fix(astro): Fix compatibility with Astro v6 Cloudflare adapter

.changeset/fix-astro-v6-cloudflare.md

@@ -0,0 +1,5 @@
+---
+'@clerk/astro': patch
+---
+
+Fix compatibility with Astro v6 Cloudflare adapter by using `cloudflare:workers` env when `locals.runtime.env` is unavailable

packages/astro/package.json

@@ -100,7 +100,7 @@
     "astro": "^5.17.1"
   },
   "peerDependencies": {
-    "astro": "^4.15.0 || ^5.0.0"
+    "astro": "^4.15.0 || ^5.0.0 || ^6.0.0"
   },
   "engines": {
     "node": ">=20.9.0"

packages/astro/src/env.d.ts

@@ -30,7 +30,7 @@ interface ImportMeta {
 
 declare namespace App {
   interface Locals {
-    runtime: { env: InternalEnv };
+    runtime?: { env: InternalEnv };
     keylessClaimUrl?: string;
     keylessApiKeysUrl?: string;
     keylessPublishableKey?: string;

packages/astro/src/server/__tests__/get-safe-env.test.ts

@@ -9,6 +9,136 @@ function createLocals(overrides: Partial<App.Locals> = {}): App.Locals {
   } as unknown as App.Locals;
 }
 
+describe('get-safe-env', () => {
+  beforeEach(() => {
+    vi.resetModules();
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('initCloudflareEnv', () => {
+    it('caches env from cloudflare:workers when available', async () => {
+      vi.doMock('cloudflare:workers', () => ({
+        env: { CLERK_SECRET_KEY: 'sk_test_cf' },
+      }));
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+
+      await initCloudflareEnv();
+
+      const env = getSafeEnv({ locals: {} } as any);
+      expect(env.sk).toBe('sk_test_cf');
+    });
+
+    it('sets cache to null when cloudflare:workers is not available', async () => {
+      vi.doMock('cloudflare:workers', () => {
+        throw new Error('Module not found');
+      });
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+
+      await initCloudflareEnv();
+
+      // Should fall through to import.meta.env (undefined in test)
+      const env = getSafeEnv({ locals: {} } as any);
+      expect(env.sk).toBeUndefined();
+    });
+
+    it('only imports once (caches result)', async () => {
+      let importCount = 0;
+      vi.doMock('cloudflare:workers', () => {
+        importCount++;
+        return { env: { CLERK_SECRET_KEY: 'sk_test_cf' } };
+      });
+
+      const { initCloudflareEnv } = await import('../get-safe-env');
+
+      await initCloudflareEnv();
+      await initCloudflareEnv();
+      await initCloudflareEnv();
+
+      expect(importCount).toBe(1);
+    });
+
+    it('only imports once even when cloudflare:workers throws', async () => {
+      let importCount = 0;
+      vi.doMock('cloudflare:workers', () => {
+        importCount++;
+        throw new Error('Module not found');
+      });
+
+      const { initCloudflareEnv } = await import('../get-safe-env');
+
+      await initCloudflareEnv();
+      await initCloudflareEnv();
+
+      expect(importCount).toBe(1);
+    });
+  });
+
+  describe('getContextEnvVar fallback chain', () => {
+    it('reads from locals.runtime.env (Astro v4/v5)', async () => {
+      const { getSafeEnv } = await import('../get-safe-env');
+      const locals = { runtime: { env: { CLERK_SECRET_KEY: 'sk_from_runtime' } } };
+
+      const env = getSafeEnv({ locals } as any);
+      expect(env.sk).toBe('sk_from_runtime');
+    });
+
+    it('falls back to cloudflareEnv when locals.runtime.env is absent', async () => {
+      vi.doMock('cloudflare:workers', () => ({
+        env: { CLERK_SECRET_KEY: 'sk_from_cf_workers' },
+      }));
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+      await initCloudflareEnv();
+
+      const env = getSafeEnv({ locals: {} } as any);
+      expect(env.sk).toBe('sk_from_cf_workers');
+    });
+
+    it('falls back to cloudflareEnv when locals.runtime throws (Astro v6)', async () => {
+      vi.doMock('cloudflare:workers', () => ({
+        env: { CLERK_SECRET_KEY: 'sk_from_cf_workers' },
+      }));
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+      await initCloudflareEnv();
+
+      // Simulate Astro v6 behavior: accessing runtime throws
+      const locals = new Proxy(
+        {},
+        {
+          get(_, prop) {
+            if (prop === 'runtime') {
+              throw new Error('locals.runtime is not available in Astro v6 Cloudflare');
+            }
+            return undefined;
+          },
+        },
+      );
+
+      const env = getSafeEnv({ locals } as any);
+      expect(env.sk).toBe('sk_from_cf_workers');
+    });
+
+    it('prefers cloudflareEnv over locals.runtime.env', async () => {
+      vi.doMock('cloudflare:workers', () => ({
+        env: { CLERK_SECRET_KEY: 'sk_from_cf_workers' },
+      }));
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+      await initCloudflareEnv();
+
+      const locals = { runtime: { env: { CLERK_SECRET_KEY: 'sk_from_runtime' } } };
+      const env = getSafeEnv({ locals } as any);
+      expect(env.sk).toBe('sk_from_cf_workers');
+    });
+  });
+});
+
 describe('getSafeEnv', () => {
   beforeEach(() => {
     vi.stubEnv('PUBLIC_CLERK_PUBLISHABLE_KEY', '');

