diff --git a/website/scripts/chart/index.js b/website/scripts/chart/index.js
index 08fe19b41..ade4ebdd4 100644
--- a/website/scripts/chart/index.js
+++ b/website/scripts/chart/index.js
@@ -92,19 +92,20 @@ export function createChart({
   config,
 }) {
   // Chart owns its index state
-  /** @type {Signal<ChartableIndexName>} */
-  const indexName = signals.createPersistedSignal({
+  /** @type {Set<(index: ChartableIndex) => void>} */
+  const onIndexChange = new Set();
+
+  const index = () => serdeChartableIndex.deserialize(indexName.value);
+
+  const indexName = createPersistedValue({
     defaultValue: /** @type {ChartableIndexName} */ ("date"),
     storageKey: "chart-index",
     urlKey: "i",
     serialize: (v) => v,
     deserialize: (s) => /** @type {ChartableIndexName} */ (s),
+    onChange: () => onIndexChange.forEach((cb) => cb(index())),
   });
 
-  const index = signals.createMemo(() =>
-    serdeChartableIndex.deserialize(indexName()),
-  );
-
   // Range state: localStorage stores all ranges per-index, URL stores current range only
   /** @typedef {{ from: number, to: number }} Range */
   const ranges = createPersistedValue({
@@ -126,11 +127,11 @@ export function createChart({
   });
 
   /** @returns {Range | null} */
-  const getRange = () => range.value ?? ranges.value[indexName()] ?? null;
+  const getRange = () => range.value ?? ranges.value[indexName.value] ?? null;
 
   /** @param {Range} value */
   const setRange = (value) => {
-    ranges.set({ ...ranges.value, [indexName()]: value });
+    ranges.set({ ...ranges.value, [indexName.value]: value });
     range.set(value);
   };
 
@@ -264,7 +265,8 @@ export function createChart({
   applyColors();
   const removeThemeListener = onThemeChange(applyColors);
 
-  signals.createEffect(index, (index) => {
+  /** @param {ChartableIndex} index */
+  function applyIndexSettings(index) {
     const minBarSpacing =
       index === "monthindex"
         ? 1
@@ -288,7 +290,9 @@ export function createChart({
           : {}),
       },
     });
-  });
+  }
+  applyIndexSettings(index());
+  onIndexChange.add(applyIndexSettings);
 
   const activeResources = /** @type {Set<MetricResource<unknown>>} */ (
     new Set()
@@ -314,39 +318,42 @@ export function createChart({
    * @param {(pane: IPaneApi<Time>) => HTMLElement} args.createChild
    */
   function addFieldsetIfNeeded({ paneIndex, id, position, createChild }) {
-    setTimeout(() => {
-      const parent = ichart
-        ?.panes()
-        .at(paneIndex)
-        ?.getHTMLElement()
-        ?.children?.item(1)?.firstChild;
+    setTimeout(
+      () => {
+        const parent = ichart
+          ?.panes()
+          .at(paneIndex)
+          ?.getHTMLElement()
+          ?.children?.item(1)?.firstChild;
 
-      if (!parent) throw Error("Parent should exist");
+        if (!parent) throw Error("Parent should exist");
 
-      const children = Array.from(parent.childNodes).filter(
-        (element) =>
-          /** @type {HTMLElement} */ (element).dataset.position === position,
-      );
+        const children = Array.from(parent.childNodes).filter(
+          (element) =>
+            /** @type {HTMLElement} */ (element).dataset.position === position,
+        );
 
-      if (children.length === 1) {
-        children[0].remove();
-      } else if (children.length > 1) {
-        throw Error("Untraceable");
-      }
+        if (children.length === 1) {
+          children[0].remove();
+        } else if (children.length > 1) {
+          throw Error("Untraceable");
+        }
 
-      const fieldset = window.document.createElement("fieldset");
-      fieldset.dataset.size = "xs";
-      fieldset.dataset.position = position;
-      fieldset.id = `${id}-${paneIndex}`;
-      const pane = ichart.panes().at(paneIndex);
-      if (!pane) throw Error("Expect pane");
-      pane
-        .getHTMLElement()
-        ?.children?.item(1)
-        ?.firstChild?.appendChild(fieldset);
+        const fieldset = window.document.createElement("fieldset");
+        fieldset.dataset.size = "xs";
+        fieldset.dataset.position = position;
+        fieldset.id = `${id}-${paneIndex}`;
+        const pane = ichart.panes().at(paneIndex);
+        if (!pane) throw Error("Expect pane");
+        pane
+          .getHTMLElement()
+          ?.children?.item(1)
+          ?.firstChild?.appendChild(fieldset);
 
-      fieldset.append(createChild(pane));
-    }, paneIndex ? 50 : 0);
+        fieldset.append(createChild(pane));
+      },
+      paneIndex ? 50 : 0,
+    );
   }
 
   /**
diff --git a/website/scripts/panes/chart.js b/website/scripts/panes/chart.js
index 47a900392..f29c55db0 100644
--- a/website/scripts/panes/chart.js
+++ b/website/scripts/panes/chart.js
@@ -1,6 +1,7 @@
 import {
   createShadow,
   createReactiveChoiceField,
+  createChoiceField,
   createHeader,
 } from "../utils/dom.js";
 import { chartElement } from "../utils/elements.js";
@@ -430,25 +431,26 @@ function createIndexSelector(option, chart) {
     );
   });
 
-  /** @type {ChartableIndexName} */
-  const defaultIndex = "date";
-  const field = createReactiveChoiceField({
-    defaultValue: defaultIndex,
-    selected: chart.indexName,
-    choices,
-    id: "index",
-    signals,
-  });
-
   const fieldset = window.document.createElement("fieldset");
   fieldset.id = "interval";
+  fieldset.dataset.size = "sm";
 
   const screenshotSpan = window.document.createElement("span");
   screenshotSpan.innerText = "interval:";
   fieldset.append(screenshotSpan);
 
-  fieldset.append(field);
-  fieldset.dataset.size = "sm";
+  /** @type {HTMLElement | null} */
+  let field = null;
+  signals.createEffect(choices, (newChoices) => {
+    if (field) field.remove();
+    field = createChoiceField({
+      initialValue: chart.indexName.value,
+      onChange: (v) => chart.indexName.set(v),
+      choices: newChoices,
+      id: "index",
+    });
+    fieldset.append(field);
+  });
 
   return fieldset;
 }
diff --git a/website/scripts/utils/persisted.js b/website/scripts/utils/persisted.js
index 7f90147b2..915104b8f 100644
--- a/website/scripts/utils/persisted.js
+++ b/website/scripts/utils/persisted.js
@@ -11,6 +11,7 @@ import { debounce } from "./timing.js";
  * @param {(v: T) => string} args.serialize
  * @param {(s: string) => T} args.deserialize
  * @param {boolean} [args.saveDefaultValue]
+ * @param {(v: T) => void} [args.onChange]
  */
 export function createPersistedValue({
   defaultValue,
@@ -19,6 +20,7 @@ export function createPersistedValue({
   serialize,
   deserialize,
   saveDefaultValue = false,
+  onChange,
 }) {
   const defaultSerialized = serialize(defaultValue);
 
@@ -60,11 +62,13 @@ export function createPersistedValue({
     set(v) {
       value = v;
       debouncedWrite(v);
+      onChange?.(v);
     },
     /** @param {T} v */
     setImmediate(v) {
       value = v;
       write(v);
+      onChange?.(v);
     },
   };
 }