feat: upgrade to Zod v4

demo/package.json

@@ -47,7 +47,7 @@
     "react-virtualized-auto-sizer": "^1.0.20",
     "react-window": "^1.8.10",
     "stainless": "workspace:*",
-    "zod": "^3.25.76",
+    "zod": "^4.3.6",
     "zustand": "^4.4.7"
   },
   "devDependencies": {

packages/client/src/codegen/generate-types.ts

@@ -146,7 +146,9 @@ function nestEndpoints(
 }
 
 function zodToString(schema: ZodTypeAny) {
-  const { node } = zodToTs(schema, undefined, { nativeEnums: "union" });
+  // zod-to-ts v1 API: zodToTs(schema, identifier?, options?)
+  // Cast to any because zod/v3 types are structurally compatible at runtime
+  const { node } = zodToTs(schema as any, undefined, { nativeEnums: "union" });
   const nodeString = printNode(node);
   // This happens with large, lazily loaded zod types
   return nodeString.replace(/\bIdentifier\b/g, "unknown");

packages/prisma/package.json

@@ -32,7 +32,7 @@
   "dependencies": {
     "lodash": "^4.17.21",
     "stainless": "workspace:*",
-    "zod": "^3.25.76"
+    "zod": "^4.3.6"
   },
   "peerDependencies": {
     "prisma": "^4.0.0"

packages/prisma/src/prismaPlugin.ts

@@ -11,8 +11,9 @@ import {
 import { includeSubPaths } from "./includeUtils";
 import { isPlainObject } from "lodash";
 
-declare module "zod" {
-  interface ZodType<Output, Def extends ZodTypeDef, Input = Output> {
+// Module augmentation for zod/v3 (stainless re-exports zod/v3 types)
+declare module "zod/v3" {
+  interface ZodType<Output, Def extends z.ZodTypeDef, Input = Output> {
     /**
      * Transforms the output value to fetch the Prisma model whose primary
      * key is the input value.  Throws if the primary key wasn't found.
@@ -79,7 +80,8 @@ z.ZodType.prototype.prismaModelLoader = function prismaModelLoader<
     }
   );
   // tsc -b is generating spurious errors here...
-  return (result as any).openapi({ effectType: "input" }) as typeof result;
+  // Removed .openapi() call - zod-openapi v5 uses .meta() which isn't available in zod/v3
+  return result;
 };
 
 z.ZodType.prototype.prismaModel = function prismaModel<

packages/stainless/package.json

@@ -50,8 +50,8 @@
     "lodash": "^4.17.21",
     "qs": "^6.11.2",
     "ts-node": "^10.9.1",
-    "zod": "^3.25.76",
-    "zod-openapi": "github:stainless-api/zod-openapi#2.8.0",
+    "zod": "^4.3.6",
+    "zod-openapi": "^5.4.6",
     "zod-validation-error": "^4.0.1"
   }
 }

packages/stainless/src/openapiSpec.ts

@@ -3,8 +3,9 @@ import {
   ZodOpenApiOperationObject,
   ZodOpenApiPathsObject,
   createDocument,
+  oas31,
 } from "zod-openapi";
-import type { OpenAPIObject } from "zod-openapi/lib-types/openapi3-ts/dist/oas31";
+type OpenAPIObject = oas31.OpenAPIObject;
 import { snakeCase } from "lodash";
 
 function allModels(
@@ -87,7 +88,9 @@ export async function openapiSpec(
     },
     servers: [{ url: "v1" }],
     components: {
-      schemas: models,
+      // Cast to any because zod/v3 types are structurally compatible with zod/v4
+      // at runtime, but TypeScript sees them as incompatible types
+      schemas: models as any,
     },
     paths,
   });

packages/stainless/src/stl.ts

@@ -1,6 +1,7 @@
 import * as z from "./z";
 import { openapiSpec } from "./openapiSpec";
-import type { OpenAPIObject } from "zod-openapi/lib-types/openapi3-ts/dist/oas31";
+import type { oas31 } from "zod-openapi";
+type OpenAPIObject = oas31.OpenAPIObject;
 import { fromZodError } from "zod-validation-error/v3";
 import coerceParams from "./coerceParams";
 export { openapiSpec };

