diff --git a/.changeset/fair-languages-run.md b/.changeset/fair-languages-run.md
new file mode 100644
index 00000000..fb890e3f
--- /dev/null
+++ b/.changeset/fair-languages-run.md
@@ -0,0 +1,5 @@
+---
+"openwiki": patch
+---
+
+fix: run clean updates when the requested output language changes
diff --git a/src/agent/index.ts b/src/agent/index.ts
index 59dd3ff4..10726863 100644
--- a/src/agent/index.ts
+++ b/src/agent/index.ts
@@ -160,7 +160,11 @@ export async function runOpenWikiAgent(
   );
 
   if (command === "update" && shouldCheckUpdateNoop(options)) {
-    const noopStatus = await getUpdateNoopStatus(cwd, openWikiIgnore);
+    const noopStatus = await getUpdateNoopStatus(
+      cwd,
+      openWikiIgnore,
+      options.language,
+    );
 
     if (noopStatus.shouldSkip) {
       const message =
diff --git a/src/agent/translation-middleware.ts b/src/agent/translation-middleware.ts
index 574c2801..4195ba27 100644
--- a/src/agent/translation-middleware.ts
+++ b/src/agent/translation-middleware.ts
@@ -5,6 +5,7 @@ import type { BackendProtocolV2, FileInfo } from "deepagents";
 import { createMiddleware } from "langchain";
 import path from "node:path";
 import { getErrorMessage } from "../diagnostics.js";
+import { getPrimaryLanguageSubtag } from "../language.js";
 import {
   OPENWIKI_TRANSLATION_PENDING_FIELD,
   readFrontmatterField,
@@ -102,23 +103,11 @@ export function resolveTranslationPlan(
     source,
     translateAll:
       requestedLanguage !== undefined &&
-      primarySubtag(requestedLanguage) !== primarySubtag(currentWikiLanguage),
+      getPrimaryLanguageSubtag(requestedLanguage) !==
+        getPrimaryLanguageSubtag(currentWikiLanguage),
   };
 }
 
-/**
- * Returns a language tag's primary subtag (for example `zh` for `zh-CN`),
- * treating an absent wiki language as English.
- */
-function primarySubtag(tag: string | undefined): string {
-  if (!tag) return "en";
-  try {
-    return new Intl.Locale(tag).language;
-  } catch {
-    return tag;
-  }
-}
-
 /**
  * Creates middleware that brings every existing wiki page into the run's target
  * language before the agent runs.
diff --git a/src/agent/utils.ts b/src/agent/utils.ts
index 3b372048..42436ef0 100644
--- a/src/agent/utils.ts
+++ b/src/agent/utils.ts
@@ -8,7 +8,7 @@ import {
   isExpectedSnapshotRaceError,
   isFileNotFoundError,
 } from "../fs-errors.js";
-import { resolveLanguage } from "../language.js";
+import { getPrimaryLanguageSubtag, resolveLanguage } from "../language.js";
 import {
   readOpenWikiOnboardingConfig,
   readRepositoryWikiInstructions,
@@ -112,6 +112,10 @@ async function readRunWikiGoal(
 /**
  * Decides whether an `update` run can be skipped because nothing meaningful changed.
  *
+ * An explicit request whose primary language differs from the persisted wiki
+ * language is meaningful even on a clean tree, because the translation pass
+ * must run before the update agent.
+ *
  * Working-tree and committed changes that only touch `openwiki/` or paths
  * excluded by `openWikiIgnore` do not count as meaningful, so an ignored path
  * changing on its own never forces a rebuild.
@@ -119,6 +123,7 @@ async function readRunWikiGoal(
 export async function getUpdateNoopStatus(
   cwd: string,
   openWikiIgnore = new OpenWikiIgnore([]),
+  requestedLanguage?: string | null,
 ): Promise<UpdateNoopStatus> {
   const lastUpdate = await readLastUpdate(cwd, "repository");
 
@@ -130,6 +135,15 @@ export async function getUpdateNoopStatus(
     return { shouldSkip: false, reason: "previous update was interrupted" };
   }
 
+  const resolvedRequestedLanguage = resolveLanguage(requestedLanguage).language;
+  if (
+    resolvedRequestedLanguage !== undefined &&
+    getPrimaryLanguageSubtag(resolvedRequestedLanguage) !==
+      getPrimaryLanguageSubtag(lastUpdate.language)
+  ) {
+    return { shouldSkip: false, reason: "output language changed" };
+  }
+
   const head = await getGitHead(cwd);
 
