Struct ExplainPoolRow 

pub struct ExplainPoolRow {
    pub rid: String,
    pub score_q: f64,
    pub similarity: f64,
    pub lex: Option<f64>,
    pub lanes_admitted: Vec<String>,
    pub rank_pre_fusion: usize,
    pub rank_post_fusion: usize,
    pub selected: bool,
}

One candidate of the explain pool. Every row carries the stable rid — cross-run joins on text substrings are the fragility this field retires.

Fields

rid: String

score_q: f64

Final score at the snapshot, quantized at the engine’s own ranking resolution (1e-6) — the exact value rank_cmp compares.

similarity: f64

Raw cosine similarity (pre-fusion signal).

lex: Option<f64>

Per-query bm25 lexical strength in (0, 1]. None is CONDITIONAL and the lane block disambiguates it (finding-1 rule: a bare null never stands alone): if lanes["fts"].status == "ran", None means the FTS lane ran and did NOT match this candidate; if "never_ran" / "ran_empty", no candidate has a strength and the lane’s reason says why. A present value is always a real match — Some(0.0) is never emitted as a placeholder.

lanes_admitted: Vec<String>

The SET of lanes that admitted or lifted this candidate — explicitly separate from numeric contributions, because a zero contribution and a lane-that-never-admitted are different facts.

rank_pre_fusion: usize

Rank within this pool by similarity alone (desc, rid asc) — “before fusion”.

rank_post_fusion: usize

Rank in the pool’s final comparator order — “after fusion”.

selected: bool

Whether this candidate survived MMR/truncation into the results.

Trait Implementations

impl Clone for ExplainPoolRow

fn clone(&self) -> ExplainPoolRow

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExplainPoolRow

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ExplainPoolRow

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ExplainPoolRow

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.