♻️ Reproduction Steps

1. In an empty directory: npm init -y && npm install @copilotkit/react-core@1.79.0 react@19 react-dom@19 typescript@5 @types/react@19 @types/react-dom@19
   (npm installs zod 4.6.7 at the top level, brought in by @ag-ui/core; zod@3.25.76 stays nested under @ag-ui/client and @copilotkit/shared.)
2. index.tsx:

import { CopilotKit } from "@copilotkit/react-core";
export const App = () => <CopilotKit runtimeUrl="/api/copilotkit">{null}</CopilotKit>;

3. tsconfig.json:

{ "compilerOptions": { "target": "ES2022", "module": "ESNext", "moduleResolution": "bundler", "jsx": "react-jsx", "strict": true, "noEmit": true, "skipLibCheck": false }, "include": ["index.tsx"] }

4. npx tsc -p .

✅ Expected Behavior

CopilotKit's own declarations type-check against the zod the app has, since the peer range is zod >= 3.25.

❌ Actual Behavior

1,687 errors, of which 1,683 come from CopilotKit declarations:

• 1,677 in @copilotkit/mcp-apps-renderer/dist/content-schema.d.mts
• 6 in @copilotkit/react-core/dist/copilotkit-*.d.mts (OpenGenerativeUIContentSchema)

e.g.
content-schema.d.mts(5,45): error TS2707: Generic type 'ZodObject<Shape, Config>' requires between 0 and 2 type arguments.
content-schema.d.mts(7,27): error TS2707: Generic type 'ZodArray' requires between 0 and 1 type arguments.
content-schema.d.mts(7,62): error TS2344: Type 'string' does not satisfy the constraint 'readonly SomeType[]'.

Cause: both packages declare zod >=3.25 as a peer but build against Zod 3 (devDependency ^3.25.76 in mcp-apps-renderer), so the emitted .d.mts uses Zod 3 type shapes behind import { z } from "zod". In an app whose zod is 4, those resolve to Zod 4 types.

zod/v3 exists in every version the peer range allows (3.25+ and 4). Changing just those two imports in the published files to import { z } from "zod/v3" removes all 1,683 errors. The 4 errors left are in third-party declarations, and one of them is a separate CopilotKit packaging issue I'll file on its own. In source, the imports are in packages/mcp-apps-renderer/src/content-schema.ts, packages/mcp-apps-renderer/src/session.ts and packages/react-core/src/v2/components/OpenGenerativeUIRenderer.tsx (unchanged on main @ 07226a2). Switching them to zod/v3 also changes which Zod builds those schemas at runtime, so I'd like to know if that's the approach you want before opening a PR.

With skipLibCheck: true (the Vite template default) none of this shows, which is probably why it has gone unnoticed. The validate-dts-imports gate from #6674 doesn't catch it either: it reports mcp-apps-renderer as clean, because zod is a required peer and resolves, just to a different major version. Related runtime fixes for Zod 4 in the same schemas: #4295 / #5025.

Screenshots

No response

𝌚 CopilotKit Version

@copilotkit/react-core@1.79.0

📄 Logs (Optional)

node_modules/@copilotkit/react-core/dist/copilotkit-DFMMPW2I.d.mts(2036,46): error TS2707: Generic type 'ZodObject<Shape, Config>' requires between 0 and 2 type arguments.
node_modules/@copilotkit/react-core/dist/copilotkit-DFMMPW2I.d.mts(2041,23): error TS2707: Generic type 'ZodArray<T>' requires between 0 and 1 type arguments.