later 0.0.49

Distributed Background jobs manager and runner for Rust
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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Later Dashboard</title>
  <style>
    :root { color-scheme: light; font-family: ui-sans-serif, system-ui, sans-serif; color: #172033; background: #f4f6fa; }
    * { box-sizing: border-box; }
    body { margin: 0; }
    header { padding: 1rem 1.5rem 0; color: white; background: #3157d5; box-shadow: 0 2px 8px #16295b33; }
    header strong { font-size: 1.2rem; }
    .header-title { padding-bottom: 1rem; }
    main { display: grid; grid-template-columns: minmax(10rem, 14rem) minmax(0, 1fr); gap: 1.5rem; max-width: 90rem; margin: 1.5rem auto; padding: 0 1.5rem; }
    #performance { grid-column: 1 / -1; display: grid; grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr)); gap: .75rem; }
    .metric { min-height: 6rem; padding: 1rem; border: 1px solid #dce1ec; border-radius: .65rem; background: white; box-shadow: 0 2px 10px #1720330d; }
    .metric-label { display: block; color: #59657a; font-size: .76rem; text-transform: uppercase; letter-spacing: .04em; }
    .metric-value { display: block; margin-top: .35rem; font-size: 1.65rem; font-weight: 650; }
    .metric-note { display: block; margin-top: .2rem; color: #6f7a8e; font-size: .75rem; }
    nav, section { background: white; border: 1px solid #dce1ec; border-radius: .65rem; box-shadow: 0 2px 10px #1720330d; }
    nav { padding: .5rem; align-self: start; }
    button { font: inherit; cursor: pointer; }
    #tabs { display: flex; gap: .25rem; align-items: center; }
    #tabs[hidden] { display: none; }
    .tab { padding: .6rem 1.1rem; border: 0; border-bottom: 3px solid transparent; border-radius: .4rem .4rem 0 0; color: #c8d3f0; background: transparent; }
    .tab:hover { color: white; }
    .tab[aria-current="true"] { color: white; border-bottom-color: white; }
    #topics-menu { position: relative; }
    #topics-menu summary { list-style: none; }
    #topics-menu summary::-webkit-details-marker { display: none; }
    #topics-menu summary::after { content: "▾"; margin-left: .35rem; font-size: .75rem; }
    #topic-list { position: absolute; z-index: 1; top: calc(100% + .25rem); left: 0; display: grid; min-width: 12rem; max-height: 16rem; overflow-y: auto; padding: .35rem; border: 1px solid #dce1ec; border-radius: .4rem; background: white; box-shadow: 0 6px 18px #17203333; }
    .topic-option { display: flex; align-items: center; justify-content: space-between; gap: .6rem; padding: .55rem .7rem; border: 0; border-radius: .3rem; color: #30394c; background: transparent; text-align: left; }
    .topic-option:hover, .topic-option[aria-current="true"] { color: #2145bd; background: #edf1ff; }
    .lag-badge { min-width: 1.6rem; padding: .05rem .45rem; border-radius: 1rem; font-size: .74rem; color: white; background: #68748d; text-align: center; }
    .lag-badge[data-zero="true"] { background: #8b95a8; opacity: .55; }
    .lag-badge[hidden] { display: none; }
    #partition-picker { display: flex; flex-direction: column; gap: .35rem; padding: .5rem .8rem .9rem; border-bottom: 1px solid #e5e8ef; margin-bottom: .5rem; }
    #partition-picker[hidden] { display: none; }
    #partition-picker label { color: #59657a; font-size: .76rem; text-transform: uppercase; letter-spacing: .04em; }
    #partition-picker select { padding: .45rem; border: 1px solid #bdc5d6; border-radius: .35rem; font: inherit; }
    .stage { display: flex; width: 100%; justify-content: space-between; padding: .7rem .8rem; border: 0; border-radius: .4rem; color: #30394c; background: transparent; text-align: left; }
    .stage:hover, .stage[aria-current="true"] { color: #2145bd; background: #edf1ff; }
    .count { min-width: 2rem; padding: .1rem .5rem; border-radius: 1rem; color: white; background: #68748d; text-align: center; }
    section { min-height: 16rem; overflow: hidden; }
    #notice { margin: 1rem; padding: .8rem 1rem; border-radius: .4rem; background: #edf1ff; }
    #notice.error { color: #851f2a; background: #ffeaed; }
    .table-scroll { overflow-x: auto; overscroll-behavior-x: contain; -webkit-overflow-scrolling: touch; }
    table { width: 100%; min-width: 42rem; border-collapse: collapse; }
    th, td { padding: .75rem 1rem; border-bottom: 1px solid #e5e8ef; text-align: left; vertical-align: top; }
    th { color: #59657a; background: #fafbfc; font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; }
    code { overflow-wrap: anywhere; }
    .job-link { padding: 0; border: 0; color: #2145bd; background: none; text-align: left; }
    footer { display: flex; justify-content: space-between; align-items: center; padding: 1rem; }
    footer button, dialog button { padding: .45rem .8rem; border: 1px solid #bdc5d6; border-radius: .35rem; background: white; }
    footer button:disabled { cursor: default; opacity: .45; }
    dialog { width: min(46rem, calc(100% - 2rem)); border: 0; border-radius: .7rem; box-shadow: 0 18px 60px #17203355; }
    dialog::backdrop { background: #17203388; }
    .dialog-head { display: flex; align-items: start; justify-content: space-between; gap: 1rem; }
    .detail-navigation { display: flex; align-items: center; gap: .6rem; margin: 1rem 0; }
    .detail-navigation span { color: #59657a; font-size: .85rem; }
    .history { padding-left: 1.25rem; }
    .relations { display: grid; gap: .5rem; }
    .relations p { margin: 0; }
    .payload { background: #f4f6fa; border: 1px solid #e5e8ef; border-radius: .35rem; padding: .6rem .8rem; font-size: .8rem; overflow-x: auto; white-space: pre-wrap; word-break: break-word; }
    .payload-note { color: #59657a; font-size: .76rem; margin: .3rem 0 0; }
    .relation-links { display: flex; flex-wrap: wrap; gap: .4rem; }
    #monitoring { grid-column: 1 / -1; overflow: visible; }
    #monitoring[hidden] { display: none; }
    .monitoring-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(19rem, 1fr)); gap: 1rem; padding: 1.1rem; }
    .chart-card h3 { margin: 0 0 .1rem; font-size: .85rem; color: #30394c; }
    .chart-note { margin: 0 0 .6rem; color: #8b95a8; font-size: .74rem; }
    .chart-card canvas { display: block; width: 100%; height: 9.5rem; }
    .chart-legend { display: flex; flex-wrap: wrap; gap: .4rem .9rem; margin-top: .5rem; font-size: .76rem; color: #59657a; }
    .chart-legend .swatch { display: inline-block; width: .6rem; height: .6rem; margin-right: .35rem; border-radius: 50%; vertical-align: middle; }
    @media (max-width: 700px) { main { grid-template-columns: 1fr; padding: 0 .75rem; } }
  </style>
</head>
<body>
  <header>
    <div class="header-title"><strong>later</strong> job dashboard</div>
    <div id="tabs" aria-label="Job views" hidden>
      <button id="all-jobs" class="tab" type="button">All</button>
      <details id="topics-menu">
        <summary class="tab">Topics</summary>
        <div id="topic-list" role="menu" aria-label="Topics"></div>
      </details>
      <button id="monitoring-tab" class="tab" type="button" hidden>Monitoring</button>
    </div>
  </header>
  <main>
    <div id="performance" aria-label="Performance over the last 60 seconds">
