diff --git a/src/api/routes.ts b/src/api/routes.ts
index c2273965cf..03cef90de1 100644
--- a/src/api/routes.ts
+++ b/src/api/routes.ts
@@ -715,7 +715,7 @@ const repositoryAiReviewSchema = z.object({
   provider: z.enum(["anthropic", "openai"]).nullable().optional(),
   model: z.string().trim().min(1).max(120).nullable().optional(),
   allAuthors: z.boolean().default(false),
-  closeOwnerAuthors: z.boolean().default(false),
+  closeOwnerAuthors: z.boolean().optional(),
 });
 
 const contributorIssueDraftGenerateSchema = z.object({
@@ -2253,7 +2253,7 @@ export function createApp() {
       aiReviewProvider: parsed.data.provider,
       aiReviewModel: parsed.data.model,
       aiReviewAllAuthors: parsed.data.allAuthors,
-      closeOwnerAuthors: parsed.data.closeOwnerAuthors,
+      closeOwnerAuthors: parsed.data.closeOwnerAuthors ?? current.closeOwnerAuthors,
     });
     // getRepositorySettings normalizes these to a concrete value or null (never undefined).
     return c.json({
diff --git a/test/unit/routes-ai-byok.test.ts b/test/unit/routes-ai-byok.test.ts
index 5fe0dcde82..bd144f8325 100644
--- a/test/unit/routes-ai-byok.test.ts
+++ b/test/unit/routes-ai-byok.test.ts
@@ -62,6 +62,22 @@ describe("maintainer AI-review config route", () => {
     expect((await getRepositorySettings(env, REPO)).closeOwnerAuthors).toBe(false);
   });
 
+  it("preserves closeOwnerAuthors when an AI-review update omits it", async () => {
+    const app = createApp();
+    const env = createTestEnv({ TOKEN_ENCRYPTION_SECRET: SECRET });
+    await upsertRepositorySettings(env, { repoFullName: REPO, closeOwnerAuthors: true });
+
+    const res = await app.request(
+      `/v1/repos/${REPO}/ai-review`,
+      { method: "PUT", headers: apiHeaders(env), body: JSON.stringify({ mode: "advisory", byok: false }) },
+      env,
+    );
+
+    expect(res.status).toBe(200);
+    expect(await res.json()).toMatchObject({ aiReviewMode: "advisory", closeOwnerAuthors: true });
+    expect((await getRepositorySettings(env, REPO)).closeOwnerAuthors).toBe(true);
+  });
+
   it("accepts a config without provider/model (stored as null)", async () => {
     const app = createApp();
     const env = createTestEnv({ TOKEN_ENCRYPTION_SECRET: SECRET });