Fix validation error reporting and clarify feature service docs

Critical fix: Errors now correctly captured and reported
- Capture errors immediately after render() in CustomScreenTestImpl
- Added saveMessagesToSession() to WebFacadeStub for framework compatibility
- Actions that fail validation now report status:'error' instead of false success

Documentation fix: Clarify two different feature services
- applyProductFeatures: Apply EXISTING features to products (most common)
- createProductFeature: Create NEW feature definitions (rare)
- Updated EditProduct and ProductFeature wiki docs with correct examples

@@ -762,13 +762,16 @@ Manage product details, features, prices, categories, and associations.
 
 Features are managed directly on the EditProduct screen (not a separate EditFeatures subscreen).
 
+**IMPORTANT:** Use `applyProductFeatures` to add existing features (like ColorGreen). 
+Use `createProductFeature` only to create NEW feature definitions.
+
 ### Add Selectable Feature (Virtual Products)
 ```
 path: PopCommerce/PopCommerceAdmin/Catalog/Product/EditProduct
-action: createProductFeature
+action: applyProductFeatures
 parameters: {
   productId: "DEMO_VAR",
-  productFeatureId: "ColorRed",
+  productFeatureIdList: ["ColorGreen"],
   applTypeEnumId: "PfatSelectable"
 }
 ```
@@ -776,10 +779,10 @@ parameters: {
 ### Add Distinguishing Feature (Variant Products)
 ```
 path: PopCommerce/PopCommerceAdmin/Catalog/Product/EditProduct
-action: createProductFeature
+action: applyProductFeatures
 parameters: {
-  productId: "DEMO_VAR_RED",
-  productFeatureId: "ColorRed",
+  productId: "DEMO_VAR_GR_SM",
+  productFeatureIdList: ["ColorGreen", "SizeSmall"],
   applTypeEnumId: "PfatDistinguishing"
 }
 ```
@@ -944,14 +947,31 @@ parameters: {
         versionName="v1">
         <fileData><![CDATA[# ProductFeature Service
 
-Apply features (like color, size) to products.
+Manage product features (color, size, etc.) - two different operations:
 
-## mantle.product.ProductServices.create#ProductFeature
+## IMPORTANT: Two Different Services
+
+1. **applyProductFeatures** - Apply EXISTING features to a product (most common)
+2. **createProductFeature** - Create a NEW feature definition (rare)
+
+Most of the time you want `applyProductFeatures` to link existing features like ColorGreen or SizeLarge to products.
+
+---
+
+## mantle.product.ProductServices.apply#ProductFeatures
+
+**Use this to apply existing features to products.**
+
+**Action:** `applyProductFeatures`
 
 **Required:**
-- `productId`: Product to add feature to
-- `productFeatureId`: Feature ID (e.g., ColorRed, SizeMedium)
-- `applTypeEnumId`: How feature applies to product
+- `productId`: Product to add features to
+- `productFeatureIdList`: List of feature IDs (e.g., ["ColorGreen", "SizeMedium"])
+
+**Optional:**
+- `applTypeEnumId`: How feature applies (default: PfatStandard)
+- `fromDate`: When feature becomes active (default: now)
+- `sequenceNum`: Display order
 
 **Application Types (applTypeEnumId):**
 - `PfatSelectable`: Customer can choose (use on virtual parent)
@@ -959,34 +979,61 @@ Apply features (like color, size) to products.
 - `PfatStandard`: Always included
 - `PfatRequired`: Must be selected at purchase
 
-**Optional:**
-- `fromDate`: When feature becomes active (default: now)
-- `sequenceNum`: Display order
-
-**Example - Virtual Parent:**
+**Example - Add Selectable Feature to Virtual Parent:**
 ```
-action: createProductFeature
+action: applyProductFeatures
 parameters: {
   productId: "DEMO_VAR",
-  productFeatureId: "ColorGreen",
+  productFeatureIdList: ["ColorGreen"],
   applTypeEnumId: "PfatSelectable"
 }
 ```
 
-**Example - Variant:**
+**Example - Add Distinguishing Feature to Variant:**
 ```
-action: createProductFeature  
+action: applyProductFeatures
 parameters: {
   productId: "DEMO_VAR_GR_SM",
-  productFeatureId: "ColorGreen",
+  productFeatureIdList: ["ColorGreen", "SizeSmall"],
   applTypeEnumId: "PfatDistinguishing"
 }
 ```
 
-## Common Feature IDs
+---
+
+## mantle.product.ProductServices.create#ProductFeature
+
+**Use this ONLY to create a NEW feature that doesn't exist yet.**
+
+**Action:** `createProductFeature`
+
+**Required:**
+- `productFeatureTypeEnumId`: Type of feature (PftColor, PftSize, etc.)
+- `description`: Feature name/description (e.g., "Green", "Extra Small")
+
+**Optional:**
+- `productId`: If provided, also applies the new feature to this product
+- `applTypeEnumId`: How to apply (if productId provided)
+- `abbrev`: Short abbreviation (e.g., "GR", "XS")
+
+**Example - Create a new color feature:**
+```
+action: createProductFeature
+parameters: {
+  productFeatureTypeEnumId: "PftColor",
+  description: "Teal",
+  abbrev: "TL",
+  productId: "DEMO_VAR",
+  applTypeEnumId: "PfatSelectable"
+}
+```
+
+---
+
+## Common Feature IDs (already exist - use with applyProductFeatures)
 
-Colors: ColorRed, ColorBlue, ColorGreen, ColorBlack, ColorWhite
-Sizes: SizeSmall, SizeMedium, SizeLarge, SizeXL]]></fileData>
+**Colors:** ColorRed, ColorBlue, ColorGreen, ColorBlack, ColorWhite
+**Sizes:** SizeSmall, SizeMedium, SizeLarge, SizeXL]]></fileData>
     </moqui.resource.DbResourceFile>
 
