As a User, I want to register using my email/mobile and password, so that I can securely access my expense data.

• Email/Mobile must be unique
• Password must satisfy minimum strength rules
• Mandatory fields missing হলে registration complete হবে না

As a User, I want to log in securely, so that I can manage my expenses and budgets.

• Wrong credentials → generic error message
• Multiple failed attempts → optional lock/delay (security)

As a User, I want to recover my password, so that I don’t lose access to my data.

• OTP / email verification required
• Reset token time-bound

As a User, I want default categories (Food, Rent, Transport), so that I can start quickly.

As a User, I want to create my own categories, so that expenses match my real life.

• Category name must be unique
• Empty name not allowed

As a User, I want to remove a category that I no longer use.

• Used categories cannot be hard-deleted
• Mark as Inactive to preserve historical reports

As a User, I want to record an expense with date, amount, and category.

• Amount must be positive
• Date cannot be in the future
• Category is mandatory

As a User, I want to be warned if I accidentally enter the same expense twice.

• Same Date + Amount + Category + Description → show warning (not block)

As a User, I want to edit or delete expenses if I made a mistake.

• Current year expenses → editable
• Previous year expenses → restricted / approval required (optional)

As a User, I want to define my budget for a year, so that I can control spending.

• Budget amount must be positive
• Only one budget per year per category
• Budget not set → treated as Unlimited

As a User, I want to be notified when my spending crosses 50%, 80%, or 100% of my budget.

• Thresholds configurable (50/80/100 default)
• Each threshold triggers only once per cycle (anti-spam)

As a User, I want the system to enforce overspending rules based on policy.

• Soft Limit: allow expense, but mark as Over Budget
• Hard Limit (optional): beyond 100% requires approval note/document

As a User, I want to receive alerts when important budget events happen.

• In-app notifications default
• Email/SMS optional
• Anti-spam: same threshold/alert once per period

As a User, I want a monthly summary of my expenses, so that I can understand my spending patterns.

• Total spent
• Category breakdown
• Budget vs Spent vs Remaining
• Over-budget categories highlight

As a User, I want corrections handled properly, so that reporting stays accurate.

• Refund ≠ Negative Expense
• Use Adjustment entry instead (audit-friendly)

As a User, I want to filter expenses by date, category, or amount.

• Start date ≤ End date
• Invalid filters rejected

As a User, I want to see spending trends, so that I can make better decisions.

• Top spending categories
• High spending months
• Spending increase/decrease compared to previous period

As an Owner, I want to create a group with members, so that we can track shared expenses.

• Role-based access: Owner vs Member
• Owner sets budgets & policies

As an Owner, I want to approve over-budget expenses, so that spending stays controlled.

• Over-budget entries require owner approval (policy-based)
• Approval note/document may be required

এই প্রজেক্ট যদি SaaS এ Transform করা হয় তাহলে প্রতিদিন লক্ষ লক্ষ Expense Entry হবে, এক্ষেত্রে আমরা কিভাবে Daily Expense report এর লোডিং টাইম ১ মিনিটের পরিবর্তে ৩-৫ সেকেন্ডে নামিয়ে আনবো