Add JSDoc to splitAnsiCarryover function

src/server.ts

@@ -81,8 +81,22 @@ function broadcastSSE(event: SSEEvent): void {
   }
 }
 
-// Detect and split any incomplete ANSI control sequence at the end of a chunk.
+/**
-// Returns [body, carry] where carry should be saved and prepended to the next chunk.
+ * Detect and split any incomplete ANSI control sequence at the end of a chunk.
+ *
+ * ANSI sequences can span multiple network packets. This function identifies
+ * incomplete sequences at the end of a chunk to prevent them from being
+ * rendered as partial/broken control codes.
+ *
+ * @param chunk - Raw output string potentially containing ANSI sequences
+ * @returns Tuple of [body, carry] where:
+ *   - body: Complete portion safe to render
+ *   - carry: Incomplete sequence to prepend to next chunk
+ *
+ * @example
+ * const [body, carry] = splitAnsiCarryover("hello\x1b[31");
+ * // body = "hello", carry = "\x1b[31"
+ */
 function splitAnsiCarryover(chunk: string): [string, string] {
   if (!chunk) return ["", ""];