      <div class="metric"><span class="metric-label">Completed / sec</span><span class="metric-value" id="jobs-per-second">0.00</span><span class="metric-note">60 second average</span></div>
      <div class="metric"><span class="metric-label">Active workers</span><span class="metric-value" id="active-workers">0</span><span class="metric-note">heartbeat in last 15s</span></div>
      <div class="metric"><span class="metric-label">Busy workers</span><span class="metric-value" id="busy-workers">0</span><span class="metric-note">jobs currently running</span></div>
      <div class="metric"><span class="metric-label">Started</span><span class="metric-value" id="started">0</span><span class="metric-note">last 60 seconds</span></div>
      <div class="metric"><span class="metric-label">Succeeded</span><span class="metric-value" id="succeeded">0</span><span class="metric-note">last 60 seconds</span></div>
      <div class="metric"><span class="metric-label">Retried</span><span class="metric-value" id="retried">0</span><span class="metric-note">last 60 seconds</span></div>
      <div class="metric"><span class="metric-label">Failed</span><span class="metric-value" id="failed">0</span><span class="metric-note">last 60 seconds</span></div>
      <div class="metric"><span class="metric-label">Regular queue wait</span><span class="metric-value" id="wait-regular">-</span><span class="metric-note" id="wait-regular-note">avg, last 60s</span></div>
      <div class="metric"><span class="metric-label">Sequential queue wait</span><span class="metric-value" id="wait-sequential">-</span><span class="metric-note" id="wait-sequential-note">avg, last 60s</span></div>
      <div class="metric"><span class="metric-label">Database size</span><span class="metric-value" id="db-size">-</span><span class="metric-note">entire database, not just Later's tables</span></div>
    </div>
    <nav id="stages" aria-label="Job stages">
      <div id="partition-picker" hidden>
        <label for="partition-select">Partition</label>
        <select id="partition-select"></select>
      </div>
      <div id="stage-buttons"></div>
    </nav>
    <section id="jobs-section" aria-live="polite">
      <div id="notice">Loading jobs...</div>
      <div id="job-table" class="table-scroll" tabindex="0" aria-label="Jobs table. Scroll horizontally to see all columns." hidden>
        <table id="jobs">
          <thead><tr><th>ID</th><th class="type">Type</th><th class="seq">Seq</th><th class="date">Date</th><th>Duration</th><th>Stage</th></tr></thead>
          <tbody></tbody>
        </table>
      </div>
      <footer id="paging" hidden>
        <button id="previous" type="button">Previous</button>
        <span id="page-label"></span>
        <button id="next" type="button">Next</button>
      </footer>
    </section>
    <section id="monitoring" aria-label="Monitoring" hidden>
      <div id="monitoring-grid" class="monitoring-grid"></div>
    </section>
  </main>
  <dialog id="details">
    <div class="dialog-head"><h2>Job details</h2><button id="close" type="button">Close</button></div>
    <div class="detail-navigation" aria-label="Jobs in the current view">
      <button id="detail-previous" type="button">Previous job</button>
      <span id="detail-position"></span>
      <button id="detail-next" type="button">Next job</button>
    </div>
    <p><strong>ID:</strong> <code id="detail-id"></code></p>
    <p><strong>Type:</strong> <code id="detail-type"></code></p>
    <p><strong>Current stage:</strong> <code id="detail-stage"></code></p>
    <p><strong>Total duration:</strong> <code id="detail-total-duration"></code></p>
    <p><strong>Processing:</strong> <code id="detail-processing-duration"></code></p>
    <p><strong>Waiting:</strong> <code id="detail-waiting-duration"></code></p>
    <p id="detail-partition-row" hidden><strong>Partition:</strong> <code id="detail-partition"></code></p>
    <h3>Related jobs</h3>
    <div id="relations" class="relations"></div>
    <h3>Payload</h3>
    <pre id="detail-payload" class="payload"></pre>
    <p id="detail-payload-note" class="payload-note" hidden>
      Shown as a positional array: fields are in declaration order, not
      named, because payloads are stored without field name metadata.
    </p>
    <h3>Previous stages</h3>
    <ol id="history" class="history"></ol>
  </dialog>
  <script>
    const BASE_APP = __LATER_DASHBOARD_BASE__;
    const TOPICS = __LATER_DASHBOARD_TOPICS__;
    // Retained-log topics configured for consumer-lag reporting
    // (Config::retained_log_lag) - independent of TOPICS (job-queue
    // partition ordering); a topic can be in one, both, or neither list.
    const LAG_TOPICS = __LATER_DASHBOARD_LAG_TOPICS__;
    // Whether the job server was built with Later's `prometheus` feature -
    // only then does the dashboard's own "metrics" command return anything,
    // so the Monitoring tab stays hidden entirely otherwise.
    const METRICS_ENABLED = __LATER_DASHBOARD_METRICS_ENABLED__;
    // Union of every topic name shown in the menu, job-queue topics first.
    const MENU_TOPICS = TOPICS.map(t => t.name)
      .concat(LAG_TOPICS.filter(name => !TOPICS.some(t => t.name === name)));
    const STAGE_ORDER = ["delayed", "waiting", "enqueued", "running", "requeued", "success", "failed"];
    const state = {
      mode: "stages", counts: {}, stage: "", topic: null, partition: 0,
      cursor: null, nextCursor: null, history: [], visibleJobs: [],
      selectedJobIndex: null, loading: false,
      // Topic name -> total retained-log consumer lag summed across every
      // group and partition, refreshed alongside everything else in
      // refresh(). Empty unless Config::retained_log_lag is configured.
      consumerLag: {},
      // Topic name -> total not-yet-completed jobs summed across every
      // partition. Always available for every topic in TOPICS.
      queueDepthTotals: {},
      // Topic name -> { partitionNumber: depth }, for the partition picker.
      queueDepthByPartition: {}
    };
    const elements = {
      tabs: document.querySelector("#tabs"), allJobs: document.querySelector("#all-jobs"),
      topicsMenu: document.querySelector("#topics-menu"), topicList: document.querySelector("#topic-list"),
      stages: document.querySelector("#stage-buttons"),
      partitionPicker: document.querySelector("#partition-picker"),
      partitionSelect: document.querySelector("#partition-select"),
      notice: document.querySelector("#notice"),
      jobTable: document.querySelector("#job-table"), body: document.querySelector("#jobs tbody"),
      paging: document.querySelector("#paging"), previous: document.querySelector("#previous"),
      next: document.querySelector("#next"), pageLabel: document.querySelector("#page-label"),
      details: document.querySelector("#details"),
      detailPrevious: document.querySelector("#detail-previous"),
      detailNext: document.querySelector("#detail-next"), detailPosition: document.querySelector("#detail-position"),
      performance: document.querySelector("#performance"), jobsSection: document.querySelector("#jobs-section"),
      monitoringTab: document.querySelector("#monitoring-tab"), monitoring: document.querySelector("#monitoring"),
      monitoringGrid: document.querySelector("#monitoring-grid")
    };

