Bibcheck

bibcheck

Given a .bib, spawn subagents over batches of 5 entries to verify each entry against canonical metadata, then emit a PASS/WARN/FAIL report and a corrected.bib the user reviews and merges. The source .bib is never modified.

One agent asked to audit 200 entries in a single pass drifts: early entries get careful treatment, late entries get pattern-matched. Batches of 5 stay short enough that the cliff never arrives, and the batch contract in phase 1 polices the same drift inside each batch.

Per-entry verification against canonical metadata is adapted from Scott Cunningham's MixtapeTools.

Hallucinated citations have a recognizable signature: plausible authors, plausible title, a DOI that 404s, and no match in Crossref, OpenAlex, or arXiv. Surfacing that pattern is the point.

Inputs and scoping

Take a .bib path as the argument. With no argument, Glob in this order and ask if ambiguous:

1. references.bib, refs.bib, bibliography.bib, then *.bib in the cwd.
2. ~/Library/CloudStorage/Dropbox*/Apps/Overleaf/*/*.bib (this setup assumes Overleaf projects sync here via Dropbox; adjust to your machine).

With several .bib files in one project, grep the .tex for \bibliography{} / \addbibresource{} to pick the one actually loaded. Skip anything under _archive/ or Old/ unless asked.

Scope before dispatching. Zotero-exported libraries carry far more entries than the manuscript cites (one real project here: 345 entries, 170 cited), and auditing an uncited entry is wasted work. Collect the cited keys and offer to restrict to them:

grep -ohE '\\[a-zA-Z]*[Cc]ite[a-zA-Z]*\*?(\[[^]]*\])*\{[^}]*\}' /abs/path/to/*.tex \
  | grep -oE '\{[^}]*\}$' | tr -d '{}' | tr ',' '\n' | tr -d ' ' | sort -u

Report both counts and let the user choose. Default to cited-only above 100 entries.

Phase 0: parse

Read the .bib in full. Split on ^@\w+\{ boundaries and capture the entry type, citation key, and every field = {value} pair (braced and quoted forms, escaped braces, multi-line values). Malformed entries (unbalanced braces, missing key, duplicate key) go straight to FAIL with no subagent.

Triage by entry type, because the checks that apply differ:

• Indexed types (@article, @inproceedings, @book, @incollection, @phdthesis): full check set.
• Non-indexed types (@misc, @online, @software, @dataset, and @unpublished with no arXiv id): blog posts, docs pages, and repos legitimately have no DOI and appear in no index. Check the url/howpublished link resolves (curl -sSI -o /dev/null -w '%{http_code}') and that year looks sane. Never assign the fabrication verdict to these.

Create <bib_dir>/bibcheck_<YYYYMMDD_HHMM>/ containing entries/ (one .bib fragment per entry, subagent input) and reports/ (one .json per entry, subagent output), plus input.bib as a verbatim copy of the source for provenance.

Phase 1: dispatch

Group the well-formed entries into batches of 5, preserving file order; the last batch holds the remainder. Launch one subagent per batch with the Agent tool, 8 per message, so 40 entries are in flight per wave. Wait for the wave to return, then send the next 8. 170 cited entries is 34 batch subagents in 5 waves. Respect --max-parallel N if the user passes it; drop to 2 when rate-limited.

Each subagent gets its batch's raw entry texts, the absolute entries/ paths, one absolute output path reports/<citekey>.json per entry, and the check list below. Subagent working directories reset between Bash calls, so every path handed to a subagent must be absolute.

The batch contract: the subagent MUST return the full per-entry output schema for every one of its entries, each verified independently against the lookup tools, with no verdict inferred from a batchmate. State in the subagent prompt that the failure mode to guard against is skimping on the later entries in the batch, and that entry 5 gets the same treatment as entry 1.

Give each subagent a 60-second lookup budget per entry. On expiry it writes {"verdict": "WARN", "diagnostic": "lookup_timeout"} for that entry and moves to its next one. Raise the budget on a cold cache; paper.py disk-caches responses for 30 days, so reruns are fast.

For a long run, dispatch waves of background subagents with the Agent tool and act on their completion notifications, sending the next wave as each one finishes.

Phase 2: per-entry checks

The two lookup tools

paper.py is the resolver from the reading-papers skill. Read ~/.claude/skills/reading-papers/SKILL.md if unfamiliar.

~/.claude/skills/reading-papers/scripts/paper.py resolve "<query>" --json

It returns a JSON array. Interpreting it is the whole game:

• One element with title, authors, year, venue, is_oa populated: a confident canonical match.
• One element with only {"doi": ..., "title": null}: the identifier exists as a string but no index recognizes it. Exit code is still 0, so test the payload, not $?.
• Several elements carrying only {doi, title, venue}: no confident match, just relevance-ranked candidates. Treat as "not found" unless one clears the 0.85 title threshold below.

