feat(ai): sync reply language with the active UI locale

Include the effective Luna locale in Kael context snapshots and refresh it before the next run after a language change. Preserve uploaded context and command language across browser and Electron requests.

Author: LeeEirc

ui/app.vue

@@ -2,6 +2,7 @@
 import type { DesktopUnlistenFn } from "~/shared/desktop/bridge";
 import type { LangType, LanguagePreference } from "~/types";
 
+import { agentClient } from "#koko/composables/agent/agentClient";
 import defaultFavicon from "~/assets/facio.ico";
 import AppWatermark from "~/components/AppWatermark.vue";
 import AclDialog from "~/components/Modal/aclDialog.vue";
@@ -31,6 +32,10 @@ const webWorkspaceFavicon = useState<string>(WORKSPACE_FAVICON_STATE_KEY, () =>
 
 const { isMacOS, isWindows } = usePlatform();
 const { locale, setLocale, t } = useI18n();
+watch(locale, (value) => agentClient.setResponseLanguage(normalizeLanguageCode(value)), {
+  immediate: true,
+  flush: "sync"
+});
 const { userTheme, applyThemePreference, applySystemThemePreference } = useThemeAdapter();
 
 const { applyPrimaryColor } = useColor();

ui/koko/composables/agent/agentClient.ts

@@ -10,6 +10,7 @@ import type {
   AgentSessionCreateResponse,
   AgentToolResultRequest
 } from "./types";
+import type { LangType } from "~/types";
 import { desktopInvoke } from "~/shared/desktop/bridge";
 import { getWebApiHeaders, getWebApiMutationHeaders, isDesktopRuntime, withWebSitePrefix } from "~/utils/runtime";
 import { normalizeAgentEvent } from "./agentSse";
@@ -78,6 +79,7 @@ interface AgentBinding {
   surface: string;
   profile: string;
   contextVersion: number;
+  context: Record<string, unknown>;
   heartbeat: ReturnType<typeof setInterval>;
 }
 
@@ -161,9 +163,24 @@ export class AgentClient {
   private readonly instanceByResource = new Map<string, string>();
   private readonly usersByResource = new Map<string, number>();
   private readonly bindings = new Map<string, AgentBinding>();
+  private responseLanguage?: LangType;
 
   constructor(private readonly request: AgentRequest = defaultAgentRequest) {}
 
+  setResponseLanguage(language: LangType) {
+    this.responseLanguage = language;
+  }
+
+  private contextWithResponseLanguage(context: Record<string, unknown> = {}): Record<string, unknown> {
+    // Keep the uploaded snapshot independent of reactive workspace state.
+    return JSON.parse(
+      JSON.stringify({
+        ...context,
+        ...(this.responseLanguage ? { response_language: this.responseLanguage } : {})
+      })
+    );
+  }
+
   retainResource(resourceSessionId: string) {
     this.usersByResource.set(resourceSessionId, (this.usersByResource.get(resourceSessionId) || 0) + 1);
   }
@@ -243,7 +260,8 @@ export class AgentClient {
         }
       });
       let contextVersion = 0;
-      if (manifest.context) {
+      const contextData = this.contextWithResponseLanguage(manifest.context);
+      if (manifest.context || this.responseLanguage) {
         const context = await this.request<KaelContext>({
           method: "PUT",
           path: sessionPath(panel.id, "context"),
@@ -252,7 +270,7 @@ export class AgentClient {
             domain: manifest.profile,
             surface,
             sensitivity: "restricted",
-            data: manifest.context
+            data: contextData
           }
         });
         contextVersion = Math.max(0, Math.floor(Number(context.version) || 1));
@@ -285,6 +303,7 @@ export class AgentClient {
         surface,
         profile: manifest.profile,
         contextVersion,
+        context: contextData,
         heartbeat
       });
       const registrationIds = Object.fromEntries(
@@ -314,6 +333,9 @@ export class AgentClient {
     message: AgentMessageRequest
   ): Promise<AgentMessageResponse> {
     const binding = this.binding(sessionId, resourceSessionId);
+    if (this.responseLanguage && binding.context.response_language !== this.responseLanguage) {
+      await this.updateContext(sessionId, resourceSessionId, binding.context);
+    }
     const created = await this.request<KaelMessage>({
       method: "POST",
       path: `${KAEL_API_ROOT}/conversations/${binding.conversationId}/messages`,
@@ -342,6 +364,7 @@ export class AgentClient {
 
