Phase 1 UX + JS transforms: tabs, windowing, percent/grouping, smoothing, stacked series, metadata pass-through, top_n

- Replace tabs with Recent/Trends/Distribution/Tables/Analysis and add sticky controls (interval, domain, window [default 7d], percent, group small, exclude '-' -> Uncached, smoothing toggle).

- Client-side transforms: time-window slicing, percent mode, group others (3%), per-report exclusions; stackedBar multi-series; moving average for error_rate.

- Generator: pass through optional UX metadata (windows_supported, window_default, group_others_threshold, exclude_values, top_n, stacked, palette) and enforce top_n LIMIT for table reports.

- Reports: add status_classes_timeseries and cache_status_timeseries; apply top_n=50 to heavy tables.

- Chart manager: add helpers (sliceWindow, excludeValues, toPercent, groupOthers, movingAverage).

- URL state + localStorage for context; per-tab filtering for Trends/Distribution/Tables.

static/chartManager.js

@@ -47,3 +47,63 @@ export function reset(container) {
   });
   container.innerHTML = '';
 }
+
+// ---- Lightweight client-side data helpers ----
+
+// Slice last N rows from a time-ordered array
+export function sliceWindow(data, n) {
+  if (!Array.isArray(data) || n === undefined || n === null) return data;
+  if (n === 'all') return data;
+  const count = Number(n);
+  if (!Number.isFinite(count) || count <= 0) return data;
+  return data.slice(-count);
+}
+
+// Exclude rows whose value in key is in excluded list
+export function excludeValues(data, key, excluded = []) {
+  if (!excluded || excluded.length === 0) return data;
+  const set = new Set(excluded);
+  return data.filter(row => !set.has(row[key]));
+}
+
+// Compute percentages for categorical distributions (valueKey default 'value')
+export function toPercent(data, valueKey = 'value') {
+  const total = data.reduce((s, r) => s + (Number(r[valueKey]) || 0), 0);
+  if (total <= 0) return data.map(r => ({ ...r }));
+  return data.map(r => ({ ...r, [valueKey]: (Number(r[valueKey]) || 0) * 100 / total }));
+}
+
+// Group categories with share < threshold into an 'Other' bucket.
+export function groupOthers(data, bucketKey, valueKey = 'value', threshold = 0.03, otherLabel = 'Other') {
+  if (!Array.isArray(data) || data.length === 0) return data;
+  const total = data.reduce((s, r) => s + (Number(r[valueKey]) || 0), 0);
+  if (total <= 0) return data;
+  const major = [];
+  let other = 0;
+  for (const r of data) {
+    const v = Number(r[valueKey]) || 0;
+    if (total && v / total < threshold) {
+      other += v;
+    } else {
+      major.push({ ...r });
+    }
+  }
+  if (other > 0) major.push({ [bucketKey]: otherLabel, [valueKey]: other });
+  return major;
+}
+
+// Simple moving average over numeric array
+export function movingAverage(series, span = 3) {
+  const n = Math.max(1, Number(span) || 1);
+  const out = [];
+  for (let i = 0; i < series.length; i++) {
+    const start = Math.max(0, i - n + 1);
+    let sum = 0, cnt = 0;
+    for (let j = start; j <= i; j++) {
+      const v = Number(series[j]);
+      if (Number.isFinite(v)) { sum += v; cnt++; }
+    }
+    out.push(cnt ? sum / cnt : null);
+  }
+  return out;
+}