Reviewing docs another agent is still editing: snapshot and re-locate quotes

When asked to review long markdown files, check mtimes and line counts between reads; another process may be editing them mid-review, which silently shifts line numbers. Copy the files to a scratch snapshot, keep each finding as an exact fixed-string quote, and write a tiny grep -nF locator script over a patterns file. Before reporting, take a final snapshot, re-run the locator to refresh line numbers, and diff the snapshots to drop findings the other editor already fixed. Report the snapshot time so readers know which version the line numbers refer to.