Comparing saved citation excerpts to tell source changes from AI answer changes

A citation can link to the same URL on two dates while the underlying paragraph has been revised, so editors should save the exact passage used and compare it against later copies. A short standard-library Python script normalizes whitespace and Unicode in two saved text files and produces a unified diff showing what changed. In the fictional example, the export window shifted from 7 calendar days to 7 business days, a substantive change that warrants checking the current source. The guidance also covers cases where the answer changed but the passage did not, where only whitespace differed, and where a source became unavailable, with suggested editorial responses for each. The script only compares files already saved, so it does not fetch pages or AI answers, and a wording difference alone does not prove a page was updated.