Struct Capabilities 

pub struct Capabilities {
    pub query: QueryCapability,
    pub correlation: bool,
    pub graph: bool,
    pub embeddings_fingerprint: Option<String>,
    pub verify: bool,
    pub representations: Vec<Representation>,
    pub resolve: bool,
}

What a provider can do, negotiated at handshake time.

Every field here is a capability a host can actually exercise. upsert and subscribe were removed in the pre-freeze sweep because neither had a wire method, a host API, a schema entry, or a conformance check — a provider could declare a capability no host on earth could use. See ADR 0004, and the design sketches under docs/sketches/ that keep both doors open for a 1.x additive minor.

Unknown fields are ignored on deserialization, so a provider still emitting the removed flags handshakes successfully — the removal breaks the Rust API, not the wire.

Fields

query: QueryCapability

correlation: bool

The provider echoes the id of a request on its reply, so a host may pipeline concurrent exchanges over one connection (SPEC.md §H4).

Negotiated explicitly rather than discovered by observation. A host that sent an id speculatively could not tell a provider that does not implement correlation from one that implements it incorrectly, which makes the guarantee uncheckable — and an uncheckable guarantee is the thing this protocol exists to avoid. A provider that does not declare it is queried in lock-step and stays fully conformant.

graph: bool

The provider serves FrameKind::Graph frames and populates Relation edges. Gates the graph conformance checks (SPEC.md §G1–G3).

embeddings_fingerprint: Option<String>

Identifies the embedding space this provider indexes, so a host never sends it a vector from a different model.

Format: <model-id>/<dimensions>[/<normalization>], e.g. bge-small-en-v1.5/384/l2. Matching is exact — see embedding_fingerprints_match and SPEC.md §E1.

verify: bool

Whether this provider answers context/verify — pull-based revalidation of frames a host already holds (docs/context-reuse.md §4). Defaults to false, so a provider that says nothing is treated as not supporting it and the host falls back to re-querying.

representations: Vec<Representation>

The frame representations this provider can return (build prompt §“Capability negotiation”). Empty ⇒ full only, the legacy default, so a provider that says nothing keeps working.

resolve: bool

Whether this provider answers context/resolve for a frame’s content_ref. Compact/reference support implies resolve support (representations_consistent).

Implementations

impl Capabilities

pub fn offered_representations(&self) -> Vec<Representation>

The representations this provider actually offers, defaulting to [full] when it advertised none (the legacy contract).

pub fn representations_consistent(&self) -> bool

Whether the advertised representations are honest: compact/reference both hand the host a content_ref to rehydrate, so a provider that cannot resolve must not advertise them. A provider offering only full is always consistent.

Trait Implementations

impl Clone for Capabilities

fn clone(&self) -> Capabilities

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Capabilities

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

Formats the value using the given formatter.

impl Default for Capabilities

fn default() -> Capabilities

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Capabilities

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Capabilities

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Capabilities

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 Capabilities