fix(groups): keep persisted group metadata in sync on membership change

src/features/groups.rs

@@ -415,6 +415,17 @@ impl<'a> Groups<'a> {
     pub async fn leave(&self, jid: &Jid) -> Result<(), anyhow::Error> {
         self.client.execute(LeaveGroupIq::new(jid)).await?;
         self.client.get_group_cache().await.invalidate(jid).await;
+        // Drop the persisted blob too: we're no longer in the group, so a stale
+        // phash from it would only force a needless full re-query if ever read.
+        if let Err(e) = self
+            .client
+            .persistence_manager
+            .backend()
+            .delete_group_metadata(&jid.to_string())
+            .await
+        {
+            log::warn!("Failed to delete persisted group metadata for {jid}: {e}");
+        }
         Ok(())
     }
 
@@ -446,7 +457,11 @@ impl<'a> Groups<'a> {
                         .filter(|r| r.is_ok())
                         .map(|r| (&r.jid, r.phone_number.as_ref())),
                 );
+                self.client.persist_group_metadata(jid, &info).await;
                 group_cache.insert(jid.clone(), Arc::new(info)).await;
+            } else {
+                // Cache expired: can't patch in place, so drop the now-stale blob.
+                self.client.invalidate_persisted_group_metadata(jid).await;
             }
         }
         Ok(result)
@@ -471,7 +486,11 @@ impl<'a> Groups<'a> {
             if let Some(info) = group_cache.get(jid).await {
                 let mut info = Arc::unwrap_or_clone(info);
                 info.remove_participants(&accepted);
+                self.client.persist_group_metadata(jid, &info).await;
                 group_cache.insert(jid.clone(), Arc::new(info)).await;
+            } else {
+                // Cache expired: can't patch in place, so drop the now-stale blob.
+                self.client.invalidate_persisted_group_metadata(jid).await;
             }
             self.client
                 .rotate_sender_key_on_participant_remove(&jid.to_string(), &accepted)
@@ -994,6 +1013,38 @@ impl Client {
     pub fn groups(&self) -> Groups<'_> {
         Groups::new(self)
     }
+
+    /// Re-serialize and persist a group's metadata after a local membership change
+    /// so the phash fast-path stays consistent: the in-memory cache expires after
+    /// ~1h, after which a stale persisted blob would force a needless full re-query
+    /// (or be compared against the server as an out-of-date phash). Shared by the
+    /// participant-mutation API and the inbound group-notification handler.
+    pub(crate) async fn persist_group_metadata(&self, jid: &Jid, info: &GroupInfo) {
+        let backend = self.persistence_manager.backend();
+        match serde_json::to_vec(info) {
+            Ok(blob) => {
+                if let Err(e) = backend.put_group_metadata(&jid.to_string(), &blob).await {
+                    log::warn!("Failed to persist group metadata for {jid}: {e}");
+                }
+            }
+            Err(e) => log::warn!("Failed to serialize group metadata for {jid}: {e}"),
+        }
+    }
+
+    /// Drop the persisted group metadata on a membership change we can't patch in
+    /// place (the in-memory cache had already expired), so the next query re-fetches
+    /// fresh instead of comparing a now-stale phash. Without this, persisting only on
+    /// a cache hit would miss the exact post-expiry case this fix targets.
+    pub(crate) async fn invalidate_persisted_group_metadata(&self, jid: &Jid) {
+        if let Err(e) = self
+            .persistence_manager
+            .backend()
+            .delete_group_metadata(&jid.to_string())
+            .await
+        {
+            log::warn!("Failed to invalidate persisted group metadata for {jid}: {e}");
+        }
+    }
 }
 
 /// Extract the invite code from any supported invite URL format.

