feat(config): support CLAUDE_CONFIG_DIR environment variable

[iwvelando]

feat(config): support CLAUDE_CONFIG_DIR environment variable

Summary

RTK now respects the CLAUDE_CONFIG_DIR environment variable, enabling users who run multiple Claude Code instances with custom config directories (e.g., CLAUDE_CONFIG_DIR=~/.claude-a claude) to install and use RTK seamlessly.

Problem

All three places that resolved the Claude config directory (init.rs, integrity.rs, hook_check.rs) had the path ~/.claude hardcoded. Users launching Claude with CLAUDE_CONFIG_DIR=~/.claude-a claude could not use rtk init --global because hooks, RTK.md, settings.json, and CLAUDE.md were always written to ~/.claude regardless of their actual config directory.

Solution

• Updated resolve_claude_dir() in init.rs to check the CLAUDE_CONFIG_DIR environment variable first, with ~ expansion support, falling back to ~/.claude if unset.
• Made resolve_claude_dir() pub(crate) so it can be reused from integrity.rs and hook_check.rs instead of duplicating logic.
• Updated integrity.rs::resolve_hook_path() to delegate to the shared resolver instead of hardcoding ~/.claude.
• Updated hook_check.rs::hook_installed_path() to delegate to the shared resolver instead of hardcoding ~/.claude.
• Updated user-facing messages in show_config() and print_manual_instructions() to display the actual resolved path instead of hardcoded ~/.claude.
• Extracted resolve_claude_dir_impl() as an inner function accepting Option<String> for testability, avoiding env var races in parallel test execution.

Testing

4 new unit tests covering:

• Default behavior (None → ~/.claude)
• Absolute custom path (/tmp/my-custom-claude-dir)
• Tilde expansion (~/.claude-custom → $HOME/.claude-custom)
• Bare tilde (~ → $HOME)

Manual Testing: CLAUDE_CONFIG_DIR Support

Environment

• Custom Claude config dir: ~/.claude-a
• Branch: feat/config-support-claude-config-dir-env-var
• Binary: ./target/release/rtk (release build)

Pre-existing state

$ cat ~/.claude-a/settings.json
{
  "model": "opus",
  "enabledPlugins": {
    "gopls-lsp@claude-plugins-official": false,
    "frontend-design@claude-plugins-official": true,
    "swift-lsp@claude-plugins-official": true
  },
  "effortLevel": "medium"
}

$ ll ~/.claude-a/hooks
ls: /Users/isaac/.claude-a/hooks: No such file or directory

Running rtk init --global with CLAUDE_CONFIG_DIR

$ CLAUDE_CONFIG_DIR=~/.claude-a ./target/release/rtk init --global

RTK hook installed/updated (global).

  Hook:      /Users/isaac/.claude-a/hooks/rtk-rewrite.sh
  RTK.md:    /Users/isaac/.claude-a/RTK.md (10 lines)
  CLAUDE.md: @RTK.md reference added

Patch existing /Users/isaac/.claude-a/settings.json? [y/N]
y

  settings.json: hook added
  Backup: /Users/isaac/.claude-a/settings.json.bak
  Restart Claude Code. Test with: git status

Post-install verification

$ cat ~/.claude-a/settings.json
{
  "model": "opus",
  "enabledPlugins": {
    "gopls-lsp@claude-plugins-official": false,
    "frontend-design@claude-plugins-official": true,
    "swift-lsp@claude-plugins-official": true
  },
  "effortLevel": "medium",
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "/Users/isaac/.claude-a/hooks/rtk-rewrite.sh"
          }
        ]
      }
    ]
  }
}

$ ll ~/.claude-a/hooks
total 8
-rwxr-xr-x  1 isaac  staff  1755 Mar  9 23:21 rtk-rewrite.sh

Result

PASS — Hook, RTK.md, CLAUDE.md reference, and settings.json patch all installed correctly under ~/.claude-a/ instead of ~/.claude/.

Usage

# Standard (unchanged)
rtk init --global

# With custom Claude config directory
CLAUDE_CONFIG_DIR=~/.claude-a rtk init --global