packages/stainless/src/z.ts

@@ -1,19 +1,21 @@
-import { extendZodWithOpenApi } from "zod-openapi";
+// Use zod/v3 compatibility layer for easier migration
+// zod-openapi v5 uses .meta() instead of .openapi(), no setup required
+import "zod-openapi";
 import {
   z,
   ParseContext,
   SafeParseReturnType,
   isValid,
   ZodFirstPartyTypeKind,
-} from "zod";
+} from "zod/v3";
 import { StlContext } from "./stl";
 import { SelectTree } from "./parseSelect";
 import { getSelects } from "./selects";
 import { getIncludes, IncludablePaths } from "./includes";
 import { pickBy } from "lodash/fp";
 import { mapValues } from "lodash";
 
-export * from "zod";
+export * from "zod/v3";
 export { selects, selectsSymbol, getSelects } from "./selects";
 export {
   includes,
@@ -22,21 +24,16 @@ export {
   IncludablePaths,
 } from "./includes";
 
-/**
- * TODO: try to come up with a better error message
- * that you must import stl _before_ zod
- * in any file that uses z.openapi(),
- * including the file that calls stl.openapiSpec().
- */
-extendZodWithOpenApi(z); // https://github.com/asteasolutions/zod-to-openapi#the-openapi-method
+// zod-openapi v5 uses Zod's native .meta() method for OpenAPI metadata
+// No setup required - importing "zod-openapi" above enables TypeScript types
 
 //////////////////////////////////////////////////
 //////////////////////////////////////////////////
 ////////////////// Metadata //////////////////////
 //////////////////////////////////////////////////
 //////////////////////////////////////////////////
 
-declare module "zod" {
+declare module "zod/v3" {
   interface ZodType<Output, Def extends ZodTypeDef, Input = Output> {
     withMetadata<M extends object>(metadata: M): ZodMetadata<this, M>;
   }
@@ -228,7 +225,7 @@ export function extractDeepMetadata<
 //////////////////////////////////////////////////
 //////////////////////////////////////////////////
 
-declare module "zod" {
+declare module "zod/v3" {
   interface ZodType<Output, Def extends ZodTypeDef, Input = Output> {
     /**
      * Marks this schema as includable via an `include[]` query param.
@@ -266,9 +263,7 @@ z.ZodType.prototype.includable = function includable(this: z.ZodTypeAny) {
       return include && zodPathIsIncluded(path, include) ? data : undefined;
     },
     this.optional()
-  )
-    .openapi({ effectType: "input" })
-    .withMetadata({ stainless: { includable: true } });
+  ).withMetadata({ stainless: { includable: true } });
 };
 
 export type isIncludable<T extends z.ZodTypeAny> = extractDeepMetadata<
@@ -301,7 +296,7 @@ function zodPathIsIncluded(
 //////////////////////////////////////////////////
 //////////////////////////////////////////////////
 
-declare module "zod" {
+declare module "zod/v3" {
   // I don't know why TS errors without this, sigh
   interface ZodTypeDef {}
 
@@ -438,7 +433,7 @@ z.ZodType.prototype.selectable = function selectable(this: z.ZodTypeAny) {
 //////////////////////////////////////////////////
 //////////////////////////////////////////////////
 
-declare module "zod" {
+declare module "zod/v3" {
   interface ZodType<Output, Def extends ZodTypeDef, Input = Output> {
     safeParseAsync(
       data: unknown,

packages/ts-to-zod/package.json

@@ -34,6 +34,6 @@
     "lodash": "^4.17.21",
     "pkg-up": "~3.1.0",
     "ts-morph": "^19.0.0",
-    "zod": "^3.25.76"
+    "zod": "^4.3.6"
   }
 }