    // Process-local Prometheus metrics, polled (not scraped) directly from
    // the same dashboard endpoint - see DashboardCmd::Metrics. No history is
    // kept server-side, so every chart starts empty on page load and only
    // ever shows what this browser tab has itself observed since.
    const CHART_COLORS = ["#2145bd", "#dc6803", "#12b76a", "#7839ee", "#e11d48", "#0891b2", "#65a30d", "#c026d3"];
    const MAX_METRIC_POINTS = 150; // ~5 minutes at the 2.5 second poll interval below
    // The x-axis is a fixed, wall-clock window rather than "however much
    // data currently spans" - the latter rescales visibly (and jarringly)
    // every time a new point arrives, especially early on when only a few
    // points exist. A fixed window instead lets requestAnimationFrame
    // scroll it continuously in real time (see drawChart), independent of
    // when the next poll happens to land.
    const CHART_WINDOW_MS = 2 * 60 * 1000;
    let monitoringAnimationFrame = null;
    const CHART_DEFS = [
      // Fed from stored per-minute readings rather than the browser's own
      // polling, so the line shows a backlog draining over hours and survives
      // a reload. `windowMs` is changed by the selector on the card.
      { key: "queueLength", title: "Queue length", unit: "", note: "Jobs waiting for a worker (sampled each minute, kept on the server).", fixedLabels: ["queued", "partitioned"], server: true, windowMs: 6 * 60 * 60 * 1000 },
      { key: "throughput", title: "Job throughput", unit: "/s", note: "Completed stage transitions per second.", fixedLabels: ["success", "failed", "requeued"] },
      { key: "workers", title: "Workers", unit: "", note: "Worker tasks in this process, by state.", fixedLabels: ["active", "busy"] },
      { key: "queueDepth", title: "Durable queue depth", unit: "", note: "Not-yet-completed jobs, by state." },
      { key: "handlerLatency", title: "Handler latency", unit: "ms", note: "Average time spent in job handlers.", fixedLabels: ["success", "error"] },
      { key: "partitionBacklog", title: "Partition backlog", unit: "", note: "Ready, unleased partition heads, by topic." },
      { key: "commands", title: "Worker commands", unit: "/s", note: "Delivery commands handled per second, by outcome.", fixedLabels: ["success", "error"] }
    ];
    const metricsState = {
      series: {},        // chartKey -> { label: [{ t, v }, ...] }
      prevCounter: {},   // "chartKey:label" -> { t, value } - for rate calculation
      prevHistogram: {}  // "chartKey:label" -> { t, count, sum } - for average calculation
    };

    function uri(command) {
      return `${BASE_APP}?${new URLSearchParams({ query: JSON.stringify(command) })}`;
    }

    // A request that never answers (a database locked by a write storm, a
    // dropped connection) must not wedge the polling loops below forever.
    const REQUEST_TIMEOUT_MS = 20000;

    async function request(command) {
      const controller = new AbortController();
      const timer = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
      let response;
      try {
        response = await fetch(uri(command), { signal: controller.signal });
      } catch (error) {
        if (error.name === "AbortError") throw new Error("Dashboard request timed out");
        throw error;
      } finally {
        clearTimeout(timer);
      }
      if (!response.ok) {
        let message = `Dashboard request failed (${response.status})`;
        try { message = (await response.json()).error || message; } catch (_) {}
        throw new Error(message);
      }
      return response.json();
    }

    function showNotice(message, error = false) {
      elements.notice.textContent = message;
      elements.notice.classList.toggle("error", error);
      elements.notice.hidden = false;
      elements.jobTable.hidden = true;
      elements.paging.hidden = true;
    }

    function renderStages() {
      const existing = elements.stages.children.length === STAGE_ORDER.length;
      STAGE_ORDER.forEach((name, index) => {
        const isCurrent = String(name === state.stage);
        const displayCount = state.counts[name] ?? 0;
        if (existing) {
          // Update in place so the sidebar doesn't flicker on every refresh.
          const button = elements.stages.children[index];
          button.setAttribute("aria-current", isCurrent);
          button.querySelector(".count").textContent = displayCount;
          return;
        }
        const button = document.createElement("button");
        button.type = "button";
        button.className = "stage";
        button.dataset.stage = name;
        button.setAttribute("aria-current", isCurrent);
        const label = document.createElement("span");
        label.textContent = name;
        const count = document.createElement("span");
        count.className = "count";
        count.textContent = displayCount;
        button.append(label, count);
        button.addEventListener("click", () => loadStage(name, null, true));
        elements.stages.append(button);
      });
    }

