P3-1: Scan optimization — only BG↔HL (50+ pair combos → 2)
P3-2: Real-time spread chart — spreadHistory ring buffer +
/api/spread-history endpoint + Chart.js spread chart
P3-3: Live position PnL — positions SSE now includes
estimated current profit/loss + current spread
P3-4: Real-time trade events — trader.OnTradeEvent callback
fires SSE 'trade_open' / 'trade_close' immediately
P3-5: Connection status monitoring — tracks last update time
per exchange, broadcast via stats.connections + /api/connections
Frontend: spread chart card, PnL column in positions,
connection status dots in stats bar,
green/red border flash on trade events
B#1 — sigCh shared across goroutines, SIGINT unreliable
→ context.WithCancel: main loop cancels ctx on SIGINT,
4 WS goroutines select on ctx.Done() instead of shared sigCh
B#3 — restoreOpenPositions missing LastScaleAt
→ Set LastScaleAt = tr.OpenedAt on restore so scale-in cooldown works
B#4 — dYdX heartbeat goroutine leaks on reconnect
→ Added stopHeartbeat chan + heartbeatMu mutex; close old channel
before spawning new heartbeat goroutine
B#5 — GetBitgetSize fmt.Sprintf rounds up, may exceed amountUSD
→ Added math.Floor(sz*multiplier)/multiplier before format to round
DOWN to nearest valid step size for every coin
B#6 — netProfit and CalcNetProfit duplicate formula
→ scanner.go netProfit now delegates to exchange.CalcNetProfit
B#7 — Aevo Run callback only 2 params, incompatible with startExchange
→ Changed to 4-arg callback func(coin, price, bid, ask) with bid=ask=0
B#8 — parseFloat uses fmt.Sscanf (slow, locale-sensitive)
→ Replaced with strconv.ParseFloat
B#9 — dYdX receives hlSymbols instead of its own symbol list
→ Added dydxSymbols var, built from c.HL like other exchanges
jackyu66git