diff --git a/frontend/sentry-init.js b/frontend/sentry-init.js
index 9e7dd76f..34c13767 100644
--- a/frontend/sentry-init.js
+++ b/frontend/sentry-init.js
@@ -9,6 +9,7 @@
 import * as Sentry from '@sentry/vue';
 import { onAppEvent } from '@/utils/app-events';
 import { isValidIP } from '@/utils/ip/valid-ip.js';
+import { readAccountId } from '@/utils/auth-hint.js';
 
 const env = import.meta.env ?? {};
 
@@ -20,6 +21,13 @@ const SCREENSHOT_CSS_NOISE = [
     'Error inlining remote css file',
 ];
 
+// Direct captures carry the FirebaseError as originalException; console
+// captures (`console.error('… sign-in failed:', error)`) surface it as the
+// event's exception type.
+const isFirebaseError = (event, hint) =>
+    hint?.originalException?.name === 'FirebaseError'
+    || (event.exception?.values ?? []).some((value) => value?.type === 'FirebaseError');
+
 // `earlyErrors` is main.js's pre-init buffer: ErrorEvent /
 // PromiseRejectionEvent entries from its temporary window listeners, plus
 // the raw Error from the mount chain's catch. Flushed right after init;
@@ -144,6 +152,11 @@ const initSentry = (app, router, earlyErrors = []) => {
             // per-source console.error lines remain the health signal.
             if (String(hint?.originalException?.message ?? '')
                 .startsWith('All sources failed to fetch IP details')) return null;
+            // Firebase errors carry account id
+            if (isFirebaseError(event, hint)) {
+                const accountId = readAccountId();
+                if (accountId) event.user = { ...event.user, id: accountId };
+            }
             if (event.logger === 'console') {
                 const firstArg = event.extra?.arguments?.[0];
                 if (typeof firstArg === 'string' && firstArg.trim()) {
diff --git a/frontend/store.js b/frontend/store.js
index e1f813e4..9e7b54ec 100644
--- a/frontend/store.js
+++ b/frontend/store.js
@@ -1,7 +1,7 @@
 // store.js
 import { defineStore } from 'pinia';
 import { isFireBaseSet, loadFirebaseAuth } from './firebase-init.js';
-import { writeAuthHint } from './utils/auth-hint.js';
+import { rememberAccountId, writeAuthHint } from './utils/auth-hint.js';
 import { markPendingRedirectSignIn, shouldFallBackToRedirect, takePendingRedirectSignIn } from './utils/auth-redirect.js';
 import { isRunningAsPwa } from './utils/pwa.js';
 import i18n from './locales/i18n.js';
@@ -275,6 +275,7 @@ export const useMainStore = defineStore('main', {
             const result = await fb.signInWithPopup(fb.auth, descriptor.build(fb));
             this.user = result.user;
             writeAuthHint(true);
+            rememberAccountId(result.user?.uid);
             window.location.reload();
             return;
           } catch (error) {
@@ -302,6 +303,7 @@ export const useMainStore = defineStore('main', {
         this.user = result.user;
         this.isSignedIn = true;
         writeAuthHint(true);
+        rememberAccountId(result.user.uid);
         return true;
       } catch (error) {
         this.handleSignInError(error, descriptor);
@@ -354,6 +356,7 @@ export const useMainStore = defineStore('main', {
           this.user = currentUser;
           if (currentUser) {
             this.isSignedIn = true;
+            rememberAccountId(currentUser.uid);
           }
           writeAuthHint(!!currentUser);
           unsubscribe(); // unsubscribe immediately after getting user state
diff --git a/frontend/utils/auth-hint.js b/frontend/utils/auth-hint.js
index 7c6f09fc..0c46bf11 100644
--- a/frontend/utils/auth-hint.js
+++ b/frontend/utils/auth-hint.js
@@ -20,3 +20,25 @@ export const writeAuthHint = (signedIn) => {
         /* storage disabled — every boot stays on the unknown path */
     }
 };
+
+// Last account id signed in on this browser.
+const ACCOUNT_ID_KEY = 'lastAccountId';
+const ACCOUNT_ID_PATTERN = /^[A-Za-z0-9_-]{1,128}$/;
+
+export const readAccountId = () => {
+    try {
+        const value = localStorage.getItem(ACCOUNT_ID_KEY);
+        return value && ACCOUNT_ID_PATTERN.test(value) ? value : null;
+    } catch {
+        return null;
+    }
+};
+
+export const rememberAccountId = (uid) => {
+    if (typeof uid !== 'string' || !ACCOUNT_ID_PATTERN.test(uid)) return;
+    try {
+        localStorage.setItem(ACCOUNT_ID_KEY, uid);
+    } catch {
+        /* storage disabled — Firebase errors just go without an account id */
+    }
+};