diff --git a/packages/shared/src/config.ts b/packages/shared/src/config.ts
index dabc004..c803422 100644
--- a/packages/shared/src/config.ts
+++ b/packages/shared/src/config.ts
@@ -15,5 +15,5 @@ export const DEFAULT_CONFIG: ConfigDefaults = {
   plan_model: "deepseek-v4-flash",
   exec_model: "deepseek-v4-flash",
   provider: "opencode-go",
-  max_time: "30m",
+  max_time: "20m",
 };
diff --git a/packages/shared/test/config.test.mjs b/packages/shared/test/config.test.mjs
new file mode 100644
index 0000000..5971147
--- /dev/null
+++ b/packages/shared/test/config.test.mjs
@@ -0,0 +1,14 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { DEFAULT_CONFIG } from "../dist/index.js";
+
+test("DEFAULT_CONFIG sets a 20-minute default max sandbox time", () => {
+  assert.equal(DEFAULT_CONFIG.max_time, "20m");
+});
+
+test("DEFAULT_CONFIG includes plan model, exec model, and provider defaults", () => {
+  assert.equal(DEFAULT_CONFIG.plan_model, "deepseek-v4-flash");
+  assert.equal(DEFAULT_CONFIG.exec_model, "deepseek-v4-flash");
+  assert.equal(DEFAULT_CONFIG.provider, "opencode-go");
+});
\ No newline at end of file