fix(zod): add type field to generated enums for openapi compatibility

packages/zod/src/coercer.test.ts

@@ -15,6 +15,16 @@ enum TestEnum {
   STRING = 'string',
 }
 
+enum NumericEnum {
+  A = 1,
+  B = 2,
+}
+
+enum MixedEnum {
+  A = 1,
+  B = 'b',
+}
+
 const nativeCases: TestCase[] = [
   {
     schema: z.number(),
@@ -141,6 +151,31 @@ const nativeCases: TestCase[] = [
     input: '123n',
     expected: '123n',
   },
+  {
+    schema: z.nativeEnum(TestEnum),
+    input: 'NUMBER',
+    expected: 'NUMBER',
+  },
+  {
+    schema: z.nativeEnum(NumericEnum),
+    input: '1',
+    expected: 1,
+  },
+  {
+    schema: z.nativeEnum(NumericEnum),
+    input: 'A',
+    expected: 'A', // invalid, should just return value since coercion failed, OR it shouldn't coerce 'A' to 1! wait, does Zod accept 'A'? NO.
+  },
+  {
+    schema: z.nativeEnum(MixedEnum),
+    input: '1',
+    expected: 1,
+  },
+  {
+    schema: z.nativeEnum(MixedEnum),
+    input: 'b',
+    expected: 'b',
+  },
 ]
 
 const combinationCases: TestCase[] = [

packages/zod/src/coercer.ts

@@ -28,6 +28,15 @@ import { guard, isObject } from '@orpc/shared'
 import { ZodFirstPartyTypeKind } from 'zod/v3'
 import { getCustomZodDef } from './schemas/base'
 
+function getValidEnumValues(obj: any): any[] {
+  const validKeys = Object.keys(obj).filter((k: any) => typeof obj[obj[k]] !== 'number')
+  const filtered: any = {}
+  for (const k of validKeys) {
+    filtered[k] = obj[k]
+  }
+  return Object.values(filtered)
+}
+
 export class ZodSmartCoercionPlugin<TContext extends Context> implements StandardHandlerPlugin<TContext> {
   init(options: StandardHandlerOptions<TContext>): void {
     options.clientInterceptors ??= []
@@ -126,13 +135,14 @@ function zodCoerceInternal(
 
     case ZodFirstPartyTypeKind.ZodNativeEnum: {
       const schema_ = schema as ZodNativeEnum<EnumLike>
+      const values = getValidEnumValues(schema_._def.values)
 
-      if (Object.values(schema_._def.values).includes(value as any)) {
+      if (values.includes(value as any)) {
         return value
       }
 
       if (typeof value === 'string') {
-        for (const expectedValue of Object.values(schema_._def.values)) {
+        for (const expectedValue of values) {
           if (expectedValue.toString() === value) {
             return expectedValue
           }

packages/zod/src/converter.test.ts

@@ -154,6 +154,16 @@ enum ExampleEnum {
   B = 'b',
 }
 
+enum NumericEnum {
+  A = 1,
+  B = 2,
+}
+
+enum MixedEnum {
+  A = 1,
+  B = 'b',
+}
+
 const nativeCases: SchemaTestCase[] = [
   {
     schema: z.boolean(),
@@ -193,11 +203,19 @@ const nativeCases: SchemaTestCase[] = [
   },
   {
     schema: z.enum(['a', 'b']),
-    input: [true, { enum: ['a', 'b'] }],
+    input: [true, { type: 'string', enum: ['a', 'b'] }],
   },
   {
     schema: z.nativeEnum(ExampleEnum),
-    input: [true, { enum: ['a', 'b'] }],
+    input: [true, { type: 'string', enum: ['a', 'b'] }],
+  },
+  {
+    schema: z.nativeEnum(NumericEnum),
+    input: [true, { type: 'number', enum: [1, 2] }],
+  },
+  {
+    schema: z.nativeEnum(MixedEnum),
+    input: [true, { enum: [1, 'b'] }],
   },
 ]
 

packages/zod/src/converter.ts

@@ -74,6 +74,15 @@ export interface ZodToJsonSchemaOptions {
   unsupportedJsonSchema?: Exclude<JSONSchema, boolean>
 }
 
+function getValidEnumValues(obj: any): any[] {
+  const validKeys = Object.keys(obj).filter((k: any) => typeof obj[obj[k]] !== 'number')
+  const filtered: any = {}
+  for (const k of validKeys) {
+    filtered[k] = obj[k]
+  }
+  return Object.values(filtered)
+}
+
 export class ZodToJsonSchemaConverter implements ConditionalSchemaConverter {
   private readonly maxLazyDepth: Exclude<ZodToJsonSchemaOptions['maxLazyDepth'], undefined>
   private readonly maxStructureDepth: Exclude<ZodToJsonSchemaOptions['maxStructureDepth'], undefined>
@@ -343,13 +352,19 @@ export class ZodToJsonSchemaConverter implements ConditionalSchemaConverter {
       case ZodFirstPartyTypeKind.ZodEnum: {
         const schema_ = schema as ZodEnum<[string, ...string[]]>
 
