diff --git a/src/chat/delivery/waku_client.nim b/src/chat/delivery/waku_client.nim
index 35422a0..8c1897e 100644
--- a/src/chat/delivery/waku_client.nim
+++ b/src/chat/delivery/waku_client.nim
@@ -451,6 +451,52 @@ proc start*(client: WakuClient) {.async.} =
         leafIndex = success.leafIndex,
         configAccount = configAccountId
 
+      # Background watcher: gifter returns a PRE-SUBMIT leaf_index snapshot,
+      # which can be wrong if a concurrent register tx claimed the slot
+      # first. Poll the gifter over a SEPARATE short-lived libp2p stream
+      # (membership status codec) until the on-chain membership PDA
+      # materialises for our id; if the authoritative leaf differs,
+      # rewrite lezGm.membershipIndex so subsequent proofs are valid. The
+      # pre-publish self-verify rejects bad proofs in the meantime.
+      let optimisticLeafChat = success.leafIndex
+      let watcherClient = gifterClient
+      let watcherPeer = gifterPeer
+      let watcherIdCommit = idCommitmentBytes
+      asyncSpawn (proc(): Future[void] {.async.} =
+        const pollEveryMs = 30_000
+        const deadlineMs = 1_800_000
+        let deadline = Moment.now() + chronos.milliseconds(deadlineMs)
+        while Moment.now() < deadline:
+          try:
+            await sleepAsync(chronos.milliseconds(pollEveryMs))
+          except CancelledError:
+            return
+          let qr =
+            try:
+              await watcherClient.queryMembershipStatus(
+                watcherPeer, configAccountId, watcherIdCommit)
+            except CancelledError:
+              return
+            except CatchableError as e:
+              Result[rln_gifter_protocol.MembershipStatusResponse, string].err(
+                "queryMembershipStatus raised: " & e.msg)
+          if qr.isErr: continue
+          let resp = qr.get()
+          if resp.errorMessage.isSome: continue
+          if not resp.registered: continue
+          if resp.leafIndex.isSome:
+            let authLeaf = resp.leafIndex.get()
+            if authLeaf != optimisticLeafChat:
+              info "Chat-client membership leaf corrected from optimistic",
+                optimistic = optimisticLeafChat, authoritative = authLeaf
+              lezGm.membershipIndex =
+                some(onchain_group_manager.MembershipIndex(authLeaf))
+              mix_lez_client.setRlnConfig(configAccountId, authLeaf.int)
+            return
+        warn "Chat-client membership confirmation timed out",
+          optimisticLeaf = optimisticLeafChat
+      )()
+
   asyncSpawn taskKeepAlive(client)
 
   if client.cfg.mixEnabled and not client.node.wakuMix.isNil:
diff --git a/vendor/nwaku b/vendor/nwaku
index 33d9d89..ce6f5c2 160000
--- a/vendor/nwaku
+++ b/vendor/nwaku
@@ -1 +1 @@
-Subproject commit 33d9d89e00be774d33ceafd3d59755d5a1089bb4
+Subproject commit ce6f5c2d5e184b7c94a65068d4e5f29936259020