Fix pagination by anchor for queued messages, tasks and metrics

tests/src/telemetry/metrics.rs

@@ -72,6 +72,114 @@ pub async fn test(test: &TestServer) {
         metric_ids.len()
     );
 
+    // Test pagination (forward and reverse)
+    let asc_order: Vec<Id> = admin
+        .registry_query_paginated(
+            ObjectType::Metric,
+            "timestamp",
+            true,
+            None,
+            None,
+            None,
+            None,
+            false,
+        )
+        .await
+        .object_ids()
+        .collect();
+    assert!(asc_order.len() > 100, "expected >100 metrics, got {}", asc_order.len());
+    let desc_order: Vec<Id> = asc_order.iter().rev().copied().collect();
+    let total = asc_order.len();
+    let limit = 25usize;
+
+    for chunk_start in [0usize, limit, total - limit] {
+        let asc = admin
+            .registry_query_paginated(
+                ObjectType::Metric,
+                "timestamp",
+                true,
+                Some(chunk_start as i32),
+                Some(limit),
+                None,
+                None,
+                false,
+            )
+            .await
+            .object_ids()
+            .collect::<Vec<_>>();
+        assert_eq!(
+            asc,
+            asc_order[chunk_start..chunk_start + limit],
+            "ascending position={chunk_start} limit={limit}",
+        );
+
+        let desc = admin
+            .registry_query_paginated(
+                ObjectType::Metric,
+                "timestamp",
+                false,
+                Some(chunk_start as i32),
+                Some(limit),
+                None,
+                None,
+                false,
+            )
+            .await
+            .object_ids()
+            .collect::<Vec<_>>();
+        assert_eq!(
+            desc,
+            desc_order[chunk_start..chunk_start + limit],
+            "descending position={chunk_start} limit={limit}",
+        );
+    }
+
+    for anchor_idx in [limit - 1, total - limit - 1] {
+        let asc = admin
+            .registry_query_paginated(
+                ObjectType::Metric,
+                "timestamp",
+                true,
+                None,
+                Some(limit),
+                Some(asc_order[anchor_idx]),
+                Some(1),
+                false,
+            )
+            .await
+            .object_ids()
+            .collect::<Vec<_>>();
+        let asc_size = std::cmp::min(limit, total - anchor_idx - 1);
+        assert_eq!(
+            asc,
+            asc_order[anchor_idx + 1..anchor_idx + 1 + asc_size],
+            "ascending anchor={} offset=1 limit={limit}",
+            asc_order[anchor_idx],
+        );
+
+        let desc = admin
+            .registry_query_paginated(
+                ObjectType::Metric,
+                "timestamp",
+                false,
+                None,
+                Some(limit),
+                Some(desc_order[anchor_idx]),
+                Some(1),
+                false,
+            )
+            .await
+            .object_ids()
+            .collect::<Vec<_>>();
+        let desc_size = std::cmp::min(limit, total - anchor_idx - 1);
+        assert_eq!(
+            desc,
+            desc_order[anchor_idx + 1..anchor_idx + 1 + desc_size],
+            "descending anchor={} offset=1 limit={limit}",
+            desc_order[anchor_idx],
+        );
+    }
+
     // Purge metrics and make sure they are gone
     test.server
         .metrics_store()