fact-check

name

fact-check

description

Fact-check a manuscript's claims against the cited sources themselves: locate each source's knowledge-base Markdown file and verify the in-text claim is actually supported. Runs a pre-flight gate that refuses unless a per-source Markdown knowledge base exists and is clean (PDFs converted via process-source); then runs citation-check; then audits claim support, overclaiming, direction, scope, and misattribution.

Claim–Source Fact Checker

Heritage and scope

This is an original Open Science Skills workflow. It extends citation-check (which verifies a citation exists, resolves, and is formatted) to the next question: does the cited source actually support the claim it is attached to? It checks claims against the project's per-source Markdown knowledge base — the files produced by process-source, where each source is converted or summarized to sources/md/<author>-<year>-<slug>.md. This is local-source verification, not open-web fact-checking: it audits whether a manuscript's sentences are backed by the documents the author has actually read and filed. Run once a draft has citations and a populated knowledge base.

Instructions

1. Pre-flight gate — orient, then refuse if the knowledge base is not ready

Orient. Identify the inputs:

• Manuscript source: LaTeX, Markdown, Word/PDF text, or pasted prose with citations or footnotes.
• Bibliography: .bib, CSL JSON, or reference list — used to resolve cite keys to author-year-title so source files can be found.
• Knowledge base: the project's per-source Markdown directory. Search in order: sources/md/, knowledge_base/md/, sources/, knowledge_base/, then any chapter-local */sources/. Also read any index or crosswalk file (sources/inventory.md, notes/source_map.md, *source*crosswalk*, *source*matrix*) that maps bib keys or titles to files.
• Scope: whole manuscript, one section, the literature review/theory sections, or a supplied list of claims.

Pre-flight gate (hard stop). This skill verifies claims against local Markdown source files; it does not fact-check from memory or the open web. A fact-check run against an absent or half-built knowledge base produces false reassurance, which is worse than no check. So before doing anything else, decide readiness and refuse to run — return a Pre-flight: NOT READY notice instead of a report — when any of the following holds:

1. No knowledge base. No per-source Markdown corpus exists: sources/md/, knowledge_base/md/, or an equivalent is missing or empty.
2. Unconverted sources (not cleaned up). Raw documents — .pdf, .docx, .epub, or scanned images — sit in the sources area (a drop-zone, sources/, sources/pdf/, */source_pdfs/) without a corresponding .md. The base is not clean: every source must be converted to Markdown first (or, if long, to a Markdown summary).
3. Coverage too low. The available Markdown does not cover the cited works in scope. Compute coverage = matched source files ÷ cited non-background works; below roughly two-thirds, treat as not ready.

Do not partially fact-check around the gap, and do not fall back to memory or web lookups for missing sources. Stop and report. The user may rerun after fixing it, or explicitly rescope the run to the already-covered subset; only then proceed with that subset.

Remediation to print on refusal:

• Convert each raw source to Markdown with the process-source skill (/oss:process-source, or the project's own /process-source command). It turns each PDF into sources/md/<author>-<year>-<slug>.md, summarizing long sources.
• Populate any cited work that has no file yet: locate the PDF, then run process-source.
• Re-run fact-check once sources/md/ covers the cited set and no raw files remain unconverted.
• Best practices: the per-source Markdown knowledge base and intake conventions are documented in the Open Science Skills repo (github.com/scdenney/open-science-skills) and the process-source skill; Anthropic's skill-authoring guidance is linked from that README.

Only when the gate passes — knowledge base present, clean, and covering the cited set in scope — continue to step 2.

2. Run citation-check first (always)

Before judging support, run the citation-check skill on the same inputs and consume its report. A claim cannot be evaluated against a source that is missing, fabricated, or mis-keyed. Carry its findings forward: any LIKELY FABRICATED, DOI RESOLVES TO DIFFERENT WORK, or in-text/reference parity break makes the dependent claim UNVERIFIABLE — citation problem, not a clean support check. Do not silently repeat citation-check's work; cite its result and build on it.

3. Build the claim inventory

For each in-text citation, parenthetical, narrative cite, or footnote that attaches a source to a substantive statement, record:

• the claim — the exact sentence or clause the citation backs;
• the cite key(s) / author-year;
• the claim type — empirical result, descriptive fact, definition/concept, method precedent, theoretical position, or direct quotation;
• the asserted strength — the verb does work: "shows" / "demonstrates" / "proves" claim more than "suggests" / "is consistent with" / "see".

Skip pure background or "see also" citations unless they carry a checkable assertion. For multi-source claims, check each source's contribution separately — a claim can be supported by one cited work and not another.

