Struct Candidate 

pub struct Candidate {
    pub node_id: [u8; 32],
    pub rate_per_mb: u64,
    pub rtt_ms: u32,
    pub reputation: f32,
    pub region: String,
    pub stake: u64,
    pub coverage: Coverage,
    pub total_bytes_hint: Option<u64>,
}

A candidate provider produced by content discovery, ready to be ranked.

Fields

node_id: [u8; 32]

Iroh NodeId (Ed25519 public key) of the candidate.

rate_per_mb: u64

Quoted price in token base units per MB, from the most recent ProbeResponse (decdn_protocol::message::ProbeResponse::rate_per_mb).

rtt_ms: u32

Round-trip latency observed during probing.

reputation: f32

Local reputation in [0.0, 1.0] from the reputation engine.

region: String

ISO 3166-1 alpha-2 region self-attested by the peer on-chain (ADR 030), resolved from the CapacityBond registry projection. Used by the geo-diversity tie-break tier.

stake: u64

On-chain stake in TOKEN base units; higher stake wins the stake tie-break tier. 0 means known to hold no bond — there is no “not looked up” state, by design (#1470).

This type has no encoding for a failed read — not the same as preventing one. A chain read succeeds for some peers and fails for others, and a mixed population is the steady state for an RPC read, not an edge case; folding a failure to 0 here would silently sink a well-staked peer below a provably-unbonded one. So the lookup layer must resolve the failure where it is still visible: retry it, or drop the candidate. Nothing in the type enforces that today — a future caller can still write stake: 0 on a failed read and it will compile. The constructor-level enforcement (a Stake obtainable only from a successful read, with Candidate’s fields made private) lands with the lookup itself; see #1470. Nothing populates this yet — on-chain integration is deferred; see ADR 019 for the capacity-bond interface that will.

coverage: Coverage

Which discovery blocks (decdn_protocol::coverage) this candidate is confirmed to hold, per its fresh ProbeResponseExt.coverage (#1506). This is the PROBE-confirmed value, never the stale DHT-lookup hint — discovery’s ranking and selection consume only what a live probe just verified. Ranking itself ignores this field; it rides alongside the rank/RTT/rate fields for a range-aware caller to read after selection.

total_bytes_hint: Option<u64>

The blob size the candidate reported on that probe (ProbeResponseExt.total_bytes), when it knows it. UNSIGNED: a sizing hint, never a commitment. The pull leg cuts its first upstream open from it. When that open runs past the blob’s end, the pull leg opens the whole blob instead; when the signed size differs from the hint, it drops the pull.

Trait Implementations

impl Clone for Candidate

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Candidate

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

Formats the value using the given formatter.