Stryker.NET

Trigger On

• the repo uses or wants

  Stryker.NET

• mutation testing is needed for high-risk code

Value

• produce a concrete project delta: code, docs, config, tests, CI, or review artifact
• reduce ambiguity through explicit planning, verification, and final validation skills
• leave reusable project context so future tasks are faster and safer

Do Not Use For

• every PR path by default in a large repo
• simple coverage collection

Inputs

• the nearest

  AGENTS.md

• target projects and critical paths
• time budget for mutation runs

Quick Start

1. Read the nearest

   AGENTS.md

   and confirm scope and constraints.
2. Run this skill's

   Workflow

   through the

   Ralph Loop

   until outcomes are acceptable.
3. Return the

   Required Result Format

   with concrete artifacts and verification evidence.

Workflow

1. Run mutation testing on critical projects, not blindly on the whole mono-repo.
2. Keep it out of the fastest PR path unless the repo explicitly accepts the runtime cost.
3. Stabilize tests first; mutation testing amplifies flaky or slow suites.

Bootstrap When Missing

If

Stryker.NET

is not configured yet:

1. Detect current state:

   • rg --files -g '.config/dotnet-tools.json'

   • dotnet tool list --local

   • dotnet tool list --global

2. Prefer local tool installation for reproducible CI:

   • dotnet new tool-manifest

     (if missing)

   • dotnet tool install dotnet-stryker

3. Choose a focused target scope and mutation budget before enabling CI.
4. Add a dedicated mutation command in

   AGENTS.md

   and CI (not in the fastest PR path by default).
5. Run

   dotnet stryker

   on the target project and return

   status: configured

   or

   status: improved

   .
6. If mutation testing is explicitly out of scope, return

   status: not_applicable

   .

Deliver

• explicit mutation-test scope
• reproducible Stryker commands

Validate

• the selected scope is affordable in CI
• mutation score is interpreted with test quality, not as a vanity number

Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

1. Plan first (mandatory):
   • analyze current state
   • define target outcome, constraints, and risks
   • write a detailed execution plan
   • list final validation skills to run at the end, with order and reason
2. Execute one planned step and produce a concrete delta.
3. Review the result and capture findings with actionable next fixes.
4. Apply fixes in small batches and rerun the relevant checks or review steps.
5. Update the plan after each iteration.
6. Repeat until outcomes are acceptable or only explicit exceptions remain.
7. If a dependency is missing, bootstrap it or return

   status: not_applicable

   with explicit reason and fallback path.

Required Result Format

• status

  :

  complete

  |

  clean

  |

  improved

  |

  configured

  |

  not_applicable

  |

  blocked

• plan

  : concise plan and current iteration step

• actions_taken

  : concrete changes made

• validation_skills

  : final skills run, or skipped with reasons

• verification

  : commands, checks, or review evidence summary

• remaining

  : top unresolved items or

  none

For setup-only requests with no execution, return

status: configured

and exact next commands.

Load References

• references/stryker.md

• references/commands.md

• references/patterns.md

Example Requests

• "Add Stryker for this library."
• "Use mutation testing on our critical domain layer."