2068218 - browser_aiwindow_*.js leak windows until shutdown, tripping the shutdown hang watchdog

Status: NEW

(Core :: Machine Learning: Frontend, defect)

Description

[Jens Stutte [:jstutte]]

Since 2026-08-28 the aiwindow browser-chrome tests leak windows until shutdown, and the process then trips the nsTerminator shutdown hang watchdog. The watchdog's TEST-UNEXPECTED-FAIL | shutdown hang | profile uploaded in ... line is classified into bug 2060167, where these tests account for roughly a third of the volume: 270 of the 815 occurrences in the 30 days to 2026-09-01, including 121 of the 162 on 08-31 alone.

The tests appearing in the affected job logs, most frequent first:

• browser/components/aiwindow/ui/test/browser/browser_aiwindow_group_tabs_button.js
• browser/components/aiwindow/ui/test/browser/browser_aiwindow_switcher.js
• browser/components/aiwindow/ui/test/browser/browser_aiwindow_organize_tabs_callout.js
• browser/components/aiwindow/ui/test/browser/browser_aiwindow_firstrun.js
• browser/components/aiwindow/ui/test/browser/browser_smartwindow_chat_browser_tabbable.js

Typical failure lines:

TEST-UNEXPECTED-FAIL | ... browser_aiwindow_group_tabs_button.js | Shutdown - leaked window until shutdown [url = chrome://browser/content/browser.xhtml]
TEST-UNEXPECTED-FAIL | ... browser_aiwindow_switcher.js | Shutdown - leaked 1 window(s) until shutdown [url = about:aichatcontent]
TEST-UNEXPECTED-FAIL | ... browser_aiwindow_switcher.js | Shutdown - leaked 1 docShell(s) until shutdown

The leaked URLs seen are chrome://browser/content/browser.xhtml (by far the most common), chrome://browser/content/aiwindow/aiWindow.html, about:aichatcontent and chrome://browser/content/aiwindow/firstrun.html.

Affects debug browser-chrome on Linux, macOS and Windows, including the -swr, -msix and -standalone variants. Onset is sharp: no occurrences before 2026-08-28, 61 on that day.

Data source: the Treeherder failuresbybug API for bug 2060167.

Filing separately from bug 2060167 because that bug is a catch-all for the shutdown hang signature and mixes at least three unrelated causes; this one belongs to the aiwindow tests.

Comment 1

[Ed Lee :Mardak]

i'm guessing bug 2064008 (landed autoland 28th merged 28th) caused this with Services.obs.addObserver
https://searchfox.org/firefox-main/rev/30d71d4c45a912c6bf7368470e095a695de67c18/browser/components/aiwindow/ui/modules/AutoTabGrouping.sys.mjs#255-256

potentially the panel is shown without hiding when tests directly close the window
https://searchfox.org/firefox-main/rev/30d71d4c45a912c6bf7368470e095a695de67c18/browser/components/aiwindow/ui/test/browser/browser_aiwindow_organize_tabs_callout.js#61,84

Comment 2

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2064008

Comment 3

[:jlewis]

Attachment: Bug 2068218 - Tear the Organize Tabs panel down when its window closes