u

src/api/middleware/logger.js

@@ -23,6 +23,10 @@ function captureResponseBody(res) {
     res.json = (payload) => {
         let out = payload;
         if (res.statusCode >= 500 && payload && typeof payload === 'object' && 'error' in payload) {
+            if (!res.locals?.error && typeof payload.error === 'string') {
+                res.locals = res.locals || {};
+                res.locals.error = new Error(payload.error);
+            }
             out = { ...payload, error: 'Internal server error' };
         }
         body = out;

src/api/routes/vfsExec.js

@@ -43,7 +43,8 @@ function appletExecErrorStatus(error) {
     if (message.includes('is not a file')) return 400;
     if (message.includes('Applet metadata') || message.includes('Applet input schema') || message.includes('Applet output schema')) return 400;
     if (message.includes('Sandbox exceeded')) return 504;
-    return 500;
+    if (message.includes('Sandbox worker did not report a result payload')) return 500;
+    return 400;
 }
 
 // #endregion
@@ -163,7 +164,7 @@ export function register(app, basePath = '') {
      *                 truncationNote:
      *                   type: string
      *       400:
-     *         description: No company selected, invalid path, not a .applet.js file, invalid input, or invalid applet metadata
+     *         description: No company selected, invalid path, not a .applet.js file, invalid input, invalid applet metadata, or applet runtime error
      *         content:
      *           application/json:
      *             schema:
@@ -187,7 +188,7 @@ export function register(app, basePath = '') {
      *             schema:
      *               $ref: '#/components/schemas/Error'
      *       500:
-     *         description: The applet threw during execution
+     *         description: Sandbox worker harness failure
      *         content:
      *           application/json:
      *             schema:
@@ -241,6 +242,7 @@ export function register(app, basePath = '') {
                 return res.status(404).json({ error: 'File not found' });
             }
         } catch (error) {
+            res.locals.error = error;
             const status = vfsFileErrorStatus(error);
             if (status === 500) console.error('Execute vfs applet failed:', error);
             return res.status(status).json({ error: error.message });
@@ -258,6 +260,7 @@ export function register(app, basePath = '') {
             emit('vfs', { companyId: selected.companyId });
             return res.json(result);
         } catch (error) {
+            res.locals.error = error;
             const status = appletExecErrorStatus(error);
             if (status === 500) console.error('Execute vfs applet failed:', error);
             return res.status(status).json({ error: error.message });

src/defaultApplets/article-lookup.applet.js

@@ -1,4 +1,4 @@
-// @applet-input-schema {"type":"object","properties":{"sku":{"type":"string","title":"Article SKU","default":"","description":"Exact SKU to inspect. Leave empty for a single-row manifest summary."}}}
+// @applet-input-schema {"type":"object","properties":{"sku":{"type":"string","title":"Article SKU","description":"Exact SKU to inspect (e.g. \"42000009\")."}},"required":["sku"]}
 // @applet-output-schema key:string;value:string
 //
 // Article lookup — the raw `GET /article/{sku}` payload as a key/value sheet.