Reject unsupported query operators during execution planning

test/execution-world.test.ts

@@ -284,3 +284,27 @@ test("implementation selection is explicit, target checked and independent of ma
     "service",
   );
 });
+
+test("execution planning rejects unsupported grouping before installing the query", async () => {
+  const workspace = await loadReaderWorkspace((name, text) =>
+    name === "queries/reader-screen.graphql"
+      ? text.replace("aggregate { count }", "groups(by: {color: true}, first: 10) { entries { aggregate { count } } }")
+      : text,
+  );
+  assert.throws(() => compileExecutionPlan(workspace), /QUERY_OPERATOR_UNSUPPORTED.*grouping/);
+});
+
+test("a count-only local query still requires complete relationship admission", async () => {
+  for (const source of [
+    "query ReplicaInputs { root { sourceRevision } }",
+    "query ReplicaInputs { root { highlights(first: 1) { entries { node { color } } } } }",
+  ]) {
+    const workspace = await loadReaderWorkspace((name, text) => {
+      if (name === "queries/replica-inputs.graphql") return source;
+      if (name === "queries/reader-screen.graphql")
+        return "query ReaderScreen { root { _qx { relations { highlights { aggregate { count } } } } } }";
+      return text;
+    });
+    assert.throws(() => compileExecutionPlan(workspace), /REPLICA_TRAVERSAL_MISSING|REPLICA_RELATION_INCOMPLETE/);
+  }
+});

test/query-aggregation.test.ts

@@ -108,3 +108,15 @@ test("typed reference operands and scalar membership tests reject unbounded lite
     /1000 operands/,
   );
 });
+
+test("new runtime operator matrix accepts direct count and rejects unsupported relational plans", async () => {
+  const { unsupportedQueryOperator } = await import("../src/execution-world/query-operators.js");
+  assert.equal(unsupportedQueryOperator(await compile("aggregate { count }")), undefined);
+  for (const expression of [
+    "aggregate { sum { estimatedHours } }",
+    "filter(where: {estimatedHours: {gt: 0}}) { aggregate { count } }",
+    "distinct(by: {estimatedHours: true}) { aggregate { count } }",
+    "aggregate { count @skip(if: true) }",
+  ])
+    assert.ok(unsupportedQueryOperator(await compile(expression)), expression);
+});