Mutate

Run mutation testing on this project by following the atdd-mutate skill. This skill exists as a Codex-native compatibility wrapper for the legacy mutate entrypoint.

Instructions

1. Check that both test streams are green before proceeding:

   • Run the unit tests
   • Run acceptance tests if a pipeline exists (./run-acceptance-tests.sh)
   • If either fails, report the failure and stop — do not mutate against a red baseline

2. Detect the project language and check if a mutation tool exists in the project.

   • Preferred: Build a custom mutation tool using TDD — a project-specific module that walks the AST, applies mutations one at a time, runs targeted tests, and reports survivors. See the atdd-mutate skill for the 4-module architecture (mutations, runner, core, hashing/selection) and mutation categories.
   • Alternative: If the user requests a faster setup, install an existing framework (Stryker, mutmut, PIT, etc. — see the atdd-mutate skill).

3. Configure the tool to:

   • Target source code only (not tests, specs, generated files, or pipeline code)
   • Exclude generated-acceptance-tests/, acceptance-pipeline/, and specs/
   • If $ARGUMENTS is provided, scope mutations to that path

4. Run the mutation tool. On the custom-tool path, run dae_mutmap.py select first and mutate only the changed functions it returns (differential mutation testing — see the atdd-mutate skill); on the framework path, enable the framework's incremental flag.

5. Report results:

   • Mutation score (percentage)
   • Total mutants, killed, survived
   • List each surviving mutant with: file, line, mutation description
   • Assessment: strong (90%+), moderate (70-89%), or weak (<70%)
   • On the custom-tool path, run dae_mutmap.py update to refresh mutation-manifest.json; combine fresh results with cached entries for unchanged functions

6. Ask whether to proceed with killing surviving mutants by using the kill-mutants skill.