4. Locate each source's Markdown file

Resolve bib key to author + year + title, then find the matching knowledge-base file:

• Match on author(s)-year plus a title slug. Naming varies across projects (hyphen-separated or underscore_separated; -and- between co-authors; first-author-only vs. all authors). Be tolerant of diacritics, name particles (de, van, von), and short vs. full titles.
• Prefer an explicit crosswalk/inventory entry when one exists over fuzzy filename matching.
• These files are frequently summaries or PDF→Markdown conversions, not full text. Note which: a faithful conversion can adjudicate fine-grained claims; a condensed summary may legitimately omit the detail a claim rests on.
• Record one of FOUND (with path), AMBIGUOUS (more than one candidate — list them, do not guess), or NOT IN KB.

5. Verify claim support

Read the located source Markdown and judge whether it supports the specific claim. Classify each:

• SUPPORTED — the source states or directly entails the claim. Quote the supporting passage.
• PARTIALLY SUPPORTED — the source supports a weaker or narrower version. Name the gap (scope, population, magnitude, hedging).
• UNSUPPORTED — the source does not contain the claim; the passage that should support it is absent.
• CONTRADICTED — the source reports the opposite or a materially different result (wrong direction, wrong sign, wrong magnitude).
• MISATTRIBUTED — the claim is real but belongs to a different work than the one cited.
• SOURCE INSUFFICIENT — the Markdown is a summary that does not carry enough detail to adjudicate; name what to check in the original PDF.
• NOT IN KB / UNVERIFIABLE — citation problem — carried from steps 2 and 4.

For every SUPPORTED, PARTIALLY SUPPORTED, or CONTRADICTED verdict, include a verbatim quote from the source (with section/page if the file carries them). Never assert support from memory, topical overlap, or plausibility.

Actively watch for:

• Overclaiming — source hedges ("may", "in this sample"), manuscript asserts a general law.
• Direction errors — source finds a null or opposite effect from what the sentence claims.
• Scope creep — a single-country, single-period, or single-population source cited for a universal claim.
• Citation stuffing — a source piled onto a claim it does not actually address.
• Stale quantitative values — numbers, point estimates, or sample sizes that do not match the source.
• Definitional drift — a concept attributed to a source that defines or uses it differently.

6. Do not over-flag

• A faithful summary that simply omits a detail is SOURCE INSUFFICIENT, not UNSUPPORTED.
• Background and framing citations are not evidentiary claims; do not demand data from them.
• Theory/position citations are supported when the source advances that position, even with no data.
• A missing source Markdown is an infrastructure gap (NOT IN KB → run process-source), not evidence of fabrication. Keep "the source doesn't support the claim" strictly separate from "I couldn't find the source."

Output

If the pre-flight gate failed, return this instead — do not fact-check anything:

# Fact-Check — Pre-flight: NOT READY

Reason: <no knowledge base | N unconverted sources | coverage X% below bar>
Knowledge base searched: <dirs>
Cited works with no Markdown file: <cite keys / author-year>
Raw files needing conversion: <paths>

## To proceed
1. Run `process-source` on the raw files / missing sources listed above
2. Confirm each cited work has sources/md/<author>-<year>-<slug>.md
3. Re-run /fact-check
Best practices: github.com/scdenney/open-science-skills · the process-source skill

Otherwise, produce a Fact-Check Report:

# Fact-Check Report

Scope: <files/sections checked>
Knowledge base: <dir(s) searched> · sources matched: <n>/<total cited>
citation-check: <ran? key carry-forward findings>
Summary: <N contradicted, N unsupported, N partial, N supported, N not-in-KB, N unverifiable>

## Contradicted / Unsupported (blocking)
| Location | Claim (short) | Cite key | Verdict | Source passage or "absent" | Suggested fix |

## Partially supported / Overclaim (recommended)
| Location | Claim | Cite key | Gap | Source passage | Suggested rewording |

## Source not in knowledge base
| Cite key | Author-year | Why unresolved | Action (process-source / locate file) |

## Supported (spot-check log)
| Location | Claim | Cite key | Source passage |

Severity:

• Blocking: a decisive or headline claim is CONTRADICTED or UNSUPPORTED; a reported quantitative result does not match the source; a citation-check failure that invalidates the claim.
• Recommended: overclaiming or partial support fixable by rewording or rescoping; misattribution where the correct source is known.
• Minor: a background citation that could be tightened; a summary-only source worth re-checking against its PDF before submission.

Quality checks

• The pre-flight gate ran first; the skill refused (with a remediation checklist) rather than fact-checking against an absent, unconverted, or low-coverage knowledge base.
• citation-check was run first and its findings were carried into the claim verdicts.
• Every SUPPORTED / PARTIAL / CONTRADICTED verdict quotes a verbatim source passage, not a paraphrase from memory.
• "Source not in knowledge base" was kept separate from "source does not support the claim."
• Summary-only sources were labeled SOURCE INSUFFICIENT rather than UNSUPPORTED.
• Claim direction, magnitude, scope, and hedging were checked — not just topical overlap.
• Background and framing citations were not treated as evidentiary claims.
• No claim was marked supported on plausibility alone.