    function lagBadge(name) {
      const badge = document.createElement("span");
      badge.className = "lag-badge";
      badge.title = "Backlog: unread retained-log records plus not-yet-completed queued jobs";
      // Stays hidden until the first refresh() populates a real reading -
      // every job-queue topic in TOPICS always ends up with one, so this
      // only matters for the brief window before that first fetch resolves.
      badge.hidden = true;
      return badge;
    }

    function renderTabs() {
      elements.tabs.hidden = false;
      const viewingAll = state.mode === "stages";
      elements.allJobs.setAttribute("aria-current", String(viewingAll));
      elements.topicsMenu.hidden = MENU_TOPICS.length === 0;
      elements.topicsMenu.querySelector("summary").setAttribute("aria-current", String(state.mode === "partition"));
      elements.monitoringTab.hidden = !METRICS_ENABLED;
      elements.monitoringTab.setAttribute("aria-current", String(state.mode === "monitoring"));
      const existing = elements.topicList.children.length === MENU_TOPICS.length;
      MENU_TOPICS.forEach((name, index) => {
        const isJobQueueTopic = TOPICS.some(t => t.name === name);
        const isCurrent = String(isJobQueueTopic && name === state.topic);
        if (existing) {
          const row = elements.topicList.children[index];
          if (isJobQueueTopic) row.setAttribute("aria-current", isCurrent);
          return;
        }
        const label = document.createElement("span");
        label.textContent = name;
        if (isJobQueueTopic) {
          const button = document.createElement("button");
          button.type = "button";
          button.className = "topic-option";
          button.setAttribute("role", "menuitem");
          button.setAttribute("aria-current", isCurrent);
          button.append(label, lagBadge(name));
          button.addEventListener("click", () => {
            elements.topicsMenu.open = false;
            switchToTopic(name);
          });
          elements.topicList.append(button);
        } else {
          // A retained-log-only topic (Config::retained_log_lag but not
          // Config::topics) has no job-queue partition view to switch to -
          // shown for its lag reading only, not clickable.
          const row = document.createElement("div");
          row.className = "topic-option";
          row.append(label, lagBadge(name));
          elements.topicList.append(row);
        }
      });
    }

    // Combines retained-log consumer lag and job-queue depth into one badge
    // per topic - most topics only ever have one of the two, but a topic
    // configured as both shows their sum, still a meaningful "how far
    // behind is this topic" signal either way.
    function renderTopicBadges() {
      MENU_TOPICS.forEach((name, index) => {
        const row = elements.topicList.children[index];
        if (!row) return;
        const badge = row.querySelector(".lag-badge");
        const lag = state.consumerLag[name];
        const depth = state.queueDepthTotals[name];
        if (lag === undefined && depth === undefined) return;
        const total = (lag || 0) + (depth || 0);
        badge.hidden = false;
        badge.dataset.zero = String(total === 0);
        badge.textContent = total;
      });
    }

    function switchToStages() {
      if (state.mode === "stages") return;
      stopMonitoringAnimation();
      state.mode = "stages";
      state.topic = null;
      elements.performance.hidden = false;
      elements.jobsSection.hidden = false;
      elements.monitoring.hidden = true;
      elements.stages.hidden = false;
      elements.partitionPicker.hidden = true;
      elements.topicsMenu.open = false;
      renderTabs();
      loadStage(state.stage || "enqueued", null, true);
    }

    function switchToTopic(name) {
      stopMonitoringAnimation();
      state.mode = "partition";
      state.topic = name;
      state.partition = 0;
      elements.performance.hidden = false;
      elements.jobsSection.hidden = false;
      elements.monitoring.hidden = true;
      elements.stages.hidden = true;
      renderTabs();
      renderPartitionPicker();
      loadPartition(name, 0, null, true);
    }

    function switchToMonitoring() {
      if (!METRICS_ENABLED || state.mode === "monitoring") return;
      state.mode = "monitoring";
      elements.topicsMenu.open = false;
      elements.performance.hidden = true;
      elements.jobsSection.hidden = true;
      elements.stages.hidden = true;
      elements.partitionPicker.hidden = true;
      elements.monitoring.hidden = false;
      renderTabs();
      CHART_DEFS.forEach(renderChart);
      startMonitoringAnimation();
    }

    // Redraws every chart's canvas on every animation frame while Monitoring
    // is the active tab, independent of the (much slower) poll interval -
    // this is what makes the x-axis scroll continuously in real time rather
    // than snapping forward once per poll. Legend text (the latest value per
    // series) only needs to change when new data actually arrives, so that
    // stays in renderChart/updateLegend, called from pollMetrics instead.
    function startMonitoringAnimation() {
      if (monitoringAnimationFrame !== null) return;
      const tick = () => {
        if (state.mode !== "monitoring") {
          monitoringAnimationFrame = null;
          return;
        }
        CHART_DEFS.forEach(def => drawChartCanvas(def));
        monitoringAnimationFrame = requestAnimationFrame(tick);
      };
      monitoringAnimationFrame = requestAnimationFrame(tick);
    }

    function stopMonitoringAnimation() {
      if (monitoringAnimationFrame !== null) {
        cancelAnimationFrame(monitoringAnimationFrame);
        monitoringAnimationFrame = null;
      }
    }

    function renderMonitoringCards() {
      elements.monitoringGrid.replaceChildren(...CHART_DEFS.map(def => {
        const card = document.createElement("div");
        card.className = "chart-card";
        const heading = document.createElement("h3");
        heading.textContent = def.title;
        const note = document.createElement("p");
        note.className = "chart-note";
        note.textContent = def.note;
        const canvas = document.createElement("canvas");
        canvas.id = `chart-${def.key}`;
        canvas.setAttribute("role", "img");
        canvas.setAttribute("aria-label", `${def.title} chart`);
        const legend = document.createElement("div");
        legend.className = "chart-legend";
        legend.id = `legend-${def.key}`;
        if (def.server) {
          const picker = document.createElement("select");
          picker.setAttribute("aria-label", `${def.title} time range`);
          [["1 hour", 60], ["6 hours", 360], ["24 hours", 1440], ["7 days", 10080]].forEach(([label, minutes]) => {
            const option = document.createElement("option");
            option.value = String(minutes);
            option.textContent = `Last ${label}`;
            picker.append(option);
          });
          picker.value = String(Math.round(def.windowMs / 60000));
          picker.addEventListener("change", () => {
            def.windowMs = Number(picker.value) * 60000;
            refreshQueueLength();
          });
          card.append(heading, note, picker, canvas, legend);
          return card;
        }
        card.append(heading, note, canvas, legend);
        return card;
      }));
    }

