feat: dedupe geoip rules

internal/corecfg/manager.go

@@ -381,7 +381,7 @@ func (m *Manager) mergeSubscriptions(subs []*model.Subscription) (map[string]int
 		combined = deepMerge(combined, data)
 	}
 
-	combined["rules"] = dedupeMatchRule(combined["rules"])
+	combined["rules"] = dedupeMatchRule(dedupeGeoIPRule(combined["rules"]))
 	mergeProxySelection(combined, selectionGroups)
 
 	return combined, proxies, true
@@ -408,6 +408,55 @@ func dedupeMatchRule(rulesRaw interface{}) interface{} {
 	return append(filtered, "MATCH,all proxies")
 }
 
+// dedupeGeoIPRule keeps only the last occurrence of each "GEOIP,<payload>"
+// rule contributed by the merged subscriptions — several subscriptions
+// commonly ship their own copy of the same rule (e.g. "GEOIP,CN,DIRECT"),
+// and concatenating them would leave redundant earlier copies ahead of the
+// one that should actually apply.
+func dedupeGeoIPRule(rulesRaw interface{}) interface{} {
+	rules, ok := rulesRaw.([]interface{})
+	if !ok {
+		return rulesRaw
+	}
+
+	lastIndex := make(map[string]int)
+	for i, item := range rules {
+		if key, ok := geoIPRuleKey(item); ok {
+			lastIndex[key] = i
+		}
+	}
+
+	filtered := make([]interface{}, 0, len(rules))
+	for i, item := range rules {
+		if key, ok := geoIPRuleKey(item); ok && lastIndex[key] != i {
+			continue
+		}
+		filtered = append(filtered, item)
+	}
+	return filtered
+}
+
+// geoIPRuleKey returns the "GEOIP,<payload>" portion of a rule line (i.e.
+// everything but its target and any trailing "no-resolve" modifier), and
+// whether the line is a GEOIP rule at all.
+func geoIPRuleKey(item interface{}) (string, bool) {
+	line, ok := item.(string)
+	if !ok || !strings.HasPrefix(line, "GEOIP,") {
+		return "", false
+	}
+
+	body := line
+	if idx := strings.LastIndex(body, ","); idx != -1 && strings.EqualFold(body[idx+1:], "no-resolve") {
+		body = body[:idx]
+	}
+
+	idx := strings.LastIndex(body, ",")
+	if idx == -1 {
+		return line, true
+	}
+	return body[:idx], true
+}
+
 func openInEditor(path string) bool {
 	return editor.OpenFileInEditor(path)
 }