Struct Envelope 

#[non_exhaustive]
pub struct Envelope {
    pub result: ResultBlock,
    pub meta: Map<String, Value>,
    pub clusters: Vec<Cluster>,
    pub page: Page,
    pub cache: EnvelopeCache,
}

Top-level envelope (§7).

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

result: ResultBlock

Result-level metadata: totals, axes, detection report.

meta: Map<String, Value>

Free-form metadata block. Defaults to empty.

clusters: Vec<Cluster>

Top-level clusters (root children).

page: Page

Page block — populated when --cluster is set, empty otherwise.

cache: EnvelopeCache

Optional source records cache used when re-processing a saved envelope. Empty for hand-authored/minimal envelopes.

Implementations

impl Envelope

pub fn looks_like_envelope(prefix: &[u8]) -> bool

§9: detect whether a byte prefix starts with a face envelope.

The check walks the prefix as a structural scan: skip BOM and leading whitespace, require an opening {, then look at the top-level keys (depth-1 strings). If both result and clusters appear before the prefix runs out, return true.

This is intentionally a structural scan, not a full serde_json::from_slice, so the §9 self-consume detection works on envelopes larger than the sniff prefix (the prefix is only ~4 KiB; an envelope’s meta block alone may exceed that). A truncated prefix that contains both target keys at depth 1 is enough to classify the input.

Returns false for any input that does not start with a JSON object (JSONL streams, JSON arrays, CSV/TSV, scalars).

Examples

use face_core::Envelope;

let env = br#"{"result":{"input_total":0},"clusters":[]}"#;
assert!(Envelope::looks_like_envelope(env));

let arr = b"[1, 2, 3]";
assert!(!Envelope::looks_like_envelope(arr));

Trait Implementations

impl Clone for Envelope

fn clone(&self) -> Envelope

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Envelope

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

Formats the value using the given formatter.

impl Default for Envelope

fn default() -> Envelope

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Envelope

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Envelope

fn eq(&self, other: &Envelope) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Envelope

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Envelope