Run JS tests on base image and use dynamic version in error message

JavaScript-only E2E tests now run against the base image to validate
the lean image works correctly for non-Python workloads. This provides
coverage for the bundled JS executor without requiring Python.

The Python unavailable error message now uses SANDBOX_VERSION env var
when available, falling back to <version> placeholder. This gives users
the exact version to use in production while keeping the placeholder
for development.

Author: ghostwriternr

packages/sandbox-container/src/runtime/process-pool.ts

@@ -231,10 +231,10 @@ export class ProcessPoolManager {
 
     // Check if Python is available
     if (language === 'python' && !PYTHON_AVAILABLE) {
+      const version = process.env.SANDBOX_VERSION || '<version>';
       return {
         stdout: '',
-        stderr:
-          'Python interpreter not available. Use the cloudflare/sandbox:<version>-python image variant for Python code execution. See https://developers.cloudflare.com/sandbox/configuration/dockerfile/',
+        stderr: `Python interpreter not available. Use the cloudflare/sandbox:${version}-python image variant for Python code execution. See https://developers.cloudflare.com/sandbox/configuration/dockerfile/`,
         success: false,
         executionId: randomUUID(),
         outputs: [],
@@ -563,8 +563,9 @@ export class ProcessPoolManager {
   ): Promise<void> {
     // Check if Python is available before trying to create a context
     if (language === 'python' && !PYTHON_AVAILABLE) {
+      const version = process.env.SANDBOX_VERSION || '<version>';
       throw new Error(
-        'Python interpreter not available. Use the cloudflare/sandbox:<version>-python image variant for Python code execution. See https://developers.cloudflare.com/sandbox/configuration/dockerfile/'
+        `Python interpreter not available. Use the cloudflare/sandbox:${version}-python image variant for Python code execution. See https://developers.cloudflare.com/sandbox/configuration/dockerfile/`
       );
     }
 

tests/e2e/code-interpreter-workflow.test.ts

@@ -267,7 +267,7 @@ describe('Code Interpreter Workflow (E2E)', () => {
 
   test('should execute simple JavaScript code', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create JavaScript context
     const ctxResponse = await fetch(`${workerUrl}/api/code/context/create`, {
@@ -297,7 +297,7 @@ describe('Code Interpreter Workflow (E2E)', () => {
 
   test('should maintain JavaScript state across executions', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create context
     const ctxResponse = await fetch(`${workerUrl}/api/code/context/create`, {
@@ -337,7 +337,7 @@ describe('Code Interpreter Workflow (E2E)', () => {
 
   test('should handle JavaScript errors gracefully', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create context
     const ctxResponse = await fetch(`${workerUrl}/api/code/context/create`, {
@@ -583,7 +583,7 @@ console.log('Sum:', sum);
 
   test('should maintain isolation across many contexts (12+)', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create 12 contexts
     const contexts: CodeContext[] = [];
@@ -653,7 +653,7 @@ console.log('Sum:', sum);
 
   test('should maintain state isolation with concurrent context execution', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create contexts sequentially
     const contexts: CodeContext[] = [];
@@ -734,7 +734,7 @@ console.log('Sum:', sum);
 
   test('should prevent concurrent execution on same context', async () => {
     currentSandboxId = createSandboxId();
-    const headers = createTestHeaders(currentSandboxId);
+    const headers = createBaseImageHeaders(currentSandboxId);
 
     // Create single context
     const ctxResponse = await fetch(`${workerUrl}/api/code/context/create`, {
@@ -911,6 +911,6 @@ console.log('Sum:', sum);
 
     // Error should guide users to the correct image variant
     expect(errorData.message).toContain('Python interpreter not available');
-    expect(errorData.message).toContain('-python');
+    expect(errorData.message).toMatch(/-python/);
   }, 120000);
 });

tests/e2e/helpers/test-fixtures.ts

@@ -66,13 +66,14 @@ export function createTestHeaders(
  * The base image is smaller but only supports JavaScript/shell execution.
  *
  * @param sandboxId - Which container instance to use
+ * @param sessionId - (Optional) Which session within that container
  */
 export function createBaseImageHeaders(
-  sandboxId: string
+  sandboxId: string,
+  sessionId?: string
 ): Record<string, string> {
   return {
-    'Content-Type': 'application/json',
-    'X-Sandbox-Id': sandboxId,
+    ...createTestHeaders(sandboxId, sessionId),
     'X-Sandbox-Type': 'base'
   };
 }