     <moqui.resource.wiki.WikiPage

@@ -397,6 +397,25 @@ class CustomScreenTestImpl implements McpScreenTest {
             try {
                 logger.info("Starting render for ${screenPathList} with root ${csti.rootScreenLocation}")
                 screenRender.render(wfs.getRequest(), wfs.getResponse())
+                
+                // IMMEDIATELY capture errors after render - before anything can clear them
+                // This is critical for transition validation errors which get cleared during redirect handling
+                if (eci.message.hasError()) {
+                    List<String> immediateErrors = new ArrayList<>(eci.message.getErrors())
+                    if (immediateErrors.size() > 0) {
+                        stri.errorMessages.addAll(immediateErrors)
+                        logger.warn("Captured ${immediateErrors.size()} errors immediately after render: ${immediateErrors}")
+                    }
+                }
+                List<org.moqui.context.ValidationError> immediateValErrors = eci.message.getValidationErrors()
+                if (immediateValErrors != null && immediateValErrors.size() > 0) {
+                    for (org.moqui.context.ValidationError ve : immediateValErrors) {
+                        String errMsg = ve.getMessage() ?: "${ve.getField()}: Validation error"
+                        stri.errorMessages.add(errMsg)
+                    }
+                    logger.warn("Captured ${immediateValErrors.size()} validation errors immediately after render")
+                }
+                
                 // get the response text from the WebFacadeStub
                 stri.outputString = wfs.getResponseText()
                 stri.jsonObj = wfs.getResponseJsonObj()
@@ -416,7 +435,7 @@ class CustomScreenTestImpl implements McpScreenTest {
             // pop the context stack, get rid of var space
             cs.pop()
 
-            // check, pass through, error messages
+            // check, pass through, error messages from ExecutionContext
             if (eci.message.hasError()) {
                 stri.errorMessages.addAll(eci.message.getErrors())
                 eci.message.clearErrors()
@@ -425,6 +444,29 @@ class CustomScreenTestImpl implements McpScreenTest {
                 logger.warn(sb.toString())
                 csti.errorCount += stri.errorMessages.size()
             }
+            
+            // Also check errors saved to session by saveMessagesToSession() during transition redirects
+            // This captures validation errors that occur during service calls but get cleared before we check
+            if (wfs instanceof WebFacadeStub) {
+                def savedErrors = wfs.getSavedErrors()
+                if (savedErrors && savedErrors.size() > 0) {
+                    stri.errorMessages.addAll(savedErrors)
+                    StringBuilder sb = new StringBuilder("Saved error messages from ${stri.screenPath}: ")
+                    for (String errorMessage in savedErrors) sb.append("\n").append(errorMessage)
+                    logger.warn(sb.toString())
+                    csti.errorCount += savedErrors.size()
+                }
+                def savedValidationErrors = wfs.getSavedValidationErrors()
+                if (savedValidationErrors && savedValidationErrors.size() > 0) {
+                    // Convert ValidationError objects to string messages
+                    for (def ve in savedValidationErrors) {
+                        def errMsg = ve.message ?: "${ve.field}: Validation error"
+                        stri.errorMessages.add(errMsg)
+                        csti.errorCount++
+                    }
+                    logger.warn("Saved validation errors from ${stri.screenPath}: ${savedValidationErrors.size()} errors")
+                }
+            }
 
             // check for error strings in output
             if (stri.outputString != null) for (String errorStr in csti.errorStrings) if (stri.outputString.contains(errorStr)) {

@@ -294,6 +294,46 @@ class WebFacadeStub implements WebFacade {
         this.responseText = "System message not implemented in stub"
     }
     
+    // Save methods - capture errors/messages before redirect so they're available after render
+    void saveMessagesToSession() {
+        // Capture current errors and validation errors from ExecutionContext
+        if (ecfi instanceof org.moqui.impl.context.ExecutionContextFactoryImpl) {
+            org.moqui.impl.context.ExecutionContextFactoryImpl ecfiImpl = (org.moqui.impl.context.ExecutionContextFactoryImpl) ecfi
+            org.moqui.context.ExecutionContext eci = ecfiImpl.getEci()
+            if (eci != null) {
+                MessageFacade mf = eci.getMessage()
+                if (mf != null) {
+                    List<String> errors = mf.getErrors()
+                    if (errors != null && errors.size() > 0) {
+                        savedErrors.addAll(errors)
+                        logger.info("WebFacadeStub.saveMessagesToSession: Captured ${errors.size()} errors: ${errors}")
+                    }
+                    List<ValidationError> valErrors = mf.getValidationErrors()
+                    if (valErrors != null && valErrors.size() > 0) {
+                        savedValidationErrors.addAll(valErrors)
+                        logger.info("WebFacadeStub.saveMessagesToSession: Captured ${valErrors.size()} validation errors")
+                    }
+                }
+            }
+        }
+    }
+    
+    void saveRequestParametersToSession() {
+        // Store parameters for potential re-display
+        sessionAttributes.put("moqui.saved.parameters", new HashMap(parameters))
+    }
+    
+    void saveErrorParametersToSession() {
+        // Store error parameters 
+        errorParameters.putAll(parameters)
+    }
+    
+    void saveParametersToSession(Map parameters) {
+        if (parameters) {
+            sessionAttributes.put("moqui.saved.parameters", new HashMap(parameters))
+        }
+    }
+    
     // Helper methods for ScreenTestImpl
     String getResponseText() { 
         if (responseText != null) {