paper-fetch

# paper-fetch Fetch the PDF for a paper given a DOI (or title). Tries multiple sources in priority order and stops at the first hit. ## Resolution order 1. **Unpaywall** — `https://api.unpaywall.org/v2/{doi}?email=$UNPAYWALL_EMAIL`, read `best_oa_location.url_for_pdf` (skipped if `UNPAYWALL_EMAIL` not set) 2. **Semantic Scholar** — `https://api.semanticscholar.org/graph/v1/paper/DOI:{doi}?fields=openAccessPdf,externalIds` 3. **arXiv** — if `externalIds.ArXiv` present, `https://arxiv.org/pdf/{arxiv_id}.pdf` 4. **PubMed Central OA** — if PMCID present, `https://www.ncbi.nlm.nih.gov/pmc/articles/{pmcid}/pdf/` 5. **bioRxiv / medRxiv** — if DOI prefix is `10.1101`, query `https://api.biorxiv.org/details/{server}/{doi}` for the latest version PDF URL 6. **Publisher direct** *(institutional mode only — `PAPER_FETCH_INSTITUTIONAL=1`)* — DOI-prefix → publisher PDF template (Nature / Science / Wiley / Springer / ACS / PNAS / NEJM / Sage / T&F / Elsevier). The caller's own subscription IP / cookies / EZproxy are what authorize the fetch; unauthorized responses fail the `%PDF` check and fall through to step 7. 7. **Sci-Hub mirrors** *(on by default; disable with `PAPER_FETCH_NO_SCIHUB=1`)* — last-resort fallback. Tries the mirror list in `PAPER_FETCH_SCIHUB_MIRRORS` (or built-in defaults `sci-hub.ru`, `sci-hub.st`, `sci-hub.su`, `sci-hub.box`, `sci-hub.red`, `sci-hub.al`, `sci-hub.mk`, `sci-hub.ee`) in order; on full miss, scrapes `https://www.sci-hub.pub/` once per process for fresh ...