refactor(routing): 暴露 system_locked_domains + 服务端 follow-up 清理(FK/Validate/dedup/exclude单源/共用Store/Builtin保留)

server/internal/httpapi/routing.go

@@ -14,10 +14,28 @@ import (
 // user hasn't customized one yet; POST validates and upserts.
 type RoutingAPI struct {
 	store *routing.Store
+	// lockedDomains are the system-forced-tunnel private-service domains
+	// (PANGOLIN_PRIVATE_SPLIT_DOMAINS, same slice injected into NodeAPI) —
+	// read-only, surfaced to GET so clients can warn users that rules against
+	// these domains silently have no effect. Never written to the persisted
+	// Profile.
+	lockedDomains []string
 }
 
 // NewRoutingAPI creates a RoutingAPI backed by the given routing.Store.
-func NewRoutingAPI(store *routing.Store) *RoutingAPI { return &RoutingAPI{store: store} }
+// lockedDomains is the system-forced private-service domain list (may be nil).
+func NewRoutingAPI(store *routing.Store, lockedDomains []string) *RoutingAPI {
+	return &RoutingAPI{store: store, lockedDomains: lockedDomains}
+}
+
+// profileResponse wraps routing.Profile for GET /v1/me/routing, adding the
+// read-only system_locked_domains list. It deliberately lives here — not on
+// routing.Profile itself — so the field can never leak into the writable
+// Profile contract that SaveProfile decodes POST bodies into.
+type profileResponse struct {
+	*routing.Profile
+	SystemLockedDomains []string `json:"system_locked_domains"`
+}
 
 // GetProfile handles GET /v1/me/routing.
 func (a *RoutingAPI) GetProfile(w http.ResponseWriter, r *http.Request) {
@@ -34,7 +52,11 @@ func (a *RoutingAPI) GetProfile(w http.ResponseWriter, r *http.Request) {
 	if p == nil {
 		p = routing.Default()
 	}
-	writeJSON(w, http.StatusOK, p)
+	locked := a.lockedDomains
+	if locked == nil {
+		locked = []string{}
+	}
+	writeJSON(w, http.StatusOK, profileResponse{Profile: p, SystemLockedDomains: locked})
 }
 
 // SaveProfile handles POST /v1/me/routing. On validation failure it returns