost factor 10-12)
- Never transmitted or stored in plaintext
Requirements:
- Session tokens are cryptographically random (256-bit)
- Tokens stored as HttpOnly cookies (prevent XSS access)
- Secure flag set (HTTPS only)
- SameSite flag to prevent CSRF
- Tokens invalidated on logout and expiration
Requirements:
- Rate limiting on login attempts (max 5 per 15 minutes)
- Account lockout after repeated failed logins
- Password reset links expire after 1 hour
- Reset links single-use only
- Email verification for account changes (optional for v1)
Requirements:
- User data isolated per account (no cross-user access)
- Database queries filtered by authenticated user ID
- Personal data encrypted at rest (optional for v1)
- GDPR compliance: data export, account deletion
- None (foundational feature)
- Book Library Management (FRD-001): Requires authentication to access library
- Book Search & Discovery (FRD-002): Requires authentication to add books
- User Preferences & Ratings (FRD-003): Requires authentication to save ratings/preferences
- AI Recommendations (FRD-004): Requires authentication to generate recommendations
- Authentication method: Simple email/password or OAuth (Google, Microsoft)? → Recommend email/password for v1, add OAuth in v2
- Email verification: Required on registration? → Optional for v1, recommended for v2
- Multi-device sessions: Allow simultaneous logins? → Yes, common for web apps
- Session duration: 24 hours, 7 days, 30 days? → 24 hours default, 30 days with "Remember me"
- Single-user mode: Should v1 support single-user without accounts? → No, simplifies architecture to assume authentication
- Account deletion grace period: Immediate or delayed? → Recommend 7-day grace period for safety
- Password requirements: Enforce complexity rules? → Minimum 8 chars + letters and numbers, reasonable balance
- Authentication service must have 99.9% uptime
- Data must be accessible within 2 seconds on login
- Support concurrent user registrations and logins
- Database must handle expected user growth
- GDPR: Right to data export and deletion
- Password storage following OWASP best practices
- Secure handling of personal data (email)
- Registration and login flows are simple and fast
- Clear error messages guide users to resolution
- Password reset is straightforward
Traceability Matrix:
| PRD Requirement | FRD Section |
|---|---|
| REQ-5: User Account Management | 2.1 - 2.4, 2.7 - 2.8 (registration, login, password reset, logout, account management, deletion) |
| REQ-6: Data Persistence | 2.5, 2.6, 3.3, 6.4 |
| REQ-10: Basic Error Handling | 6.1 - 6.5 |
Document Version: 1.0
Status: Ready for Technical Review