Strategy Spec Reference

A spec is a JSON object. scripts/spec.py validates it before any data loads, so a mistake costs a second instead of a long read.

Fields

Field	Type	Default	Meaning
`name`	string	required	Strategy label, carried into the result
`indicators`	object	required	Named indicators, at least one
`entry`	object	required	One condition; the position is held while it holds
`size`	number	`1.0`	Fraction of equity when in position, in `(0, 1]`
`stop_loss_pct`	number	none	Stop distance in percent from entry
`take_profit_pct`	number	none	Target distance in percent from entry
`fees_bps`	number	`0.0`	Fee in basis points, charged both sides
`slippage_bps`	number	`0.0`	Fixed slippage in basis points
`signal_delay`	integer	`1`	Bars between signal and fill

Indicators

"indicators": {
  "fast": { "type": "sma", "period": 20 },
  "rsi14": { "type": "rsi", "period": 14, "source": "close" }
}

type is sma, ema or rsi. period is a positive integer. source is open, high, low or close, defaulting to close.

Each name becomes a signal you can reference in entry.

Entry condition

"entry": { "left": "fast", "op": ">", "right": "slow" }

op is >, <, >= or <=. Each side is an indicator name, a price column, or a number:

"entry": { "left": "rsi14", "op": "<", "right": 30 }
"entry": { "left": "close", "op": ">", "right": "slow" }

The strategy holds size while the condition is true and goes flat when it turns false. A crossing is the condition becoming true, so a moving-average crossover is written as the comparison, not as a separate crossing operator.

Why `signal_delay` defaults to 1

At 0 the strategy fills on the bar that produced the signal. Unless the fill price is knowable at signal time, that is look-ahead, and it inflates results in a way no later stress test recovers. backtest-expert lists it among its red flags. Setting it to 0 is allowed and reported as a warning.

Parameter count

count_parameters counts what the robustness dimension penalises:

one per indicator period
one per numeric threshold used in entry
one when size is explicitly supplied
one per bracket distance set

Fees, slippage and signal_delay are excluded. They are costs and conventions, not knobs you tune until the equity curve improves.

A spec with more than four parameters triggers a warning before it runs.

What validation refuses

Refused	Reason
Unknown `type`	The three supported kinds are named in the error
`period` of 0, negative, or `True`	`True` is an `int` in Python and would build a period of one
`entry` naming an undeclared indicator	The error lists what is declared
`size` outside `(0, 1]`	Sizing above equity needs leverage the spec does not model
Negative `fees_bps` or `slippage_bps`	A negative cost is a rebate the engine does not model
Empty `indicators`	A condition needs something to compare

Full example

{
  "name": "rsi_oversold_costed",
  "indicators": {
    "rsi14": { "type": "rsi", "period": 14 }
  },
  "entry": { "left": "rsi14", "op": "<", "right": 30 },
  "size": 0.5,
  "stop_loss_pct": 2.0,
  "take_profit_pct": 4.0,
  "fees_bps": 5.0,
  "slippage_bps": 2.0,
  "signal_delay": 1
}

Five parameters: the RSI period, the threshold of 30, the explicit position size, the stop and the target.

/manifoldbt-backtester

referencesstrategy_spec.md