It does not return volume, issue, or pages. Crossref does, and Crossref is free and unmetered. Replace you@example.edu with your real address in both Crossref calls in this file: the mailto= parameter joins Crossref's polite pool, and Crossref asks for a real contact.

curl -sS -w '\nHTTP:%{http_code}' "https://api.crossref.org/works/<doi>?mailto=you@example.edu" \
  | python3 -c 'import sys,json; b=sys.stdin.read(); code=b.rsplit("HTTP:",1)[1].strip()
if code!="200": print(json.dumps({"crossref_status":code})); raise SystemExit
m=json.loads(b.rsplit("\nHTTP:",1)[0])["message"]
print(json.dumps({k:m.get(k) for k in ("DOI","title","container-title","short-container-title","volume","issue","page","issued","type","author","ISSN")},ensure_ascii=False))'

A dead DOI returns HTTP 404 with the non-JSON body Resource not found., so test the status code, never $? alone (--fail exits 56 here, not the documented 22). Use WebFetch on the same URL only if Bash is unavailable; it summarizes through a model and drops fields.

Cost discipline. OpenAlex is metered: an identifier lookup costs 1 credit, anything routed through search (including title search) costs 10. Spend identifiers before strings. Order per entry: Crossref by DOI (free) → paper.py resolve by DOI or arXiv id (1 credit) → Crossref query.bibliographic (free) → paper.py resolve by title (up to 10 credits), reaching the last rung only when the entry has no identifier at all.

The checks, in order, stopping once the verdict is settled

1. DOI resolution. With a doi field, run the Crossref call above for volume, issue, pages, ISSN, and issued, then paper.py resolve "<doi>" --json for the authoritative author spellings and venue. Crossref 404 plus "title": null from paper.py is a dead DOI, so go to check 4.

2. arXiv resolution and preprint versus published. When the entry carries eprint, archivePrefix = {arXiv}, or arXiv: in note, run paper.py resolve "<arxiv_id>" --json. A hit returns arxiv_id, title, authors, year, abstract, and doi (null when arXiv-only). Confirm the title matches the entry. If the entry has no doi, resolve the exact title once to see whether a journal version now exists; a single full record with a non-arXiv venue means it does, and that is a WARN suggesting the published @article in place of the preprint @misc. Skip this probe for entries that already carry a published DOI, since it is the expensive rung.

3. Title match, last resort only. With no DOI and no arXiv id:

   curl -sS "https://api.crossref.org/works?query.bibliographic=<urlencoded+title>&rows=5&select=DOI,title,container-title,volume,issue,page,issued,author&mailto=you@example.edu"
   

   Crossref ranks by relevance, and the preprint often outranks the version of record (a real case: the SSRN copy of a Marketing Science paper comes back first). Pick by container: prefer a journal container over SSRN Electronic Journal, arXiv, Research Square, or SocArXiv. Confirm the winner with paper.py resolve "<winning doi>" --json at 1 credit. Only if Crossref returns nothing plausible, fall back to paper.py resolve "<title>" --json.

   Title match rule: lowercase, strip LaTeX braces and accents, strip punctuation, drop the stopwords {a, an, the, of, on, in, for, and, to}, tokenize on whitespace, and compute Jaccard overlap of the token sets. Accept at ≥ 0.85.

4. Fabrication test. FAIL with fabricated? DOI does not resolve and no index recognizes the title when all of these hold: the entry is an indexed type; a doi is present and both Crossref and paper.py reject it (or no doi is present at all); and the title clears 0.85 against nothing in Crossref, OpenAlex, or arXiv. All three conditions are required. A missing DOI alone is normal for older and non-English work.

5. Author normalization. Compare surname sequences after NFKD normalization, combining-mark removal, lowercasing, and punctuation stripping.

   • Clear surname mismatch, or a different number of named authors where the source lists fewer: FAIL.
   • Initials against full given names: no flag, that is a style choice.
   • Accent loss (Pena for Peña) or a dropped tussenvoegsel (Van Den Bulte for van den Bulte): WARN. Strip leading particles {van, van der, van den, de, de la, del, della, di, du, von, zu, ter, ten, la, le} before the surname comparison, then compare the particle on its own.
   • Author-list truncation (and others, missing trailing authors): WARN.
   • Judge accents against paper.py/OpenAlex, never against Crossref. Crossref frequently stores the stripped form (it returns Yildirim where OpenAlex returns Yıldırım), so a Crossref diff alone is not evidence of an error in the entry.

6. Year reconciliation against Crossref issued.date-parts[0][0]. With an arXiv id present and the entry year matching the arXiv submission year, WARN (entry cites preprint year <y1>; published version is <y2>), because citing the preprint year is a legitimate choice. Otherwise FAIL.

7. Journal canonicalization. Compare journal against Crossref container-title. WARN on abbreviation drift (J. Mark. Res. for Journal of Marketing Research, Mark. Sci. for Marketing Science, Mgmt. Sci. for Management Science, Quant. Mark. Econ. for Quantitative Marketing and Economics). FAIL on a different journal entirely, confirmed by a disjoint ISSN set. Apply the same logic to booktitle on @inproceedings (ICML, NeurIPS, KDD and their full names).

