diff --git a/src/tool.ts b/src/tool.ts
index b2e8cdf..dd68f74 100644
--- a/src/tool.ts
+++ b/src/tool.ts
@@ -138,6 +138,10 @@ export function createSubagentTool(deps: {
         mode: "single" | "parallel" | "chain";
       }) => {
         const model = (deps.resolveChildModel ?? resolveChildModel)({
+          // compatibility: newer resolveChildModel expects { callModel, presetModel }
+          // older hooks/tests used { taskModel, topLevelModel }
+          callModel: input.taskModel,
+          presetModel: params.model,
           taskModel: input.taskModel,
           topLevelModel: params.model,
         });