0030. Default browser and links from other apps

Status

Accepted

Date

2026-11-01

Context

A browser is only used every day when it opens the links of other apps. Each system decides differently which browser that is: Windows 10 and 11 let only the user choose, in the system settings, among browsers that registered themselves; macOS asks the user to confirm a change; Linux desktops follow xdg-settings. Links arrive as command line arguments of a new start, or as open-url events on macOS. A link on the command line must never act as a switch of the browser.

Decision

• Links: the browser opens http and https links from its command line, from the start of a second instance and from open-url events, at most 50 per start, in new tabs of the window used last. A start with links and without a session to restore shows only them. Every other argument is ignored.
• Registration on Windows: the NSIS installer registers the browser under StartMenuInternet and RegisteredApplications with a program id for web links whose command passes the link after --, and the uninstaller removes it unless an update replaces the version. The Windows smoke test checks both. Making the browser the default opens the Windows settings on its page; the browser counts as the default only when the user chose it for both http and https.
• macOS and Linux: the app declares itself a viewer of web links and asks the system to make it the handler of http and https links.
• Policy: DefaultBrowserSettingEnabled set to false shows the setting as managed, without its button, and the browser refuses the change.
• MSI installations are not registered; organizations manage the default browser of their computers with their own tools. An AppImage has no installed desktop entry. The setting tells both that they cannot become the default browser.

Consequences

Positive:

• Links from email and chat apps open in a tab, on all three systems.
• No switch can be passed through a link.

Negative:

• On Windows, the browser cannot make itself the default; the user finishes the change in the system settings.