fix E4.3: extract entities from content instead of namespace

E4.3 bug: admin.go used mem["namespace"] which is empty (LanceDB
map keys are different from struct field names). Fixed by:
- Replace namespace lookup with content-based entity extraction
- Reuse distill/engine.go heuristic: capitalized words, Chinese
  entities (2-20 chars), tech tokens (alphanumeric/digits)
- Get max graph degree across all extracted entities
- Add isStopWord, stripNonChinese, isTechToken, isAllDigits helpers

Fixes: degree always 0 in ShouldForget call, graph integration broken.

go/internal/api/routes/admin.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/xiaoxue/memoryweave/internal/governance"
@@ -68,13 +69,10 @@ func (aa *AdminAPI) Forget(w http.ResponseWriter, r *http.Request) {
 		lastAccess := parseTimeStr(mem["last_recalled_at"])
 		recallCnt := intVal(mem["recall_count"])
 		tier := strVal(mem["tier"])
+		content := strVal(mem["content"])
 
-		// E4.3: 获取实体图谱度，取 namespace 和 content 中实体的最大度
-		entity := strVal(mem["namespace"])
-		degree := 0
-		if entity != "" {
-			degree = aa.GraphStore.GetEntityDegree(entity)
-		}
+		// E4.3 修复: 从 content 提取实体（而非读 namespace），取图谱最大度
+		degree := extractTopEntityDegree(content, aa.GraphStore)
 
 		if aa.Forgetter.ShouldForget(lastAccess, recallCnt, tier, degree) {
 			aa.LanceDB.SoftDelete(strVal(mem["id"]), "auto_forget")
@@ -141,7 +139,8 @@ func (aa *AdminAPI) Audit(w http.ResponseWriter, r *http.Request) {
 	respond(w, 200, map[string]interface{}{"audit_logs": logs, "count": len(logs)})
 }
 
-// 辅助函数
+// ─── 辅助函数 ───────────────────────────────────────────────────────────────
+
 func parseTimeStr(s interface{}) time.Time {
 	if s == nil {
 		return time.Time{}
@@ -158,10 +157,10 @@ func parseTimeStr(s interface{}) time.Time {
 
 func intVal(v interface{}) int {
 	switch n := v.(type) {
-	case int:       return n
-	case int32:     return int(n)
-	case int64:     return int(n)
-	case float64:   return int(n)
+	case int:     return n
+	case int32:   return int(n)
+	case int64:   return int(n)
+	case float64: return int(n)
 	case json.Number:
 		i, _ := n.Int64()
 		return int(i)
@@ -174,8 +173,117 @@ func strVal(v interface{}) string {
 		return ""
 	}
 	switch s := v.(type) {
-	case string: return s
-	case json.Number: return s.String()
+	case string:      return s
+	case json.Number:  return s.String()
 	}
 	return fmt.Sprintf("%v", v)
 }
+
+// ─── E4.3: 图谱度提取 ──────────────────────────────────────────────────────
+
+// extractTopEntityDegree 从 content 提取实体，返回图中度数最高的实体度数
+// 复用 distill/engine.go 的启发式逻辑（大写单词、中文实体、技术标记）
+func extractTopEntityDegree(content string, gs governance.GraphStore) int {
+	if content == "" || gs == nil {
+		return 0
+	}
+	seen := make(map[string]bool)
+	var candidates []string
+
+	words := strings.Fields(content)
+	for _, w := range words {
+		w = strings.Trim(w, ",.;:!?，。；：！？、\"'()（）[]【】")
+		if len(w) < 2 {
+			continue
+		}
+		// 大写字母开头的英文词（Hermes, ComfyUI, Redis 等）
+		runes := []rune(w)
+		if len(runes) >= 2 && runes[0] >= 'A' && runes[0] <= 'Z' {
+			normalized := strings.ToLower(w)
+			if !seen[normalized] && !isStopWord(normalized) {
+				seen[normalized] = true
+				candidates = append(candidates, w)
+			}
+		}
+		// 中文实体（2-20 个纯中文字符）
+		cleanChinese := stripNonChinese(w)
+		if len(cleanChinese) >= 2 && len(cleanChinese) <= 20 {
+			if !seen[cleanChinese] {
+				seen[cleanChinese] = true
+				candidates = append(candidates, cleanChinese)
+			}
+		}
+		// 技术标记（数字+字母组合或纯数字）
+		if isTechToken(w) || isAllDigits(w) {
+			if !seen[w] {
+				seen[w] = true
+				candidates = append(candidates, w)
+			}
+		}
+	}
+
+	maxDegree := 0
+	for _, entity := range candidates {
+		d := gs.GetEntityDegree(entity)
+		if d > maxDegree {
+			maxDegree = d
+		}
+	}
+	return maxDegree
+}
+
+// isStopWord 停用词表（与 distill/engine.go 保持一致）
+func isStopWord(w string) bool {
+	stops := []string{
+		"the", "and", "for", "are", "but", "not", "you", "all", "can", "had",
+		"her", "was", "one", "our", "out", "this", "that", "with", "from",
+		"your", "what", "when", "where", "which", "their", "will", "would",
+		"there", "could", "other", "into", "just", "has", "have", "were",
+		"they", "been", "more", "than",
+	}
+	for _, s := range stops {
+		if w == s {
+			return true
+		}
+	}
+	return false
+}
+
+// stripNonChinese 提取纯中文字符串
+func stripNonChinese(s string) string {
+	var result []rune
+	for _, r := range s {
+		if r >= 0x4E00 && r <= 0x9FFF {
+			result = append(result, r)
+		}
+	}
+	return string(result)
+}
+
+// isTechToken 判断是否为技术标记（数字+字母混合）
+func isTechToken(s string) bool {
+	hasDigit := false
+	hasLetter := false
+	for _, r := range s {
+		if r >= '0' && r <= '9' {
+			hasDigit = true
+		}
+		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') {
+			hasLetter = true
+		}
+	}
+	return hasDigit && hasLetter
+}
+
+// isAllDigits 判断是否全为数字
+func isAllDigits(s string) bool {
+	if len(s) == 0 {
+		return false
+	}
+	for _, r := range s {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}