Transcript Incremental Projection

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

NucleicRemote/NucleicRemote/Models/RemoteStore.swift

@@ -659,6 +659,19 @@ final class RemoteStore: ObservableObject {
             self.openEvents = Self.mergedEvents(self.openEvents, batch.events)
             self.persistOpenTranscript()
         }
+        cb.transcriptPrefetched = { [weak self] sessionID, events in
+            guard let self else { return }
+            self.prefetchInFlight = nil
+            if !events.isEmpty {
+                // Merge into whatever the cache already holds (the fetch pulled only the gap);
+                // `saveEvents` re-caps to the tail window on write.
+                Task {
+                    let cached = await SessionCache.loadEvents(sessionID)
+                    await SessionCache.saveEvents(Self.mergedEvents(cached, events), for: sessionID)
+                }
+            }
+            self.pumpTranscriptPrefetch()
+        }
         cb.openDiff = { [weak self] diff in
             guard let self, hostID == self.openSessionHostID, diff.sessionID == self.openSessionID else { return }
             self.openDiff = diff