Diff the meaning, not just the text
Text diff says what characters changed. Semantic diff says what the model is now being asked to believe, prioritize, refuse, or produce. That is the diff that matters for behavior.
Look for modal verbs, scope words, exception clauses, examples that imply new rules, and output format changes. These are the places where small edits become big runtime differences.
A useful semantic diff ends with a test plan: which fixtures should change, which must not change, and which new example proves the edit worked.
A one-word modal change can be a policy change.
Aha moment
The smallest text diff can be the biggest behavioral diff when it changes authority, scope, or obligation.
Try this
Review prompt edits for new duties, removed constraints, softened verbs, and examples that imply new policy.
Watch for
- May, should, and must changes hidden in wording cleanup
- Examples that contradict the written rule
- Output contracts changed without matching tests