Regression Test

Answer: What happens differently to an existing user who upgrades without changing their project?

Investigate and report. Do not fix product code, implement edition transitions, regenerate goldens, publish findings, or create issues as part of this skill. The number of bugs found is not a success metric. Unchanged bugs do not count as new regressions, but a worsening of an existing bug can. New functionality matters here when it affects existing workflows.

Use the hypothesis-driven, real-execution discipline of field-test, with the comparative evidence and edition analysis below. Passing today's unit tests alone does not establish upgrade compatibility. Under plan mode, research and specify the experiments; wait for execution mode before writing fixtures or executing the investigation.

1. Freeze the comparison

Interpret supplied baseline, candidate, and subsystem arguments. Otherwise: