diff --git a/eslint.config.js b/eslint.config.js
index 3d6ea0f0..23fbb902 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -46,6 +46,7 @@ export default [
         window: 'readonly',
         document: 'readonly',
         navigator: 'readonly',
+        fetch: 'readonly',
       },
     },
     plugins: {
diff --git a/tests_integ/__fixtures__/test-helpers.ts b/tests_integ/__fixtures__/test-helpers.ts
index 7311bf50..87770aa9 100644
--- a/tests_integ/__fixtures__/test-helpers.ts
+++ b/tests_integ/__fixtures__/test-helpers.ts
@@ -1,17 +1,34 @@
-import { readFileSync } from 'node:fs'
-import { join } from 'node:path'
-
 /**
  * Helper to load fixture files from Vite URL imports.
- * Vite ?url imports return paths like '/tests_integ/__resources__/file.png' in test environment.
+ * Works in both Node.js and browser environments with a unified async API.
  *
  * @param url - The URL from a Vite ?url import
- * @returns The file contents as a Uint8Array
+ * @returns Promise resolving to the file contents as a Uint8Array
+ *
+ * @remarks
+ * Implementation uses environment-specific approaches:
+ * - **Browser**: Uses fetch() with HTTP URLs from Vite dev server
+ * - **Node.js**: Uses fs.readFile since Node's fetch() doesn't support file:// protocol
+ *
+ * Note: Node.js's native fetch() (v18+) explicitly does not support file:// URLs.
+ * This limitation is documented in the Node.js fetch implementation and returns
+ * "not implemented... yet..." error. The hybrid approach is necessary until Node.js
+ * adds file:// protocol support to fetch().
  */
-export const loadFixture = (url: string): Uint8Array => {
+export const loadFixture = async (url: string): Promise<Uint8Array> => {
+  // Browser environment: Vite serves files over HTTP during development
+  if (url.startsWith('http')) {
+    const arrayBuffer = await fetch(url).then((b) => b.arrayBuffer())
+    return new Uint8Array(arrayBuffer)
+  }
+
+  // Node.js environment: Use file system since fetch() doesn't support file:// protocol
+  const { readFile } = await import('node:fs/promises')
+  const { join } = await import('node:path')
   const relativePath = url.startsWith('/') ? url.slice(1) : url
   const filePath = join(process.cwd(), relativePath)
-  return new Uint8Array(readFileSync(filePath))
+  const buffer = await readFile(filePath)
+  return new Uint8Array(buffer)
 }
 
 /**
diff --git a/tests_integ/agent.test.ts b/tests_integ/agent.test.ts
index b4606597..c9292b86 100644
--- a/tests_integ/agent.test.ts
+++ b/tests_integ/agent.test.ts
@@ -117,7 +117,7 @@ describe.each(providers)('Agent with $name', ({ name, skip, createModel }) => {
         })
 
         // Create image block
-        const imageBytes = loadFixture(yellowPngUrl)
+        const imageBytes = await loadFixture(yellowPngUrl)
         const imageBlock = new ImageBlock({
           format: 'png',
           source: { bytes: imageBytes },
diff --git a/tests_integ/bedrock.test.ts b/tests_integ/bedrock.test.ts
index 1c91f535..66189360 100644
--- a/tests_integ/bedrock.test.ts
+++ b/tests_integ/bedrock.test.ts
@@ -376,7 +376,7 @@ describe.skipIf(!(await shouldRunTests()))('BedrockModel Integration Tests', ()
       })
 
       // PDF document
-      const pdfBytes = loadFixture(letterPdfUrl)
+      const pdfBytes = await loadFixture(letterPdfUrl)
       const pdfDocBlock = new DocumentBlock({
         name: 'letter',
         format: 'pdf',
diff --git a/tests_integ/browser/agent.browser.test.ts b/tests_integ/browser/agent.browser.test.ts
index 675c2b5a..804158ba 100644
--- a/tests_integ/browser/agent.browser.test.ts
+++ b/tests_integ/browser/agent.browser.test.ts
@@ -8,30 +8,11 @@ import { httpRequest } from '@strands-agents/sdk/vended_tools/http_request'
 import { z } from 'zod'
 
 import { collectGenerator } from '../../src/__fixtures__/model-test-helpers.js'
+import { loadFixture } from '../__fixtures__/test-helpers.js'
 
 // Import fixtures
 import yellowPngUrl from '../__resources__/yellow.png?url'
 
-// Environment detection for browser vs Node.js
-const isNode = typeof process !== 'undefined' && typeof process.versions !== 'undefined' && !!process.versions.node
-
-// Browser-compatible fixture loader
-const loadFixture = async (url: string): Promise<Uint8Array> => {
-  if (isNode) {
-    // In Node.js, use synchronous file reading
-    const { readFileSync } = await import('node:fs')
-    const { join } = await import('node:path')
-    const relativePath = url.startsWith('/') ? url.slice(1) : url
-    const filePath = join(process.cwd(), relativePath)
-    return new Uint8Array(readFileSync(filePath))
-  } else {
-    // In browser, use fetch API
-    const response = await globalThis.fetch(url)
-    const arrayBuffer = await response.arrayBuffer()
-    return new Uint8Array(arrayBuffer)
-  }
-}
-
 // Calculator tool for testing
 const calculatorTool = tool({
   name: 'calculator',
diff --git a/vitest.config.ts b/vitest.config.ts
index 8028acab..4bc30454 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -31,6 +31,11 @@ const getOpenAIAPIKey: BrowserCommand<[], string | undefined> = async ({
 }
 
 export default defineConfig({
+  server: {
+    fs: {
+      allow: ['.'],
+    },
+  },
   test: {
     projects: [
       {