diff --git a/clients/admin/src/auth/jwt.ts b/clients/admin/src/auth/jwt.ts
index 4390ba4a3d..4c18a57eb7 100644
--- a/clients/admin/src/auth/jwt.ts
+++ b/clients/admin/src/auth/jwt.ts
@@ -15,7 +15,9 @@ export function decodeJwt(token: string | null | undefined): JwtClaims | null {
   try {
     const payload = parts[1].replace(/-/g, "+").replace(/_/g, "/");
     const padded = payload + "=".repeat((4 - (payload.length % 4)) % 4);
-    const json = atob(padded);
+    // atob yields one char per byte; the payload is UTF-8, so decode the bytes
+    // or "Comitê" renders as "Comitê".
+    const json = new TextDecoder().decode(Uint8Array.from(atob(padded), (c) => c.charCodeAt(0)));
     return JSON.parse(json) as JwtClaims;
   } catch {
     return null;
diff --git a/clients/admin/tests/auth/jwt-utf8.spec.ts b/clients/admin/tests/auth/jwt-utf8.spec.ts
new file mode 100644
index 0000000000..2e77c05b98
--- /dev/null
+++ b/clients/admin/tests/auth/jwt-utf8.spec.ts
@@ -0,0 +1,21 @@
+import { expect, test } from "@playwright/test";
+import { seedAuthedSession, TEST_USER } from "../helpers/auth-seed";
+import { installAdminShellMocks, ADMIN_PERMS } from "../helpers/shell-mocks";
+
+// Regression: the JWT payload is UTF-8. Decoding it with a bare atob() read the
+// bytes as Latin-1, so a claim like "Comitê de Ética" rendered as "Comitê".
+
+test("renders non-ASCII name claims from the access token intact", async ({ page }) => {
+  await seedAuthedSession(page, {
+    ...TEST_USER,
+    firstName: "Comitê",
+    lastName: "de Ética",
+    permissions: [...ADMIN_PERMS],
+  });
+  await installAdminShellMocks(page);
+
+  await page.goto("/");
+
+  await expect(page.getByText(/Comitê/).first()).toBeVisible();
+  await expect(page.getByText(/Ã/)).toHaveCount(0);
+});
diff --git a/clients/admin/tests/helpers/auth-seed.ts b/clients/admin/tests/helpers/auth-seed.ts
index c631a344ac..09a38f2da5 100644
--- a/clients/admin/tests/helpers/auth-seed.ts
+++ b/clients/admin/tests/helpers/auth-seed.ts
@@ -16,7 +16,11 @@ export type SeededUser = {
 
 function fakeJwt(payload: Record<string, unknown>): string {
   const b64url = (obj: unknown) =>
-    btoa(JSON.stringify(obj)).replace(/=+$/, "").replace(/\+/g, "-").replace(/\//g, "_");
+    // UTF-8 bytes, like the server emits, so non-ASCII claims hit the real decode path.
+    btoa(String.fromCharCode(...new TextEncoder().encode(JSON.stringify(obj))))
+      .replace(/=+$/, "")
+      .replace(/\+/g, "-")
+      .replace(/\//g, "_");
   return [b64url({ alg: "HS256", typ: "JWT" }), b64url(payload), "sig"].join(".");
 }
 
diff --git a/clients/dashboard/src/auth/jwt.ts b/clients/dashboard/src/auth/jwt.ts
index 811b19dd81..2bd60e37d5 100644
--- a/clients/dashboard/src/auth/jwt.ts
+++ b/clients/dashboard/src/auth/jwt.ts
@@ -31,7 +31,9 @@ export function decodeJwt(token: string | null | undefined): JwtClaims | null {
   try {
     const payload = parts[1].replace(/-/g, "+").replace(/_/g, "/");
     const padded = payload + "=".repeat((4 - (payload.length % 4)) % 4);
-    const json = atob(padded);
+    // atob yields one char per byte; the payload is UTF-8, so decode the bytes
+    // or "Comitê" renders as "Comitê".
+    const json = new TextDecoder().decode(Uint8Array.from(atob(padded), (c) => c.charCodeAt(0)));
     return JSON.parse(json) as JwtClaims;
   } catch {
     return null;
diff --git a/clients/dashboard/tests/auth/jwt-utf8.spec.ts b/clients/dashboard/tests/auth/jwt-utf8.spec.ts
new file mode 100644
index 0000000000..3b099dcfda
--- /dev/null
+++ b/clients/dashboard/tests/auth/jwt-utf8.spec.ts
@@ -0,0 +1,17 @@
+import { expect, test } from "@playwright/test";
+import { installShellMocks } from "../helpers/shell-mocks";
+import { seedAuthedSession, TEST_USER } from "../helpers/auth-seed";
+
+// Regression: the JWT payload is UTF-8. Decoding it with a bare atob() read the
+// bytes as Latin-1, so a claim like "Comitê de Ética" rendered as
+// "Comitê de Åtica" in the user menu and the overview greeting.
+
+test("renders non-ASCII name claims from the access token intact", async ({ page }) => {
+  await seedAuthedSession(page, { ...TEST_USER, firstName: "Comitê", lastName: "de Ética" });
+  await installShellMocks(page);
+
+  await page.goto("/");
+
+  await expect(page.getByText("Comitê de Ética").first()).toBeVisible();
+  await expect(page.getByText(/Ã/)).toHaveCount(0);
+});
diff --git a/clients/dashboard/tests/helpers/auth-seed.ts b/clients/dashboard/tests/helpers/auth-seed.ts
index 3eaf4bd166..19b95541a2 100644
--- a/clients/dashboard/tests/helpers/auth-seed.ts
+++ b/clients/dashboard/tests/helpers/auth-seed.ts
@@ -33,12 +33,16 @@ const TENANT_KEY = "fsh.dashboard.tenant";
 
 /**
  * Encode a minimal JWT (header.payload.signature) where every segment is
- * base64url-encoded JSON. Signature is a junk string — the dashboard
- * never validates it (only the server does), so this is safe.
+ * base64url-encoded UTF-8 JSON, like the server emits (so non-ASCII claims
+ * such as "Comitê de Ética" exercise the real decode path). Signature is a
+ * junk string — the dashboard never validates it (only the server does).
  */
 function fakeJwt(payload: Record<string, unknown>): string {
   const b64url = (obj: unknown) =>
-    btoa(JSON.stringify(obj)).replace(/=+$/, "").replace(/\+/g, "-").replace(/\//g, "_");
+    btoa(String.fromCharCode(...new TextEncoder().encode(JSON.stringify(obj))))
+      .replace(/=+$/, "")
+      .replace(/\+/g, "-")
+      .replace(/\//g, "_");
   return [b64url({ alg: "HS256", typ: "JWT" }), b64url(payload), "sig"].join(".");
 }