Fix template deduplication by separating structure comparison from content storage

- Replace content-aware extractCleanTemplate with structure-only extractStructureSignature for template comparison
- Add extractTemplateForStorage to preserve actual content for meaningful template display
- Update generateTemplateSignature to use purely structural comparison ignoring text content
- Remove redundant extractClassSignature function (functionality moved to extractStructureSignature)
- Resolves issue where identical DOM structures created multiple templates due to content differences
- Knowledge cards and other collections now correctly deduplicate to single templates while preserving content for previews

internal/engine/collection.go

@@ -3,7 +3,6 @@ package engine
 import (
 	"context"
 	"fmt"
-	"sort"
 	"strings"
 	"time"
 
@@ -86,7 +85,7 @@ func (e *ContentEngine) extractAndStoreTemplatesAndItems(collectionNode *html.No
 	templateIndex := 0
 	for child := collectionNode.FirstChild; child != nil; child = child.NextSibling {
 		if child.Type == html.ElementNode {
-			templateHTML := e.extractCleanTemplate(child)
+			templateHTML := e.extractTemplateForStorage(child)
 			templateSignature := e.generateTemplateSignature(child)
 
 			// Check if we've already seen this exact template structure + styling
@@ -233,7 +232,7 @@ func (e *ContentEngine) processChildElementsAsContent(childElement *html.Node, s
 
 			// Extract the content
 			htmlContent := e.extractHTMLContent(n)
-			template := e.extractCleanTemplate(n)
+			template := e.extractTemplateForStorage(n)
 
 			// Store content entry
 			contentEntries = append(contentEntries, ContentEntry{
@@ -476,42 +475,10 @@ func (e *ContentEngine) cloneNode(node *html.Node) *html.Node {
 }
 
 // generateTemplateSignature creates a unique signature for template comparison
-// This combines structural HTML + class-based styling differences
+// This is purely structure + class based, completely ignoring content
 func (e *ContentEngine) generateTemplateSignature(element *html.Node) string {
-	// Get the clean template HTML (structure)
-	structuralHTML := e.extractCleanTemplate(element)
-
-	// Extract class-based styling signature
-	stylingSignature := e.extractClassSignature(element)
-
-	// Combine both for a unique signature
-	return fmt.Sprintf("%s|%s", structuralHTML, stylingSignature)
-}
-
-// extractClassSignature recursively extracts and normalizes class attributes
-func (e *ContentEngine) extractClassSignature(element *html.Node) string {
-	var signature strings.Builder
-
-	e.walkNodes(element, func(n *html.Node) {
-		if n.Type == html.ElementNode {
-			// Get classes for this element
-			classes := GetClasses(n)
-			if len(classes) > 0 {
-				// Sort classes for consistent comparison
-				sortedClasses := make([]string, len(classes))
-				copy(sortedClasses, classes)
-				sort.Strings(sortedClasses)
-
-				// Add to signature: element[class1,class2,...]
-				signature.WriteString(fmt.Sprintf("%s[%s];", n.Data, strings.Join(sortedClasses, ",")))
-			} else {
-				// Element with no classes
-				signature.WriteString(fmt.Sprintf("%s[];", n.Data))
-			}
-		}
-	})
-
-	return signature.String()
+	// Get content-agnostic structure signature
+	return e.extractStructureSignature(element)
 }
 
 // generateTemplateNameFromSignature creates human-readable template names