fix(chat): translate session replay cursors

tkmind-proxy.mjs

@@ -44,6 +44,7 @@ import {
   isSessionStreamReplayEnabled,
   parseSessionSseBlock,
   parseSessionStreamLastEventId,
+  resolveUpstreamResumeEventId,
   shouldPersistSessionStreamEvent,
   shouldSkipUpstreamAfterSessionReplay,
 } from './session-stream.mjs';
@@ -2154,6 +2155,7 @@ export function createTkmindProxy({
     let clientClosed = false;
     const replayEnabled = isSessionStreamReplayEnabled() && sessionStreamStore;
     const initialLastEventId = parseSessionStreamLastEventId(req.get('last-event-id'));
+    let upstreamLastEventId = replayEnabled ? null : initialLastEventId;
     const abortUpstream = () => {
       clientClosed = true;
       upstreamAbort.abort();
@@ -2210,17 +2212,22 @@ export function createTkmindProxy({
           if (!res.writableEnded) res.end();
           return;
         }
+        upstreamLastEventId = resolveUpstreamResumeEventId(
+          batch?.events ?? [],
+          batch?.cursorEvent ?? null,
+        );
       }
 
       const pathname = `/sessions/${sessionId}/events`;
       const sessionTarget = await resolveTarget(sessionId);
+      const upstreamHeaders = { Accept: 'text/event-stream' };
+      if (upstreamLastEventId) {
+        upstreamHeaders['Last-Event-ID'] = upstreamLastEventId;
+      }
       const upstream = await apiFetch(sessionTarget, apiSecret, pathname, {
         method: 'GET',
         signal: upstreamAbort.signal,
-        headers: {
-          Accept: 'text/event-stream',
-          'Last-Event-ID': req.get('last-event-id') ?? '',
-        },
+        headers: upstreamHeaders,
       });
       if (clientClosed) return;