2049494 - Windows launch-on-login can silently re-enable itself on later startups for existing users (first-run enable gate is not durable)

Status: ASSIGNED

(Firefox :: Shell Integration, defect)

Description

[[e-mail]]

Symptom / reports

Windows users report that "Open Firefox when your computer starts" (launch-on-login) turns itself back ON after they disable it -- not just once
on a new install, but repeatedly on subsequent startups. Reddit: https://www.reddit.com/r/firefox/comments/1ubmddw/comment/ot1b7m5/

Root cause (code analysis)

The default-enable of launch-on-login is gated solely on nsIToolkitProfileService.isFirstRun, which is recomputed every startup, and can be true on more than the genuine first run:

• By design: new install path / different install hash (side-by-side installs, moved/portable install, install-dir layout change).
• Gap: installs.ini not persisting the install Default (roaming / OneDrive-redirected AppData, locked-down/enterprise profiles, AV)
• Gap: Launching exclusively via -P / --profile, which never establishes the install default (the -P/--profile arms of SelectStartupProfile return without setting it or clearing mIsFirstRun).

Meanwhile, there is no durable "default already applied" marker for launch on login. Any time isFirstRun re-evaluates true for an established user launch-on-login is re-enabled, silently overriding the user's choice.

Telemetry evidence

BigQuery, firefox_desktop.metrics, 1% sample, Windows, release, last 21 days, using os.environment.launch_on_login_state cross-referenced with
launch_on_login.user_toggle: 91% of disable to enable transitions currently are happening without a user toggle, which is about 5,000 clients a week.

Proposed fix

Add "launch-on-login default already applied" and set it when:

• The default is actually applied
• The profile starts up and isFirstStartup evaluates to false
• The user uses Firefox preferences to change the setting from enabled to disabled
  And then check this pref before enabling launch on login if ever isFirstRun evaluates to true again.

Comment 1

[iain holmes]

Attachment: Bug 2049494 - Set a preference after enabling Launch on Login. r=#firefox-desktop-core-reviewers,mconley

isFirstRun can be reset and return a false positive in certain scenarios which causes the launch
on login preference to be reenabled even after the user disables it.

This change sets a preference flag so we can tell if we've already enabled it once, so we don't
revert user changes.