⚡ Bolt: Optimize handle ID generation to reduce GC overhead

.jules/bolt.md

@@ -77,3 +77,6 @@ Optimized metric route processing to O(N) by creating a mapping of routes direct
 ## 2024-07-13 - [Optimize Export Dictionary FK lookups]
 **Learning:** Found O(N * C * E) performance bottleneck in ERD export dictionaries due to repeated array searching with `edges.some()` inside a nested loop over nodes and columns.
 **Action:** Replace repeated linear array scans for edges by precomputing O(1) Set lookups of foreign key column handles per node before looping.
+## 2024-07-28 - Avoid Array.from for String Iteration in High-Frequency Paths
+**Learning:** Using `Array.from(string, callback).join("-")` for string processing creates unnecessary intermediate array allocations, adding garbage collection (GC) pressure, especially when executed in high-frequency paths like generating handle IDs for nodes and edges in large graphs.
+**Action:** Replace `Array.from(string)` processing with a standard `for...of` loop (which natively supports Unicode code point iteration) and direct string concatenation to eliminate array allocations and improve execution speed.

frontend/src/erd/handleUtils.ts

@@ -1,10 +1,18 @@
 export function sanitizeHandleId(columnName: string): string {
-  const encoded = Array.from(columnName, (char) => {
-    // Array.from only yields non-empty Unicode scalars, so codePointAt(0) is defined.
-    return char.codePointAt(0)!.toString(16).padStart(4, '0')
-  }).join('-')
+  if (!columnName) return 'c-empty';
 
-  return `c-${encoded || 'empty'}`
+  let encoded = '';
+  let isFirst = true;
+  for (const char of columnName) {
+    if (!isFirst) {
+      encoded += '-';
+    }
+    // for...of correctly iterates over Unicode code points in JavaScript strings
+    encoded += char.codePointAt(0)!.toString(16).padStart(4, '0');
+    isFirst = false;
+  }
+
+  return `c-${encoded}`;
 }
 
 export function sourceColumnHandleId(columnName: string): string {