feat(transport): introduce transport abstraction and socket-mode support for RustBridge

ts/classes.linescanner.ts

@@ -0,0 +1,51 @@
+import type { IRustBridgeLogger } from './interfaces/index.js';
+
+/**
+ * Buffer-based newline scanner for streaming binary data.
+ * Accumulates chunks and emits complete lines via callback.
+ * Used by both StdioTransport and SocketTransport.
+ */
+export class LineScanner {
+  private buffer: Buffer = Buffer.alloc(0);
+  private maxPayloadSize: number;
+  private logger: IRustBridgeLogger;
+
+  constructor(maxPayloadSize: number, logger: IRustBridgeLogger) {
+    this.maxPayloadSize = maxPayloadSize;
+    this.logger = logger;
+  }
+
+  /**
+   * Feed a chunk of data. Calls onLine for each complete newline-terminated line found.
+   */
+  public push(chunk: Buffer, onLine: (line: string) => void): void {
+    this.buffer = Buffer.concat([this.buffer, chunk]);
+
+    let newlineIndex: number;
+    while ((newlineIndex = this.buffer.indexOf(0x0A)) !== -1) {
+      const lineBuffer = this.buffer.subarray(0, newlineIndex);
+      this.buffer = this.buffer.subarray(newlineIndex + 1);
+
+      if (lineBuffer.length > this.maxPayloadSize) {
+        this.logger.log('error', `Inbound message exceeds maxPayloadSize (${lineBuffer.length} bytes), dropping`);
+        continue;
+      }
+
+      const line = lineBuffer.toString('utf8').trim();
+      if (line) {
+        onLine(line);
+      }
+    }
+
+    // Prevent OOM if sender never sends newline
+    if (this.buffer.length > this.maxPayloadSize) {
+      this.logger.log('error', `Buffer exceeded maxPayloadSize (${this.buffer.length} bytes) without newline, clearing`);
+      this.buffer = Buffer.alloc(0);
+    }
+  }
+
+  /** Reset the internal buffer. */
+  public clear(): void {
+    this.buffer = Buffer.alloc(0);
+  }
+}