    // Assigns each label a stable color by hashing its name, rather than by
    // position - a dynamic label set (topics, queue states) can gain or
    // lose entries between polls without every other line's color shifting.
    function colorForLabel(label) {
      let hash = 0;
      for (let i = 0; i < label.length; i += 1) hash = (hash * 31 + label.charCodeAt(i)) >>> 0;
      return CHART_COLORS[hash % CHART_COLORS.length];
    }

    function formatMetricValue(value, unit) {
      if (!Number.isFinite(value)) return "-";
      const rounded = value >= 100 ? Math.round(value) : Math.round(value * 100) / 100;
      const text = value >= 1000 ? rounded.toLocaleString() : String(rounded);
      return unit ? `${text}${unit}` : text;
    }

    function familyIndex(families) {
      const byName = {};
      (families || []).forEach(family => { byName[family.name] = family; });
      return byName;
    }

    function sumByLabel(byName, metricName, groupLabel) {
      const family = byName[metricName];
      const totals = {};
      if (!family) return totals;
      family.metrics.forEach(metric => {
        const key = groupLabel ? (metric.labels[groupLabel] ?? "unknown") : "total";
        totals[key] = (totals[key] || 0) + (metric.value || 0);
      });
      return totals;
    }

    function sumHistogramByLabel(byName, metricName, groupLabel) {
      const family = byName[metricName];
      const totals = {};
      if (!family) return totals;
      family.metrics.forEach(metric => {
        if (!metric.histogram) return;
        const key = groupLabel ? (metric.labels[groupLabel] ?? "unknown") : "total";
        const bucket = totals[key] || { count: 0, sum: 0 };
        bucket.count += metric.histogram.sample_count || 0;
        bucket.sum += metric.histogram.sample_sum || 0;
        totals[key] = bucket;
      });
      return totals;
    }

    function pushMetricPoint(chartKey, label, t, v) {
      const series = (metricsState.series[chartKey] ??= {});
      const points = (series[label] ??= []);
      points.push({ t, v });
      if (points.length > MAX_METRIC_POINTS) points.shift();
    }

    function recordGauge(chartKey, totals, now) {
      Object.entries(totals).forEach(([label, value]) => pushMetricPoint(chartKey, label, now, value));
    }

    // Prometheus counters only ever go up, so a usable rate needs two polls -
    // the first sighting of any label just seeds `prevCounter` with no point
    // plotted yet.
    function recordCounterRate(chartKey, totals, now) {
      Object.entries(totals).forEach(([label, value]) => {
        const key = `${chartKey}:${label}`;
        const previous = metricsState.prevCounter[key];
        metricsState.prevCounter[key] = { t: now, value };
        if (!previous) return;
        const deltaSeconds = (now - previous.t) / 1000;
        if (deltaSeconds <= 0) return;
        // max(0, ...) guards against a process restart resetting the counter
        // below its last-seen value, which would otherwise plot as negative.
        pushMetricPoint(chartKey, label, now, Math.max(0, (value - previous.value) / deltaSeconds));
      });
    }

    function recordHistogramRate(chartKey, totals, now) {
      Object.entries(totals).forEach(([label, { count, sum }]) => {
        const key = `${chartKey}:${label}`;
        const previous = metricsState.prevHistogram[key];
        metricsState.prevHistogram[key] = { t: now, count, sum };
        if (!previous) return;
        const deltaCount = count - previous.count;
        if (deltaCount <= 0) return;
        pushMetricPoint(chartKey, label, now, Math.max(0, ((sum - previous.sum) / deltaCount) * 1000));
      });
    }

    // Reads the stored queue-length readings for the graph's selected range.
    // A missed refresh just leaves the previous line in place.
    async function refreshQueueLength() {
      const def = CHART_DEFS.find(candidate => candidate.key === "queueLength");
      if (!def) return;
      let history;
      try { history = await request({ cmd: "queue_history", minutes: Math.round(def.windowMs / 60000) }); }
      catch (_) { return; }
      metricsState.series.queueLength = {
        queued: history.points.map(point => ({ t: point.t, v: point.queued })),
        partitioned: history.points.map(point => ({ t: point.t, v: point.partitioned }))
      };
      if (state.mode === "monitoring") renderChart(def);
    }

    async function pollMetrics() {
      if (!METRICS_ENABLED) return;
      let families;
      try { families = await request({ cmd: "metrics" }); }
      catch (_) { return; } // a missed sample just leaves a gap, not a page-wide error
      const byName = familyIndex(families);
      const now = Date.now();
      recordCounterRate("throughput", sumByLabel(byName, "later_job_transitions_total", "stage"), now);
      recordGauge("workers", sumByLabel(byName, "later_workers", "state"), now);
      recordGauge("queueDepth", sumByLabel(byName, "later_queue_jobs", "state"), now);
      recordHistogramRate("handlerLatency", sumHistogramByLabel(byName, "later_job_handler_duration_seconds", "outcome"), now);
      recordGauge("partitionBacklog", sumByLabel(byName, "later_partition_backlog", "topic"), now);
      recordCounterRate("commands", sumByLabel(byName, "later_worker_commands_total", "outcome"), now);
      if (state.mode === "monitoring") CHART_DEFS.forEach(renderChart);
    }

    function chartLabels(def) {
      const series = metricsState.series[def.key] || {};
      return def.fixedLabels
        ? def.fixedLabels.filter(label => series[label] && series[label].length > 0)
        : Object.keys(series).filter(label => series[label].length > 0);
    }

    // Legend text (the latest value per series) only needs to update when
    // new data actually arrives - called from pollMetrics, on its own poll
    // cadence. The canvas itself redraws separately and far more often (see
    // startMonitoringAnimation) so the line can keep scrolling smoothly
    // between polls too.
    function renderChart(def) {
      updateLegend(def);
      drawChartCanvas(def);
    }

    function updateLegend(def) {
      const legend = document.querySelector(`#legend-${def.key}`);
      if (!legend) return;
      const series = metricsState.series[def.key] || {};
      const labels = chartLabels(def);
      if (labels.length === 0) {
        legend.replaceChildren(document.createTextNode("Collecting data..."));
        return;
      }
      legend.replaceChildren(...labels.map(label => {
        const points = series[label];
        const latest = points[points.length - 1].v;
        const item = document.createElement("span");
        const swatch = document.createElement("i");
        swatch.className = "swatch";
        swatch.style.background = colorForLabel(label);
        item.append(swatch, document.createTextNode(`${label}: ${formatMetricValue(latest, def.unit)}`));
        return item;
      }));
    }

    function drawChartCanvas(def) {
      const canvas = document.querySelector(`#chart-${def.key}`);
      if (!canvas) return;
      const series = metricsState.series[def.key] || {};
      const labels = chartLabels(def);
      drawChart(canvas, labels.map(label => ({ color: colorForLabel(label), points: series[label] })), def.windowMs || CHART_WINDOW_MS);
    }

