Guard fallback pulls after abort

src/app/core/sync.ts

@@ -76,6 +76,8 @@ const pullOneWithFallback = async (
   signal: AbortSignal,
   onEvent?: (event: TrustedEvent) => void,
 ) => {
+  if (signal.aborted) return
+
   const cachedEvents = repository.query([filter]).filter(isSignedEvent)
   const since = last(cachedEvents.slice(10))?.created_at || 0
 
@@ -93,7 +95,7 @@ const pullOneWithFallback = async (
         return
       }
 
-      // If visibility flips while the negentropy diff is opening, skip the fallback path and let teardown win.
+      // If teardown wins while the diff is opening, skip the fallback path and let cleanup stay in control.
       const diff = new Difference({relay: url, filter, events: cachedEvents, signal})
 
       diff.on(DifferenceEvent.Error, () => {
@@ -129,6 +131,8 @@ const listen = ({url, signal, filters, onEvent}: SyncOpts) => {
 }
 
 const pullAndListen = (options: SyncOpts) => {
+  if (options.signal.aborted) return
+
   pullWithFallback(options)
   listen(options)
 }