perf(encoding): optimize StringEncoder with direct encodeInto

Author: google-labs-jules[bot]

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-01-19 - Avoid Intermediate Buffers with TextEncoder
+**Learning:** TextEncoder.encodeInto works directly with Uint8Array views on SharedArrayBuffer. Intermediate buffers and copying are unnecessary and can double the execution time.
+**Action:** Check TextEncoder usage for direct writing to destination buffers.

src/encoding/StringEncoder.ts

@@ -1,35 +1,20 @@
 import Serializable from "./Serializable";
 
 export default class StringEncoder implements Serializable<string> {
-    // Default size of the decoder buffer that's always reused (in bytes)
-    private static readonly ENCODER_BUFFER_SIZE = 16384
-
     private textEncoder = new TextEncoder();
     private textDecoder = new TextDecoder();
 
-    private encoderBuffer: ArrayBuffer = new ArrayBuffer(StringEncoder.ENCODER_BUFFER_SIZE);
-    private encoderArray: Uint8Array = new Uint8Array(this.encoderBuffer);
-    private currentDecoderBufferSize: number = StringEncoder.ENCODER_BUFFER_SIZE;
-
     decode(buffer: Uint8Array): string {
         return this.textDecoder.decode(buffer);
     }
 
     encode(stringValue: string, destination: Uint8Array): number {
         // Safari does not support the encodeInto function
         if (this.textEncoder.encodeInto !== undefined) {
-            const maxStringLength = stringValue.length * 3;
-
-            if (this.currentDecoderBufferSize < maxStringLength) {
-                this.encoderBuffer = new ArrayBuffer(maxStringLength);
-                this.encoderArray = new Uint8Array(this.encoderBuffer);
-                this.currentDecoderBufferSize = maxStringLength;
-            }
-
-            const writeResult = this.textEncoder.encodeInto(stringValue, this.encoderArray);
-            const writeLength = writeResult.written || 0;
-            destination.set(this.encoderArray.subarray(0, writeLength));
-            return writeLength;
+            // Optimization: Write directly to destination to avoid intermediate buffer and copy.
+            // destination is guaranteed to be large enough (max string length * 3) by the caller (ShareableArray).
+            const writeResult = this.textEncoder.encodeInto(stringValue, destination);
+            return writeResult.written || 0;
         } else {
             const encodedString = this.textEncoder.encode(stringValue);
             destination.set(encodedString);