implementing

.github/workflows/mutation.yml

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+name: Mutation Testing
+
+on:
+  schedule:
+    # Weekly on Monday at 06:00 UTC
+    - cron: '0 6 * * 1'
+  workflow_dispatch:
+    # Allow manual trigger from GitHub UI
+
+jobs:
+  mutants:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: wasm32-unknown-unknown
+
+      - name: Install cargo-mutants
+        uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-mutants
+
+      - name: Run mutation tests
+        run: cargo mutants --no-fail-fast 2>&1 | tee mutation-report.txt
+
+      - name: Extract mutation score
+        id: score
+        run: |
+          SCORE=$(grep -oP '\d+\.?\d*% mutation score' mutation-report.txt || echo "0%")
+          echo "score=$SCORE" >> "$GITHUB_OUTPUT"
+          echo "Mutation score: $SCORE"
+
+      - name: Upload mutation report
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: mutation-report
+          path: mutation-report.txt
+
+      - name: Upload mutants directory
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: mutants-dir
+          path: mutants/
+
+      - name: Check minimum mutation score
+        run: |
+          SCORE=$(grep -oP '\d+\.?\d*(?=% mutation score)' mutation-report.txt || echo "0")
+          if [ "$(echo "$SCORE < 80" | bc -l)" -eq 1 ]; then
+            echo "❌ Mutation score ${SCORE}% is below target of 80%"
+            exit 1
+          fi
+          echo "✅ Mutation score ${SCORE}% meets target of 80%"

.mutants.toml

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+# Mutation testing configuration for cargo-mutants
+#
+# Reference: https://github.com/sourcefrog/cargo-mutants
+
+# Exclude test files from mutation — mutating test code is not useful
+# and would produce false positives.
+exclude_files = [
+    "src/test.rs",
+    "src/security_test.rs",
+]
+
+# Exclude generated code directories
+exclude_dirs = [
+    "target",
+]
+
+# Only mutate source files in src/ (exclude build scripts, CI config, etc.)
+include_paths = ["src/"]
+
+# Test timeout per mutant (seconds)
+# Soroban contract tests can be slow; 120s prevents hangs from infinite loops
+test_timeout = 120
+
+# Run tests in a single thread to avoid flaky failures from shared state
+test_flags = ["--test-threads=1"]
+
+# Do not fail fast — continue testing remaining mutants even if some fail
+# This ensures we get a complete mutation report in a single CI run
+no_fail_fast = true