feat(core): Wire up chat code path for model configs. (#12850)

packages/core/src/services/modelConfig.integration.test.ts

@@ -231,4 +231,42 @@ describe('ModelConfigService Integration', () => {
       topP: 0.95, // from base
     });
   });
+
+  it('should correctly merge static aliases, runtime aliases, and overrides', () => {
+    // Re-instantiate service for this isolated test to not pollute other tests
+    const service = new ModelConfigService(complexConfig);
+
+    // Register a runtime alias, simulating what AgentExecutor does.
+    // This alias extends a static base and provides its own settings.
+    service.registerRuntimeModelConfig('agent-runtime:my-agent', {
+      extends: 'creative-writer', // extends a multi-level alias
+      modelConfig: {
+        generateContentConfig: {
+          temperature: 0.1, // Overrides parent
+          maxOutputTokens: 8192, // Adds a new property
+        },
+      },
+    });
+
+    // Resolve the configuration for the runtime alias, with a matching agent scope
+    const resolved = service.getResolvedConfig({
+      model: 'agent-runtime:my-agent',
+      overrideScope: 'core',
+    });
+
+    // Assert the final merged configuration.
+    expect(resolved.model).toBe('gemini-1.5-pro-latest'); // from 'default-text-model'
+    expect(resolved.generateContentConfig).toEqual({
+      // from 'core' agent override, wins over runtime alias's 0.1 and creative-writer's 0.9
+      temperature: 0.5,
+      // from 'base' alias
+      topP: 0.95,
+      // from 'creative-writer' alias
+      topK: 50,
+      // from runtime alias
+      maxOutputTokens: 8192,
+      // from 'core' agent override
+      stopSequences: ['AGENT_STOP'],
+    });
+  });
 });