fact-check

name	fact-check
description	Verify the factual accuracy of a document against the actual codebase, correct inaccuracies in place. Use when validating HTML review pages, plan documents, or any document making claims about code.

Load the visual-explainer skill, then verify the factual accuracy of a document that makes claims about a codebase. Read the file, extract every verifiable claim, check each against the actual code and git history, correct inaccuracies in place, and add a verification summary.

For HTML files: read ./references/css-patterns.md to match the existing page's styling when inserting the verification summary.

Target file — determine what to verify from $1:

• Explicit path: verify that specific file (.html, .md, or any text document)
• No argument: verify the most recently modified .html file in ~/.agent/diagrams/ (ls -t ~/.agent/diagrams/*.html | head -1)

Auto-detect the document type and adjust the verification strategy:

• HTML review pages (diff-review, plan-review, project-recap): detect from page content, verify against the git ref or plan file the review was based on
• Plan/spec documents (markdown): verify file references, function/type names, behavior descriptions, and architecture claims against the current codebase
• Any other document: extract and verify whatever factual claims about code it contains

Phase 1: Extract claims. Read the file. Extract every verifiable factual claim:

• Quantitative: line counts, file counts, function counts, module counts, test counts, any numeric metrics
• Naming: function names, type names, module names, file paths referenced in the document
• Behavioral: descriptions of what code does, how things work, before/after comparisons
• Structural: architecture claims, dependency relationships, import chains, module boundaries
• Temporal: git history claims, commit attributions, timeline entries

Skip subjective analysis (opinions, design judgments, readability assessments) — these aren't verifiable facts.

Phase 2: Verify against source. For each extracted claim, go to the source:

• Re-read every file referenced in the document — check function signatures, type definitions, behavior descriptions against the actual code
• For claims about git history: re-run git commands (git diff --stat, git log, git diff --name-status, etc.) and compare output against the document's numbers
• For diff-reviews: read both the ref version (git show <ref>:file) and working tree version to verify before/after claims aren't swapped or fabricated
• For plan docs: verify that files, functions, and types the plan references actually exist and behave as described
• For project-recaps: re-run git log commands to verify activity narrative and timeline

Classify each claim:

• Confirmed: claim matches the code/output exactly
• Corrected: claim was inaccurate — note what was wrong and what the correct value is
• Unverifiable: claim can't be checked (e.g., references a file that doesn't exist, or a behavior that requires runtime testing)

Phase 3: Correct in place. Edit the file directly using surgical text replacements:

• Fix incorrect numbers, function names, file paths, behavior descriptions
• Fix before/after swaps (a common error class in review pages)
• If a section is fundamentally wrong (not just a detail error), rewrite that section's content while preserving the surrounding structure
• For HTML: preserve layout, CSS, animations, Mermaid diagrams (unless they contain factual errors in node labels or edge descriptions)
• For markdown: preserve heading structure, formatting, and document organization

Phase 4: Add verification summary.

• HTML files: insert a verification section as a banner at the top or final section, matching the page's existing styling. Use a subtle card with muted colors.
• Markdown files: append a ## Verification Summary section at the end of the document.

Include in the summary:

• Total claims checked
• Claims confirmed (with count)
• Corrections made (with brief list of what was fixed: "Changed processCleanup to runCleanup to match actual function name in worker.ts:45")
• Unverifiable claims flagged (if any)

Phase 5: Report. Tell the user what was checked, what was corrected, and open the file (HTML in browser, markdown path in chat). If nothing needed correction, say so — the verification still has value as confirmation.

This is not a re-review. It does not second-guess analysis, opinions, or design judgments. It does not change the document's structure or organization. It is a fact-checker — it verifies that the data presented matches reality, corrects what doesn't, and leaves everything else alone.

Write corrections to the original file.

Ultrathink.

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