How it works

What Craft already does

Craft has had a quiet version of this since 4.5, and it is worth knowing exactly what it is before reading anything Stop Sign claims to add.

craft\services\Elements::trackActivity() writes to an elementactivity table. Every open element editor polls elements/recent-activity every fifteen seconds, and Craft.ElementEditor._checkActivity() renders the result as a row of 26px avatars in the editor header, each with a tooltip reading "Dana Reyes is editing this entry."

It is deliberately understated, and it stops in five specific places:

1. It is a tooltip on a small avatar. There is no banner, no colour, and nothing that interrupts. On a busy editor screen it is genuinely easy to miss.
2. There is nothing at save time. Craft's activity feature has no opinion about the save button. An author who has not looked at the avatars saves straight over the top.
3. The staleness prompt is full-page only. The "someone changed this — Reload" button lives inside an isFullPage branch, so editing in a slideout gives no conflict signal at all.
4. It keeps no history. Craft's garbage collector deletes every elementactivity row older than sixty seconds. The question "did anyone overwrite anyone last Tuesday?" has no answer on a stock install.
5. It cannot see your own second tab. getRecentActivity() takes an $excludeUserId and the controller always passes the current user, so two windows of the same account — a real and common way to lose work — are invisible to it.

Stop Sign is those five gaps.

Presence

Every open editor sends a heartbeat: one upsert and one indexed read, every ten seconds by default.

The row is keyed on (elementId, siteId, userId, sessionToken) — per tab, not per user. That is the only shape that can answer "you have this open in another tab", and it is why Stop Sign keeps its own table rather than reading Craft's: elementactivity is keyed per user and is emptied every sixty seconds, so it can never answer anything but "in the last minute", and the window is not configurable.

The heartbeat carries dontExtendSession, exactly as Craft's own poll does. Without it, an editor left open would keep a control panel session alive indefinitely and the plugin would quietly defeat userSessionDuration on every site that installed it.

A hidden tab stops beating — you are not there — unless it has unsaved changes, in which case it keeps beating at a quarter rate. Closing a laptop lid should not hand your half-finished entry to somebody else.

One verdict

The banner, the save guard, the read-only state, the history row and the console output all read from a single Verdict object built on the server.

This is not tidiness. A warning that says one thing in the banner and something else in the modal is worse than no warning at all, because the author stops believing either of them. The wording is decided once and the browser only renders it.

The levels, strongest first:

Level	When
locked	Somebody else holds the lock
danger	Somebody else is typing, or the element moved under you
warning	Somebody else has it open but has not typed
notice	Your own account, in another tab
clear	Nothing to say

The save guard

Stop Sign wraps handleSubmit on each ElementEditor instance. Nothing global is patched.

That one method is enough for everything, because Craft.ElementEditorSlideout.handleSubmit() does its own bookkeeping and then calls straight through to this.elementEditor.handleSubmit(event). Full-page saves, slideout saves and ⌘S in both arrive at the same place.

The check is taken fresh, not reused from the last heartbeat. Ten seconds is easily long enough for a colleague to open the entry, and a guard that waves through a collision it could have seen is worse than no guard.

If the guard endpoint cannot be reached, the save goes through. A plugin that makes saving impossible when its own endpoint is down is a worse outage than the collision it was preventing.

Staleness

The browser sends the canonical dateUpdated it started from; the server compares it to the current one.

Two things make this better than Craft's version. It works in slideouts, and it names the person — stopsign_saves records who last saved each element, because nothing on a canonical element row does. Revisions come closest and can be switched off per section, so a warning built on them would silently degrade to "updated by nobody" on exactly the sections whose owners disabled revisions to save space.

Your own save never counts as somebody moving the element under you. Without that guard the modal would fire on an author's own second save of the session, which is the fastest possible way to teach somebody to click straight through it.

Soft locks

Off by default. See Locking.