Module source 

Source abstraction. Each Tier 1/2/3 fetcher implements this trait.

Binding spec: docs/PUBLIC_API.md §2 (trait surface), docs/ARCHITECTURE.md §6 (per-fetch data flow), and docs/PROVENANCE_LOG.md §3 (the Fetch row source impls emit).

Phase 1 ships the trait + supporting types; concrete impls (Crossref, Unpaywall, arXiv) land in follow-up PRs (see docs/SOURCES.md for the source matrix and tiering).

Structs

FetchContext

Per-fetch context shared by all Source impls.

FetchResult

What a successful fetch returns to the caller.

Enums

FetchError

Errors returned by Source::fetch.

Traits

Source

The trait implemented by every Tier 1 / 2 / 3 fetcher.