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+# CLAUDE.md
+
+@GUIDELINES_NEST_TRPC.md
+
+The imported guidelines are binding. Two always-on rules:
+- Stryker mutation testing is local-only — never wire it into CI.
+- Pre-PR ritual: `npm run test:mutation` (scope with `STRYKER_MUTATE` to changed files) and report surviving mutants in the PR body.