While working on the internal configuration editor at ReviewThat Labs, Lena was tasked with helping developers debug their nested logic. Eva suggested adding a small utility that calculates the length of the largest segment where every opening bracket is properly closed. For instance, in a messy sequence like ")()())", the tool should identify that the longest valid section is "()()" and return a length of four. This helper ensures the team can quickly isolate the most complete parts of their configuration files.