Add support for CLAUDE_CONFIG_DIR

Cargo.toml

@@ -32,6 +32,7 @@ ureq = "2"
 hostname = "0.4"
 
 [dev-dependencies]
+temp-env = "0.3"
 
 [profile.release]
 opt-level = 3

INSTALL.md

@@ -89,6 +89,8 @@ rtk gain  # MUST show token savings, not "command not found"
 
 ### Recommended: Global Hook-First Setup
 
+> **Custom config directory**: If you've set `CLAUDE_CONFIG_DIR`, RTK respects it — all paths below use that directory instead of `~/.claude`.
+
 **Best for: All projects, automatic RTK usage**
 
 ```bash

README.md

@@ -544,6 +544,8 @@ The hook runs as a Claude Code [PreToolUse hook](https://docs.anthropic.com/en/d
 
 ### Quick Install (Automated)
 
+> **Custom config directory**: If you've set `CLAUDE_CONFIG_DIR`, RTK respects it — all paths below use that directory instead of `~/.claude`.
+
 ```bash
 rtk init -g
 # → Installs hook to ~/.claude/hooks/rtk-rewrite.sh (with executable permissions)

src/config.rs

@@ -1,7 +1,21 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 
+/// Resolve the Claude Code config directory.
+///
+/// Mirrors Claude Code's own logic:
+///   1. `CLAUDE_CONFIG_DIR` env var (if set)
+///   2. Fallback: `~/.claude`
+pub fn claude_config_dir() -> Result<PathBuf> {
+    if let Ok(dir) = std::env::var("CLAUDE_CONFIG_DIR") {
+        return Ok(PathBuf::from(dir));
+    }
+    dirs::home_dir()
+        .map(|h| h.join(".claude"))
+        .context("Cannot determine home directory. Is $HOME set?")
+}
+
 #[derive(Debug, Serialize, Deserialize, Default)]
 pub struct Config {
     #[serde(default)]
@@ -184,4 +198,21 @@ history_days = 90
         let config: Config = toml::from_str(toml).expect("valid toml");
         assert!(config.hooks.exclude_commands.is_empty());
     }
+
+    #[test]
+    fn test_claude_config_dir_env_override() {
+        temp_env::with_var("CLAUDE_CONFIG_DIR", Some("/tmp/custom-claude"), || {
+            let dir = claude_config_dir().unwrap();
+            assert_eq!(dir, PathBuf::from("/tmp/custom-claude"));
+        });
+    }
+
+    #[test]
+    fn test_claude_config_dir_default() {
+        temp_env::with_var_unset("CLAUDE_CONFIG_DIR", || {
+            let dir = claude_config_dir().unwrap();
+            let home = dirs::home_dir().unwrap();
+            assert_eq!(dir, home.join(".claude"));
+        });
+    }
 }

src/discover/provider.rs

@@ -36,8 +36,7 @@ pub struct ClaudeProvider;
 impl ClaudeProvider {
     /// Get the base directory for Claude Code projects.
     fn projects_dir() -> Result<PathBuf> {
-        let home = dirs::home_dir().context("could not determine home directory")?;
-        let dir = home.join(".claude").join("projects");
+        let dir = crate::config::claude_config_dir()?.join("projects");
         if !dir.exists() {
             anyhow::bail!(
                 "Claude Code projects directory not found: {}\nMake sure Claude Code has been used at least once.",

src/hook_check.rs

@@ -50,8 +50,10 @@ pub fn parse_hook_version(content: &str) -> u8 {
 }
 
 fn hook_installed_path() -> Option<PathBuf> {
-    let home = dirs::home_dir()?;
-    let path = home.join(".claude").join("hooks").join("rtk-rewrite.sh");
+    let path = crate::config::claude_config_dir()
+        .ok()?
+        .join("hooks")
+        .join("rtk-rewrite.sh");
     if path.exists() {
         Some(path)
     } else {