diff --git a/tests/test_gemini_config.mjs b/tests/test_gemini_config.mjs
new file mode 100644
index 0000000..6609e0a
--- /dev/null
+++ b/tests/test_gemini_config.mjs
@@ -0,0 +1,54 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import vm from "node:vm";
+
+const source = await readFile(new URL("../web/gemini_config.js", import.meta.url), "utf8");
+let extension;
+vm.runInNewContext(source.replace(/^import .*;\r?$/m, ""), {
+  app: { registerExtension(value) { extension = value; } },
+});
+
+function nodeType() {
+  return class {
+    constructor() {
+      this.widgets = [
+        { name: "cache_seed", value: 42, linkedWidgets: [{ value: "randomize" }] },
+        { name: "use_cache", value: false },
+        { name: "seed", value: 7, linkedWidgets: [{ value: "randomize" }] },
+      ];
+    }
+    onNodeCreated() { this.created = true; return "original result"; }
+    configure(savedControl) { this.widgets[0].linkedWidgets[0].value = savedControl; }
+  };
+}
+
+test("new API config nodes default only cache_seed control to fixed", () => {
+  const Node = nodeType();
+  extension.beforeRegisterNodeDef(Node, { name: "SSL_GeminiAPIKeyConfig" });
+  const node = new Node();
+  assert.equal(node.onNodeCreated(), "original result");
+  assert.equal(node.created, true);
+  assert.equal(node.widgets[0].linkedWidgets[0].value, "fixed");
+  assert.equal(node.widgets[0].value, 42);
+  assert.equal(node.widgets[1].value, false);
+  assert.equal(node.widgets[2].linkedWidgets[0].value, "randomize");
+  // Workflow configuration restores serialized choices after node creation.
+  node.configure("increment");
+  assert.equal(node.widgets[0].linkedWidgets[0].value, "increment");
+  node.configure("randomize");
+  assert.equal(node.widgets[0].linkedWidgets[0].value, "randomize");
+});
+
+test("other node classes and missing seed controls are untouched", () => {
+  const Other = nodeType();
+  extension.beforeRegisterNodeDef(Other, { name: "SSL_GeminiTextPrompt" });
+  const other = new Other();
+  other.onNodeCreated();
+  assert.equal(other.widgets[0].linkedWidgets[0].value, "randomize");
+  const Config = nodeType();
+  extension.beforeRegisterNodeDef(Config, { name: "SSL_GeminiAPIKeyConfig" });
+  const config = new Config();
+  config.widgets = [];
+  assert.doesNotThrow(() => config.onNodeCreated());
+});
diff --git a/tests/test_groups.toml b/tests/test_groups.toml
index 62803d1..74344a2 100644
--- a/tests/test_groups.toml
+++ b/tests/test_groups.toml
@@ -16,3 +16,8 @@ frontend_tests = [
 paths = ["__init__.py", "response_schema.py", "web/response_schema.js", "web/response_schema_model.js", "web/response_schema_widgets.js", "web/response_schema_style.js", "package.json", "package-lock.json"]
 python_tests = ["tests/test_response_schema.py"]
 frontend_tests = ["tests/test_response_schema_model.mjs", "tests/test_response_schema_widgets.mjs"]
+
+[groups.gemini_config_frontend]
+paths = ["web/gemini_config.js", "tests/test_gemini_config.mjs"]
+python_tests = []
+frontend_tests = ["tests/test_gemini_config.mjs"]
diff --git a/web/gemini_config.js b/web/gemini_config.js
new file mode 100644
index 0000000..d27c647
--- /dev/null
+++ b/web/gemini_config.js
@@ -0,0 +1,16 @@
+import { app } from "../../scripts/app.js";
+
+app.registerExtension({
+  name: "GeminiExpandedAPI.ConfigSeedDefault",
+  beforeRegisterNodeDef(nodeType, nodeData) {
+    if (nodeData.name !== "SSL_GeminiAPIKeyConfig") return;
+    const onNodeCreated = nodeType.prototype.onNodeCreated;
+    nodeType.prototype.onNodeCreated = function () {
+      const result = onNodeCreated?.apply(this, arguments);
+      const seed = this.widgets?.find((widget) => widget.name === "cache_seed");
+      const control = seed?.linkedWidgets?.[0];
+      if (control) control.value = "fixed";
+      return result;
+    };
+  },
+});