fix(Google Gemini Chat Model Node): Point the AI builder to the model catalog for new Gemini models (#40159)

Co-authored-by: Mutasem Aldmour <[email protected]>
Co-authored-by: Claude Opus 5.5 <[email protected]>

packages/@n8n/nodes-langchain/nodes/llms/LmChatGoogleGemini/LmChatGoogleGemini.node.ts

@@ -99,7 +99,10 @@ const modelRLC: INodeProperties = {
 	},
 	default: 'models/gemini-2.5-flash',
 	builderHint: {
-		propertyHint: MODEL_SELECTION_HINT,
+		// The dropdown loads through declarative routing, which the builder's resource lookup cannot call.
+		propertyHint:
+			'This node declares no model-list lookup, so its models cannot be listed, even with a connected credential. For a new choice, use current Google provider catalog information and choose a Gemini 3.x or newer model ID with the "models/" prefix. Do not choose Gemini 2.x or older. ' +
+			MODEL_SELECTION_HINT,
 	},
 };
 

packages/@n8n/nodes-langchain/nodes/llms/LmChatGoogleGemini/test/LmChatGoogleGemini.test.ts

@@ -0,0 +1,26 @@
+import { LmChatGoogleGemini } from '../LmChatGoogleGemini.node';
+
+describe('LmChatGoogleGemini', () => {
+	it('should send every model field to the provider catalog with a Gemini 3.x floor', () => {
+		const hints = new LmChatGoogleGemini().description.properties
+			.filter((p) => p.name === 'modelName')
+			.map((p) => p.builderHint?.propertyHint);
+
+		expect(hints).toHaveLength(3);
+		for (const hint of hints) {
+			expect(hint).toContain('even with a connected credential');
+			expect(hint).toContain('use current Google provider catalog information');
+			expect(hint).toContain('Do not choose Gemini 2.x or older');
+		}
+	});
+
+	it('should not name builder tools in the model hint', () => {
+		const hints = new LmChatGoogleGemini().description.properties
+			.filter((p) => p.name === 'modelName')
+			.map((p) => p.builderHint?.propertyHint);
+
+		for (const hint of hints) {
+			expect(hint).not.toMatch(/searchModels|explore-resources|nodes\(/);
+		}
+	});
+});