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/);
+  }
+});