diff --git a/coderd/apikey.go b/coderd/apikey.go
index b0cc6a26a4..e78ad5d373 100644
--- a/coderd/apikey.go
+++ b/coderd/apikey.go
@@ -582,5 +582,20 @@ func (api *API) createAPIKey(ctx context.Context, params apikey.CreateParams) (*
 		Value:    sessionToken,
 		Path:     "/",
 		HttpOnly: true,
+		// MaxAge is set so the browser persists the cookie to disk rather
+		// than keeping it in memory as a session cookie. Standalone PWAs
+		// (display: standalone) run in their own browser process, and
+		// mobile OSes kill that process when the app is swiped away —
+		// deleting in-memory cookies and forcing an unexpected login.
+		//
+		// We use a long static value (1 year) instead of the key's
+		// LifetimeSeconds because the server refreshes the key's
+		// ExpiresAt on activity but does not re-set the cookie. Tying
+		// MaxAge to the key lifetime would cause the cookie to expire
+		// client-side even when the server-side key is still valid.
+		//
+		// Security is not affected: the server validates ExpiresAt on
+		// every request regardless of the cookie's MaxAge.
+		MaxAge: int((365 * 24 * time.Hour).Seconds()),
 	}), &newkey, nil
 }
diff --git a/coderd/apikey_test.go b/coderd/apikey_test.go
index 823e2faa6b..14e22d0221 100644
--- a/coderd/apikey_test.go
+++ b/coderd/apikey_test.go
@@ -394,6 +394,55 @@ func TestSessionExpiry(t *testing.T) {
 	}
 }
 
+// TestSessionCookieMaxAge verifies that the session cookie is a persistent
+// cookie (has MaxAge set) rather than a session cookie. Standalone PWAs
+// run in their own browser process and mobile OSes purge in-memory
+// (session) cookies when that process is killed, so the cookie must be
+// persisted to disk.
+func TestSessionCookieMaxAge(t *testing.T) {
+	t.Parallel()
+
+	ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitLong)
+	defer cancel()
+
+	client := coderdtest.New(t, nil)
+
+	// Create the first user (password-based login).
+	req := codersdk.CreateFirstUserRequest{
+		Email:    "testuser@coder.com",
+		Username: "testuser",
+		Password: "SomeSecurePassword!",
+	}
+	_, err := client.CreateFirstUser(ctx, req)
+	require.NoError(t, err)
+
+	// Login via the raw HTTP endpoint so we can inspect the Set-Cookie header.
+	loginURL, err := client.URL.Parse("/api/v2/users/login")
+	require.NoError(t, err)
+
+	res, err := client.Request(ctx, http.MethodPost, loginURL.String(), codersdk.LoginWithPasswordRequest{
+		Email:    req.Email,
+		Password: req.Password,
+	})
+	require.NoError(t, err)
+	defer res.Body.Close()
+	require.Equal(t, http.StatusCreated, res.StatusCode)
+
+	oneYear := int((365 * 24 * time.Hour).Seconds())
+	var found bool
+	for _, cookie := range res.Cookies() {
+		if cookie.Name == codersdk.SessionTokenCookie {
+			// MaxAge should be set to a long value so the browser
+			// persists the cookie to disk. The server handles real
+			// expiry via the API key's ExpiresAt field.
+			require.Equal(t, oneYear, cookie.MaxAge,
+				"Session cookie MaxAge should be set to 1 year for disk persistence")
+			found = true
+		}
+	}
+	require.True(t, found, "session cookie should be present in login response")
+}
+
 func TestAPIKey_OK(t *testing.T) {
 	t.Parallel()