diff --git a/crates/asap_types/src/capability_matching.rs b/crates/asap_types/src/capability_matching.rs
index 3ddd270e..57330399 100644
--- a/crates/asap_types/src/capability_matching.rs
+++ b/crates/asap_types/src/capability_matching.rs
@@ -235,11 +235,18 @@ pub fn compatible_agg_types(stat: Statistic) -> &'static [AggregationType] {
         // signed-counter matrix). `CountSketchAccumulator` answers
         // `Statistic::Topk` directly — see
         // `precompute_operators/count_sketch_accumulator.rs:284`.
-        // Without CountSketch listed here, `topk(K, top_endpoint_qps)`
-        // capability-misses and the warm engine returns `status=error`.
+        // `CountSketchWithHeap` is the explicit heap-bearing variant
+        // that also satisfies Topk through the heap directly
+        // (parallel to `CountMinSketchWithHeap`); the analyzer's
+        // `topk(...)` candidate returns `FrequencyTopk(Any)` so
+        // either heap-bearing variant matches.
+        // Without CountSketch / CountSketchWithHeap listed here,
+        // `topk(K, top_endpoint_qps)` capability-misses and the
+        // warm engine returns `status=error`.
         Statistic::Topk => &[
             AggregationType::CountMinSketchWithHeap,
             AggregationType::CountSketch,
+            AggregationType::CountSketchWithHeap,
         ],
     }
 }
diff --git a/crates/promql_utilities/src/query_logics/logics.rs b/crates/promql_utilities/src/query_logics/logics.rs
index 8aa4c4c3..9772c18f 100644
--- a/crates/promql_utilities/src/query_logics/logics.rs
+++ b/crates/promql_utilities/src/query_logics/logics.rs
@@ -101,6 +101,12 @@ pub fn does_precompute_operator_support_subpopulations(
         // CountMinSketchWithHeap is only supported for Topk — does not support subpopulations
         AggregationType::CountMinSketchWithHeap if matches!(statistic, Statistic::Topk) => false,
 
+        // CountSketch is the signed-counter equivalent of CMS — same
+        // subpopulation shape for Sum/Count statistics. The
+        // heap-bearing variant covers Topk like its CMS counterpart.
+        AggregationType::CountSketch => matches!(statistic, Statistic::Sum | Statistic::Count),
+        AggregationType::CountSketchWithHeap if matches!(statistic, Statistic::Topk) => false,
+
         // Default: not supported
         _ => panic!("Unexpected precompute operator: {}", precompute_operator),
     }
@@ -186,6 +192,28 @@ mod tests {
             Statistic::Sum,
             AggregationType::CountMinSketch,
         ));
+
+        // Sibling CountSketch path — must not panic, matches
+        // CountMinSketch's Sum/Count subpopulation shape.
+        assert!(does_precompute_operator_support_subpopulations(
+            Statistic::Sum,
+            AggregationType::CountSketch,
+        ));
+        assert!(does_precompute_operator_support_subpopulations(
+            Statistic::Count,
+            AggregationType::CountSketch,
+        ));
+
+        // Heap-bearing variants on Topk — both return false (heap
+        // is per-policy, not subpopulation-keyed) and must not panic.
+        assert!(!does_precompute_operator_support_subpopulations(
+            Statistic::Topk,
+            AggregationType::CountMinSketchWithHeap,
+        ));
+        assert!(!does_precompute_operator_support_subpopulations(
+            Statistic::Topk,
+            AggregationType::CountSketchWithHeap,
+        ));
     }
 
     #[test]