@camunda/session-heartbeat

Activity-driven session heartbeat for Camunda webapps whose sessions are managed by the Camunda security library (CSL).

The package tracks genuine browser activity — pointer, keyboard, wheel, scroll, and the tab regaining visibility — and calls CSL's POST {basePath}/session/heartbeat endpoint at most once per interval, only when activity actually happened. It exists so Operate, Tasklist, Optimize, and any future adopter share one implementation instead of each reimplementing the same listener and throttle logic.

Background: CSL ADR-0042 — Configurable session idle timeout driven by client activity.

Why a heartbeat is needed

With camunda.security.session.heartbeat.enabled=true, CSL stops treating ordinary backend traffic as proof of user presence: only a call to the heartbeat endpoint extends the session. A host that enables the flag without a frontend sending heartbeats logs its users out after camunda.security.session.max-inactive-interval, however actively they are using the application.

The flag defaults to false, so adopting this package is safe and inert until a host turns it on.

Installation

npm install @camunda/session-heartbeat

react is an optional peer dependency, needed only for the ./react entry point.

Usage

React

import {useSessionHeartbeat} from '@camunda/session-heartbeat/react';

function AuthenticatedLayout() {
    useSessionHeartbeat({
        url: '/session/heartbeat',
        csrfToken: () => sessionStorage.getItem('X-CSRF-TOKEN'),
        onUnauthorized: () => {
            authenticationStore.disableSession();
        },
    });

    return <Outlet />;
}

Call it once inside the authenticated part of the application, so the heartbeat starts after login and stops when the user leaves it. Callbacks and csrfToken are read fresh on every heartbeat, so inline functions do not restart the timer; changing url, intervalMs, or enabled does.

Without React

import {createSessionHeartbeat} from '@camunda/session-heartbeat';

const stopSessionHeartbeat = createSessionHeartbeat({url: '/session/heartbeat'});

// on teardown
stopSessionHeartbeat();

Options

Choosing intervalMs

Keep it well under the host's camunda.security.session.max-inactive-interval — a heartbeat is what resets that clock, and one lost request must not cost the user their session. A quarter of the configured interval or less is a good rule of thumb; the 60s default suits CSL's 30m default.

Behavior worth knowing

• The endpoint needs a CSRF token. CSL exempts only /login and /logout from CSRF protection, so a session-bearing POST /session/heartbeat without a valid X-CSRF-TOKEN is rejected — with 401, not 403, since the webapp chain maps the CSRF denial onto its auth-failure handler. Pass csrfToken from wherever the application keeps it.
• A 401 therefore means "this heartbeat was not accepted", not strictly "the session is gone". A missing or stale token produces the same status as an expired session, so onUnauthorized fires in both cases. That matches how a webapp's own request layer usually treats 401; if an application needs to tell the two apart, the response body carries a CSRF-specific detail.
• Starting counts as activity, so the first interval always sends one heartbeat. This surfaces broken wiring immediately, at the cost of extending an abandoned session by one interval.
• At most one heartbeat per interval, and none at all for an interval with no activity. A heartbeat is also skipped while a previous one is still in flight.
• A 401 does not stop the heartbeat. The consumer decides what an expired session means; unmounting the hook (or setting enabled: false) is what stops it.
• Each tab heartbeats independently. They share one session, so the cost is one extra request per tab per interval; there is no cross-tab coordination.
• Requests are credentialed (credentials: 'include') and aborted on teardown.

Development

npm run build -w @camunda/session-heartbeat        # bundle + type declarations
npm run typecheck -w @camunda/session-heartbeat
npm run test:unit -w @camunda/session-heartbeat    # Vitest browser mode

See Session heartbeat in the monorepo docs for the adoption checklist and publishing steps.