fix(react-core): stabilize provider defaults

Author: marthakelly

packages/react-core/src/v2/providers/CopilotKitProvider.tsx

@@ -4,31 +4,25 @@ import type { AbstractAgent } from "@ag-ui/client";
 import type { FrontendTool } from "@copilotkit/core";
 import type React from "react";
 import {
-  type ReactNode,
   useMemo,
   useEffect,
   useLayoutEffect,
   useReducer,
   useRef,
   useState,
 } from "react";
+import type { ReactNode } from "react";
 // Context extracted to ../context.ts for cross-platform reuse (React Native)
-import {
-  CopilotKitContext,
-  type CopilotKitContextValue,
-  LicenseContext,
-} from "../context";
+import { CopilotKitContext, LicenseContext } from "../context";
+import type { CopilotKitContextValue } from "../context";
 export type { CopilotKitContextValue } from "../context";
 export { CopilotKitContext, useLicenseContext } from "../context";
 import { z } from "zod";
 import { CopilotKitInspector } from "../components/CopilotKitInspector";
 import type { Anchor } from "@copilotkit/web-inspector";
 import { LicenseWarningBanner } from "../components/license-warning-banner";
-import {
-  createLicenseContextValue,
-  type LicenseContextValue,
-  type DebugConfig,
-} from "@copilotkit/shared";
+import { createLicenseContextValue } from "@copilotkit/shared";
+import type { LicenseContextValue, DebugConfig } from "@copilotkit/shared";
 import type { CopilotKitCoreErrorCode } from "@copilotkit/core";
 import {
   MCPAppsActivityContentSchema,
@@ -62,6 +56,9 @@ import { zodToJsonSchema } from "zod-to-json-schema";
 
 const HEADER_NAME = "X-CopilotCloud-Public-Api-Key";
 const COPILOT_CLOUD_CHAT_URL = "https://api.cloud.copilotkit.ai/copilotkit/v1";
+const EMPTY_HEADERS: Record<string, string> = {};
+const EMPTY_PROPERTIES: Record<string, unknown> = {};
+const EMPTY_AGENTS: Record<string, AbstractAgent> = {};
 
 const DEFAULT_DESIGN_SKILL = `When generating UI with generateSandboxedUi, follow these design principles inspired by shadcn/ui:
 
@@ -246,14 +243,14 @@ function useStableArrayProp<T>(
 export const CopilotKitProvider: React.FC<CopilotKitProviderProps> = ({
   children,
   runtimeUrl,
-  headers: headersProp = {},
+  headers: headersProp = EMPTY_HEADERS,
   credentials,
   publicApiKey,
   publicLicenseKey,
   licenseToken,
-  properties = {},
-  agents__unsafe_dev_only: agents = {},
-  selfManagedAgents = {},
+  properties = EMPTY_PROPERTIES,
+  agents__unsafe_dev_only: agents = EMPTY_AGENTS,
+  selfManagedAgents = EMPTY_AGENTS,
   renderToolCalls,
   renderActivityMessages,
   renderCustomMessages,

packages/react-core/src/v2/providers/__tests__/CopilotKitProvider.stability.test.tsx

@@ -4,12 +4,9 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { z } from "zod";
 import type { ReactFrontendTool } from "../../types/frontend-tool";
 import type { ReactToolCallRenderer } from "../../types";
-import {
-  CopilotKitProvider,
-  useCopilotKit,
-  type CopilotKitContextValue,
-} from "../CopilotKitProvider";
-import { CopilotKitCoreReact } from "../../lib/react-core";
+import { CopilotKitProvider, useCopilotKit } from "../CopilotKitProvider";
+import type { CopilotKitContextValue } from "../CopilotKitProvider";
+import type { CopilotKitCoreReact } from "../../lib/react-core";
 import { useFrontendTool } from "../../hooks/use-frontend-tool";
 
 // Mock console methods to suppress expected warnings
@@ -149,6 +146,41 @@ describe("CopilotKitProvider stability", () => {
   });
 
   describe("setter calls on prop changes", () => {
+    it("does not re-sync an empty local agent registry on unchanged rerenders", () => {
+      const setAgentsCalls: unknown[] = [];
+      let spyAttached = false;
+
+      function SpyAttacher() {
+        const { copilotkit } = useCopilotKit();
+        if (!spyAttached) {
+          const original =
+            copilotkit.setAgents__unsafe_dev_only.bind(copilotkit);
+          copilotkit.setAgents__unsafe_dev_only = (agents) => {
+            setAgentsCalls.push(agents);
+            return original(agents);
+          };
+          spyAttached = true;
+        }
+        return null;
+      }
+
+      const { rerender } = render(
+        <CopilotKitProvider runtimeUrl="http://localhost:3000/api">
+          <SpyAttacher />
+        </CopilotKitProvider>,
+      );
+
+      setAgentsCalls.length = 0;
+
+      rerender(
+        <CopilotKitProvider runtimeUrl="http://localhost:3000/api">
+          <SpyAttacher />
+        </CopilotKitProvider>,
+      );
+
+      expect(setAgentsCalls).toHaveLength(0);
+    });
+
     it("calls setTools when frontendTools change instead of recreating instance", () => {
       const setToolsSpy = vi.fn();
       let spyAttached = false;