Merge Message Context Windows

Problem Statement

You are building a message threading feature that tracks "context windows" for ongoing conversations. Each window is represented as a pair of integers [start, end], where start and end are timestamps of messages. Because multiple services log these windows, you often receive redundant or overlapping data.

Given a list of message windows intervals where intervals[i] = [start_i, end_i], merge all overlapping intervals and return an array of the non-overlapping intervals that cover all the windows in the input.

Function Signature

def merge_windows(intervals: List[List[int]]) -> List[List[int]]:

Constraints

• 1 <= intervals.length <= 10^4
• 0 <= start_i <= end_i <= 10^9

Examples

Example 1: Input: intervals = [[1, 3], [2, 6], [8, 10], [15, 18]] Output: [[1, 6], [8, 10], [15, 18]] Explanation: Since [1, 3] and [2, 6] overlap, merge them into [1, 6].

Example 2: Input: intervals = [[1, 4], [4, 5]] Output: [[1, 5]] Explanation: Windows that share a boundary point are considered overlapping and should be merged.

Edge Cases

• Single interval in the list.
• All intervals are disjoint.
• All intervals are nested within one another (e.g., [[1, 10], [2, 5], [6, 7]]).