fix: implement deterministic ID generation for consistent content injection

- Replace random UUID suffix with deterministic hash-based signature
- Use element DOM path, sibling position, and content preview for uniqueness
- Ensure same elements always get the same content ID across enhancements
- Fix critical bug where content updates weren't being injected into static files

This resolves the enhance button workflow: API content updates → enhance trigger → static file injection.

internal/engine/id_generator.go

@@ -1,11 +1,11 @@
 package engine
 
 import (
+	"crypto/sha256"
 	"fmt"
 	"path/filepath"
 	"strings"
 
-	"github.com/google/uuid"
 	"golang.org/x/net/html"
 )
 
@@ -23,7 +23,7 @@ func NewIDGenerator() *IDGenerator {
 	}
 }
 
-// Generate creates a content ID for an HTML element using lightweight hierarchical approach
+// Generate creates a content ID for an HTML element using deterministic approach
 func (g *IDGenerator) Generate(node *html.Node, filePath string) string {
 	// 1. File context (minimal)
 	fileName := g.getFileName(filePath)
@@ -35,12 +35,19 @@ func (g *IDGenerator) Generate(node *html.Node, filePath string) string {
 	// 3. Build readable prefix (deterministic, no runtime counting)
 	prefix := g.buildDeterministicPrefix(fileName, tag, primaryClass)
 
-	// 5. Add UUID-based suffix for guaranteed uniqueness
-	uuidSuffix := uuid.New().String()[:6] // Use first 6 chars of UUID
+	// 4. Create deterministic suffix based on element characteristics
+	signature := g.createDeterministicSignature(node, filePath)
 
-	finalID := fmt.Sprintf("%s-%s", prefix, uuidSuffix)
+	finalID := fmt.Sprintf("%s-%s", prefix, signature)
+
+	// Ensure uniqueness within this session
+	counter := 1
+	originalID := finalID
+	for g.usedIDs[finalID] {
+		finalID = fmt.Sprintf("%s-%d", originalID, counter)
+		counter++
+	}
 
-	// Ensure uniqueness (should be guaranteed by hash, but safety check)
 	g.usedIDs[finalID] = true
 
 	return finalID
@@ -111,9 +118,42 @@ func (g *IDGenerator) buildPrefix(fileName, tag, primaryClass string, index int)
 	return strings.Join(parts, "-")
 }
 
-// createSignature creates a unique signature for collision resistance (DEPRECATED - using UUID now)
+// createDeterministicSignature creates a deterministic signature for element identification
+func (g *IDGenerator) createDeterministicSignature(node *html.Node, filePath string) string {
+	// Build signature from stable characteristics
+	var sigParts []string
+
+	// 1. DOM path (simplified, max 3 levels)
+	domPath := g.getSimpleDOMPath(node)
+	if domPath != "" {
+		sigParts = append(sigParts, domPath)
+	}
+
+	// 2. Sibling position
+	siblingIndex := g.getSiblingIndex(node)
+	sigParts = append(sigParts, fmt.Sprintf("pos%d", siblingIndex))
+
+	// 3. Content preview (first few chars for uniqueness)
+	contentPreview := g.getContentPreview(node)
+	if contentPreview != "" {
+		// Use first 20 chars for signature
+		if len(contentPreview) > 20 {
+			contentPreview = contentPreview[:20]
+		}
+		sigParts = append(sigParts, contentPreview)
+	}
+
+	// 4. Create hash of combined signature
+	combined := strings.Join(sigParts, "|")
+	hash := sha256.Sum256([]byte(combined))
+
+	// Use first 6 characters of hash for short, deterministic suffix
+	return fmt.Sprintf("%x", hash)[:6]
+}
+
+// createSignature creates a unique signature for collision resistance (DEPRECATED - using deterministic now)
 func (g *IDGenerator) createSignature(node *html.Node, filePath string) string {
-	// This method is kept for compatibility but not used in UUID-based generation
+	// This method is kept for compatibility but not used in deterministic generation
 	return ""
 }