diff --git a/frontend/src/app/page.tsx b/frontend/src/app/page.tsx
index 77837df6..2e0b62e1 100644
--- a/frontend/src/app/page.tsx
+++ b/frontend/src/app/page.tsx
@@ -1322,7 +1322,8 @@ export default function Home() {
     const birthPlace = selectedBirthPlace(nextProfile);
     const { data, error } = await createBrowserSupabaseClient()
       .from("profiles")
-      .update({
+      .upsert({
+        id: account.user.id,
         name: nextProfile.name.trim() || null,
         birth_date: nextProfile.date || null,
         birth_time: nextProfile.time || null,
@@ -1334,8 +1335,7 @@ export default function Home() {
         longitude: birthPlace?.lon ?? null,
         timezone_offset: birthPlace?.tz ?? null,
         updated_at: new Date().toISOString(),
-      })
-      .eq("id", account.user.id)
+      }, { onConflict: "id" })
       .select("id")
       .maybeSingle();
     if (error) throw error;
diff --git a/frontend/supabase/migrations/20260718010000_recover_missing_profile_rows.sql b/frontend/supabase/migrations/20260718010000_recover_missing_profile_rows.sql
new file mode 100644
index 00000000..ee5ab568
--- /dev/null
+++ b/frontend/supabase/migrations/20260718010000_recover_missing_profile_rows.sql
@@ -0,0 +1,25 @@
+begin;
+
+drop policy if exists profiles_insert_own on public.profiles;
+create policy profiles_insert_own
+  on public.profiles
+  for insert
+  to authenticated
+  with check ((select auth.uid()) = id);
+
+grant insert (
+  id,
+  name,
+  birth_date,
+  birth_time,
+  country_code,
+  province_code,
+  city_code,
+  district_code,
+  latitude,
+  longitude,
+  timezone_offset,
+  updated_at
+) on public.profiles to authenticated;
+
+commit;
diff --git a/frontend/tests/profile-persistence.test.ts b/frontend/tests/profile-persistence.test.ts
new file mode 100644
index 00000000..625301e9
--- /dev/null
+++ b/frontend/tests/profile-persistence.test.ts
@@ -0,0 +1,8 @@
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import test from "node:test";
+
+test("upserts a missing profile when saving account details", () => {
+  const source = readFileSync(new URL("../src/app/page.tsx", import.meta.url), "utf8");
+  assert.match(source, /\.from\("profiles"\)\s*\.upsert\(/);
+});