fetch-preprint-recent

Fetch preprints from bioRxiv or medRxiv for a date window, normalize the records, and keyword-filter them.

Workflow

- [ ] Step 1: Validate inputs (server, from, to, keywords)
- [ ] Step 2: Page through the details endpoint until messages.cursor exhausted
- [ ] Step 3: Normalize each record to the canonical shape
- [ ] Step 4: Dedupe within the window (keep latest version per DOI)
- [ ] Step 5: Keyword-filter on lowercased title + abstract
- [ ] Step 6: Return matched records + a summary (total fetched, total matched, pages fetched)

Step 1 — Validate inputs

Required:

• server: one of biorxiv or medrxiv (the API uses these literal strings)
• from: YYYY-MM-DD, inclusive
• to: YYYY-MM-DD, inclusive, must be ≥ from
• keywords: list of strings; may include multi-word phrases; case-insensitive matching

Reject if window > 31 days (the API supports it but you almost never want to dump a month of preprints in one call without a stronger filter — flag and confirm).

Step 2 — Page through the endpoint

The endpoint is:

https://api.biorxiv.org/details/{server}/{from}/{to}/{cursor}

• Start with cursor=0.
• The response shape is:

  {
    "messages": [{"status": "ok", "interval": "2026-05-04/2026-05-10", "cursor": "0", "count": 100, "total": 327}],
    "collection": [ { record }, { record }, ... ]
  }
  

• After consuming collection, increment cursor by 100 (the page size is fixed) and refetch until cursor + count >= total.
• Cap pages at 20 (2,000 records) as a safety; if you hit the cap, surface a "window may be over-broad" warning and return what you have.

Use WebFetch with the URL. If WebFetch returns malformed JSON or a 5xx, retry once with a 2-second backoff; on second failure, return partial results with a fetch_errors field listing the failed cursors.

Step 3 — Normalize each record

The API returns fields like doi, title, authors, author_corresponding, author_corresponding_institution, date, version, type, license, category, jatsxml, abstract, published, server. Reduce to:

{
  "id": "10.1101/2026.05.07.123456",          // doi
  "title": "...",
  "authors": ["Smith J", "Doe A", ...],        // split the API's `authors` string on `;`
  "abstract": "...",
  "date": "2026-05-07",
  "server": "biorxiv",                          // or "medrxiv"
  "version": 1,
  "category": "neuroscience",                   // bioRxiv subject area
  "url": "https://www.biorxiv.org/content/10.1101/2026.05.07.123456v1",
  "published_doi": null                         // populated if the preprint has been published; from `published` field
}

URL pattern: https://www.{server}.org/content/{doi}v{version} (no https://doi.org/ redirect — direct to the preprint server keeps the abstract page accessible).

Step 4 — Dedupe within the window

The same DOI can appear with multiple version values if the authors revised mid-window. Keep the highest version per DOI. Drop the rest.

Step 5 — Keyword-filter

For each kept record, check whether any keyword (or phrase) appears in lowercase(title + " " + abstract). Match logic:

• Multi-word keyword like "protein language model" → must appear as a contiguous substring.
• Single-word keyword like "crispr" → must appear with word boundaries (don't match "crisper").
• OR across all keywords (paper kept if any keyword matches).

Track which keyword(s) matched per paper — downstream paper-relevance-filter will use that signal.

Step 6 — Return

Return a payload like:

{
  "server": "biorxiv",
  "window": "2026-05-04/2026-05-10",
  "fetched_total": 327,
  "matched_total": 14,
  "pages_fetched": 4,
  "fetch_errors": [],
  "records": [ {normalized record + "matched_keywords": [...]} , ... ]
}

Cache the raw API JSON (pre-normalization) to the agent's .cache/ directory under {YYYY-WW}-{server}.json so a re-run can skip the network if the user wants to re-synthesize without re-fetching.

Common Patterns

Pattern A — One server, one window: standard call. Use this in a weekly digest.

Pattern B — Multi-week catch-up: call once per week, never one giant 28-day window. The cursor pagination is fine but the keyword filter is more honest at weekly granularity (matches the way papers are released and discussed).

Pattern C — Preprint-only follow-up of a known paper: if you already have a DOI, do not use this skill. Use a direct WebFetch on https://api.biorxiv.org/details/{server}/{doi} instead.

Guardrails

1. Don't fetch without a window. "Recent" must always resolve to specific from/to dates before the call.
2. Don't keyword-filter server-side — the API doesn't support it; attempting via URL params silently returns everything.
3. Don't trust the abstract field to be present. Some entries have empty abstracts; treat those as title-only matches and flag in the output.
4. Don't dedupe across servers in this skill. Cross-server dedupe (bioRxiv ↔ medRxiv ↔ PubMed) belongs to the calling agent, not here.
5. Don't transform DOIs. Keep them as-returned; downstream tools rely on the exact 10.1101/... string.
6. Don't claim "no papers" on a fetch error. Distinguish "fetched and filtered to zero" from "fetch failed." The first is a thin week; the second is a bug.

Quick Reference

Field	Source	Notes
Endpoint	api.biorxiv.org/details/{server}/{from}/{to}/{cursor}	Same host serves both bioRxiv and medRxiv; only {server} varies
Auth	None	Public API. Be polite — don't hammer.
Page size	100, fixed	Cursor is the offset into the window's results
Window cap	31 days (soft); 7 days is the typical weekly call	Wider windows = thousands of records before keyword filter
Rate limit	Not formally documented; ~1 req/sec is safe	Backoff on 5xx
URL pattern	https://www.{server}.org/content/{doi}v{version}	Linkable to abstract page
Server values	biorxiv, medrxiv	Case-sensitive in path