[BUG] CLAUDE_CONFIG_DIR environment variable behavior unclear - still creates local .claude/ directories

Environment

• Platform (select one):
• Anthropic API
• AWS Bedrock
• Google Vertex AI
• Other:
• Claude CLI version: Latest
• Operating System: Linux
• Terminal: bash

### Bug Description

I have the CLAUDE_CONFIG_DIR environment variable set to centralize Claude Code configuration, but Claude Code still creates local .claude/ directories in individual workspaces. The purpose and expected behavior of CLAUDE_CONFIG_DIR is unclear since it's not documented in the official documentation.

Steps to Reproduce

1. Set CLAUDE_CONFIG_DIR=/path/to/global/claude/config environment variable
2. Start Claude Code session in a workspace directory
3. Use Claude Code tools that require permissions (e.g., Bash commands)
4. Observe that a local .claude/settings.local.json file is created in the workspace

### Expected Behavior

It's unclear what the expected behavior should be since CLAUDE_CONFIG_DIR is not documented. Possible expectations:

• All configuration centralized: CLAUDE_CONFIG_DIR should prevent any local .claude/ directories from being created
• Hybrid approach: Global config in CLAUDE_CONFIG_DIR, workspace-specific settings still stored locally
• Different purpose: CLAUDE_CONFIG_DIR serves a different purpose than local settings

### Actual Behavior

Despite having CLAUDE_CONFIG_DIR set, Claude Code creates both:

1. Global configuration in $CLAUDE_CONFIG_DIR/:

/mnt/bn/xxx/.claude/
├── .claude.json
├── .claude.json.backup
├── .credentials.json
├── projects/
├── shell-snapshots/
├── statsig/
└── todos/

1. Local workspace configuration:

/opt/tiger/aiic_verl/.claude/
└── settings.local.json

### Additional Context

• The CLAUDE_CONFIG_DIR environment variable is not mentioned in the official documentation:
• https://docs.anthropic.com/en/docs/claude-code/settings
• https://docs.anthropic.com/en/docs/claude-code/cli-reference
• This makes it impossible to determine if the current behavior is a bug or intended functionality
• Would appreciate clarification on the purpose of this environment variable and whether it should be documented

Request: Could you please document the purpose and behavior of CLAUDE_CONFIG_DIR and clarify whether creating both global and local config directories is the intended behavior?