fix: honor CLAUDE_CONFIG_DIR in hooks (#37)

ponytail-activate.js and ponytail-runtime.js hardcoded ~/.claude for the
flag file and settings lookup, ignoring CLAUDE_CONFIG_DIR. Add a shared
getClaudeDir() to ponytail-config.js and use it in both. Regression test
added to hooks.test.js.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hooks/ponytail-activate.js

@@ -8,8 +8,7 @@
 
 const fs = require('fs');
 const path = require('path');
-const os = require('os');
-const { getDefaultMode } = require('./ponytail-config');
+const { getDefaultMode, getClaudeDir } = require('./ponytail-config');
 const { getPonytailInstructions } = require('./ponytail-instructions');
 const {
   clearMode,
@@ -18,7 +17,7 @@ const {
   writeHookOutput,
 } = require('./ponytail-runtime');
 
-const claudeDir = path.join(os.homedir(), '.claude');
+const claudeDir = getClaudeDir();
 const settingsPath = path.join(claudeDir, 'settings.json');
 
 const mode = getDefaultMode();

hooks/ponytail-config.js

@@ -50,6 +50,11 @@ function getConfigPath() {
   return path.join(getConfigDir(), 'config.json');
 }
 
+function getClaudeDir() {
+  // ponytail: CLAUDE_CONFIG_DIR overrides ~/.claude, matching Claude Code.
+  return process.env.CLAUDE_CONFIG_DIR || path.join(os.homedir(), '.claude');
+}
+
 function getDefaultMode() {
   // 1. Environment variable (highest priority)
   const envMode = process.env.PONYTAIL_DEFAULT_MODE;
@@ -89,6 +94,7 @@ module.exports = {
   getDefaultMode,
   getConfigDir,
   getConfigPath,
+  getClaudeDir,
   normalizeMode,
   normalizeConfigMode,
   normalizePersistedMode,

hooks/ponytail-runtime.js

@@ -1,11 +1,11 @@
 const fs = require('fs');
 const path = require('path');
-const os = require('os');
+const { getClaudeDir } = require('./ponytail-config');
 
 const isCodex = Boolean(process.env.PLUGIN_DATA);
 const statePath = isCodex
   ? path.join(process.env.PLUGIN_DATA, '.ponytail-active')
-  : path.join(os.homedir(), '.claude', '.ponytail-active');
+  : path.join(getClaudeDir(), '.ponytail-active');
 
 function setMode(mode) {
   fs.mkdirSync(path.dirname(statePath), { recursive: true });