diff --git a/hive-matrix-mcp/src/main.rs b/hive-matrix-mcp/src/main.rs
index bcb641c5..3b80bc4a 100644
--- a/hive-matrix-mcp/src/main.rs
+++ b/hive-matrix-mcp/src/main.rs
@@ -749,6 +749,27 @@ async fn restore_account(cfg: &AccountCfg, is_primary: bool) -> Result<Option<Cl
     Ok(Some(client))
 }
 
+/// The server-side sync filter every account uses. The default (no filter)
+/// ships presence, typing notices, full member state and unbounded
+/// timelines in every delta, about 50 MB/h on a busy public homeserver.
+/// This keeps what the daemon uses: room messages (short timelines; unread
+/// scanning pages back with `/messages`), read receipts (the agent's own
+/// receipt marks what it has read), invites and account data. Members are
+/// lazy-loaded: `Room::members` fetches the full list on demand.
+fn sync_filter() -> matrix_sdk::ruma::api::client::sync::sync_events::v3::Filter {
+    use matrix_sdk::ruma::api::client::{filter::FilterDefinition, sync::sync_events::v3::Filter};
+    let definition: FilterDefinition = serde_json::from_value(serde_json::json!({
+        "presence": {"not_types": ["*"]},
+        "room": {
+            "ephemeral": {"not_types": ["m.typing"]},
+            "state": {"lazy_load_members": true},
+            "timeline": {"limit": 20},
+        },
+    }))
+    .expect("the sync filter is a valid filter definition");
+    Filter::FilterDefinition(definition)
+}
+
 /// `client`'s sync loop, sweeping invites and unread rooms into todos tagged
 /// `tag` after each sync. Builds the loop only; nothing runs until it is
 /// polled. Never wipes the todo set: that is `main`'s, once, at startup.
@@ -762,17 +783,20 @@ fn account_sync_loop(client: &Client, tag: Option<String>) -> SyncLoop {
     let unread_notified = Arc::new(tokio::sync::Mutex::new(std::collections::HashSet::new()));
     Box::pin(async move {
         sync_client
-            .sync_with_callback(SyncSettings::default(), move |_response| {
-                let client = cb_client.clone();
-                let invite_notified = invite_notified.clone();
-                let unread_notified = unread_notified.clone();
-                let tag = tag.clone();
-                async move {
-                    timeline::sweep_invites(&client, &invite_notified, tag.as_deref()).await;
-                    timeline::sweep_unread(&client, &unread_notified, tag.as_deref()).await;
-                    matrix_sdk::LoopCtrl::Continue
-                }
-            })
+            .sync_with_callback(
+                SyncSettings::default().filter(sync_filter()),
+                move |_response| {
+                    let client = cb_client.clone();
+                    let invite_notified = invite_notified.clone();
+                    let unread_notified = unread_notified.clone();
+                    let tag = tag.clone();
+                    async move {
+                        timeline::sweep_invites(&client, &invite_notified, tag.as_deref()).await;
+                        timeline::sweep_unread(&client, &unread_notified, tag.as_deref()).await;
+                        matrix_sdk::LoopCtrl::Continue
+                    }
+                },
+            )
             .await
             .context("matrix-sdk sync loop exited")?;
         Ok(())
@@ -781,6 +805,28 @@ fn account_sync_loop(client: &Client, tag: Option<String>) -> SyncLoop {
 
 #[cfg(test)]
 mod tests {
+    /// The filter keeps the sync cheap: no presence, no typing, lazy members,
+    /// short timelines. Receipts must stay: the unread check reads the
+    /// agent's own.
+    #[test]
+    fn the_sync_filter_drops_the_bulk_and_keeps_receipts() {
+        use matrix_sdk::ruma::api::client::sync::sync_events::v3::Filter;
+
+        let Filter::FilterDefinition(def) = super::sync_filter() else {
+            panic!("an inline definition, not a filter id");
+        };
+        let v = serde_json::to_value(&def).expect("serialize");
+        assert_eq!(v["presence"]["not_types"], serde_json::json!(["*"]));
+        let ephemeral = &v["room"]["ephemeral"]["not_types"];
+        assert_eq!(*ephemeral, serde_json::json!(["m.typing"]));
+        assert!(
+            !ephemeral.to_string().contains("receipt"),
+            "receipts are kept"
+        );
+        assert_eq!(v["room"]["state"]["lazy_load_members"], true);
+        assert_eq!(v["room"]["timeline"]["limit"], 20);
+    }
+
     use std::time::Duration;
 
     use tokio::time::Instant;