How it works

One round#

Every interval seconds, for each presence that is on:

The application calls read with the time, the pages the extension reported and the options.
If read returned null, the presence has nothing to show this round.
It calls activity and meta with what read returned.
It checks the activity against Discord’s limits and applies the person’s privacy rules.
It compares every presence with something to show and sends one to Discord.

read gathers and activity presents. When a site changes its layout, you touch read and the manifest. When you want a new button, you touch activity.

Why the script does not run in the page#

The extension reads only what the manifest names, with code of its own that never changes. Your script receives the values in the application, far from the page. So a page can never run your code, and your code can never see a password field, a message or a cookie that the manifest did not name. Reviewers can read the manifest and know everything a presence reads.

Why a script starts with nothing#

The script runs in a small JavaScript engine inside the application, with no network, no files and no eval. Each permission adds one door to host, and the application checks every call against the manifest. People see the list before they turn a presence on, and an update that asks for more waits for their answer.

Which presence wins#

Only one activity shows at a time. Each presence has a priority from 0 to 100: the person’s choice, or the default for its kind (game 80, video 60, music 40, other 20). A status the person writes by hand always wins.

A paused presence gives way to one that plays.
foreground raises a presence while its window has focus.
On a tie, the activity already on display stays, so the card does not jump.

What privacy does#

Before anything reaches Discord, the person’s rules can exclude a site or a program, hide the titles or the buttons and links of one presence, show only the name of the service, or hide everything after some time away from the keyboard. Excluding a site or a program looks at domains and at application in meta, which is why a presence declares them.

Why the limits#

Many presences can run at once on a computer that is also playing a game. The time and memory limits keep one slow script from costing the others, and a script that goes over a limit only loses that round.

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