⚡ Bolt: Cache parsed YAML to prevent repetitive synchronous file I/O (#91)

- Implement an in-memory `Map` to cache parsed YAML objects.
- Use `structuredClone` to prevent caller mutations from corrupting the cached object state.
- Implement negative caching for missing files.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

lib/config/parser.ts

@@ -2,15 +2,39 @@ import fs from 'fs';
 import path from 'path';
 import yaml from 'js-yaml';
 
+// ⚡ Bolt Optimization: Cache parsed YAML to prevent repetitive synchronous
+// file I/O and expensive parsing during production runtime.
+const yamlCache = new Map<string, unknown>();
+
 export function loadYaml<T>(filename: string): T | null {
+  const isProd = process.env.NODE_ENV === 'production';
+
+  if (isProd && yamlCache.has(filename)) {
+    const cached = yamlCache.get(filename);
+    // ⚡ Bolt Optimization: Use `structuredClone` to prevent caller mutations
+    // from corrupting the cached object state, while preserving JS native types.
+    return cached === null ? null : structuredClone(cached as T);
+  }
+
   const yamlPath = path.join(process.cwd(), 'content', filename);
 
   if (!fs.existsSync(yamlPath)) {
+    // ⚡ Bolt Optimization: Implement negative caching for missing files.
+    if (isProd) {
+      yamlCache.set(filename, null);
+    }
     return null;
   }
 
   const raw = fs.readFileSync(yamlPath, 'utf8');
-  return (yaml.load(raw) || {}) as T;
+  const parsed = (yaml.load(raw) || {}) as T;
+
+  if (isProd) {
+    yamlCache.set(filename, parsed);
+    return structuredClone(parsed);
+  }
+
+  return parsed;
 }
 
 const UUID_REGEX = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;