fix: generate Blob for $ref schemas with format: binary (#3030)

* fix: generate Blob for contentMediaType: application/octet-stream in model types

* fix: update generateZodValidationSchemaDefinition to use 'test' for context spec

Author: matsu3m

packages/core/src/getters/scalar.test.ts

@@ -0,0 +1,62 @@
+import { describe, expect, it } from 'vitest';
+
+import type { ContextSpec, OpenApiSchemaObject } from '../types';
+import { getScalar } from './scalar';
+
+const context = {
+  output: {
+    override: {
+      useDates: false,
+    },
+  },
+} as ContextSpec;
+
+describe('getScalar (contentMediaType: application/octet-stream)', () => {
+  it('contentMediaType: application/octet-stream without formDataContext → Blob', () => {
+    // Simulates $ref-based schema after upgrader converts format: binary →
+    // contentMediaType: application/octet-stream (Swagger 2.0 / OAS 3.0 → 3.1)
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+      contentMediaType: 'application/octet-stream',
+    };
+
+    const result = getScalar({ item: schema, name: 'file', context });
+
+    expect(result.value).toBe('Blob');
+  });
+
+  it('contentEncoding: base64 with contentMediaType: application/octet-stream → string', () => {
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+      contentMediaType: 'application/octet-stream',
+      contentEncoding: 'base64',
+    };
+
+    const result = getScalar({ item: schema, name: 'data', context });
+
+    expect(result.value).toBe('string');
+  });
+
+  it('plain string without contentMediaType or format: binary → string', () => {
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+    };
+
+    const result = getScalar({ item: schema, name: 'name', context });
+
+    expect(result.value).toBe('string');
+  });
+
+  it('non-octet-stream contentMediaType without formDataContext → string', () => {
+    // contentMediaType other than application/octet-stream is only handled
+    // in the form-data context (formDataContext?.atPart)
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+      contentMediaType: 'image/png',
+    };
+
+    const result = getScalar({ item: schema, name: 'avatar', context });
+
+    expect(result.value).toBe('string');
+  });
+});

packages/core/src/getters/scalar.ts

@@ -50,6 +50,8 @@ export function getScalar({
   const schemaConst = item.const as string | undefined;
   const schemaFormat = item.format as string | undefined;
   const schemaNullable = item.nullable as boolean | undefined;
+  const schemaContentMediaType = item.contentMediaType as string | undefined;
+  const schemaContentEncoding = item.contentEncoding as string | undefined;
 
   const nullable =
     (isArray(schemaType) && schemaType.includes('null')) ||
@@ -172,6 +174,15 @@ export function getScalar({
         if (fileType) {
           value = fileType === 'binary' ? 'Blob' : 'Blob | string';
         }
+      } else if (
+        schemaContentMediaType === 'application/octet-stream' &&
+        !schemaContentEncoding
+      ) {
+        // The @scalar/openapi-parser upgrader converts format: binary to
+        // contentMediaType: application/octet-stream when upgrading
+        // Swagger 2.0 / OAS 3.0 → OAS 3.1. Treat it the same as
+        // format: binary so $ref-based model types generate Blob.
+        value = 'Blob';
       }
 
       if (

packages/zod/src/index.ts

@@ -508,6 +508,18 @@ export const generateZodValidationSchemaDefinition = (
           break;
         }
 
+        // The @scalar/openapi-parser upgrader converts format: binary to
+        // contentMediaType: application/octet-stream when upgrading
+        // Swagger 2.0 / OAS 3.0 → OAS 3.1. Treat it the same as
+        // format: binary so $ref-based model types generate File validation.
+        if (
+          schema.contentMediaType === 'application/octet-stream' &&
+          !schema.contentEncoding
+        ) {
+          functions.push(['instanceof', 'File']);
+          break;
+        }
+
         if (isZodV4) {
           if (
             ![

packages/zod/src/zod.test.ts

@@ -5154,3 +5154,60 @@ describe('zod split mode regressions', () => {
     expect(parsed.zod).not.toContain('looseObject({');
   });
 });
+
+describe('generateZodValidationSchemaDefinition (contentMediaType: application/octet-stream)', () => {
+  it('contentMediaType: application/octet-stream → instanceof File', () => {
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+      contentMediaType: 'application/octet-stream',
+    };
+
+    const result = generateZodValidationSchemaDefinition(
+      schema,
+      {
+        output: {
+          override: {
+            useDates: false,
+          },
+        },
+      } as ContextSpec,
+      'test',
+      true,
+      false,
+      { required: true },
+    );
+
+    expect(result).toEqual({
+      functions: [['instanceof', 'File']],
+      consts: [],
+    });
+  });
+
+  it('contentEncoding: base64 with contentMediaType: application/octet-stream → string', () => {
+    const schema: OpenApiSchemaObject = {
+      type: 'string',
+      contentMediaType: 'application/octet-stream',
+      contentEncoding: 'base64',
+    };
+
+    const result = generateZodValidationSchemaDefinition(
+      schema,
+      {
+        output: {
+          override: {
+            useDates: false,
+          },
+        },
+      } as ContextSpec,
+      'test',
+      true,
+      false,
+      { required: true },
+    );
+
+    expect(result).toEqual({
+      functions: [['string', undefined]],
+      consts: [],
+    });
+  });
+});