fix: Elementor idempotent-lifecycle mu-plugin (redeclaration fatal)

[luthermonson]

Summary

Adds muplugins/elementor-idempotent-lifecycle.php to fix the Elementor Cannot redeclare class Elementor\Element_Column fatal that hits every request from N >= 2 under this adapter's per-request init re-fire. Reproduced locally against Elementor 4.1.4; fix verified.

Root cause (source-verified)

Elementor's Plugin::init() (registered on init priority 0 at plugin.php:833) calls $this->init_components(), which instantiates new Elements_Manager(). Elements_Manager::__construct() at elements.php:58 calls the private require_files(), which at elements.php:461-463 does:

private function require_files() {
    require_once ELEMENTOR_PATH . 'includes/base/element-base.php';
    require ELEMENTOR_PATH . 'includes/elements/column.php';    // NOT require_once
    require ELEMENTOR_PATH . 'includes/elements/section.php';
    require ELEMENTOR_PATH . 'includes/elements/repeater.php';
}

Under FPM, init fires once per process -> require_files() runs once -> correct. Under this adapter's per-request init re-fire, request N >= 2 -> new Elements_Manager() again -> require (not require_once) -> redeclaration fatal.

Fix

Mu-plugin at wp_loaded PHP_INT_MAX that on the first fire (boot-time) does remove_action('init', [\Elementor\Plugin::instance(), 'init'], 0) — strips exactly the callback that triggers the redeclaring chain. All other Elementor hooks (REST, admin, editor, widget-render) stay intact. Static flag ensures the callback only fires once even though wp_loaded re-fires per request.

Reproduction (local, this branch)

• WP 7.0 + Elementor 4.1.4, installed via wordpress:cli-2.10.0-php8.2
• Composer pulls ephpm/wordpress-worker:dev-fix/elementor-idempotent-lifecycle (this branch)
• ePHPm image: docker.io/ephpm/ephpm:v0.4.2-php8.4
• Config: mode = "worker", worker_count = 1, worker_populate_superglobals = true

Without the mu-plugin (removed from wp-content/mu-plugins/):

[hit 1] GET / -> 200
[hit 2] GET / -> 200   (succeeded because worker recycled)
[hit 3] GET / -> 200   (recycled again)
worker log:
[PHP] PHP Fatal error: Cannot redeclare class Elementor\Element_Column
  (previously declared in /app/wp-content/plugins/elementor/includes/elements/column.php:19)
  in /app/wp-content/plugins/elementor/includes/elements/column.php on line 19
worker booted worker_id=1
worker booted worker_id=2
worker booted worker_id=3

Each request kills a worker; ePHPm recycles and retries, so the client still gets 200 but the pool is churning.

With the mu-plugin (muplugins/elementor-idempotent-lifecycle.php in wp-content/mu-plugins/):

[hit 1..5] GET / -> 200
worker log: worker booted worker_id=0  (once, no recycles)
              — no `Cannot redeclare` lines —

Same 5 requests, single worker, zero crashes.

Docs

• Adds a "Running Elementor" section to README mirroring the existing "Running WooCommerce" one, with drop-in copy instructions and the fix rationale.

Not addressed by this PR (scope)

• Auditing remaining Elementor codepaths for per-request idempotency (widget cache clearing, breakpoint state, editor preview flow). Ship with a conservative worker_max_requests and instrument for regressions.
• Adding an Elementor-bearing e2e fixture to this adapter's e2e/ suite. Not blocking this PR — validated against a real Elementor install as described above.

Related

• WooCommerce cart lifecycle fix (v0.1.1, 2026-07-10)
• Lab retest note that surfaced this: https://github.com/tinfoyle/ePHPm-lab/blob/main/docs/wordpress-worker-investigation.md — "v5 Retest Against v0.1.1"