    // A dependency-free line chart - Later's dashboard is a single embedded
    // HTML file with no build step, so pulling in a charting library isn't
    // worth it for a handful of simple time series. The x-axis is a fixed
    // window ending "now" (CHART_WINDOW_MS), not however far the data
    // happens to span - combined with being redrawn on every animation
    // frame (not just every poll), that's what makes the line scroll
    // smoothly in real time instead of snapping forward in visible jumps
    // once every poll interval. Curves are drawn through quadratic
    // midpoints rather than straight segments between raw points, which
    // reads as noticeably less jagged for noisy series like per-second
    // rates without hiding real spikes.
    function drawChart(canvas, series, windowMs = CHART_WINDOW_MS) {
      const ctx = canvas.getContext("2d");
      const dpr = window.devicePixelRatio || 1;
      const rect = canvas.getBoundingClientRect();
      const width = Math.max(rect.width, 1);
      const height = Math.max(rect.height, 1);
      const pixelWidth = Math.round(width * dpr);
      const pixelHeight = Math.round(height * dpr);
      if (canvas.width !== pixelWidth || canvas.height !== pixelHeight) {
        canvas.width = pixelWidth;
        canvas.height = pixelHeight;
      }
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      ctx.clearRect(0, 0, width, height);

      const now = Date.now();
      const windowStart = now - windowMs;
      const visibleSeries = series
        .map(({ color, points }) => ({ color, points: points.filter(point => point.t >= windowStart) }))
        .filter(entry => entry.points.length >= 2);
      if (visibleSeries.length === 0) {
        ctx.fillStyle = "#9aa4b8";
        ctx.font = "12px ui-sans-serif, system-ui, sans-serif";
        ctx.fillText("Collecting data...", 10, height / 2);
        return;
      }

      const padding = 8;
      const plotWidth = width - padding * 2;
      const plotHeight = height - padding * 2;
      const maxV = Math.max(1, ...visibleSeries.flatMap(entry => entry.points.map(point => point.v)));
      const x = t => padding + ((t - windowStart) / windowMs) * plotWidth;
      const y = v => padding + plotHeight - (v / maxV) * plotHeight;

      ctx.strokeStyle = "#e5e8ef";
      ctx.lineWidth = 1;
      for (let i = 0; i <= 2; i += 1) {
        const gy = padding + (plotHeight / 2) * i;
        ctx.beginPath();
        ctx.moveTo(padding, gy);
        ctx.lineTo(width - padding, gy);
        ctx.stroke();
      }

      ctx.fillStyle = "#9aa4b8";
      ctx.font = "11px ui-sans-serif, system-ui, sans-serif";
      ctx.textBaseline = "top";
      // Top right: a draining line starts at the top left and would sit on it.
      ctx.textAlign = "right";
      ctx.fillText(Math.round(maxV).toLocaleString(), width - padding - 2, padding + 2);
      ctx.textAlign = "left";

      visibleSeries.forEach(({ color, points }) => {
        ctx.strokeStyle = color;
        ctx.lineWidth = 1.75;
        ctx.lineJoin = "round";
        ctx.lineCap = "round";
        ctx.beginPath();
        ctx.moveTo(x(points[0].t), y(points[0].v));
        for (let i = 1; i < points.length - 1; i += 1) {
          const px = x(points[i].t);
          const py = y(points[i].v);
          const midX = (px + x(points[i + 1].t)) / 2;
          const midY = (py + y(points[i + 1].v)) / 2;
          ctx.quadraticCurveTo(px, py, midX, midY);
        }
        const last = points[points.length - 1];
        ctx.lineTo(x(last.t), y(last.v));
        ctx.stroke();
      });
    }

    function renderPartitionPicker() {
      const topic = TOPICS.find(candidate => candidate.name === state.topic);
      if (!topic) { elements.partitionPicker.hidden = true; return; }
      elements.partitionPicker.hidden = false;
      const depths = state.queueDepthByPartition[topic.name] || {};
      const options = [];
      for (let partition = 0; partition < topic.partition_count; partition += 1) options.push(partition);
      elements.partitionSelect.replaceChildren(...options.map(partition => {
        const option = document.createElement("option");
        option.value = String(partition);
        const depth = depths[partition];
        option.textContent = depth === undefined
          ? `Partition ${partition}`
          : `Partition ${partition} (${depth} queued)`;
        return option;
      }));
      elements.partitionSelect.value = String(state.partition);
    }

    function renderPerformance(performance, dbSizeBytes) {
      document.querySelector("#jobs-per-second").textContent = Number(performance.jobs_per_second || 0).toFixed(2);
      for (const name of ["active_workers", "busy_workers", "started", "succeeded", "retried", "failed"]) {
        document.querySelector(`#${name.replaceAll("_", "-")}`).textContent = performance[name] ?? 0;
      }
      for (const mode of ["regular", "sequential"]) {
        const wait = (performance.wait_time || {})[mode] || { count: 0, avg_ms: 0, max_ms: 0 };
        document.querySelector(`#wait-${mode}`).textContent = wait.count > 0 ? formatDuration(wait.avg_ms) : "-";
        document.querySelector(`#wait-${mode}-note`).textContent = wait.count > 0
          ? `avg of ${wait.count}, max ${formatDuration(wait.max_ms)}`
          : "no recent dispatches";
      }
      // `null` when the storage backend has no meaningful single-database
      // size to report (Redis, in-memory) - only SQLite/PostgreSQL do.
      document.querySelector("#db-size").textContent = dbSizeBytes == null ? "-" : formatBytes(dbSizeBytes);
    }

    function formatBytes(bytes) {
      const value = Number(bytes);
      if (!Number.isFinite(value) || value < 0) return "-";
      if (value < 1024) return `${value} B`;
      if (value < 1024 ** 2) return `${(value / 1024).toFixed(1)} KB`;
      if (value < 1024 ** 3) return `${(value / 1024 ** 2).toFixed(1)} MB`;
      return `${(value / 1024 ** 3).toFixed(2)} GB`;
    }