   async updateContext(sessionId: string, resourceSessionId: string, context: Record<string, unknown>) {
     const binding = this.binding(sessionId, resourceSessionId);
+    const contextData = this.contextWithResponseLanguage(context);
     const response = await this.request<KaelContext>({
       method: "PUT",
       path: sessionPath(binding.panelId, "context"),
@@ -350,10 +373,11 @@ export class AgentClient {
         domain: binding.profile,
         surface: binding.surface,
         sensitivity: "restricted",
-        data: context
+        data: contextData
       }
     });
     binding.contextVersion = Math.max(binding.contextVersion + 1, Math.floor(Number(response.version) || 0));
+    binding.context = contextData;
   }
 
   async resolveApproval(

ui/koko/tests/agent/agentClient.test.ts

@@ -133,6 +133,56 @@ it("forwards the executor command policy without marking every shell call read-o
   }
 });
 
+it("includes the response language even without an executor context", async () => {
+  const requests: AgentHttpRequest[] = [];
+  const client = new AgentClient(kaelRequest(requests));
+  client.setResponseLanguage("en");
+  try {
+    await client.createSession({ ...manifest, context: undefined }, "auto");
+    expect(requests.find((request) => request.path.endsWith("/context"))?.body).toMatchObject({
+      data: { response_language: "en" }
+    });
+  } finally {
+    client.dispose();
+  }
+});
+
+it("refreshes response language before the next run without changing the command language or user text", async () => {
+  const requests: AgentHttpRequest[] = [];
+  const client = new AgentClient(kaelRequest(requests));
+  client.setResponseLanguage("zh");
+  const context = reactive({ language: "shell", selected_asset: { id: "asset-1" }, response_language: "en" });
+  const message = {
+    message_id: "message-1",
+    idempotency_key: "send-1",
+    role: "user" as const,
+    parts: [{ type: "text" as const, text: "inspect" }]
+  };
+  try {
+    await client.createSession(manifest, "auto");
+    await client.updateContext("panel-1", "resource-1", context);
+    expect(requests.filter((request) => request.path.endsWith("/context")).at(-1)?.body).toMatchObject({
+      data: { language: "shell", selected_asset: { id: "asset-1" }, response_language: "zh" }
+    });
+    // Switching UI language must resend the last uploaded snapshot, not later reactive edits.
+    context.selected_asset.id = "asset-2";
+    requests.length = 0;
+    client.setResponseLanguage("zh_hant");
+    await client.sendMessage("panel-1", "resource-1", message);
+    expect(requests.map((request) => request.path.split("/").at(-1))).toEqual(["context", "messages", "runs"]);
+    expect(requests[0]?.body).toMatchObject({
+      base_version: 2,
+      data: { language: "shell", selected_asset: { id: "asset-1" }, response_language: "zh_hant" }
+    });
+    expect(requests[1]?.body).toMatchObject({ parts: message.parts });
+    requests.length = 0;
+    await client.sendMessage("panel-1", "resource-1", { ...message, idempotency_key: "send-2" });
+    expect(requests.map((request) => request.path.split("/").at(-1))).toEqual(["messages", "runs"]);
+  } finally {
+    client.dispose();
+  }
+});
+
 it("maps messages, runs, approvals, and tool results to canonical Kael resources", async () => {
   const requests: AgentHttpRequest[] = [];
   const client = new AgentClient(kaelRequest(requests));
@@ -204,6 +254,7 @@ it.each([false, true])("sends reactive AI context, messages and results as JSON
   );
   const client = new AgentClient();
   try {
+    client.setResponseLanguage("pt_br");
     await client.createSession({ ...manifest, profile: "workspace" }, "auto");
     const state = reactive({ default_terminal_target: { target_id: "target-1", asset_name: "host-a" } });
     // Spreading a reactive context unwraps only its root; the target remains a Vue Proxy.
@@ -225,7 +276,7 @@ it.each([false, true])("sends reactive AI context, messages and results as JSON
     });
     state.default_terminal_target.asset_name = "host-b";
     expect(requests.filter((request) => request.path.endsWith("/context")).at(-1)?.body).toMatchObject({
-      data: { default_terminal_target: { target_id: "target-1", asset_name: "host-a" } }
+      data: { response_language: "pt_br", default_terminal_target: { target_id: "target-1", asset_name: "host-a" } }
     });
     expect(requests.find((request) => request.path.endsWith("/messages"))?.body).toMatchObject({
       parts: [{ type: "text", text: "Inspect the current terminal" }]