diff --git a/extension/src/setup/__tests__/setup-steps.test.ts b/extension/src/setup/__tests__/setup-steps.test.ts
index e8212ad..e574f81 100644
--- a/extension/src/setup/__tests__/setup-steps.test.ts
+++ b/extension/src/setup/__tests__/setup-steps.test.ts
@@ -1,5 +1,15 @@
-import { describe, it, expect, afterEach } from 'vitest';
-import { state, clearWizardState, renderVaultNew } from '../setup-steps';
+import { describe, it, expect, afterEach, vi } from 'vitest';
+import { state, clearWizardState, renderVaultNew, triggerRelkeyDownload } from '../setup-steps';
+
+describe('triggerRelkeyDownload', () => {
+  afterEach(() => clearWizardState());
+
+  it('triggers a vault.relkey download from the relkey bytes', () => {
+    const dl = vi.fn();
+    triggerRelkeyDownload(new Uint8Array([1, 2, 3]), dl);
+    expect(dl).toHaveBeenCalledWith('vault.relkey', expect.any(Blob));
+  });
+});
 
 describe('renderVaultNew — second-factor container choice', () => {
   afterEach(() => clearWizardState());
diff --git a/extension/src/setup/setup-steps.ts b/extension/src/setup/setup-steps.ts
index db8984b..e9f858a 100644
--- a/extension/src/setup/setup-steps.ts
+++ b/extension/src/setup/setup-steps.ts
@@ -54,6 +54,7 @@ export interface WizardState {
   passphraseVisible: boolean;
   confirmVisible: boolean;
   referenceImageBytes: Uint8Array | null;
+  relkeyBytes: Uint8Array | null;
   creating: boolean;
   attaching: boolean;
   error: string | null;
@@ -64,7 +65,7 @@ export const state: WizardState = {
   stepId: 'mode', mode: null, hostType: 'gitea', hostUrl: '', repoPath: '', apiToken: '',
   connectionTested: false, vaultProbe: null, carrierImageBytes: null, secondFactor: 'image', referenceImageBytesAttach: null,
   passphrase: '', passphraseConfirm: '', passphraseScore: -1, passphraseGuessesLog10: -1,
-  passphraseVisible: false, confirmVisible: false, referenceImageBytes: null,
+  passphraseVisible: false, confirmVisible: false, referenceImageBytes: null, relkeyBytes: null,
   creating: false, attaching: false, error: null, deviceName: '',
 };
 