    function stageDate(stage) {
      if (!stage || !stage.date) return "";
      const date = new Date(stage.date);
      if (Number.isNaN(date.valueOf())) return stage.date;
      // `Date` only carries millisecond precision; read the fractional
      // seconds straight from the source timestamp so up to microsecond
      // precision survives when the server sent it.
      const match = /\.(\d+)/.exec(stage.date);
      const fraction = match
        ? match[1].slice(0, 6).padEnd(3, "0")
        : String(date.getMilliseconds()).padStart(3, "0");
      return `${date.toLocaleString()}.${fraction}`;
    }

    function formatDuration(milliseconds) {
      const value = Number(milliseconds);
      if (!Number.isFinite(value) || value < 0) return "-";
      if (value < 1) return "<1 ms";
      if (value < 1000) return `${Math.round(value)} ms`;
      if (value < 60000) return `${(value / 1000).toFixed(2)} s`;
      if (value < 3600000) return `${(value / 60000).toFixed(2)} min`;
      return `${(value / 3600000).toFixed(2)} h`;
    }

    function renderJobs(response) {
      const rows = response.result.map(job => {
        const row = document.createElement("tr");
        const idCell = document.createElement("td");
        const link = document.createElement("button");
        link.type = "button";
        link.className = "job-link";
        link.textContent = job.id.slice(-6);
        link.title = job.id;
        link.addEventListener("click", () => loadJob(job.id));
        idCell.append(link);
        const type = document.createElement("td");
        type.className = "type";
        type.textContent = job.info.payload_type;
        const seq = document.createElement("td");
        seq.className = "seq";
        seq.textContent = job.info.sequence ?? "-";
        const date = document.createElement("td");
        date.className = "date";
        date.textContent = stageDate(job.info.stage);
        const duration = document.createElement("td");
        duration.textContent = formatDuration(job.timing.total_ms);
        const stage = document.createElement("td");
        stage.textContent = job.info.stage.type;
        row.append(idCell, type, seq, date, duration, stage);
        return row;
      });
      elements.body.replaceChildren(...rows);
      elements.notice.hidden = response.result.length > 0;
      elements.notice.classList.remove("error");
      elements.notice.textContent = "Nothing to show here";
      const selectedId = state.selectedJobIndex === null
        ? null
        : state.visibleJobs[state.selectedJobIndex]?.id;
      state.visibleJobs = response.result;
      state.selectedJobIndex = selectedId === null
        ? null
        : state.visibleJobs.findIndex(job => job.id === selectedId);
      if (state.selectedJobIndex === -1) state.selectedJobIndex = null;
      updateDetailNavigation();
      elements.jobTable.hidden = response.result.length === 0;
      state.nextCursor = response.paging.next_cursor;
      elements.pageLabel.textContent = `Page ${state.history.length + 1}`;
      elements.previous.disabled = state.history.length === 0;
      elements.next.disabled = state.nextCursor === null;
      elements.paging.hidden = state.history.length === 0 && state.nextCursor === null;
    }

    async function loadStage(stage, cursor, reset = false, silent = false) {
      if (state.loading) return;
      state.loading = true;
      if (reset || state.stage !== stage) state.history = [];
      state.stage = stage;
      state.cursor = cursor;
      renderStages();
      // A silent (background) refresh keeps the current table visible while
      // it fetches, instead of flashing "Loading jobs..." over it every tick.
      if (!silent) showNotice("Loading jobs...");
      try { renderJobs(await request({ cmd: "jobs_in_stage", stage, cursor })); }
      catch (error) { showNotice(error.message, true); }
      finally { state.loading = false; }
    }

    async function loadPartition(topic, partition, cursor, reset = false, silent = false) {
      if (state.loading) return;
      state.loading = true;
      if (reset || state.topic !== topic || state.partition !== partition) state.history = [];
      state.mode = "partition";
      state.topic = topic;
      state.partition = partition;
      state.cursor = cursor;
      if (!silent) showNotice("Loading jobs...");
      try { renderJobs(await request({ cmd: "partition_jobs", topic, partition, cursor })); }
      catch (error) { showNotice(error.message, true); }
      finally { state.loading = false; }
    }

    function showJob(job) {
      const info = job.info;
      location.hash = encodeURIComponent(info.id);
      const index = state.visibleJobs.findIndex(candidate => candidate.id === info.id);
      state.selectedJobIndex = index === -1 ? null : index;
      updateDetailNavigation();
      document.querySelector("#detail-id").textContent = info.id;
      document.querySelector("#detail-type").textContent = info.payload_type;
      document.querySelector("#detail-stage").textContent = info.stage.type;
      document.querySelector("#detail-total-duration").textContent = formatDuration(job.timing.total_ms);
      document.querySelector("#detail-processing-duration").textContent = formatDuration(job.timing.processing_ms);
      document.querySelector("#detail-waiting-duration").textContent = formatDuration(job.timing.waiting_ms);
      const relations = job.relations || {};
      const partition = relations.partition;
      const partitionRow = document.querySelector("#detail-partition-row");
      if (partition) {
        document.querySelector("#detail-partition").textContent =
          `${partition.topic} / partition ${partition.partition} / sequence ${partition.sequence}`;
        partitionRow.hidden = false;
      } else {
        partitionRow.hidden = true;
      }
      const relationRows = [];
      if (relations.parent_job_id) {
        relationRows.push(relationRow("Parent", [relations.parent_job_id]));
      }
      if ((relations.continuation_job_ids || []).length > 0) {
        relationRows.push(relationRow("Continues with", relations.continuation_job_ids));
      }
      if (relations.continuations_truncated) {
        const note = document.createElement("p");
        note.textContent = "Only the first 25 continuation jobs are shown.";
        relationRows.push(note);
      }
      if (partition && partition.previous_job_id) {
        relationRows.push(relationRow("Previous in partition", [partition.previous_job_id]));
      }
      if (partition && partition.next_job_id) {
        relationRows.push(relationRow("Next in partition", [partition.next_job_id]));
      }
      if (relationRows.length === 0) {
        const empty = document.createElement("p");
        empty.textContent = "No related jobs";
        relationRows.push(empty);
      }
      document.querySelector("#relations").replaceChildren(...relationRows);
      const payload = job.payload;
      const payloadNote = document.querySelector("#detail-payload-note");
      const payloadEl = document.querySelector("#detail-payload");
      if (payload && payload.format === "msgpack") {
        payloadEl.textContent = JSON.stringify(payload.value, null, 2);
        payloadNote.hidden = !Array.isArray(payload.value);
      } else if (payload && payload.format === "raw") {
        payloadEl.textContent = payload.value;
        payloadNote.hidden = true;
      } else {
        payloadEl.textContent = "(unavailable)";
        payloadNote.hidden = true;
      }
      document.querySelector("#history").replaceChildren(...info.previous_stages.slice().reverse().map(stage => {
        const item = document.createElement("li");
        item.textContent = `${stage.type} - ${stageDate(stage)}`;
        return item;
      }));
      if (!elements.details.open) elements.details.showModal();
    }

