Enum PdfLegStatus 

#[non_exhaustive]
pub enum PdfLegStatus {
    Fetched,
    NoOaUrl,
    Blocked {
        code: ErrorCode,
        message: String,
        denial: Option<DenialContext>,
        suggested_arxiv_id: Option<String>,
    },
}

Outcome of a successful fetch_paper call.

Wire shape mirrors docs/MCP_TOOLS.md §5 FetchResult minus the envelope chrome the MCP server wraps it in (ok: true, ref, optional error).

path is the absolute path of the resource the orchestrator wrote to the store. For arXiv refs and successful DOI OA-PDF fetches this is <root>/<safekey>.pdf; for the DOI metadata-only fallback (OA URL host off the oa-publisher allowlist, or PDF leg failed for another transport reason — docs/REDIRECT_ALLOWLIST.md §3 informed-best- effort posture) this is <root>/.metadata/<safekey>.toml. Outcome of the DOI OA-PDF leg, carried on FetchPaperOutcome so a caller can NEVER silently report a blocked PDF as a plain “metadata-only” success (issue #118). The product promise is “immediately explain WHY a paper can’t be fetched” — the distinction between “there was no OA PDF to fetch” and “an OA PDF existed but we were blocked, and here is the reason” is exactly that explanation.

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.

Fetched

A PDF was fetched and written to disk (arXiv always; DOI when the OA-publisher leg succeeded).

NoOaUrl

No OA URL was discovered (Unpaywall reported no best_oa_location). Metadata-only is the correct, expected result here — not a failure.

Blocked

An OA URL was discovered but the PDF could not be retrieved (host outside the oa-publisher allowlist, not-a-PDF body, transport failure, …). Metadata was still written, but the caller MUST surface this reason rather than pretending the fetch was a clean metadata-only success.

Fields

code: ErrorCode

Closed-set code, mapped from the underlying transport error via the canonical From<FetchError> for ErrorCode.

message: String

Human-readable one-line reason (the FetchError display).

denial: Option<DenialContext>

Structured denial side-channel (ADR-0023) when the failure was an allowlist / scheme denial; None otherwise.

suggested_arxiv_id: Option<String>

Actionable suggested arXiv ID for the same paper when Unpaywall metadata includes an arXiv alternative but the PDF leg was blocked.

Trait Implementations

impl Clone for PdfLegStatus

fn clone(&self) -> PdfLegStatus

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PdfLegStatus

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

Formats the value using the given formatter.