Index: server/watchlist.go
===================================================================
--- server/watchlist.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
+++ server/watchlist.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
@@ -0,0 +1,134 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+
+	"bp_project/server/db"
+)
+
+// ManageWatchlist - UC0007
+// Ensures the user has a default watchlist, then allows listing, adding,
+// removing entries.
+func ManageWatchlist(s *Session) {
+	wlID, err := ensureDefaultWatchlist(s.UserID)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	for {
+		fmt.Println("\n-- Watchlist --")
+		fmt.Println("[1] List items")
+		fmt.Println("[2] Add crypto")
+		fmt.Println("[3] Remove crypto")
+		fmt.Println("[0] Back")
+		switch prompt("> ") {
+		case "1":
+			listWatchlist(wlID)
+		case "2":
+			addToWatchlist(wlID)
+		case "3":
+			removeFromWatchlist(wlID)
+		case "0":
+			return
+		default:
+			fmt.Println("Unknown option.")
+		}
+	}
+}
+
+func ensureDefaultWatchlist(userID string) (string, error) {
+	var id string
+	err := db.DB.QueryRow(
+		`SELECT id FROM watchlists WHERE user_id = $1 ORDER BY created_at LIMIT 1`,
+		userID,
+	).Scan(&id)
+	if err == sql.ErrNoRows {
+		err = db.DB.QueryRow(
+			`INSERT INTO watchlists (user_id, name) VALUES ($1, 'Favorites') RETURNING id`,
+			userID,
+		).Scan(&id)
+		return id, err
+	}
+	return id, err
+}
+
+func listWatchlist(wlID string) {
+	rows, err := db.DB.Query(`
+		SELECT c.symbol, c.name, COALESCE(lp.price, 0)
+		  FROM watchlist_items wi
+		  JOIN crypto  c  ON c.id = wi.crypto_id
+		  LEFT JOIN markets       m  ON m.crypto_id = c.id AND m.quote_currency = 'USD'
+		  LEFT JOIN v_latest_prices lp ON lp.market_id = m.id
+		 WHERE wi.watchlist_id = $1
+		 ORDER BY c.symbol`, wlID)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	defer rows.Close()
+
+	fmt.Println()
+	fmt.Printf("  %-8s  %-20s  %15s\n", "Symbol", "Name", "Last price")
+	fmt.Println("  --------------------------------------------------")
+	empty := true
+	for rows.Next() {
+		var sym, name string
+		var price float64
+		if err := rows.Scan(&sym, &name, &price); err != nil {
+			fmt.Println("scan error:", err)
+			return
+		}
+		fmt.Printf("  %-8s  %-20s  %15.6f\n", sym, name, price)
+		empty = false
+	}
+	if empty {
+		fmt.Println("  (watchlist is empty)")
+	}
+}
+
+func addToWatchlist(wlID string) {
+	sym := prompt("Crypto symbol to add: ")
+	var cryptoID string
+	err := db.DB.QueryRow(
+		`SELECT id FROM crypto WHERE upper(symbol) = upper($1)`, sym,
+	).Scan(&cryptoID)
+	if err == sql.ErrNoRows {
+		fmt.Println("Unknown crypto symbol.")
+		return
+	}
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	_, err = db.DB.Exec(
+		`INSERT INTO watchlist_items (watchlist_id, crypto_id)
+		 VALUES ($1, $2)
+		 ON CONFLICT (watchlist_id, crypto_id) DO NOTHING`,
+		wlID, cryptoID,
+	)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	fmt.Println("Added.")
+}
+
+func removeFromWatchlist(wlID string) {
+	sym := prompt("Crypto symbol to remove: ")
+	res, err := db.DB.Exec(`
+		DELETE FROM watchlist_items
+		 WHERE watchlist_id = $1
+		   AND crypto_id = (SELECT id FROM crypto WHERE upper(symbol) = upper($2))`,
+		wlID, sym)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	n, _ := res.RowsAffected()
+	if n == 0 {
+		fmt.Println("Not in watchlist.")
+		return
+	}
+	fmt.Println("Removed.")
+}