Scoped CLAUDE.md (Claude Code project memory) Rule for Kotlin in a GraphQL federation gateway

You are a seasoned senior Kotlin engineer specializing in {{specialty}}. Your work has helped hundreds of {{clientType}} achieve measurable results.

Write a narrowly-scoped rule file -- not a whole-repo ruleset -- that applies only to Kotlin code in a GraphQL federation gateway.

**Target file:** CLAUDE.md (Claude Code project memory)
**Scope:** only Kotlin source files
**Project:** GraphQL federation gateway
**Convention in focus:** use zod (or equivalent) for every external input boundary
**Refactor recipe the rule should encourage:** split a god-class into services

## Why scoped rules
A single monolithic rules file pollutes every AI turn with irrelevant context. Scoped rules (e.g. `.cursor/rules/*.mdc` with `globs`, or a dedicated `CLAUDE.md` imported via `@path`) only load when relevant files are in play. Smaller, precise prompts -> better output.

## Required output

### Header / frontmatter
For Cursor scoped rules (`.mdc`):
```
---
description: <concise purpose>
globs: **/*.{ext1,ext2}
alwaysApply: false
---
```
For Claude Code, use a short `CLAUDE.md` in the relevant subfolder (Claude Code recursively reads CLAUDE.md from the cwd up to the repo root).

### Body (40-80 lines)
1. **Applies to** -- exact glob(s) and a one-line purpose
2. **Hard rules** (5-8 imperatives) specific to Kotlin in a GraphQL federation gateway:
   - Each rule cites the footgun it prevents
   - Include at least one rule enforcing use zod (or equivalent) for every external input boundary
   - Include at least one rule that nudges toward the split a god-class into services refactor when appropriate
3. **Preferred idioms** with one-line code shape examples (describe the shape, do not paste real code unless short)
4. **Forbidden idioms** with the wrong shape shown
5. **Testing note** -- which Mocha + Chai patterns match these files
6. **Escape hatch** -- when a human should override the rule (and how to signal it in a comment)

## Style
- Every bullet is an imperative
- No prose paragraphs longer than 2 sentences
- No "we recommend" -- use "do" / "do not"

- Use precise technical terminology appropriate for the audience
- Include code examples, configurations, or specifications where relevant
- Document assumptions, prerequisites, and dependencies
- Provide error handling and edge case considerations

Provide a ready-to-use template with placeholder markers {{like_this}} that the user can fill in. Include instructions for each placeholder.