RC2_ENTRY_EXTRA_ARG

Entry verbs (buy, sell_short) take exactly one positional arg — the symbol slot.

What it means

Entry verbs are auto-sized from the class-level sizing declaration. They take exactly one positional argument: the trading symbol. Everything else (stop, reason, sizing overrides) is a keyword arg.

Why it happens

You probably tried to pass quantity positionally — habit from self.sell(self.trade, qty):

class Bad(Strategy):
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        if self.trade.is_flat:
            self.buy(self.trade, 100)       # ❌ — second positional arg

How to fix it

To override the sizing model on this trade, use the kwarg that matches the model:

class QuantityOverride(Strategy):
    trade = Symbol()
    sizing = FixedQuantity()

    def execute(self):
        if self.trade.is_flat:
            self.buy(self.trade, qty=100)            # ✅ FixedQuantity → qty=

class CapitalOverride(Strategy):
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        if self.trade.is_flat:
            self.buy(self.trade, percent=50)         # ✅ FixedCapital → percent=

If you just want the default-sized entry, pass the symbol and nothing else:

class DefaultSized(Strategy):
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        sma = SMA(20, on=self.trade)
        if self.trade.is_flat:
            self.buy(self.trade, stop=sma.value)          # ✅ uses the sizing model
        if self.trade.is_short:
            self.buy_to_cover(self.trade, self.trade.position, reason="Cover")