prompt-regression

To check for prompt regressions after editing Claude Code harness rules, run a validation probe that compares current AI response patterns against saved baselines to detect silent behavioral shifts.

Harness validation is the process of testing trigger routing integrity, mandatory chain preservation, and gate condition enforcement after modifying core rules or skills to ensure expected AI workflows execute correctly.

You can validate trigger mapping changes by running targeted probe tests that check only the regression probes relevant to your changed files, avoiding unnecessary full-suite runs for small edits.

You need pre-merge validation for AI behavior changes whenever you update skill trigger phrases, modify CLAUDE.md core onboarding rules, or alter trigger mappings to prevent broken workflows from shipping.

Modifying core rules causes silent behavioral regressions because AI behavior can break without warning when trigger mappings or skill configurations are updated, leading to unexpected responses and broken workflow chains.

Yes, you can use prompt regression testing for CLAUDE.md onboarding rule modifications to confirm the AI still initiates correct workflows and follows required chains when given standard prompts.