{# ECharts-side chart-readiness wrapper. Templates that emit
   <div> chart containers + echarts.init() use fsEChartsInit(el,
   opts) instead of echarts.init(el, opts). The wrapper:

   - calls fsBeaconAcquire() before init
   - delegates to echarts.init(el, opts)
   - registers chart.on('finished', fsBeaconRelease) once: ECharts
     can fire 'finished' multiple times (after setOption, resize,
     theme change), but we only release ONCE — first paint is
     sufficient for PDF capture; later updates don't add new pending
     work from the beacon's perspective
   - if echarts.init throws (missing library, bad element), the
     wrapper releases the acquire (fail-closed) so the beacon
     doesn't strand the counter and the PDF doesn't hang

   CALLER RESPONSIBILITY: fsEChartsInit acquires the beacon before
   echarts.init returns. If the INITIAL chart.setOption(...) call
   throws, the chart never paints, the 'finished' listener registered
   below never fires, and the acquire strands — so the caller MUST
   wrap that initial call in try/catch and call window.fsBeaconRelease()
   in the catch handler. The wrapper can't see post-return throws,
   and a stranded acquire forces PDF rendering through the full 30s
   BEACON_TIMEOUT.

   DO NOT wrap subsequent chart-method calls (setTheme, resize,
   dispatchAction, additional setOption calls after first paint) in
   release-on-throw. Once the chart paints, 'finished' fires and
   fsBeaconRelease has already been called; a second release from a
   catch block prematurely flips fsReportReady when other charts are
   still pending. The beacon coordinator's clamp-to-0 logic catches
   single-chart over-release but not multi-chart cases. Let subsequent
   throws propagate to the caller's regular error handling.

   See dev/template_migration.md § Pattern 2 for the canonical pattern.

   fsBeaconAcquire/Release are provided by _ready_beacon.html,
   the shared coordinator that owns window.fsReportReady. This
   wrapper does NOT own that flag; the beacon does. Chart.js
   uses the same beacon via _chart_ready.html. #}
{% include "_ready_beacon.html" %}
<script>
(function () {
    if (typeof window.fsEChartsInit === 'function') {
        return;  // Already defined; another include path beat us to it.
    }
    window.fsEChartsInit = function (el, opts) {
        window.fsBeaconAcquire();
        var chart;
        try {
            chart = echarts.init(el, null, opts || { renderer: 'canvas' });
        } catch (e) {
            // Fail-closed: release the acquire so the beacon counter
            // doesn't strand. PDF captures without this chart instead
            // of hanging for the 30s timeout.
            window.fsBeaconRelease();
            throw e;
        }
        var released = false;
        chart.on('finished', function () {
            if (released) return;  // One-shot: ignore subsequent finished
                                   // events (setOption, resize, theme).
            released = true;
            window.fsBeaconRelease();
        });
        return chart;
    };
})();
</script>