Index: server/account.go
===================================================================
--- server/account.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
+++ server/account.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
@@ -0,0 +1,98 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"bp_project/server/db"
+)
+
+// ShowBalance prints the logged-in user's balances.
+func ShowBalance(s *Session) {
+	var avail, invested float64
+	err := db.DB.QueryRow(
+		`SELECT available_balance, invested_balance FROM users WHERE id = $1`,
+		s.UserID,
+	).Scan(&avail, &invested)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	fmt.Printf("\n  Available: %.4f USD\n", avail)
+	fmt.Printf("  Invested : %.4f USD\n", invested)
+	fmt.Printf("  Total    : %.4f USD\n", avail+invested)
+}
+
+// Deposit - UC0003
+// Transactional: updates users.available_balance and inserts a ledger row.
+func Deposit(s *Session) {
+	fmt.Println("\n-- Deposit virtual funds --")
+	amtStr := prompt("Amount (USD): ")
+	amt, err := strconv.ParseFloat(amtStr, 64)
+	if err != nil || amt <= 0 {
+		fmt.Println("Invalid amount.")
+		return
+	}
+
+	tx, err := db.DB.Begin()
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	defer tx.Rollback()
+
+	if _, err := tx.Exec(
+		`UPDATE users
+		    SET available_balance = available_balance + $1,
+		        updated_at        = now()
+		  WHERE id = $2`,
+		amt, s.UserID,
+	); err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	if _, err := tx.Exec(
+		`INSERT INTO transactions (user_id, type, amount, currency, description)
+		 VALUES ($1, 'deposit', $2, 'USD', 'Virtual deposit')`,
+		s.UserID, amt,
+	); err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	if err := tx.Commit(); err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	fmt.Printf("Deposited %.4f USD.\n", amt)
+}
+
+// ShowTransactions lists the last 20 ledger entries for the user.
+func ShowTransactions(s *Session) {
+	rows, err := db.DB.Query(
+		`SELECT created_at, type, amount, currency, COALESCE(description, '')
+		   FROM transactions
+		  WHERE user_id = $1
+		  ORDER BY created_at DESC
+		  LIMIT 20`,
+		s.UserID,
+	)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	defer rows.Close()
+
+	fmt.Println()
+	fmt.Printf("  %-20s  %-8s  %12s  %-3s  %s\n", "When", "Type", "Amount", "Cur", "Description")
+	fmt.Println("  " + strings.Repeat("-", 70))
+	for rows.Next() {
+		var when, typ, cur, desc string
+		var amt float64
+		if err := rows.Scan(&when, &typ, &amt, &cur, &desc); err != nil {
+			fmt.Println("scan error:", err)
+			return
+		}
+		fmt.Printf("  %-20s  %-8s  %12.4f  %-3s  %s\n", when[:19], typ, amt, cur, desc)
+	}
+}