    function updateDetailNavigation() {
      const index = state.selectedJobIndex;
      const jobCount = state.visibleJobs.length;
      const isInView = Number.isInteger(index) && index >= 0 && index < jobCount;
      elements.detailPrevious.disabled = !isInView || index === 0;
      elements.detailNext.disabled = !isInView || index === jobCount - 1;
      elements.detailPosition.textContent = isInView
        ? `Job ${index + 1} of ${jobCount}`
        : "Not in the current view";
    }

    function relationRow(label, jobIds) {
      const row = document.createElement("p");
      const title = document.createElement("strong");
      title.textContent = `${label}: `;
      const links = document.createElement("span");
      links.className = "relation-links";
      links.replaceChildren(...jobIds.map(id => {
        const link = document.createElement("button");
        link.type = "button";
        link.className = "job-link";
        link.textContent = id;
        link.addEventListener("click", () => loadJob(id));
        return link;
      }));
      row.append(title, links);
      return row;
    }

    async function loadJob(id) {
      try { showJob(await request({ cmd: "job", id })); }
      catch (error) { showNotice(error.message, true); }
    }

    function loadAdjacentJob(offset) {
      if (state.selectedJobIndex === null) return;
      const job = state.visibleJobs[state.selectedJobIndex + offset];
      if (job) loadJob(job.id);
    }

    function reload(cursor) {
      if (state.mode === "partition") loadPartition(state.topic, state.partition, cursor);
      else loadStage(state.stage, cursor);
    }

    async function refreshConsumerLag() {
      if (LAG_TOPICS.length === 0) return;
      try {
        const readings = await request({ cmd: "consumer_lag" });
        const totals = {};
        readings.forEach(reading => {
          totals[reading.topic] = (totals[reading.topic] || 0) + reading.lag;
        });
        state.consumerLag = totals;
      } catch (_) {
        // Silently skipped - a missed lag reading isn't worth a page-wide
        // error banner the way a failed job-list refresh is.
      }
    }

    async function refreshQueueDepth() {
      if (TOPICS.length === 0) return;
      try {
        const readings = await request({ cmd: "partition_queue_depth" });
        // The server only reports partitions with at least one queued job,
        // so every configured topic is seeded at 0 first - otherwise a
        // fully caught-up topic would never get an entry here at all, and
        // its badge would stay hidden forever instead of showing "0".
        const totals = {};
        TOPICS.forEach(topic => { totals[topic.name] = 0; });
        const byPartition = {};
        readings.forEach(reading => {
          totals[reading.topic] = (totals[reading.topic] || 0) + reading.depth;
          (byPartition[reading.topic] ??= {})[reading.partition] = reading.depth;
        });
        state.queueDepthTotals = totals;
        state.queueDepthByPartition = byPartition;
      } catch (_) {
        // Silently skipped, same reasoning as refreshConsumerLag.
      }
    }

    async function refresh() {
      try {
        const response = await request({ cmd: "count" });
        const previousCount = state.counts[state.stage];
        state.counts = response.stages;
        renderPerformance(response.performance, response.db_size_bytes);
        if (state.mode === "stages") {
          renderStages();
          if (!state.stage) await loadStage("enqueued", null, true);
          else if (previousCount !== state.counts[state.stage]) await loadStage(state.stage, state.cursor, false, true);
        } else if (state.mode === "partition") {
          await loadPartition(state.topic, state.partition, state.cursor, false, true);
        }
        // state.mode === "monitoring": nothing job-list-related to refresh
        // here - pollMetrics() (its own interval) handles that view. Calling
        // loadPartition() unconditionally in this branch used to also match
        // "monitoring", and loadPartition() unconditionally sets
        // state.mode = "partition" - silently kicking the dashboard out of
        // Monitoring one refresh cycle (≤2.5s) after switching to it, which
        // froze every chart in place since pollMetrics() only redraws them
        // while state.mode is still "monitoring".
      } catch (error) { showNotice(error.message, true); }
      await Promise.all([refreshConsumerLag(), refreshQueueDepth()]);
      renderTopicBadges();
      if (state.mode === "partition") renderPartitionPicker();
    }

    elements.previous.addEventListener("click", () => {
      if (state.history.length === 0) return;
      reload(state.history.pop());
    });
    elements.next.addEventListener("click", () => {
      if (state.nextCursor === null) return;
      state.history.push(state.cursor);
      reload(state.nextCursor);
    });
    elements.partitionSelect.addEventListener("change", () => {
      loadPartition(state.topic, Number(elements.partitionSelect.value), null, true);
    });
    elements.allJobs.addEventListener("click", switchToStages);
    elements.monitoringTab.addEventListener("click", switchToMonitoring);
    elements.detailPrevious.addEventListener("click", () => loadAdjacentJob(-1));
    elements.detailNext.addEventListener("click", () => loadAdjacentJob(1));
    document.querySelector("#close").addEventListener("click", () => { elements.details.close(); location.hash = ""; });
    window.addEventListener("hashchange", () => {
      const id = decodeURIComponent(location.hash.slice(1));
      if (id) loadJob(id);
    });

    renderMonitoringCards();
    renderTabs();
    if (location.hash.length > 1) loadJob(decodeURIComponent(location.hash.slice(1)));
    // Each poll waits for the previous one to finish before the next delay
    // starts. A fixed setInterval kept firing while a slow response (large
    // backlog, busy database) was still in flight, so requests piled up
    // unbounded, each holding a database connection - making the slowness
    // worse until the page showed nothing at all.
    function pollEvery(task, delayMs) {
      const tick = async () => {
        try { await task(); } finally { setTimeout(tick, delayMs); }
      };
      tick();
    }
    pollEvery(refresh, 2500);
    if (METRICS_ENABLED) {
      pollEvery(pollMetrics, 2500);
      pollEvery(refreshQueueLength, 15000);
    }
  </script>
</body>
</html>