feat: implement Pi Switch i18n UI and agent config switch

src/hooks/useConfig.ts

@@ -0,0 +1,80 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+import { invoke } from "@tauri-apps/api/core";
+import { useTranslation } from "../i18n";
+import type { Agent, Config } from "../types";
+
+interface UseConfigReturn {
+  config: Config | null;
+  dirty: boolean;
+  error: string | null;
+  loading: boolean;
+  refresh: () => Promise<void>;
+  save: () => Promise<void>;
+  updateConfig: (updater: (config: Config) => Config) => void;
+}
+
+export function useConfig(agent: Agent): UseConfigReturn {
+  const { t } = useTranslation();
+  const [config, setConfig] = useState<Config | null>(null);
+  const configRef = useRef(config);
+  const [dirty, setDirty] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+
+  useEffect(() => {
+    configRef.current = config;
+  }, [config]);
+
+  const refresh = useCallback(async () => {
+    setLoading(true);
+    setError(null);
+    try {
+      const loadedConfig = await invoke<Config>("load_agent_config_command", {
+        agent,
+      });
+      setConfig(loadedConfig);
+      setDirty(false);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err);
+      setError(message);
+      console.error("useConfig refresh failed:", message);
+    } finally {
+      setLoading(false);
+    }
+  }, [agent]);
+
+  useEffect(() => {
+    refresh();
+  }, [refresh]);
+
+  const updateConfig = useCallback((updater: (config: Config) => Config) => {
+    setConfig((prev) => (prev ? updater(prev) : prev));
+    setDirty(true);
+  }, []);
+
+  const save = useCallback(async () => {
+    const current = configRef.current;
+    if (!current) return;
+    setLoading(true);
+    setError(null);
+    try {
+      await invoke("save_agent_config_command", { agent, config: current });
+      await refresh();
+    } catch (err) {
+      const raw = err instanceof Error ? err.message : String(err);
+      setError(raw);
+    } finally {
+      setLoading(false);
+    }
+  }, [refresh, t, agent]);
+
+  return {
+    config,
+    dirty,
+    error,
+    loading,
+    refresh,
+    save,
+    updateConfig,
+  };
+}