-        return [true, { enum: schema_._def.values }]
+        return [true, { type: 'string', enum: schema_._def.values }]
       }
 
       case ZodFirstPartyTypeKind.ZodNativeEnum: {
         const schema_ = schema as ZodNativeEnum<EnumLike>
-
-        return [true, { enum: Object.values(schema_._def.values) }]
+        const values = getValidEnumValues(schema_._def.values)
+        const hasString = values.some(v => typeof v === 'string')
+        const hasNumber = values.some(v => typeof v === 'number')
+        const type = hasString && hasNumber ? undefined : hasNumber ? 'number' : 'string'
+        const json: any = { enum: values }
+        if (type)
+          json.type = type
+        return [true, json]
       }
 
       case ZodFirstPartyTypeKind.ZodArray: {

packages/zod/src/zod4/coercer.native.test.ts

@@ -6,6 +6,16 @@ enum TestEnum {
   STRING = 'string',
 }
 
+enum NumericEnum {
+  A = 1,
+  B = 2,
+}
+
+enum MixedEnum {
+  A = 1,
+  B = 'b',
+}
+
 testSchemaSmartCoercion([
   {
     name: 'number - 12345',

packages/zod/src/zod4/converter.native.test.ts

@@ -6,6 +6,16 @@ enum ExampleEnum {
   B = 'b',
 }
 
+enum NumericEnum {
+  A = 1,
+  B = 2,
+}
+
+enum MixedEnum {
+  A = 1,
+  B = 'b',
+}
+
 testSchemaConverter([
   {
     name: 'boolean',
@@ -90,12 +100,22 @@ testSchemaConverter([
   {
     name: 'enum(["a", "b"])',
     schema: z.enum(['a', 'b']),
-    input: [true, { enum: ['a', 'b'] }],
+    input: [true, { type: 'string', enum: ['a', 'b'] }],
   },
   {
     name: 'enum(ExampleEnum)',
     schema: z.enum(ExampleEnum),
-    input: [true, { enum: ['a', 'b'] }],
+    input: [true, { type: 'string', enum: ['a', 'b'] }],
+  },
+  {
+    name: 'enum(NumericEnum)',
+    schema: z.enum(NumericEnum),
+    input: [true, { type: 'number', enum: [1, 2] }],
+  },
+  {
+    name: 'enum(MixedEnum)',
+    schema: z.enum(MixedEnum),
+    input: [true, { enum: [1, 'b'] }],
   },
   {
     name: 'file()',

packages/zod/src/zod4/converter.structure.test.ts

@@ -43,17 +43,17 @@ testSchemaConverter([
   {
     name: 'tuple([z.enum(["a", "b"])])',
     schema: z.tuple([z.enum(['a', 'b'])]),
-    input: [true, { type: 'array', prefixItems: [{ enum: ['a', 'b'] }] }],
+    input: [true, { type: 'array', prefixItems: [{ type: 'string', enum: ['a', 'b'] }] }],
   },
   {
     name: 'tuple([z.enum(["a", "b"])], z.string())',
     schema: z.tuple([z.enum(['a', 'b'])], z.string()),
-    input: [true, { type: 'array', prefixItems: [{ enum: ['a', 'b'] }], items: { type: 'string' } }],
+    input: [true, { type: 'array', prefixItems: [{ type: 'string', enum: ['a', 'b'] }], items: { type: 'string' } }],
   },
   {
     name: 'zm.tuple([zm.enum(["a", "b"])], zm.string()).check(zm.minLength(4), zm.maxLength(10))',
     schema: zm.tuple([zm.enum(['a', 'b'])], zm.string()).check(zm.minLength(4), zm.maxLength(10)),
-    input: [true, { type: 'array', prefixItems: [{ enum: ['a', 'b'] }], items: { type: 'string' }, minItems: 4, maxItems: 10 }],
+    input: [true, { type: 'array', prefixItems: [{ type: 'string', enum: ['a', 'b'] }], items: { type: 'string' }, minItems: 4, maxItems: 10 }],
   },
   {
     name: 'set(z.string())',

packages/zod/src/zod4/converter.ts

@@ -85,6 +85,17 @@ export interface ZodToJsonSchemaConverterOptions {
   >[]
 }
 
+function getValidEnumValues(obj: any): any[] {
+  if (Array.isArray(obj))
+    return obj
+  const validKeys = Object.keys(obj).filter((k: any) => typeof obj[obj[k]] !== 'number')
+  const filtered: any = {}
+  for (const k of validKeys) {
+    filtered[k] = obj[k]
+  }
+  return Object.values(filtered)
+}
+
 export class ZodToJsonSchemaConverter implements ConditionalSchemaConverter {
   private readonly maxLazyDepth: Exclude<ZodToJsonSchemaConverterOptions['maxLazyDepth'], undefined>
   private readonly maxStructureDepth: Exclude<ZodToJsonSchemaConverterOptions['maxStructureDepth'], undefined>
@@ -430,7 +441,14 @@ export class ZodToJsonSchemaConverter implements ConditionalSchemaConverter {
 
           case 'enum': {
             const enum_ = schema as $ZodEnum
-            return [true, { enum: Object.values(enum_._zod.def.entries) }]
+            const values = getValidEnumValues(enum_._zod.def.entries)
+            const hasString = values.some(v => typeof v === 'string')
+            const hasNumber = values.some(v => typeof v === 'number')
+            const type = hasString && hasNumber ? undefined : hasNumber ? 'number' : 'string'
+            const json: any = { enum: values }
+            if (type)
+              json.type = type
+            return [true, json]
           }
 
           case 'literal': {