server: fix paging if only notmuch results are found

server/src/nm.rs

@@ -50,7 +50,13 @@ pub async fn search(
     last: Option<i32>,
     query: String,
 ) -> Result<Vec<(i32, ThreadSummary)>, async_graphql::Error> {
-    let (offset, limit) = compute_offset_limit(after, before, first, last);
+    let (offset, mut limit) = compute_offset_limit(after, before, first, last);
+    if before.is_none() {
+        // When searching forward, the +1 is to see if there are more pages of data available.
+        // Searching backwards implies there's more pages forward, because the value represented by
+        // `before` is on the next page.
+        limit = limit + 1;
+    }
     Ok(nm
         .search(&query, offset as usize, limit as usize)?
         .0