chore: import upstream snapshot with attribution

use-cases/claude-code-plugin/hooks/scripts/utils/debug.js

@@ -0,0 +1,61 @@
+/**
+ * Shared debug utility for EverMem hooks
+ *
+ * Usage:
+ *   import { debug, setDebugPrefix } from './utils/debug.js';
+ *   setDebugPrefix('inject');  // Optional: add prefix to log lines
+ *   debug('hookInput:', data);
+ *
+ * Enable by setting EVERMEM_DEBUG=1 in .env file or environment
+ * Logs are written to /tmp/evermem-debug.log
+ */
+
+import { appendFileSync } from 'fs';
+import { isConfigured } from './config.js';  // This loads .env
+
+const DEBUG_LOG_PATH = '/tmp/evermem-debug.log';
+
+// Check debug flag (after config.js loads .env)
+const DEBUG = process.env.EVERMEM_DEBUG === '1';
+
+// Optional prefix for log lines (e.g., 'inject' or 'store')
+let debugPrefix = '';
+
+/**
+ * Set a prefix for debug log lines
+ * @param {string} prefix - Prefix to add (e.g., 'inject', 'store')
+ */
+export function setDebugPrefix(prefix) {
+  debugPrefix = prefix ? `[${prefix}] ` : '';
+}
+
+/**
+ * Write debug message to log file
+ * Only writes when EVERMEM_DEBUG=1
+ *
+ * @param {...any} args - Arguments to log (objects are JSON stringified)
+ */
+export function debug(...args) {
+  if (!DEBUG) return;
+
+  const msg = args.map(a =>
+    typeof a === 'object' ? JSON.stringify(a, null, 2) : a
+  ).join(' ');
+
+  const timestamp = new Date().toISOString();
+  const line = `[${timestamp}] ${debugPrefix}${msg}\n`;
+
+  try {
+    appendFileSync(DEBUG_LOG_PATH, line);
+  } catch (e) {
+    // Silent on write errors
+  }
+}
+
+/**
+ * Check if debug mode is enabled
+ * @returns {boolean}
+ */
+export function isDebugEnabled() {
+  return DEBUG;
+}