diff --git a/src/net/ch-client.js b/src/net/ch-client.js
index 4cd0da2..81a4ec0 100644
--- a/src/net/ch-client.js
+++ b/src/net/ch-client.js
@@ -45,21 +45,28 @@ export async function authedFetch(ctx, url, sql, signal) {
       headers: { Authorization: authHeader(bearer) },
       signal,
     });
+    // A 2xx confirms the credentials are good for the rest of the session.
+    if (resp.ok) ctx.authConfirmed = true;
     let authExpired = resp.status === 401 || resp.status === 403;
     if (!authExpired && !resp.ok) {
       const peek = await resp.clone().text();
       if (isAuthExpiredBody(peek)) authExpired = true;
     }
     if (authExpired) {
+      // Once this session has authenticated successfully, the same credentials
+      // are still valid — so a later 401/403 is a *query-level* error ClickHouse
+      // maps to that HTTP status (ACCESS_DENIED, or UNKNOWN_USER from e.g.
+      // `SHOW CREATE USER <missing>`), not a sign-in problem. Return it so the
+      // caller shows it as a normal query error instead of force-logging-out.
+      if (ctx.authConfirmed) return resp;
       if (attempt === 0 && (await ctx.refresh())) {
         bearer = await ctx.getToken();
         attempt++;
         continue;
       }
-      // getToken() already guaranteed a non-expired token above, so a 401/403
-      // that survives the one refresh-retry means CH rejected a *valid* login —
-      // an authorization/identity problem, not session expiry. Surface CH's own
-      // reason so it's diagnosable.
+      // First-contact 401/403 with a non-expired token: CH rejected the login
+      // itself — an authorization/identity problem, not session expiry. Surface
+      // CH's own reason so it's diagnosable.
       const reason = parseExceptionText(await resp.clone().text());
       ctx.onSignedOut(authDeniedMessage(resp.status, reason));
       throw new Error('signed out');
diff --git a/src/ui/app.js b/src/ui/app.js
index b002eaf..ece15c2 100644
--- a/src/ui/app.js
+++ b/src/ui/app.js
@@ -117,6 +117,7 @@ export function createApp(env = {}) {
     app.idpId = null;
     app.authMode = 'oauth';
     chCtx.origin = loc.origin;
+    chCtx.authConfirmed = false; // a fresh sign-in starts unconfirmed again
     ['oauth_id_token', 'oauth_refresh_token', 'oauth_verifier', 'oauth_state', 'oauth_idp',
       'ch_basic_auth', 'ch_basic_user', 'ch_basic_origin'].forEach((k) => ss.removeItem(k));
   }
@@ -184,6 +185,9 @@ export function createApp(env = {}) {
     // Where queries POST: the serving origin for OAuth, or the (possibly
     // cross-origin) target chosen at credential sign-in for basic mode.
     origin: app.authMode === 'basic' ? (ss.getItem('ch_basic_origin') || loc.origin) : loc.origin,
+    // Flips true after the first 2xx; gates whether a later 401/403 is treated
+    // as a sign-in failure (only before auth is confirmed) or a query error.
+    authConfirmed: false,
     getToken,
     refresh,
     authHeader,
diff --git a/tests/unit/ch-client.test.js b/tests/unit/ch-client.test.js
index 20b6234..f6e2738 100644
--- a/tests/unit/ch-client.test.js
+++ b/tests/unit/ch-client.test.js
@@ -90,6 +90,20 @@ describe('authedFetch', () => {
     expect(msg).toContain('not authorizing you');
     expect(msg).toContain('Server: Code: 516. DB::Exception: Authentication failed');
   });
+  it('marks the ctx authenticated on a successful response', async () => {
+    const ctx = ctxWith(async () => jsonResp({ ok: 1 }));
+    await authedFetch(ctx, 'u', 'sql');
+    expect(ctx.authConfirmed).toBe(true);
+  });
+  it('once authenticated, a later 403 is returned as a query error (no sign-out)', async () => {
+    // e.g. SHOW CREATE USER <missing> → HTTP 403 / UNKNOWN_USER, mid-session.
+    const ctx = ctxWith(async () => textResp('Code: 192. DB::Exception: There is no user x', false, 403),
+      { authConfirmed: true });
+    const resp = await authedFetch(ctx, 'u', 'sql');
+    expect(resp.status).toBe(403);
+    expect(ctx.onSignedOut).not.toHaveBeenCalled();
+    expect(ctx.refresh).not.toHaveBeenCalled();
+  });
   it('treats a token_verification body as auth-expired', async () => {
     let n = 0;
     const ctx = ctxWith(