gemini-for-claude-mcp: Instructions file for Claude Code

CLAUDE.md

This file provides mandatory guidance to Claude Code when working with this repository. All standards are non-negotiable.

Project Overview

MCP server bridging Gemini AI capabilities to Claude Code. Built with Clean Architecture (Ports and Adapters) and Feature-Based Structure.

Reference: See ARCHITECTURE.md for detailed architectural patterns.

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MANDATORY STANDARDS

1. TypeScript Configuration (Non-Negotiable)

{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitOverride": true,
    "forceConsistentCasingInFileNames": true,
    "verbatimModuleSyntax": true
  }
}

FORBIDDEN:

• any type - use unknown with type guards
• Type assertions (as) without prior narrowing
• Non-null assertions (!) - handle nullability explicitly
• @ts-ignore or @ts-expect-error without linked issue

REQUIRED:

• Explicit return types on all exported functions
• readonly on all properties that should not mutate
• Discriminated unions for complex state

---

2. Error Handling (neverthrow Pattern)

All use cases MUST return Result<T, E> from neverthrow:

import { Result, ok, err } from 'neverthrow';

type UseCaseResult<T> = Result<T, DomainError>;

// CORRECT
async execute(input: Input): Promise<UseCaseResult<Output>> {
  if (!valid) return err(new ValidationError('Invalid input'));
  return ok(result);
}

// FORBIDDEN - raw throws in use cases
async execute(input: Input): Promise<Output> {
  throw new Error('Something went wrong'); // NEVER
}

Domain Errors: Define typed error classes per feature:

abstract class DomainError {
  abstract readonly code: string;
  abstract readonly message: string;
}

class ValidationError extends DomainError {
  readonly code = 'VALIDATION_ERROR';
  constructor(readonly message: string) { super(); }
}