   if (!head) {
diff --git a/src/language.ts b/src/language.ts
index 897df165..a4e9d784 100644
--- a/src/language.ts
+++ b/src/language.ts
@@ -58,3 +58,20 @@ export function resolveLanguage(
     warning: `Unrecognized language "${trimmed}"; generating in English. Use a BCP-47 code such as zh-CN, hi, or pt-BR.`,
   };
 }
+
+/**
+ * Returns a language tag's primary subtag (for example `zh` for `zh-CN`),
+ * treating an absent tag as English. Malformed persisted values are returned as
+ * written so they cannot accidentally compare equal to a valid requested tag.
+ */
+export function getPrimaryLanguageSubtag(
+  tag: string | null | undefined,
+): string {
+  if (!tag) return "en";
+
+  try {
+    return new Intl.Locale(tag).language;
+  } catch {
+    return tag;
+  }
+}
diff --git a/src/startup.ts b/src/startup.ts
index 909650db..3cb22ca2 100644
--- a/src/startup.ts
+++ b/src/startup.ts
@@ -132,7 +132,11 @@ async function canSkipCleanUpdateBeforeCredentials(
   }
 
   try {
-    const noopStatus = await getUpdateNoopStatus(cwd);
+    const noopStatus = await getUpdateNoopStatus(
+      cwd,
+      undefined,
+      command.language,
+    );
 
     return noopStatus.shouldSkip;
   } catch {
diff --git a/test/language.test.ts b/test/language.test.ts
index 3964bdf0..f18567ae 100644
--- a/test/language.test.ts
+++ b/test/language.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, test } from "vitest";
-import { resolveLanguage } from "../src/language.ts";
+import { getPrimaryLanguageSubtag, resolveLanguage } from "../src/language.ts";
 
 describe("resolveLanguage", () => {
   test("canonicalizes recognized BCP-47 codes", () => {
@@ -31,3 +31,19 @@ describe("resolveLanguage", () => {
     }
   });
 });
+
+describe("getPrimaryLanguageSubtag", () => {
+  test("compares language variants by their primary subtag", () => {
+    expect(getPrimaryLanguageSubtag("en-GB")).toBe("en");
+    expect(getPrimaryLanguageSubtag("zh-CN")).toBe("zh");
+  });
+
+  test("treats an absent persisted language as English", () => {
+    expect(getPrimaryLanguageSubtag(undefined)).toBe("en");
+    expect(getPrimaryLanguageSubtag(null)).toBe("en");
+  });
+
+  test("preserves malformed persisted values for a safe mismatch", () => {
+    expect(getPrimaryLanguageSubtag("not_a_locale")).toBe("not_a_locale");
+  });
+});
diff --git a/test/startup.test.ts b/test/startup.test.ts
index 5a1dd16a..40546f05 100644
--- a/test/startup.test.ts
+++ b/test/startup.test.ts
@@ -173,6 +173,25 @@ describe("resolveStartupCommand", () => {
     expect(result).toBe(command);
   });
 
+  test("requires credentials when a clean update requests a language change", async () => {
+    const repo = await createRepoWithOpenWiki();
+    const head = await git(repo, ["rev-parse", "HEAD"]);
+    await writeLastUpdate(repo, head);
+
+    const result = await resolveStartupCommand(
+      updatePrintCommand({ language: "fr" }),
+      {
+        cwd: repo,
+        isStdinTTY: false,
+      },
+    );
+
+    expect(result.kind).toBe("error");
+    if (result.kind === "error") {
+      expect(result.message).toContain("OPENROUTER_API_KEY is required");
+    }
+  });
+
   test("still requires credentials when update --print has source changes", async () => {
     const repo = await createRepoWithOpenWiki();
     const head = await git(repo, ["rev-parse", "HEAD"]);
diff --git a/test/update-noop.test.ts b/test/update-noop.test.ts
index f4dd8fa1..8939eba2 100644
--- a/test/update-noop.test.ts
+++ b/test/update-noop.test.ts
@@ -63,6 +63,29 @@ describe("getUpdateNoopStatus", () => {
     expect(status.shouldSkip).toBe(true);
   });
 
+  test("does not skip a clean update that requests a different language", async () => {
+    const repo = await createRepoWithOpenWiki();
+    const head = await git(repo, ["rev-parse", "HEAD"]);
+    await writeLastUpdate(repo, head, { language: "en" });
+
+    const status = await getUpdateNoopStatus(repo, undefined, "fr");
+
+    expect(status).toEqual({
+      shouldSkip: false,
+      reason: "output language changed",
+    });
+  });
+
+  test("still skips an equivalent primary-language request", async () => {
+    const repo = await createRepoWithOpenWiki();
+    const head = await git(repo, ["rev-parse", "HEAD"]);
+    await writeLastUpdate(repo, head, { language: "en" });
+
+    const status = await getUpdateNoopStatus(repo, undefined, "en-GB");
+
+    expect(status.shouldSkip).toBe(true);
+  });
+
   test("detects a no-op when only the committed run metadata is dirty", async () => {
     // A committed wiki leaves openwiki/.last-update.json tracked, so the next
     // run sees it as an unstaged modification: " M openwiki/.last-update.json".