Enum WarningCode 

#[non_exhaustive]
pub enum WarningCode {
    CommunityFilterNoop,
    PprNoSubstrate,
    NoReranker,
    AuthoredAdjacencyEmpty,
    BelowConfidenceFloor,
    WarningsTruncated,
    PprSizeGateSkipped,
}

Closed enum of every warning the retrieve pipeline can emit.

New variants require (a) a sibling warnings/<snake_case>.txt message body, (b) a docs/warnings/<snake_case>.md remediation markdown with an ## Agent fallback section, and (c) a line in the WarningCode::remediation_ref match arm. The xtask lint-warnings binary asserts all three at CI time; a missing body or doc is a hard CI failure.

#[non_exhaustive] so adding a variant is an additive wire change - existing callers match with a catch-all and keep compiling.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

CommunityFilterNoop

community_filter: true was accepted but the commit has no authored edges AND no vector index was available, so the expander had no substrate to operate on.

PprNoSubstrate

graph_mode = "ppr" was accepted but the commit has no authored edges AND no vector index was available, so the PPR walk degraded to the identity pass (input order unchanged).

NoReranker

rerank was requested but no reranker provider could be opened (bad spec, missing credentials, unreachable endpoint); results carry their fusion scores unchanged.

AuthoredAdjacencyEmpty

graph_expand was accepted but the commit has no authored edges so the walk added no neighbours. Distinct from WarningCode::CommunityFilterNoop: graph_expand ignores the vector-derived KNN substrate, so vectors alone do not suppress this warning.

BelowConfidenceFloor

Every candidate scored below the configured confidence floor, so the items[] array is empty by gate rather than by a retrieval failure. Reserved for callers using the (future) min_confidence knob; wired through now so the warning code is part of the stable v1 surface.

WarningsTruncated

Synthetic: more than WARNINGS_CAP warnings were generated; the tail was dropped to bound the response size. Never emit this manually - it is produced exclusively by cap_warnings.

PprSizeGateSkipped

Gap 02 #17: graph_mode = "ppr" was requested but the graph exceeds crate::ppr::PPR_DEFAULT_MAX_NODES and the caller did not opt in via ppr_opt_in = true. PPR is skipped and the pipeline falls back to the decay-BFS expansion to prevent unbounded query latency.

Implementations

impl WarningCode

pub const fn as_str(self) -> &'static str

Canonical wire name. Stable across versions; downstream dashboards and agent routing tables key on these strings.

pub const fn knob(self) -> &'static str

Canonical agent-facing knob name this warning is about. Stable across versions. Agents read warning.knob to decide which knob to drop or substitute on the fallback call.

pub const fn message(self) -> &'static str

Compile-time-constant message body for this code.

Sourced via include_str! from crates/mnem-core/src/retrieve/warnings/<code>.txt. Never varies with user input; this is the sole anti-prompt-injection guarantee.

pub const fn remediation_ref(self) -> &'static str

Path (relative to repo root) of the remediation markdown for this code. xtask lint-warnings asserts the file exists at CI time; agents dereference the ref to get the full ## Agent fallback section.

pub const fn all() -> &'static [Self]

Complete ordered list of every variant. Used by xtask lint-warnings to walk the catalog; the exhaustive match in a unit test pins the list to the enum definition.

Trait Implementations

impl Clone for WarningCode

fn clone(&self) -> WarningCode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WarningCode

impl Debug for WarningCode

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for WarningCode

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for WarningCode

impl Hash for WarningCode

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for WarningCode

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for WarningCode

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 WarningCode