Though a clause inserted last week into a draft agreement between the town and New Canaan Library would appear to forestall a decision on whether to demolish the original 1913 library building for at least two years during construction, the fate of that structure must be decided far sooner, an attorney said Tuesday. While it’s true that the library will operate out of its existing building until the new one is completed and ready for move-in, the Planning & Zoning Commission must approve the library’s full plan for the site even before construction starts, including for the century-old structure overlooking Main and Cherry Streets, according to Ted O’Hanlan, a longtime partner at Stamford-based Robinson + Cole who was nominated last week as a state Superior Court judge (the class of nominees awaits confirmation by the General Assembly). P&Z “has to approve a plan before we can start anything, so this will be resolved by then,”” O’Hanlan told members of the Board of Selectmen during their regular meeting, held via videoconference. “I don’t believe it can be an open issue,” O’Hanlan added, where construction can commence without a final plan for the 1913 library. “The library plans to put forward a very articulated reason why it’s not proposing to save the 1913 building,” he said.