@@ -563,7 +564,7 @@ function attachVaultNew(ctx: StepContext): () => void {
   document.getElementById('create-btn')?.addEventListener('click', async () => {
     state.passphrase = (document.getElementById('passphrase') as HTMLInputElement).value;
     state.passphraseConfirm = (document.getElementById('passphrase-confirm') as HTMLInputElement).value;
-    if (!state.carrierImageBytes) {
+    if (state.secondFactor === 'image' && !state.carrierImageBytes) {
       state.error = 'Please select a carrier JPEG image';
       ctx.rerender();
       return;
@@ -650,19 +651,36 @@ const deviceStep: SetupStep = {
       } else {
         state.creating = true;
         ctx.rerender();
-        const resp = await swSend({
-          type: 'create_vault',
-          config: vaultConfig(),
-          passphrase: state.passphrase,
-          carrierImageBytes: state.carrierImageBytes!.buffer as ArrayBuffer,
-          deviceName: state.deviceName,
-        });
-        state.creating = false;
-        if (resp.ok) {
-          const data = resp.data as { referenceImageBytes: Uint8Array };
-          state.referenceImageBytes = new Uint8Array(data.referenceImageBytes);
-          ctx.goto('done');
-        } else { state.error = lookupErrorCopy(resp.error).body; ctx.rerender(); }
+        let resp;
+        if (state.secondFactor === 'keyfile') {
+          resp = await swSend({
+            type: 'create_vault',
+            config: vaultConfig(),
+            passphrase: state.passphrase,
+            secondFactor: 'keyfile',
+            deviceName: state.deviceName,
+          });
+          state.creating = false;
+          if (resp.ok) {
+            const data = resp.data as { relkeyBytes: Uint8Array };
+            state.relkeyBytes = new Uint8Array(data.relkeyBytes);
+            ctx.goto('done');
+          } else { state.error = lookupErrorCopy(resp.error).body; ctx.rerender(); }
+        } else {
+          resp = await swSend({
+            type: 'create_vault',
+            config: vaultConfig(),
+            passphrase: state.passphrase,
+            carrierImageBytes: state.carrierImageBytes!.buffer as ArrayBuffer,
+            deviceName: state.deviceName,
+          });
+          state.creating = false;
+          if (resp.ok) {
+            const data = resp.data as { referenceImageBytes: Uint8Array };
+            state.referenceImageBytes = new Uint8Array(data.referenceImageBytes);
+            ctx.goto('done');
+          } else { state.error = lookupErrorCopy(resp.error).body; ctx.rerender(); }
+        }
       }
     });
     return () => {};
@@ -675,19 +693,25 @@ const doneStep: SetupStep = {
   id: 'done',
   render() {
     const isAttach = state.mode === 'attach';
+    const isKeyfile = !isAttach && state.secondFactor === 'keyfile';
     const qrBannerHtml = isAttach ? '' : `
       <div class="recovery-qr-banner" id="recovery-qr-banner" style="margin-bottom:16px;">
         <div class="recovery-qr-banner__header">
           <span style="font-size:20px;">◫</span>
           <strong>Generate a recovery QR before you go</strong>
         </div>
-        <p class="muted" style="font-size:12px;margin:4px 0 8px;">If you lose your reference image, this QR lets you recover your vault. Print it and store it safely.</p>
+        <p class="muted" style="font-size:12px;margin:4px 0 8px;">If you lose your second factor, this QR lets you recover your vault. Print it and store it safely.</p>
         <div class="recovery-qr-banner__actions">
           <button class="btn btn-primary" id="setup-gen-qr">Generate now</button>
           <button class="btn" id="setup-skip-qr">Skip — I'll do this in Settings</button>
         </div>
       </div>`;
-    const refSection = isAttach ? '' : `
+    const refSection = isAttach ? '' : isKeyfile ? `
+      <div class="form-group">
+        <label class="label">key file</label>
+        <p class="muted" style="margin-bottom:8px;">Save this key file — it is your second factor. Without it you cannot unlock your vault.</p>
+        <button class="btn btn-primary" id="download-relkey-btn">download vault.relkey</button>
+      </div>` : `
       <div class="form-group">
         <label class="label">reference image</label>
         <p class="muted" style="margin-bottom:8px;">Download and store this image securely. It is your second factor for decryption. Without it, you cannot unlock the vault.</p>
@@ -756,6 +780,10 @@ const doneStep: SetupStep = {
       document.body.removeChild(a);
       URL.revokeObjectURL(url);
     });
+    document.getElementById('download-relkey-btn')?.addEventListener('click', () => {
+      if (!state.relkeyBytes) return;
+      triggerRelkeyDownload(state.relkeyBytes);
+    });
     document.getElementById('copy-config-btn')?.addEventListener('click', async () => {
       const blob = document.getElementById('config-blob');
       if (!blob) return;
@@ -783,6 +811,27 @@ export const STEPS: ReadonlyArray<SetupStep> = [
   modeStep, hostStep, connectionStep, vaultStep, deviceStep, doneStep,
 ];
 
+// --- Relkey download helper ---
+
+function defaultBlobDownload(name: string, blob: Blob): void {
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = name;
+  document.body.appendChild(a);
+  a.click();
+  document.body.removeChild(a);
+  URL.revokeObjectURL(url);
+}
+
+export function triggerRelkeyDownload(
+  relkeyBytes: Uint8Array,
+  trigger: (name: string, blob: Blob) => void = defaultBlobDownload
+): void {
+  const blob = new Blob([relkeyBytes.buffer as ArrayBuffer], { type: 'application/octet-stream' });
+  trigger('vault.relkey', blob);
+}
+
 // --- Sensitive-state cleanup ---
 
 export function clearWizardState(): void {
@@ -790,6 +839,7 @@ export function clearWizardState(): void {
   state.carrierImageBytes?.fill(0);
   state.referenceImageBytes?.fill(0);
   state.referenceImageBytesAttach?.fill(0);
+  state.relkeyBytes?.fill(0);
   state.mode = null;
   state.hostType = 'gitea';
   state.hostUrl = '';
@@ -807,6 +857,7 @@ export function clearWizardState(): void {
   state.passphraseVisible = false;
   state.confirmVisible = false;
   state.referenceImageBytes = null;
+  state.relkeyBytes = null;
   state.creating = false;
   state.attaching = false;
   state.error = null;