Struct MetadataOnlyOutcome 

#[non_exhaustive]
pub struct MetadataOnlyOutcome {
    pub source: String,
    pub resolver_profile: String,
    pub license: Option<String>,
    pub oa_url: Option<String>,
    pub metadata: Value,
}

Outcome of a successful metadata_only call.

Mirrors the wire shape documented in docs/MCP_TOOLS.md §11: the source identifies which resolver produced the metadata, license is the OA license string when known (Unpaywall channel), oa_url is the discovered OA URL (never followed by this orchestrator), and metadata is the source’s native JSON payload (Crossref message, Unpaywall work record, or the parsed arXiv Atom-feed object).

metadata is serialized as-is by the MCP envelope builder (crates/doiget-mcp/src/lib.rs); we deliberately do NOT normalize here so the agent can see exactly what the source returned.

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.

source: String

Resolver key that produced the metadata payload. One of "crossref", "unpaywall", "arxiv" (the closed set named in docs/MCP_TOOLS.md §11 type alias).

resolver_profile: String

Resolver profile under which the canonical-digest (ADR-0021 §1) was minted for this call. In Slice 4 this equals Self::source verbatim (the metadata-only path emits one row per consulted resolver); future slices that introduce overlapping resolvers MAY have resolver_profile != source. Surfaced through the doiget_metadata_only MCP envelope per ADR-0021 §4.

license: Option<String>

OA license string when the resolver could supply one (today only the Unpaywall fallback path populates this). None when the primary source did not surface a license.

oa_url: Option<String>

Discovered OA URL — surfaced to the caller for separate action, never followed by this orchestrator. The Crossref response’s message.link[] array is mined first; the Unpaywall fallback path uses best_oa_location.url_for_pdf (or url).

metadata: Value

Source’s native metadata payload. For Crossref this is the message object; for Unpaywall the work record; for arXiv the parsed Atom-feed JSON (see crate::sources::arxiv::parse_atom_feed).

Trait Implementations

impl Clone for MetadataOnlyOutcome

fn clone(&self) -> MetadataOnlyOutcome

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MetadataOnlyOutcome

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

Formats the value using the given formatter.