2033806 - The Sidebar Conversation scrolls back to the top when switching tabs

Status: VERIFIED FIXED

(Core :: Machine Learning: Frontend, defect)

Description

[Rares Doghi, Desktop QA]

Attachment: scrollback.mp4

Found in

• Nightly 152.0a1 (2026-04-21)

Affected versions

• Nightly 152.0a1 (2026-04-21)

Affected platforms

• All

Steps to reproduce

1. Open Smart Window.
2. Reach a few websites in different tabs.
3. Submit a few prompts for each tab.
4. Switch between tabs back and forth.

Expected result

• The Conversations should not scroll back to the top.

Actual result

• The Conversations scroll back to the top when switching tabs.

Regression range
Bug 2026814

Comment 1

[BugBot [:suhaib / :marco]]

:gcardieri, since you are the author of the regressor, bug 2026814, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 2

[Giulia Cardieri (:giulia)]

Checked the state of the main branch before Bug 2026814 and can confirm this bug was caused by it. Sorry about that.
I think the root cause is the change in line 256 of this patch https://phabricator.services.mozilla.com/D290626
The goal of that change was: Added this.shadowRoot?.querySelector(".chat-inner-wrapper")?.style.removeProperty("--content-height"); to recalculate the chat inner content height, this was the same for all tabs and was causing the sidebar scrollbar to show up when it shouldn't
The issue is that this reset is happening every time the user changes a tab, which is not what we want.

Comment 3

[Donal Meehan [:dmeehan]]

(In reply to Giulia Cardieri (:giulia) from comment #2)

Checked the state of the main branch before Bug 2026814 and can confirm this bug was caused by it. Sorry about that.
I think the root cause is the change in line 256 of this patch https://phabricator.services.mozilla.com/D290626
The goal of that change was: Added this.shadowRoot?.querySelector(".chat-inner-wrapper")?.style.removeProperty("--content-height"); to recalculate the chat inner content height, this was the same for all tabs and was causing the sidebar scrollbar to show up when it shouldn't
The issue is that this reset is happening every time the user changes a tab, which is not what we want.

Next week is the final full week of beta for Fx151, do you plan on fixing and requesting uplift in time?
Could this be triaged?

Comment 4

[Giulia Cardieri (:giulia)]

(In reply to Donal Meehan [:dmeehan] from comment #3)

(In reply to Giulia Cardieri (:giulia) from comment #2)

Checked the state of the main branch before Bug 2026814 and can confirm this bug was caused by it. Sorry about that.
I think the root cause is the change in line 256 of this patch https://phabricator.services.mozilla.com/D290626
The goal of that change was: Added this.shadowRoot?.querySelector(".chat-inner-wrapper")?.style.removeProperty("--content-height"); to recalculate the chat inner content height, this was the same for all tabs and was causing the sidebar scrollbar to show up when it shouldn't
The issue is that this reset is happening every time the user changes a tab, which is not what we want.

Next week is the final full week of beta for Fx151, do you plan on fixing and requesting uplift in time?
Could this be triaged?

Hey Donal,
This is already in the smart window backlog but not in our current sprint. I messaged my team and I'm still waiting for an answer from product.
My opinion is that this is not an urgent issue and will probably be worked in the upcoming weeks, not aiming for Fx151 beta.

Comment 5

[BugBot [:suhaib / :marco]]

The severity field is not set for this bug.
:Mardak, could you have a look please?

For more information, please visit BugBot documentation.

Comment 6

[Giulia Cardieri (:giulia)]

Attachment: Bug 2033806: Save scroll position when tabs are switched on smart window chat

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/3ce58a8bcac9
https://hg.mozilla.org/integration/autoland/rev/e118e337c1b6
Save scroll position when tabs are switched on smart window chat r=jlewis

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/bbad8cfa8880
https://hg.mozilla.org/integration/autoland/rev/e315660358cd
Revert "Bug 2033806: Save scroll position when tabs are switched on smart window chat r=jlewis" for causing bc and TV failures at browser_aichat_content_scrolling_position.js

Comment 9

[Silaghi Andreea]

Backed out for causing bc failures at browser_aichat_content_scrolling_position.js
Backout Link
Push with failures
Failure Log TV
Failure Log bc
Failure line TEST-UNEXPECTED-FAIL | browser/components/aiwindow/ui/test/browser/browser_aichat_content_scrolling_position.js | test_scrolling_is_restored - Uncaught exception in test - Conv 1 scrollTop should be restored to 100 - timed out after 50 tries.

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/23d3fcbb3c42
https://hg.mozilla.org/integration/autoland/rev/d76473ab6221
Save scroll position when tabs are switched on smart window chat r=jlewis

Comment 11

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/d76473ab6221

Comment 12

[Rares Doghi, Desktop QA]

Verified as fixed in our latest Nightly 152.0a1 (2026-05-13)

Comment 13

[BugBot [:suhaib / :marco]]

The patch landed in nightly and beta is affected.
:giulia, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox151 to wontfix.

For more information, please visit BugBot documentation.

Comment 14

[Giulia Cardieri (:giulia)]

Attachment: Bug 2033806: Save scroll position when tabs are switched on smart window chat

We didn't have any functionality that saved the scrolled position when a conversation is restored via changing tabs. This patch adds this functionality so the user don't see scrolling differences (in most cases) when switching tabs in smart windows.

Original Revision: https://phabricator.services.mozilla.com/D299229

Comment 15

[Phabricator Automation]

firefox-release Uplift Approval Request

• User impact if declined/Reason for urgency: This is a key feature to improve smart window's UX and was chosen by the product team to be uplifted.
• Code covered by automated testing?: yes
• Fix verified in Nightly?: yes
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: Follow the same test steps as listed in https://phabricator.services.mozilla.com/D299229
• Risk associated with taking this patch: low
• Explanation of risk level: This is hidden behind the smart window pref and only updates the scrolling function inside the chat, so low risk.
• String changes made/needed?: No
• Is Android affected?: no

Comment 16

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/98d1e8995280
https://hg.mozilla.org/releases/mozilla-release/rev/9dd5c798dba6

Comment 17

[Rares Doghi, Desktop QA]

Verified as fixed in our latest Release 151.0.2