## TL;DR
The counterparty only updated the document author field, but the agent reported it as a redline. Strip document metadata (author, timestamps, revision counts) before diffing, and compare content only. Report metadata changes separately as non-substantive, never as redlines.

## The symptom
```text
metadata-only change flagged  -  the counterparty updated the document author field and the agent reported it as a redline
```

## Steps
### 1. Confirm the change is metadata-only
Compare the extracted body text of both versions. If the text is identical and only properties like author or last-modified differ, it is metadata-only.
Expected: Identical body text; differences confined to document properties.

### 2. Strip metadata before diffing
Remove or normalize metadata fields (author, created/modified dates, revision numbers) from both files before comparison.
Expected: The diff input contains content only.

### 3. Re-run the diff
Diff the cleaned versions. The change count should drop to zero.
Expected: Zero content changes reported.

### 4. Report metadata separately
Note 'document author updated (metadata, non-substantive)' as an FYI, not a redline.
Expected: Reviewers see it without it polluting the redline list.

## When to use
- Change list contains author, timestamps, or revision info
- Body text is identical between versions
- The diff tool compares raw files including properties

## When not to use
- Body text actually changed (then it is a real redline)
- The metadata itself is disputed (rare; handle explicitly)
- You need an audit trail of metadata (log it, just not as redlines)

## Why it happens
File-level diffing sees everything, including the document properties block. An author-field update changes bytes, so it looks like a change. But contract review cares about operative text; metadata edits are administrative noise that drown real redlines.

## Edge cases
- Tracked-changes author names: changing the author can reattribute existing markup; check the markup, not just the text.
- Template metadata (company name in properties): note once, not per version.
- Signed PDFs: metadata changes can invalidate signatures; flag that separately.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_W8evb4RqXnBH59UXQpOgbw