packages/astro/src/server/clerk-middleware.ts

@@ -28,7 +28,7 @@ import { canUseKeyless } from '../utils/feature-flags';
 import { buildClerkHotloadScript } from './build-clerk-hotload-script';
 import { clerkClient } from './clerk-client';
 import { createCurrentUser } from './current-user';
-import { getClientSafeEnv, getSafeEnv } from './get-safe-env';
+import { getClientSafeEnv, getSafeEnv, initCloudflareEnv } from './get-safe-env';
 import { resolveKeysWithKeylessFallback } from './keyless/utils';
 import { serverRedirectWithAuth } from './server-redirect-with-auth';
 import type {
@@ -79,6 +79,8 @@ export const clerkMiddleware: ClerkMiddleware = (...args: unknown[]): any => {
       return next();
     }
 
+    await initCloudflareEnv();
+
     const clerkRequest = createClerkRequest(context.request);
 
     // Resolve keyless URLs per-request in development

packages/astro/src/server/get-safe-env.ts

@@ -3,15 +3,55 @@ import type { APIContext } from 'astro';
 
 type ContextOrLocals = APIContext | APIContext['locals'];
 
+/**
+ * Cached env object from `cloudflare:workers` for Astro v6+ Cloudflare adapter.
+ * - `undefined`: not yet attempted
+ * - `null`: attempted but not available (non-Cloudflare environment)
+ * - object: the env object from `cloudflare:workers`
+ */
+let cloudflareEnv: Record<string, string> | null | undefined;
+
+/**
+ * @internal
+ * Attempts to import env from `cloudflare:workers` and caches the result.
+ * This is needed for Astro v6+ where `locals.runtime.env` is no longer available.
+ * Safe to call in non-Cloudflare environments — will no-op.
+ */
+async function initCloudflareEnv(): Promise<void> {
+  if (cloudflareEnv !== undefined) {
+    return;
+  }
+  try {
+    // Use a variable to prevent TypeScript from resolving the module specifier
+    const moduleName = 'cloudflare:workers';
+    const mod = await import(/* @vite-ignore */ moduleName);
+    cloudflareEnv = mod.env;
+  } catch {
+    cloudflareEnv = null;
+  }
+}
+
 /**
  * @internal
  * Isomorphic handler for reading environment variables defined from Vite or are injected in the request context (CF Pages)
  */
 function getContextEnvVar(envVarName: keyof InternalEnv, contextOrLocals: ContextOrLocals): string | undefined {
   const locals = 'locals' in contextOrLocals ? contextOrLocals.locals : contextOrLocals;
 
-  if (locals?.runtime?.env) {
-    return locals.runtime.env[envVarName];
+  // Astro v6+ Cloudflare adapter: env from cloudflare:workers
+  // Checked first to avoid the expensive try/catch on locals.runtime.env,
+  // which throws on every call in Astro v6 Cloudflare environments.
+  if (cloudflareEnv) {
+    return cloudflareEnv[envVarName];
+  }
+
+  // Astro v4/v5 Cloudflare adapter: env is on locals.runtime.env
+  try {
+    if (locals?.runtime?.env) {
+      return locals.runtime.env[envVarName];
+    }
+  } catch {
+    // Astro v6 Cloudflare adapter throws when accessing locals.runtime.env
   }
 
   // Prefer process.env for runtime environments (e.g., Node.js adapter)
@@ -79,4 +119,4 @@ function getClientSafeEnv(context: ContextOrLocals) {
   };
 }
 
-export { getSafeEnv, getClientSafeEnv };
+export { getSafeEnv, getClientSafeEnv, initCloudflareEnv };