SDK client fails inside Claude Code hooks due to inherited CLAUDECODE env var

[wazum]

Description

When tdd-guard runs as a Claude Code hook with the default configuration (no VALIDATION_CLIENT set), the SDK client spawns a child Claude Code process via @anthropic-ai/claude-agent-sdk. This child process inherits the CLAUDECODE=1 environment variable from the parent session and refuses to start:

Error: Claude Code cannot be launched inside another Claude Code session.
Nested sessions share runtime resources and will crash all active sessions.

This causes tdd-guard to block all Edit/Write operations with:

Error during validation: Claude Code process exited with code 1

This affects every default installation — no special configuration is needed to trigger it.

Root Cause

ClaudeAgentSdk.getQueryOptions() does not pass an env option to query(), so the SDK inherits process.env including CLAUDECODE=1. The child Claude process interprets this as a nested session and exits.

This is a known upstream issue:

• anthropics/claude-agent-sdk-python#573
• anthropics/claude-code#25803

Suggested Fix

Strip CLAUDECODE from the environment passed to the SDK:

// in ClaudeAgentSdk.getQueryOptions()
env: this.getCleanEnvironment(),

// new private method
private getCleanEnvironment(): Record<string, string | undefined> {
  const { CLAUDECODE, ...rest } = process.env
  return rest
}

Environment

• tdd-guard 1.1.0
• Claude Code 2.x (native install)
• @anthropic-ai/claude-agent-sdk (any version)
• macOS / Linux