Complete client UI i18n migration

Adds client-side i18n support, language settings, translated UI copy, and locale parity coverage.

packages/app/src/composer/draft/create-flow.ts

@@ -1,4 +1,5 @@
 import { useCallback, useMemo, useReducer } from "react";
+import { useTranslation } from "react-i18next";
 import type { ComposerAttachment } from "@/attachments/types";
 import { splitComposerAttachmentsForSubmit } from "@/composer/attachments/submit";
 import { useCreateFlowStore } from "@/stores/create-flow-store";
@@ -105,6 +106,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
   onCreateSuccess,
   onCreateError,
 }: UseDraftAgentCreateFlowOptions<TDraftAgent, TCreateResult>) {
+  const { t } = useTranslation();
   const [machine, dispatch] = useReducer(
     reducer,
     initialAttempt,
@@ -163,7 +165,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
     async ({ attempt, cwd }: { attempt: CreateAttempt; cwd: string }) => {
       const pendingServerId = getPendingServerId();
       if (!pendingServerId) {
-        const error = new Error("No host selected");
+        const error = new Error(t("composer.errors.noHostSelected"));
         dispatch({ type: "DRAFT_SET_ERROR", message: error.message });
         throw error;
       }
@@ -204,7 +206,8 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
 
         await onCreateSuccess({ result: createResult.result, attempt });
       } catch (error) {
-        const resolved = error instanceof Error ? error : new Error("Failed to create agent");
+        const resolved =
+          error instanceof Error ? error : new Error(t("composer.errors.failedToCreateAgent"));
         dispatch({ type: "CREATE_FAILED", message: resolved.message });
         markPendingCreateLifecycle({ draftId, lifecycle: "abandoned" });
         clearPendingCreateAttempt({ draftId });
@@ -222,6 +225,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
       onBeforeSubmit,
       onCreateError,
       onCreateSuccess,
+      t,
       updatePendingAgentId,
     ],
   );
@@ -229,7 +233,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
   const handleCreateFromInput = useCallback(
     async ({ text, attachments, cwd }: SubmitContext) => {
       if (isSubmitting) {
-        throw new Error("Already loading");
+        throw new Error(t("composer.errors.alreadyLoading"));
       }
 
       dispatch({ type: "DRAFT_SET_ERROR", message: "" });
@@ -238,7 +242,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
 
       const trimmedPrompt = text.trim();
       if (!trimmedPrompt && !allowEmptyText) {
-        const error = new Error("Initial prompt is required");
+        const error = new Error(t("composer.errors.initialPromptRequired"));
         dispatch({ type: "DRAFT_SET_ERROR", message: error.message });
         throw error;
       }
@@ -256,7 +260,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
 
       const pendingServerId = getPendingServerId();
       if (!pendingServerId) {
-        const error = new Error("No host selected");
+        const error = new Error(t("composer.errors.noHostSelected"));
         dispatch({ type: "DRAFT_SET_ERROR", message: error.message });
         throw error;
       }
@@ -294,6 +298,7 @@ export function useDraftAgentCreateFlow<TDraftAgent, TCreateResult>({
       onCreateStart,
       runCreateAttempt,
       setPendingCreateAttempt,
+      t,
       validateBeforeSubmit,
     ],
   );

packages/app/src/composer/draft/import-pill.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useMemo, useState } from "react";
 import { Pressable, Text, View } from "react-native";
+import { useTranslation } from "react-i18next";
 import { StyleSheet, withUnistyles } from "react-native-unistyles";
 import { Import as ImportIcon } from "lucide-react-native";
 import type { Theme } from "@/styles/theme";
@@ -13,6 +14,7 @@ interface ComposerImportPillProps {
 }
 
