Fetch Historical Transcript Data

Nucleic-Session: 11465D90-A8F3-43AA-A1DC-37EA1EC1B909
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Models/HostConnection.swift

@@ -630,6 +630,21 @@ final class HostConnection {
         Task { await client.send(msg) }
     }
 
+    /// Pull the open session's *full* transcript via mesh full-transcript sync and merge it into the
+    /// transcript on screen. The cold `subscribe` only returns the host's 200-event tail, so without
+    /// this the phone shows nothing from before it connected. `afterSeq: 0` asks for the whole history
+    /// (overlap with the tail is deduped on arrival). Idempotent per open — guarded by
+    /// `didStartFullFetch` — and a no-op when the host predates `canSyncTranscripts` (the tail still
+    /// shows) or the connection isn't live yet (the reconnect handler retries once it is).
+    func fetchFullTranscript(_ sessionID: SessionID) {
+        guard sessionID == openSessionID, !didStartFullFetch,
+              capabilities.canSyncTranscripts, client != nil else { return }
+        didStartFullFetch = true
+        let requestID = UUID().uuidString
+        transcriptFetchRequestID = requestID
+        send(.fetchTranscript(TranscriptFetch(requestID: requestID, sessionID: sessionID, afterSeq: 0)))
+    }
+
     /// The device's network path changed (Wi-Fi ⇄ cellular, joined/left a network). React now rather
     /// than waiting for a zombie LAN socket to time out or the reconnect backoff to elapse — this is
     /// what makes the transport switch feel immediate. Only reconnect-managed hosts (a pinned host)