//@version=6
// SEIHAI experiment 001, fixed-window v1.1.0. Compiled on TradingView 2026-11-11. No profitability claim.
strategy("AI Lab 01 | SMA 20/60 cost experiment", overlay = true,
     initial_capital = 10000, currency = currency.USD,
     default_qty_type = strategy.fixed, default_qty_value = 0.01,
     pyramiding = 0, commission_type = strategy.commission.percent,
     commission_value = 0.10, slippage = 2,
     margin_long = 100, margin_short = 100,
     calc_on_every_tick = false, calc_on_order_fills = false,
     process_orders_on_close = false, use_bar_magnifier = false)

int startAt = timestamp("01 Jan 2022 00:00 +0000")
int endAt = timestamp("01 Jan 2025 00:00 +0000")
float units = input.float(0.01, "Fixed BTC quantity (educational)", minval = 0.000001)

if barstate.isfirst
    if startAt >= endAt
        runtime.error("Start must precede End.")
    if not timeframe.isdaily or timeframe.multiplier != 1
        runtime.error("Use a 1D chart for this experiment.")
    if not chart.is_standard
        runtime.error("Use standard candles, not synthetic chart prices.")

float fast = ta.sma(close, 20)
float slow = ta.sma(close, 60)
bool crossedUp = ta.crossover(fast, slow)
bool crossedDown = ta.crossunder(fast, slow)
bool warmed = bar_index >= 199 and not na(slow[1])
bool entryWindow = time >= startAt and time_close < endAt

if barstate.isconfirmed
    if strategy.position_size > 0 and (crossedDown or time_close >= endAt)
        strategy.close("Long", comment = time_close >= endAt ? "Window end" : "Cross down")
    else if warmed and entryWindow and crossedUp and strategy.position_size == 0
        strategy.entry("Long", strategy.long, qty = units)

plot(fast, "SMA 20", color = color.orange, linewidth = 2)
plot(slow, "SMA 60", color = color.blue, linewidth = 2)
bgcolor(entryWindow ? color.new(color.blue, 94) : na, title = "Entry window")