A session is meant to be either the main thread or a tile, never both.
openSessionTile enforced this from the tile side (refusing to tile the
selected session), but the main side never dropped an existing tile — so
any path that routes main to a session that's already tiled (cold-start
remembered-session restore, a pasted/Cmd-K route, a notification jump)
painted the same transcript twice: the workspace pane from the route and
the tile pane in parallel, both fighting one runtime.
resumeSession is the single chokepoint every load-into-main path funnels
through, so close the redundant tile there once the session becomes the
selection. The warm cache/runtime binding survives for main to reuse.
Brooklyn Nicholson
ab741ed331