Transcript Incremental Projection

Nucleic-Session: 0FFD007B-0696-4517-9429-129C7B0FD5AC
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Views/SessionDetailView.swift

@@ -633,22 +633,28 @@ struct TranscriptList: View {
             // they scroll away, which lets new content land off-screen below instead of dragging
             // the viewport, and restore `.bottom` once they're back at the end.
             .defaultScrollAnchor(isScrolledToBottom ? .bottom : nil)
+            .onScrollPhaseChange { _, newPhase in scrollPhase = newPhase }
             // Track the live scroll position straight from the scroll view's geometry: how much
-            // content still sits below the viewport bottom. Within the slack threshold means the
-            // user is parked at the end (live output keeps following); scrolling up flips this
-            // false, which drops the anchor (above) and reveals the jump-to-bottom chevron.
-            .onScrollGeometryChange(for: Bool.self) { geo in
-                geo.contentSize.height - geo.containerSize.height - geo.contentOffset.y
-                    <= bottomFollowThreshold
-            } action: { _, atBottom in
-                // While the chat is opening the layout grows over a few passes and the scroll
-                // offset lags each growth by a frame — sampling that frame reads "not at bottom"
-                // even though `.defaultScrollAnchor(.bottom)` is about to re-pin. So during the
-                // open window accept only "at bottom" readings; honor real scroll-ups after.
-                if transcriptSettling {
-                    if atBottom { isScrolledToBottom = true }
-                } else {
-                    isScrolledToBottom = atBottom
+            // content still sits below the viewport bottom. Parked within the follow threshold
+            // means live output keeps following; a *user* scroll past the (wider) unfollow
+            // threshold flips it false, which drops the anchor (above) and reveals the chevron.
+            // Asymmetric on purpose — see `bottomUnfollowThreshold` / `isUserScrolling`: a
+            // programmatic geometry change (anchor re-pin, bar resize, keyboard, autoscroll
+            // animation) may re-engage following but can never disengage it, so no layout
+            // feedback cycle through this gate can sustain itself. Tracking the rounded distance
+            // (not a Bool) also means every scroll emits fresh values, so the gate can't latch
+            // against a stale reading (the old settle-window latch bug).
+            .onScrollGeometryChange(for: CGFloat.self) { geo in
+                (geo.contentSize.height - geo.containerSize.height - geo.contentOffset.y).rounded()
+            } action: { _, distance in
+                if distance <= bottomFollowThreshold {
+                    isScrolledToBottom = true
+                } else if !transcriptSettling, distance > bottomUnfollowThreshold, isUserScrolling {
+                    // While the chat is opening the layout grows over a few passes and the offset
+                    // lags each growth by a frame — those frames read "not at bottom" even though
+                    // `.defaultScrollAnchor(.bottom)` is about to re-pin, so settling accepts
+                    // only re-engagement (the `!transcriptSettling` above).
+                    isScrolledToBottom = false
                 }
             }
             // Detect when the opening layout has come to rest: track the content height while