fix: resolve disableAutoRebuild and fork() initialization issues

- Fix disableAutoRebuild being ignored when indexes are empty on startup
- Add second check after needsRebuild to enable lazy loading properly
- Auto-create initial commit in fork() if none exists, eliminating manual setup
- Resolves Workshop team's 30-minute startup delays with large datasets (5.9M relationships)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/brainy.ts

@@ -2159,7 +2159,20 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       const refManager = (this.storage as any).refManager
       const currentBranch = (this.storage as any).currentBranch || 'main'
 
-      // Step 1: Copy storage ref (COW layer - instant!)
+      // Step 1: Ensure initial commit exists (required for fork)
+      const currentRef = await refManager.getRef(currentBranch)
+      if (!currentRef) {
+        // Auto-create initial commit if none exists
+        await this.commit(`Initial commit on ${currentBranch}`, {
+          author: options?.author || 'Brainy',
+          timestamp: Date.now()
+        })
+        if (!this.config.silent) {
+          console.log(`📝 Auto-created initial commit on ${currentBranch} (required for fork)`)
+        }
+      }
+
+      // Step 2: Copy storage ref (COW layer - instant!)
       await refManager.copyRef(currentBranch, branchName)
 
       // Step 2: Create new Brainy instance pointing to fork branch
@@ -4348,14 +4361,22 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       const needsRebuild =
         metadataStats.totalEntries === 0 ||
         hnswIndexSize === 0 ||
-        graphIndexSize === 0 ||
-        this.config.disableAutoRebuild === false // Explicitly enabled
+        graphIndexSize === 0
 
       if (!needsRebuild) {
         // All indexes already populated, no rebuild needed
         return
       }
 
+      // BUG FIX: If disableAutoRebuild === true, skip rebuild even if indexes are empty
+      // Indexes will load lazily on first query
+      if (this.config.disableAutoRebuild === true) {
+        if (!this.config.silent) {
+          console.log('⚡ Indexes empty but auto-rebuild disabled - using lazy loading')
+        }
+        return
+      }
+
       // Small dataset: Rebuild all indexes for best performance
       if (totalCount < AUTO_REBUILD_THRESHOLD || this.config.disableAutoRebuild === false) {
         if (!this.config.silent) {