diff --git a/src/testing/create-plugin-module.test.ts b/src/testing/create-plugin-module.test.ts
new file mode 100644
index 000000000..94163ee3f
--- /dev/null
+++ b/src/testing/create-plugin-module.test.ts
@@ -0,0 +1,103 @@
+import { beforeEach, describe, expect, it, mock } from "bun:test"
+import { getLocale, initI18n, t } from "../shared/i18n"
+import { createPluginModule } from "./create-plugin-module"
+
+const mockInitConfigContext = mock(() => {})
+const mockDetectExternalSkillPlugin = mock(() => ({ detected: false, pluginName: null, allPlugins: [] }))
+const mockGetSkillPluginConflictWarning = mock(() => "")
+const mockInjectServerAuthIntoClient = mock(() => {})
+const mockLogLegacyPluginStartupWarning = mock(() => {})
+const mockMigrateLegacyWorkspaceDirectory = mock(() => ({ migrated: false, skipped: [] }))
+const mockLoadPluginConfig = mock(() => ({}))
+const mockIsTmuxIntegrationEnabled = mock(
+  (pluginConfig: { tmux?: { enabled?: boolean } | undefined }) => pluginConfig.tmux?.enabled ?? false,
+)
+const mockCreateRuntimeTmuxConfig = mock(() => ({
+  enabled: false,
+  layout: "tiled" as const,
+  main_pane_size: 60,
+  main_pane_min_width: 80,
+  agent_pane_min_width: 40,
+  isolation: "inline" as const,
+}))
+const mockCreateManagers = mock(() => ({
+  backgroundManager: { shutdown: async () => {} },
+  skillMcpManager: { disconnectAll: async () => {} },
+  configHandler: async () => {},
+}))
+const mockCreateTools = mock(async () => ({
+  mergedSkills: [],
+  availableSkills: [],
+  filteredTools: {},
+}))
+const mockCreateHooks = mock(() => ({
+  disposeHooks: () => {},
+  compactionContextInjector: undefined,
+  compactionTodoPreserver: undefined,
+  claudeCodeHooks: undefined,
+}))
+const mockCreatePluginInterface = mock(() => ({}))
+const mockInitializeOpenClaw = mock(async () => {})
+const mockStartTmuxCheck = mock(() => {})
+const mockInstallAgentSortShim = mock(() => {})
+const mockSetAgentSortOrder = mock(() => {})
+const mockLog = mock(() => {})
+const mockCreateModelCacheState = mock(() => ({}))
+const mockCreateFirstMessageVariantGate = mock(() => ({
+  shouldOverride: () => false,
+  markApplied: () => {},
+  markSessionCreated: () => {},
+  clear: () => {},
+}))
+
+function createTestPluginModule(): ReturnType<typeof createPluginModule> {
+  return createPluginModule({
+    initConfigContext: mockInitConfigContext,
+    detectExternalSkillPlugin: mockDetectExternalSkillPlugin,
+    getSkillPluginConflictWarning: mockGetSkillPluginConflictWarning,
+    injectServerAuthIntoClient: mockInjectServerAuthIntoClient,
+    logLegacyPluginStartupWarning: mockLogLegacyPluginStartupWarning,
+    migrateLegacyWorkspaceDirectory: mockMigrateLegacyWorkspaceDirectory,
+    loadPluginConfig: mockLoadPluginConfig as never,
+    isTmuxIntegrationEnabled: mockIsTmuxIntegrationEnabled as never,
+    createRuntimeTmuxConfig: mockCreateRuntimeTmuxConfig as never,
+    createManagers: mockCreateManagers as never,
+    createTools: mockCreateTools as never,
+    createHooks: mockCreateHooks as never,
+    createPluginInterface: mockCreatePluginInterface as never,
+    initializeOpenClaw: mockInitializeOpenClaw as never,
+    startTmuxCheck: mockStartTmuxCheck,
+    installAgentSortShim: mockInstallAgentSortShim,
+    setAgentSortOrder: mockSetAgentSortOrder,
+    log: mockLog,
+    createModelCacheState: mockCreateModelCacheState as never,
+    createFirstMessageVariantGate: mockCreateFirstMessageVariantGate as never,
+  })
+}
+
+describe("createPluginModule()", () => {
+  beforeEach(() => {
+    mockLoadPluginConfig.mockClear()
+    initI18n({ locale: "en", fallback: "en" })
+  })
+
+  describe("#given plugin config sets i18n.locale to zh", () => {
+    it("#then production startup applies the configured locale", async () => {
+      // given
+      const pluginModule = createTestPluginModule()
+      mockLoadPluginConfig.mockReturnValue({
+        i18n: { locale: "zh" },
+      })
+
+      // when
+      await pluginModule.server({
+        directory: "/tmp/project",
+        client: {},
+      } as Parameters<typeof pluginModule.server>[0])
+
+      // then
+      expect(getLocale()).toBe("zh")
+      expect(t("toast.task_completed")).toBe("任务完成")
+    })
+  })
+})
diff --git a/src/testing/create-plugin-module.ts b/src/testing/create-plugin-module.ts
index 684890976..b7f58bcda 100644
--- a/src/testing/create-plugin-module.ts
+++ b/src/testing/create-plugin-module.ts
@@ -18,6 +18,7 @@ import {
 import { installAgentSortShim, setAgentSortOrder } from "../shared/agent-sort-shim"
 import { detectExternalSkillPlugin, getSkillPluginConflictWarning } from "../shared/external-plugin-detector"
 import { createFirstMessageVariantGate } from "../shared/first-message-variant"
+import { initI18n } from "../shared/i18n"
 import { log } from "../shared/logger"
 import { logLegacyPluginStartupWarning } from "../shared/log-legacy-plugin-startup-warning"
 import { migrateLegacyWorkspaceDirectory } from "../shared/legacy-workspace-migration"
@@ -39,6 +40,7 @@ export type PluginModuleDeps = {
   getSkillPluginConflictWarning: typeof getSkillPluginConflictWarning
   injectServerAuthIntoClient: typeof injectServerAuthIntoClient
   loadPluginConfig: typeof loadPluginConfig
+  initI18n: typeof initI18n
   initializeOpenClaw: typeof initializeOpenClaw
   isTmuxIntegrationEnabled: typeof isTmuxIntegrationEnabled
   startTmuxCheck: typeof startTmuxCheck
@@ -62,6 +64,7 @@ const defaultPluginModuleDeps: PluginModuleDeps = {
   getSkillPluginConflictWarning,
   injectServerAuthIntoClient,
   loadPluginConfig,
+  initI18n,
   initializeOpenClaw,
   isTmuxIntegrationEnabled,
   startTmuxCheck,
@@ -93,6 +96,7 @@ export function createPluginModule(overrides: Partial<PluginModuleDeps> = {}): P
     deps.injectServerAuthIntoClient(input.client)
 
     const pluginConfig = deps.loadPluginConfig(input.directory, input)
+    deps.initI18n(pluginConfig.i18n?.locale ? { locale: pluginConfig.i18n.locale } : undefined)
     deps.setAgentSortOrder(pluginConfig.agent_order)
 
     if (pluginConfig.openclaw) {