feat: US-196 - Fix node -e stderr/errors not appearing in interactive shell

Author: NathanFlurry

packages/runtime/node/src/driver.ts

@@ -472,6 +472,13 @@ class NodeRuntimeDriver implements RuntimeDriver {
         },
       });
 
+      // Emit errorMessage as stderr (covers ReferenceError, SyntaxError, throw)
+      if (result.errorMessage) {
+        const errBytes = new TextEncoder().encode(result.errorMessage + '\n');
+        ctx.onStderr?.(errBytes);
+        proc.onStderr?.(errBytes);
+      }
+
       // Cleanup isolate
       executionDriver.dispose();
       this._activeDrivers.delete(ctx.pid);

packages/secure-exec-node/src/execution.ts

@@ -278,7 +278,10 @@ export async function executeWithRuntime<T = unknown>(
 			};
 		}
 
-		const errMessage = err instanceof Error ? err.message : String(err);
+		// Include error class name (e.g. "SyntaxError: ...") to match Node.js output
+		const errMessage = err instanceof Error
+			? (err.name && err.name !== 'Error' ? `${err.name}: ${err.message}` : err.message)
+			: String(err);
 		const exitMatch = errMessage.match(/process\.exit\((\d+)\)/);
 
 		if (exitMatch) {

packages/secure-exec/tests/kernel/cross-runtime-terminal.test.ts

@@ -169,6 +169,109 @@ describe.skipIf(wasmSkip)('cross-runtime exec: node', () => {
   }, 15_000);
 });
 
+// ---------------------------------------------------------------------------
+// Node kernel.exec() stderr tests
+// ---------------------------------------------------------------------------
+
+describe.skipIf(wasmSkip)('cross-runtime exec: node stderr', () => {
+  let ctx: IntegrationKernelResult;
+
+  afterEach(async () => {
+    await ctx?.dispose();
+  });
+
+  it('kernel.exec node -e with undefined var returns ReferenceError on stderr', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    const result = await ctx.kernel.exec('node -e "lskdjf"');
+    expect(result.exitCode).not.toBe(0);
+    expect(result.stderr).toContain('ReferenceError');
+  });
+
+  it('kernel.exec node -e throw Error returns message on stderr', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    const result = await ctx.kernel.exec('node -e "throw new Error(\'boom\')"');
+    expect(result.exitCode).not.toBe(0);
+    expect(result.stderr).toContain('boom');
+  });
+
+  it('kernel.exec node -e with syntax error returns SyntaxError on stderr', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    const result = await ctx.kernel.exec('node -e "({"');
+    expect(result.exitCode).not.toBe(0);
+    expect(result.stderr).toContain('SyntaxError');
+  });
+
+  it('kernel.exec node -e console.error returns stderr', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    const result = await ctx.kernel.exec('node -e "console.error(\'ERRMSG\')"');
+    expect(result.stderr).toContain('ERRMSG');
+    expect(result.exitCode).toBe(0);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Node cross-runtime terminal: stderr tests
+// ---------------------------------------------------------------------------
+
+describe.skipIf(wasmSkip)('cross-runtime terminal: node stderr', () => {
+  let harness: TerminalHarness;
+  let ctx: IntegrationKernelResult;
+
+  afterEach(async () => {
+    await harness?.dispose();
+    await ctx?.dispose();
+  });
+
+  it('node -e with undefined var shows ReferenceError on terminal', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    harness = new TerminalHarness(ctx.kernel);
+
+    await harness.waitFor(PROMPT);
+    await harness.type('node -e "lskdjf"\n');
+    await harness.waitFor(PROMPT, 2, 10_000);
+
+    const screen = harness.screenshotTrimmed();
+    expect(screen).toContain('ReferenceError');
+  }, 15_000);
+
+  it('node -e throw Error shows error message on terminal', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    harness = new TerminalHarness(ctx.kernel);
+
+    await harness.waitFor(PROMPT);
+    await harness.type('node -e "throw new Error(\'boom\')"\n');
+    await harness.waitFor(PROMPT, 2, 10_000);
+
+    const screen = harness.screenshotTrimmed();
+    expect(screen).toContain('boom');
+  }, 15_000);
+
+  it('node -e syntax error shows SyntaxError on terminal', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    harness = new TerminalHarness(ctx.kernel);
+
+    await harness.waitFor(PROMPT);
+    await harness.type('node -e "({"\n');
+    await harness.waitFor(PROMPT, 2, 10_000);
+
+    const screen = harness.screenshotTrimmed();
+    expect(screen).toContain('SyntaxError');
+  }, 15_000);
+
+  it('stderr callback chain: NodeRuntimeDriver → ctx.onStderr → PTY slave', async () => {
+    ctx = await createIntegrationKernel({ runtimes: ['wasmvm', 'node'] });
+    harness = new TerminalHarness(ctx.kernel);
+
+    await harness.waitFor(PROMPT);
+    // console.error goes through onStdio → ctx.onStderr → PTY write
+    await harness.type('node -e "console.error(\'STDERRTEST\')"\n');
+    await harness.waitFor(PROMPT, 2, 10_000);
+
+    const screen = harness.screenshotTrimmed();
+    expect(screen).toContain('STDERRTEST');
+  }, 15_000);
+});
+
 // ---------------------------------------------------------------------------
 // Python cross-runtime terminal tests
 // ---------------------------------------------------------------------------