Struct PositionTracker 

pub struct PositionTracker { /* private fields */ }

Stateful refinement layer on top of compute_guidance.

compute_guidance is pure and scores a single snapshot. The tracker remembers each position (keyed by position_id) and adds two rules that require history:

1. Trailing give-back — once a position has been a meaningful winner (peak ≥ TrailingConfig::arm_ratio) and then surrenders enough of that peak (TrailingConfig::giveback_frac), upgrade a Hold to Reduce to bank the remaining profit. The stateless rule can’t see the prior peak, so it would just Hold.
2. Sticky exit — once we’ve advised Exit, a later snapshot that merely drifts back inside the bands keeps Exit rather than flip- flopping to Hold on a one-tick bounce.

Snapshots without a position_id are not tracked; their guidance passes through unchanged (fully backward compatible).

Implementations

impl PositionTracker

pub fn new() -> Self

New tracker with default TrailingConfig.

pub fn with_config(config: TrailingConfig) -> Self

New tracker with explicit config.

pub async fn tracked(&self) -> usize

Number of positions currently tracked (after pruning). For metrics/tests.

pub async fn finalize(&self, position_id: &str) -> Option<PositionState>

Remove and return a position’s accumulated state. Call this when the position closes so its guidance history can be joined with the realized outcome (see PositionOutcome::from_close). Returns None if the position was never tracked.

pub async fn observe(&self, event: &PositionEvent, base: Guidance) -> Guidance

Refine stateless base guidance using this position’s history, record the updated state, and return the (possibly upgraded) guidance.

Positions without a position_id are returned unchanged and not tracked. The critical section is pure (no .await while the lock is held), so this stays cheap under load.

Trait Implementations

impl Default for PositionTracker

fn default() -> Self

Returns the “default value” for a type.