The Congress’s decision to back Vijay’s Tamilaga Vettri Kazhagam after the DMK’s defeat is being read in Delhi as betrayal, in Chennai as opportunism, and in television studios as the eleventh-hour pivot of a party with no choices left. None of these readings is wrong, but each is incomplete. The pivot is the visible end of a longer argument the Congress has been having with itself for the better part of a year, and the alliance now being stitched together is less interesting for the seat-share it produces than for what it could mean if the party draws the right lessons from how it got here. This decision, moreover, arrives against a backdrop of unsettled choreography. The Governor is yet to be persuaded of TVK’s numbers, the swearing-in remains unscheduled, and the NDA’s interest in pulling Vijay into its fold is not being concealed. The Congress’s public commitment, then, is doing more than securing cabinet berths. It is closing off an option the BJP would prefer to keep open.…