Fix input line wrapping pushing chat up

- Horizontal scroll for input when exceeding terminal width
- Never wraps to next line or disturbs scroll region

main.c

@@ -768,10 +768,58 @@ static size_t utf8_back(const char *buf, size_t pos)
 static void redraw_input(const char *input_line, size_t input_len,
                          size_t input_pos)
 {
+	int avail = term_cols - 2; /* columns available after "> " */
+	size_t total_cols = display_cols(input_line, input_len);
 	size_t cpos_cols = display_cols(input_line, input_pos);
+
 	printf("\033[%d;1H\033[K\033[32m>\033[0m ", term_rows);
-	fwrite(input_line, 1, input_len, stdout);
+
-	printf("\033[%d;%dH", term_rows, (int)(cpos_cols + 3));
+	if ((int)total_cols <= avail) {
+		/* Fits entirely */
+		fwrite(input_line, 1, input_len, stdout);
+		printf("\033[%d;%dH", term_rows, (int)(cpos_cols + 3));
+	} else {
+		/* Scroll horizontally: show a window around cursor */
+		size_t win_start_bytes = 0;
+		size_t win_start_cols = 0;
+
+		/* If cursor is past the visible area, shift window */
+		if ((int)cpos_cols >= avail) {
+			/* Move window so cursor is near the right edge */
+			size_t target_cols = cpos_cols - (size_t)(avail - 1);
+			size_t i = 0, cols = 0;
+			while (i < input_len && cols < target_cols) {
+				unsigned char c = (unsigned char)input_line[i];
+				if (c < 0x80) i++;
+				else if ((c & 0xE0) == 0xC0) i += 2;
+				else if ((c & 0xF0) == 0xE0) i += 3;
+				else if ((c & 0xF8) == 0xF0) i += 4;
+				else i++;
+				cols++;
+			}
+			win_start_bytes = i;
+			win_start_cols = cols;
+		}
+
+		/* Write characters that fit in avail columns */
+		size_t i = win_start_bytes;
+		int cols_written = 0;
+		while (i < input_len && cols_written < avail) {
+			unsigned char c = (unsigned char)input_line[i];
+			size_t clen = 1;
+			if (c >= 0x80) {
+				if ((c & 0xE0) == 0xC0) clen = 2;
+				else if ((c & 0xF0) == 0xE0) clen = 3;
+				else if ((c & 0xF8) == 0xF0) clen = 4;
+			}
+			fwrite(input_line + i, 1, clen, stdout);
+			i += clen;
+			cols_written++;
+		}
+
+		int cursor_col = (int)(cpos_cols - win_start_cols + 3);
+		printf("\033[%d;%dH", term_rows, cursor_col);
+	}
 	fflush(stdout);
 }