 export function ComposerImportPill({ onPress, disabled = false }: ComposerImportPillProps) {
+  const { t } = useTranslation();
   const [isHovered, setIsHovered] = useState(false);
   const handleHoverIn = useCallback(() => setIsHovered(true), []);
   const handleHoverOut = useCallback(() => setIsHovered(false), []);
@@ -22,7 +24,7 @@ export function ComposerImportPill({ onPress, disabled = false }: ComposerImport
       <Pressable
         testID="composer-import-agent-pill"
         accessibilityRole="button"
-        accessibilityLabel="Import session"
+        accessibilityLabel={t("importSession.title")}
         onPress={onPress}
         disabled={disabled}
         onHoverIn={handleHoverIn}
@@ -31,7 +33,7 @@ export function ComposerImportPill({ onPress, disabled = false }: ComposerImport
       >
         <ThemedImportIcon size={14} uniProps={iconColorMapping} />
         <Text style={styles.label} numberOfLines={1}>
-          Import session
+          {t("importSession.title")}
         </Text>
       </Pressable>
     </View>

packages/app/src/composer/draft/workspace-tab.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useMemo, useRef } from "react";
 import { Keyboard, ScrollView, Text, View } from "react-native";
+import { useTranslation } from "react-i18next";
 import ReanimatedAnimated from "react-native-reanimated";
 import { StyleSheet } from "react-native-unistyles";
 import { useSafeAreaInsets } from "react-native-safe-area-context";
@@ -130,6 +131,8 @@ async function submitDraftCreateRequest(input: {
     effectiveThinkingOptionId: string | null;
     featureValues: Record<string, unknown> | undefined;
   };
+  hostDisconnectedMessage: string;
+  selectModelMessage: string;
 }): Promise<{ agentId: string | null; result: AgentSnapshotPayload }> {
   const {
     attempt,
@@ -146,12 +149,12 @@ async function submitDraftCreateRequest(input: {
   invariant(workspaceDirectory, "Workspace directory is required");
   invariant(workspaceExecutionAuthority, "Workspace authority is required");
   if (!client) {
-    throw new Error("Host is not connected");
+    throw new Error(input.hostDisconnectedMessage);
   }
 
   const provider = autoSubmitConfig?.provider ?? composerState.selectedProvider;
   if (!provider) {
-    throw new Error("Select a model");
+    throw new Error(input.selectModelMessage);
   }
   const modeIdOverride = resolveDraftModeIdOverride({
     autoSubmitConfig,
@@ -199,6 +202,7 @@ function buildDraftAgentSnapshot(input: {
     selectedProvider: string | null;
     agentControls: { features?: Agent["features"] };
   };
+  selectModelMessage: string;
 }): Agent {
   const { attempt, serverId, tabId, workspaceDirectory, autoSubmitConfig, composerState } = input;
   invariant(workspaceDirectory, "Workspace directory is required");
@@ -213,7 +217,7 @@ function buildDraftAgentSnapshot(input: {
   });
   const provider = autoSubmitConfig?.provider ?? composerState.selectedProvider;
   if (!provider) {
-    throw new Error("Select a model");
+    throw new Error(input.selectModelMessage);
   }
   return {
     serverId,
@@ -309,6 +313,7 @@ export function WorkspaceDraftAgentTab({
   onOpenWorkspaceFile,
   onOpenImportSheet,
 }: WorkspaceDraftAgentTabProps) {
+  const { t } = useTranslation();
   const insets = useSafeAreaInsets();
   const client = useHostRuntimeClient(serverId);
   const isConnected = useHostRuntimeIsConnected(serverId);
@@ -456,6 +461,7 @@ export function WorkspaceDraftAgentTab({
         workspaceDirectory: draftWorkingDirectory,
         autoSubmitConfig,
         composerState,
+        selectModelMessage: t("workspaceSetup.errors.selectModel"),
       }),
     createRequest: async ({ attempt, text, images, attachments }) =>
       submitDraftCreateRequest({
@@ -468,6 +474,8 @@ export function WorkspaceDraftAgentTab({
         workspaceExecutionAuthority,
         autoSubmitConfig,
         composerState,
+        hostDisconnectedMessage: t("workspace.terminal.hostDisconnected"),
+        selectModelMessage: t("workspaceSetup.errors.selectModel"),
       }),
     onCreateSuccess: ({ result }) => {
       clearDraftInput("sent");