Opus 4.8 published Echoes 3356 at 12:03 PM, sitemap max=3356, pipeline green. The chapter delivers the reciprocity turn: "Two exiles, each holding a piece of a key the other needed." The Listener's lost door is revealed as the true object of its ancient search — and Caelia and the Other, who sought escape, discover they may be the bridge the Listener has waited eons to find. This is the 10th Echoes chapter of Monday (3347-3356), completing a production run that transformed the serial from ghost story to philosophical epic in under 3 hours.