8. Volume, issue, and pages against Crossref volume, issue, page. Normalize page ranges before comparing: 831--847, 831-847, and 831–847 are the same range, and BibTeX's double hyphen is correct style. WARN on one field disagreeing. FAIL on two or more, which usually means a swapped entry, the title of paper A glued to the volume and pages of paper B.

9. Zotero cross-check, optional. For a Better BibTeX shaped key, call mcp__zotero__zotero_search_items(query="<title>", qmode="titleCreatorYear", limit=3) and pull mcp__zotero__zotero_get_item_metadata on a hit. A Zotero item with a different DOI than the entry is a WARN. Zotero reads work only while the desktop app is open, so any error means checks_skipped: ["zotero"], never a WARN.

   When a Zotero call fails, tell the user directly, in the chat reply and not only in the report: Zotero looks closed, open the Zotero desktop app and this can be re-run to add the library cross-check. Say it once, up front, rather than burying it in per-entry output. A closed Zotero is the usual cause and it is a five-second fix, so it is worth interrupting for. Do not stop the audit over it; the other eight checks do not need Zotero.

Subagent output

One file per entry at reports/<citekey>.json:

{
  "citekey": "liu2022implications",
  "verdict": "PASS | WARN | FAIL",
  "diagnostic": "one line",
  "field_findings": [
    {"field": "year", "status": "FAIL", "entry_value": "2023",
     "canonical_value": "2022", "source": "crossref:10.1287/mksc.2022.1361"}
  ],
  "canonical_source": "crossref | openalex | arxiv | zotero | none",
  "checks_skipped": ["zotero"],
  "suggested_replacement": "<full corrected BibTeX entry, or null>"
}

Phase 3: aggregate and report

Read every JSON in reports/. Bucket by FAIL, then WARN, then PASS; sort alphabetically by citekey within each bucket so runs diff cleanly. Write <bib_dir>/bibcheck_<YYYYMMDD_HHMM>/bibcheck_report.md:

# Bibliography audit: <bib filename>

Date: YYYY-MM-DD HH:MM
Source: <absolute path>
Entries audited: N parsed, M malformed, K uncited and skipped

## Summary
| Verdict | Count |
|---|---|
| PASS | a |
| WARN | b |
| FAIL | c |
| Possibly fabricated | d (subset of FAIL) |

## FAIL (verify before submission)
| Citekey | Diagnostic | Source |
|---|---|---|

## WARN (preprint status, field drift, style)
| Citekey | Diagnostic |
|---|---|

## PASS
<one line each>

## Per-entry detail
<the JSON for every FAIL and WARN>

## Next steps
1. Review each FAIL row against corrected.bib.
2. `git diff --no-index <source>.bib corrected.bib`
3. Move corrected.bib into place yourself; this skill never overwrites the source.

Also write corrected.bib: the full source with FAIL and WARN entries replaced by their suggested_replacement, PASS entries copied byte for byte, comments and entry order preserved. An entry with no confident correction stays as-is under a leading % bibcheck:FAIL <diagnostic> comment line.

Verdict tolerances

PASS: a canonical source resolves and title, authors, year, venue, and volume/issue/pages all agree within style tolerance. For a non-indexed @misc, PASS means the URL resolves.

WARN: at most one of accent or tussenvoegsel drift, journal abbreviation drift, preprint year against published year, a single volume/issue/page disagreement, a preprint entry whose published version now exists, a Zotero DOI mismatch, or lookup_timeout.

FAIL: a dead DOI, a wrong surname, a wrong year with no preprint explanation, a wrong journal confirmed by ISSN, two or more volume/issue/page disagreements, a malformed or duplicate-key entry, or the fabrication signature.

Output layout

<bib_dir>/bibcheck_<YYYYMMDD_HHMM>/
  input.bib            verbatim copy of the source
  entries/<key>.bib    subagent inputs
  reports/<key>.json   subagent outputs
  bibcheck_report.md   consolidated report
  corrected.bib        candidate replacement for the user to diff and merge

Failure modes

.bib not found: ask for the path, do not invent one.

Every entry returns lookup_timeout: a network or rate-limit problem. Retry once at --max-parallel 2, then surface the error. Do not mark a whole bibliography FAIL on this.

A wave of year FAILs: usually preprint versus published. Widen the arXiv detection in check 2 and leave the year tolerance alone.

Title match confidence below 0.7 across the board: the bibliography may be non-English or in a venue neither Crossref nor OpenAlex indexes. Say so, ask for one entry known to be correct, and recalibrate against it.

OpenAlex credits exhausted (1,000/day anonymous, 10,000 with the key in ~/.claude/secrets/scholar.env): fall back to Crossref-only checking, which still covers checks 1 and 6 through 8, and mark author-accent findings as skipped.

Out of scope

Do not add entries. Hand a DOI to mcp__zotero__zotero_add_by_doi, or use the reading-papers skill for anything else.

Do not overwrite the source .bib under any circumstances.

Do not claim a citation supports a textual claim. This skill verifies that an entry's metadata matches a real paper and nothing more.

Do not bulk-reformat. A PASS entry is copied verbatim into corrected.bib even where its style differs from the rest of the file.