Emitted to allow external systems to synchronize with the framework's
limit order lifecycle: open (limit filled) and close (position exited).
Note: Only covers the scheduled → pending → closed lifecycle.
Signals that were never activated (cancelled scheduled signals) do NOT emit SignalOpenContract.
Discriminated union for signal sync events.
Emitted to allow external systems to synchronize with the framework's limit order lifecycle: open (limit filled) and close (position exited).
Note: Only covers the scheduled → pending → closed lifecycle. Signals that were never activated (cancelled scheduled signals) do NOT emit SignalOpenContract.