Leg Handler and Order Management

In Buildalgos.com, a Leg represents a fully managed trading position. It is created with addLeg() and then automatically tracks stop-loss, target, re-entry conditions, and lifecycle events.

Each addLeg(...) call spawns an internal LegHandler object and returns a unique legID (UUID).

Why Use addLeg Instead of placeOrder?

Feature	addLeg	placeOrder
Automatic SL / Target	✅	❌
Trailing stop-loss	✅	❌
Re-entry after SL / Target	✅	❌
Wait-Trade (delayed entry)	✅	❌
Group square-offs	✅	Manual
Position tracking	Auto	Manual
Best for	Systematic strategies	One-off discretionary trades

addLeg() Signature

leg_id = self.addLeg(
    transactionType='buy',                # "buy" or "sell"
    optionType='PE',                      # "CE" | "PE" (ignored for FUT/CASH)
    qty=75,
    Symbol: Optional[str] = None,
    strikeSelection={'strikeBy': 'moneyness','strikeVal': 0,'asof': 'None','roundoff': None},
    expiry={'expType': 'weekly','expNo': 0},
    target={'isTarget': True,'targetOn': '%','targetValue': 50},
    SL={'isSL': True,'SLon': '%','SLvalue': 35},
    trailSL={'isTrailSL': False,'trailSLon': 'val','trailSL_X': 1,'trailSL_Y': 1},
    reEntryTg={'isReEntry': False,'reEntryOn': 'asap','reEntryVal': 0,'reEntryMaxNo': 20},
    reEntrySL={'isReEntry': False,'reEntryOn': 'asap','reEntryVal': None,'reEntryMaxNo': 20},
    waitTrade={'isWT': False,'wtOn': 'val-up','wtVal': 1,'triggers': []},
    segment='OPT',                     # "OPT" | "FUT"
    entryValidity='Day',              # currently only "DAY"
    squareoff='this',                 # "this" | "all" | [legIDs]
    legName:Optional[str] = None,
    webhook={'is': False,'entryMessage': {},'exitMessage': {}}
)

This structure allows for flexible, reusable, and fully-managed execution flows for any options or futures strategy.

Top Level Parameters

Parameter	Values	Description
transactionType	'buy' or 'sell'	Buy or sell leg
symbol	str or None	Optional: direct symbol override; else uses strikeSelection
optionType	'CE' or 'PE'	Option type (for options); otherwise None
qty	int	Quantity (usually multiple of lot size)
segment	"OPT" | "FUT"	Segment to trade
entryValidity	'Day'	Order validity
remark	str	Optional note, e.g. 'Entering Leg'
legName	str	Optional unique ID, e.g. 'lg_ac380_1'

Nested Parameters Dictionaries

strikeSelection :

Key	Type	Example Values	Description
strikeBy	str	'premium above', 'premium near', 'premium below', 'moneyness', 'delta above', 'delta below', 'delta near'	Method used to select the strike price
strikeVal	int	1–9999 (for 'premium'), -10 to 10 (for 'moneyness'), or -1 to 1 (for 'delta').	Value used according to strike-selection logic
asof	str or None	'09:30:00', 'None' (default)	Time reference for strike selection
roundoff	int or None	None, 100, 200, 500, 1000	Round strike to nearest value (e.g., 100)

expiry Selection:

Key	Type	Example Value	Description
expType	str	'weekly'	Expiry type (weekly/monthly)
expNo	int	0	0 = nearest, 1 = next

Stop-Loss (SL) & Target (target):

Key	Choices / Type	Effect / Description
isSL / isTarget	True / False (bool)	Enable/disable SL or target logic
SLon / targetOn	"val" (absolute ₹),  "%" (percentage),  "mtm" (₹ P&L)	How exit threshold is computed
SLvalue / targetValue	number(float/int)	Magnitude of SL/target

Trailing SL (trailSL):

Note : Value must be between 0-100% for %

Key	Type	Example Value	Description
isTrailSL	bool	True	Enable trailing SL
trailSLon	str	'%', 'val'	Based on value or %
trailSL_X	float	2	Distance (₹ or %) that triggers a trailing SL adjustment
trailSL_Y	float	0.98	Amount (₹ or %) by which SL is tightened each time trailSL_X is hit

Re-Entry Rules (reEntrySL, reEntryTg):

Key	Type / Choices	Description
isReEntry	bool (True/False)	Enables re-entry after SL/target
reEntryOn	str Choices: "asap", "asap-rev" "cost", "costrev" "withWT", "withWT-rev" "action"	"asap": immediately "asap-rev": reverse transactionType "cost": re-enter at exit cost "cost-rev": cost price + reverse "withWT": re-enter with waitTrade "withWT-rev": reverse + waitTrade "action": based on predefined CE/PE action logic
reEntryVal	None or self.act	Default: None If reEntryOn == "action" → set reEntryVal = self.act
reEntryMaxNo	int	Max allowed re-entry attempts (range 1–20)

Wait‑Trade (waitTrade):

Delays order entry until the instrument's price changes by a defined amount or percentage.

Key	Type	Allowed Values / Examples	Description
isWT	bool	True, False	Enable/disable wait-trade logic
wtOn	str	"val-up" → price ↑ by ₹X "val-down" → price ↓ by ₹X "%val-up" → price ↑ by X% "%val-down" → price ↓ by X%	Price-change condition required to place the leg
wtVal	float	1, 2.5, …	Required move (₹ or %) — depends on wtOn
triggers	list	Optional list of other leg definitions	Auto-trigger extra legs when the wait condition is met

webhook (Custom Webhooks):

Key	Type	Example Value	Description
is	bool	False	Whether webhook is active
entryMessage	dict	{}	Custom webhook payload on entry
exitMessage	dict	{}	Custom webhook payload on exit