src/handlers/notification.rs

@@ -1380,6 +1380,9 @@ async fn handle_group_notification(client: &Arc<Client>, node: Arc<OwnedNodeRef>
                             .iter()
                             .map(|p| (&p.jid, p.phone_number.as_ref())),
                     );
+                    client
+                        .persist_group_metadata(&notification.group_jid, &info)
+                        .await;
                     group_cache
                         .insert(notification.group_jid.clone(), Arc::new(info))
                         .await;
@@ -1388,6 +1391,11 @@ async fn handle_group_notification(client: &Arc<Client>, node: Arc<OwnedNodeRef>
                         "Patched group cache for {}: added {} participants",
                         notification.group_jid.observe(), participants.len()
                     );
+                } else {
+                    // Cache expired: can't patch in place, so drop the now-stale blob.
+                    client
+                        .invalidate_persisted_group_metadata(&notification.group_jid)
+                        .await;
                 }
             }
             GroupNotificationAction::Remove { participants, .. } => {
@@ -1396,6 +1404,9 @@ async fn handle_group_notification(client: &Arc<Client>, node: Arc<OwnedNodeRef>
                 if let Some(info) = group_cache.get(&notification.group_jid).await {
                     let mut info = Arc::unwrap_or_clone(info);
                     info.remove_participants(&users);
+                    client
+                        .persist_group_metadata(&notification.group_jid, &info)
+                        .await;
                     group_cache
                         .insert(notification.group_jid.clone(), Arc::new(info))
                         .await;
@@ -1404,6 +1415,11 @@ async fn handle_group_notification(client: &Arc<Client>, node: Arc<OwnedNodeRef>
                         "Patched group cache for {}: removed {} participants",
                         notification.group_jid.observe(), participants.len()
                     );
+                } else {
+                    // Cache expired: can't patch in place, so drop the now-stale blob.
+                    client
+                        .invalidate_persisted_group_metadata(&notification.group_jid)
+                        .await;
                 }
                 client
                     .rotate_sender_key_on_participant_remove(

storages/sqlite-storage/src/sqlite_store.rs

@@ -2538,6 +2538,28 @@ impl ProtocolStore for SqliteStore {
         Ok(())
     }
 
+    async fn delete_group_metadata(&self, group_jid: &str) -> Result<()> {
+        let pool = self.pool.clone();
+        let device_id = self.device_id;
+        let group_jid = group_jid.to_string();
+        tokio::task::spawn_blocking(move || -> Result<()> {
+            let mut conn = pool
+                .get()
+                .map_err(|e| StoreError::Connection(Box::new(e)))?;
+            diesel::delete(
+                group_metadata::table
+                    .filter(group_metadata::group_jid.eq(&group_jid))
+                    .filter(group_metadata::device_id.eq(device_id)),
+            )
+            .execute(&mut conn)
+            .map_err(|e| StoreError::Database(Box::new(e)))?;
+            Ok(())
+        })
+        .await
+        .map_err(|e| StoreError::Database(Box::new(e)))??;
+        Ok(())
+    }
+
     async fn get_tc_token(&self, jid: &str) -> Result<Option<TcTokenEntry>> {
         let pool = self.pool.clone();
         let device_id = self.device_id;
@@ -3648,6 +3670,10 @@ mod tests {
             store.get_group_metadata(jid).await.unwrap().as_deref(),
             Some(&b"blob-v2"[..])
         );
+
+        // Delete drops the blob so the next query re-fetches in full.
+        store.delete_group_metadata(jid).await.unwrap();
+        assert!(store.get_group_metadata(jid).await.unwrap().is_none());
     }
 
     #[tokio::test]

wacore/src/store/in_memory.rs

@@ -517,6 +517,11 @@ impl ProtocolStore for InMemoryBackend {
         Ok(())
     }
 
+    async fn delete_group_metadata(&self, group_jid: &str) -> Result<()> {
+        self.state.lock().await.group_metadata.remove(group_jid);
+        Ok(())
+    }
+
     // --- TcToken Storage ---
 
     async fn get_tc_token(&self, jid: &str) -> Result<Option<TcTokenEntry>> {
@@ -730,6 +735,9 @@ mod tests {
             backend.get_group_metadata(jid).await.unwrap().as_deref(),
             Some(&b"blob-v2"[..])
         );
+        // Delete drops the blob so the next query re-fetches in full.
+        backend.delete_group_metadata(jid).await.unwrap();
+        assert!(backend.get_group_metadata(jid).await.unwrap().is_none());
     }
 
     #[tokio::test]

wacore/src/store/traits.rs

@@ -398,6 +398,13 @@ pub trait ProtocolStore: Send + Sync {
         Ok(())
     }
 
+    /// Remove the persisted group metadata blob for `group_jid` (e.g. on leave),
+    /// so the next query re-fetches in full instead of comparing a stale phash.
+    /// No-op by default.
+    async fn delete_group_metadata(&self, _group_jid: &str) -> Result<()> {
+        Ok(())
+    }
+
     // --- TcToken Storage ---
 
     /// Get a trusted contact token for a JID (stored under LID).