Struct CapabilityMatrix 

#[non_exhaustive]
pub struct CapabilityMatrix {
    pub identity: BackendIdentity,
    pub caps: BTreeMap<Capability, CapabilityStatus>,
}

Full capability snapshot for a backend: its BackendIdentity plus a stable-ordered map of Capability → CapabilityStatus.

BTreeMap (not HashMap) so iteration order is deterministic — ff-server’s JSON response is byte-stable, cairn’s operator UI can render rows in a fixed order, and tests comparing matrices across runs do not race on hash randomization.

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.

identity: BackendIdentity

Backend identity tuple this matrix was assembled for.

caps: BTreeMap<Capability, CapabilityStatus>

Per-capability status. Absent capabilities are treated as CapabilityStatus::Unknown by Self::get.

Implementations

impl CapabilityMatrix

pub fn new(identity: BackendIdentity) -> Self

Build an empty matrix tagged with the given backend identity. Backends populate rows via Self::set before returning the matrix from capabilities_matrix().

pub fn set(&mut self, cap: Capability, status: CapabilityStatus) -> &mut Self

Record the status for one capability. Returns &mut self so backends can chain setup in a builder-style declaration.

pub fn get(&self, cap: Capability) -> CapabilityStatus

Look up one capability’s status. Absent rows return CapabilityStatus::Unknown — callers that need to distinguish “absent” from “explicitly marked unknown” must consult self.caps directly.

pub fn supports(&self, cap: Capability) -> bool

Convenience predicate: the capability is CapabilityStatus::Supported or CapabilityStatus::Partial. Both map to “you can call the trait method and it will work (possibly with a caveat)”; Unsupported and Unknown both map to “don’t dispatch, or be ready to catch Unavailable.”

Trait Implementations

impl Clone for CapabilityMatrix

fn clone(&self) -> CapabilityMatrix

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CapabilityMatrix

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

Formats the value using the given formatter.