refactor: cleanup

src/components/create-group-dialog.tsx

@@ -15,6 +15,7 @@ import {
 } from "@/components/ui/dialog";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
+import { translateBackendError } from "@/lib/backend-errors";
 import type { ProfileGroup } from "@/types";
 import { RippleButton } from "./ui/ripple";
 
@@ -50,8 +51,7 @@ export function CreateGroupDialog({
       onClose();
     } catch (err) {
       console.error("Failed to create group:", err);
-      const errorMessage =
-        err instanceof Error ? err.message : t("groups.createFailed");
+      const errorMessage = translateBackendError(t, err);
       setError(errorMessage);
       toast.error(errorMessage);
     } finally {

src/components/delete-group-dialog.tsx

@@ -16,6 +16,7 @@ import {
 import { Label } from "@/components/ui/label";
 import { RadioGroup, RadioGroupItem } from "@/components/ui/radio-group";
 import { ScrollArea } from "@/components/ui/scroll-area";
+import { translateBackendError } from "@/lib/backend-errors";
 import type { BrowserProfile, ProfileGroup } from "@/types";
 import { RippleButton } from "./ui/ripple";
 
@@ -97,8 +98,7 @@ export function DeleteGroupDialog({
       onClose();
     } catch (err) {
       console.error("Failed to delete group:", err);
-      const errorMessage =
-        err instanceof Error ? err.message : t("groups.deleteFailed");
+      const errorMessage = translateBackendError(t, err);
       setError(errorMessage);
       toast.error(errorMessage);
     } finally {

src/components/edit-group-dialog.tsx

@@ -15,6 +15,7 @@ import {
 } from "@/components/ui/dialog";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
+import { translateBackendError } from "@/lib/backend-errors";
 import type { ProfileGroup } from "@/types";
 import { RippleButton } from "./ui/ripple";
 
@@ -61,8 +62,7 @@ export function EditGroupDialog({
       onClose();
     } catch (err) {
       console.error("Failed to update group:", err);
-      const errorMessage =
-        err instanceof Error ? err.message : t("groups.updateFailed");
+      const errorMessage = translateBackendError(t, err);
       setError(errorMessage);
       toast.error(errorMessage);
     } finally {

src/components/group-management-dialog.tsx

@@ -495,9 +495,15 @@ export function GroupManagementDialog({
       const results = await Promise.allSettled(
         ids.map((groupId) => invoke("delete_profile_group", { groupId })),
       );
-      const failed = results.filter((r) => r.status === "rejected");
-      if (failed.length > 0) {
-        showErrorToast(t("groups.deleteFailed"));
+      const firstRejection = results.find((r) => r.status === "rejected") as
+        | PromiseRejectedResult
+        | undefined;
+      if (firstRejection) {
+        showErrorToast(
+          parseBackendError(firstRejection.reason)
+            ? translateBackendError(t, firstRejection.reason)
+            : t("groups.deleteFailed"),
+        );
       } else {
         showSuccessToast(t("groups.deleteSuccess"));
       }
@@ -507,9 +513,7 @@ export function GroupManagementDialog({
       onGroupManagementComplete();
     } catch (err) {
       console.error("Bulk group delete failed:", err);
-      showErrorToast(
-        err instanceof Error ? err.message : t("groups.deleteFailed"),
-      );
+      showErrorToast(translateBackendError(t, err));
     } finally {
       setIsBulkDeleting(false);
     }

src/components/profile-data-table.tsx

@@ -1250,14 +1250,16 @@ export function ProfilesDataTable({
           (id) => newSelection[id],
         );
 
-        // Only update external state if selection actually changed
-        const prevIds = Object.keys(prevSelection).filter(
-          (id) => prevSelection[id],
+        // Only update external state if selection actually changed.
+        // A Set gives O(1) membership; Array.includes() inside .every() would
+        // be O(n*m) over large selections.
+        const prevIdSet = new Set(
+          Object.keys(prevSelection).filter((id) => prevSelection[id]),
         );
 
         if (
-          selectedIds.length !== prevIds.length ||
-          !selectedIds.every((id) => prevIds.includes(id))
+          selectedIds.length !== prevIdSet.size ||
+          !selectedIds.every((id) => prevIdSet.has(id))
         ) {
           onSelectedProfilesChange(selectedIds);
         }
@@ -1559,10 +1561,13 @@ export function ProfilesDataTable({
           "get_all_traffic_snapshots",
         );
         const newSnapshots: Record<string, TrafficSnapshot> = {};
+        // O(1) membership; runningProfileIds.includes() in this loop would be
+        // O(snapshots * runningProfiles).
+        const runningSet = new Set(runningProfileIds);
         for (const snapshot of allSnapshots) {
           if (snapshot.profile_id) {
             // Only keep snapshots for profiles that are currently running
-            if (runningProfileIds.includes(snapshot.profile_id)) {
+            if (runningSet.has(snapshot.profile_id)) {
               const existing = newSnapshots[snapshot.profile_id];
               if (!existing || snapshot.last_update > existing.last_update) {
                 newSnapshots[snapshot.profile_id] = snapshot;
@@ -1591,9 +1596,10 @@ export function ProfilesDataTable({
 
     setTrafficSnapshots((prev) => {
       const cleaned: Record<string, TrafficSnapshot> = {};
+      const runningSet = new Set(runningProfileIds);
       for (const [profileId, snapshot] of Object.entries(prev)) {
         // Only keep snapshots for profiles that are currently running
-        if (runningProfileIds.includes(profileId)) {
+        if (runningSet.has(profileId)) {
           cleaned[profileId] = snapshot;
         }
       }

src/components/proxy-form-dialog.tsx

@@ -21,6 +21,7 @@ import {
   SelectTrigger,
   SelectValue,
 } from "@/components/ui/select";
+import { translateBackendError } from "@/lib/backend-errors";
 import type { StoredProxy } from "@/types";
 import { RippleButton } from "./ui/ripple";
 
@@ -127,9 +128,11 @@ export function ProxyFormDialog({
       onClose();
     } catch (error) {
       console.error("Failed to save proxy:", error);
-      const errorMessage =
-        error instanceof Error ? error.message : String(error);
-      toast.error(t("proxies.form.saveFailed", { error: errorMessage }));
+      toast.error(
+        t("proxies.form.saveFailed", {
+          error: translateBackendError(t, error),
+        }),
+      );
     } finally {
       setIsSubmitting(false);
     }