import pandas as pd


def data_processing(df: pd.DataFrame) -> pd.DataFrame:
    """
    For each id, creates a new row with the longest content and the highest score
    from the available rows with the same id. Adds a boolean column 'updated'
    indicating whether the row was updated.

    Parameters:
    - df (pd.DataFrame): The input DataFrame with columns 'id', 'content', and 'score'.

    Returns:
    - pd.DataFrame: A DataFrame with unique ids, where each id is associated
                    with the longest content available and the highest score from
                    potentially different rows, and a boolean column 'updated'.
    """

    # Create a copy of the original DataFrame to avoid modifying it directly
    original_df = df.copy()

    # Create a column for content length
    df['content_length'] = df['content'].str.len()

    # Find row with the longest content for each 'id'
    idx_longest_content = df.groupby('id')['content_length'].idxmax()
    df_longest_content = df.loc[idx_longest_content][['id', 'content']]

    # Find row with the highest score for each 'id'
    idx_highest_score = df.groupby('id')['score'].idxmax()
    df_highest_score = df.loc[idx_highest_score][['id', 'score']]

    # Merge the two DataFrames on 'id'
    df_merged = pd.merge(df_longest_content, df_highest_score, on='id')

    # Merge with original DataFrame to compare content and score
    df_merged = df_merged.merge(original_df, on='id', suffixes=('', '_original'))

    # Check if the content or score was updated for each id
    df_merged['updated'] = (df_merged['content'] != df_merged['content_original'])

    # Drop original content and score columns
    df_merged.drop(columns=['content_original', 'score_original'], inplace=True)

    # Drop duplicates to keep only the rows with longest content and highest score
    df_merged.drop_duplicates(subset='id', inplace=True)

    return df_merged


if __name__ == '__main__':
    # Mock data
    data = {
        'id': [1, 1, 2, 2, 3],
        'content': ['short', 'much longer content', 'mid', 'size', 'constant'],
        'score': [10, 5, 7, 9, 6],
        'another_column': ['a', 'a', 'b', 'b', 'c']
        }

    df = pd.DataFrame(data)

    print("Original DataFrame:")
    print(df)
    print("\nFiltered DataFrame:")
    print(data_processing(df))