Function paper_tex_source 

pub async fn paper_tex_source(
    base: &Url,
    id: &ArxivId,
    max_chars: Option<usize>,
    ctx: &FetchContext,
) -> Result<PaperTexSource, FetchError>

Fetch the LaTeX source of an arXiv paper.

base is the arXiv export base URL (production ARXIV_SRC_DEFAULT_BASE; tests inject a wiremock origin). max_chars caps the returned tex_source character count (None = no cap); truncation is flagged, never silent.

Errors

• FetchError::Http — transport / status failure.
• FetchError::TextUnavailable — PDF-only submission or no .tex files in the tarball.
• FetchError::SourceSchema — URL construction or gzip/tar parse error.
• FetchError::Log — provenance append failed (fail-closed).