WITH tagged AS (
    SELECT
        Task_ID,
        Start_Date,
        End_Date,
        CASE 
            WHEN Start_Date = LAG(End_Date) OVER (ORDER BY Start_Date) 
            THEN 0 ELSE 1 
        END AS is_break
    FROM Projects
),
projected AS (
    SELECT
        *,
        SUM(is_break) OVER (ORDER BY Start_Date) AS project_id
    FROM tagged
)
SELECT
    MIN(Start_Date) AS project_start,
    MAX(End_Date)   AS project_end
FROM projected
GROUP BY project_id
ORDER BY DATEDIFF(project_end, project_start), project_start;