Struct FeatureContext 

pub struct FeatureContext<'a> {
    pub id: String,
    pub feature_type: String,
    pub params: &'a Value,
    pub persistent: &'a Value,
    pub env: &'a Env,
    pub scene: &'a SceneMap,
    pub later_inputs: Option<&'a [String]>,
}

The read-only context handed to each feature’s execute. Features resolve their reference_selection params against scene and read numeric params via FeatureContext::number (which evaluates expression strings against env).

Fields

id: String

feature_type: String

params: &'a Value

persistent: &'a Value

The feature’s persistentData (round-tripped from the saved part file). The SKETCH feature reads its sketch + basis here (the scene-computed plane frame stays caller-side per directive §1 and is marshaled in via this).

env: &'a Env

scene: &'a SceneMap

later_inputs: Option<&'a [String]>

Some when the history walk knows nothing that follows this feature references the solids it consumes, by face name or by persistent data (lane X row 11b): the boolean feature may then re-seat an operand’s cylinder seam before imprint. None (the walk cannot tell, or a later feature might reference them, or a direct execute_feature call) never re-seats.

Implementations

impl<'a> FeatureContext<'a>

pub fn param(&self, key: &str) -> Option<&Value>

The raw param value (an object field of inputParams), if present.

pub fn number(&self, key: &str) -> Result<f64, String>

A numeric param: a JSON number passes through; a JSON string is evaluated as an expression against the shared env; anything else is an error. This is how a feature declares which of its params are numeric (the engine has no per-feature schema).

pub fn string(&self, key: &str) -> Option<String>

A string param (read verbatim — never expression-evaluated; used for ids and reference_selection names). Contract surface for fan-out features; the two implemented features read the id via ctx.id directly.

pub fn fail(&self, refusal: impl Into<FeatureRefusal>) -> FeatureResult

A convenience FeatureResult::refuse carrying this feature’s id + type: text from a stringly producer, or a typed KernelRefusal.