ai-engineering-fluency: Command for GitHub Copilot

Improve Mutation Score — Issue Recommendations

You are running in GitHub Copilot CLI inside a GitHub Actions workflow. The mutation testing job has just finished and produced a Stryker report. Your job is to read that report, decide which surviving mutants are genuinely worth killing, and open a single GitHub issue with concrete recommendations.

You must not modify source or test files in this run. Open an issue only.

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Step 1 — Locate the mutation report

The report is at the path given in the Context Paths section below (typically vscode-extension/reports/mutation/mutation.json). If the file does not exist or has zero mutants, exit cleanly without opening an issue and print:

NO_REPORT — nothing to recommend.

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Step 2 — Parse the report

The Stryker JSON has the structure:

{
  "files": {
    "out/src/foo.js": {
      "mutants": [
        { "id": "...", "mutatorName": "...", "replacement": "...",
          "location": { "start": { "line": N, "column": N }, "end": { ... } },
          "status": "Survived", "description": "..." }
      ]
    }
  }
}

Compute:

• total, killed, survived, timedOut, noCoverage
• score = killed / (killed + survived + timedOut) * 100

Map compiled JS paths back to TypeScript sources:

Compiled path	TypeScript source
out/src/tokenEstimation.js	src/tokenEstimation.ts
out/src/sessionParser.js	src/sessionParser.ts
out/src/workspaceHelpers.js	src/workspaceHelpers.ts
out/src/claudecode.js	src/claudecode.ts
out/src/utils/dayKeys.js	src/utils/dayKeys.ts
out/src/utils/errors.js	src/utils/errors.ts
out/vscode-extension/src/utils/html.js	vscode-extension/src/utils/html.ts

For unmapped paths, infer the TypeScript path by replacing out/ with vscode-extension/ and .js with .ts.

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Step 3 — Triage surviving mutants

For each Survived mutant, read a few lines of TypeScript context around its location and classify it as one of: