Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/tools/js/CharacterSheet/containers/SpellSlotManager/SpellSlotManagerGroup/SpellSlotManagerGroup.tsx

@@ -0,0 +1,77 @@
+import React from "react";
+
+import {
+  Collapsible,
+  CollapsibleHeaderContent,
+} from "@dndbeyond/character-components/es";
+import {
+  FormatUtils,
+  SpellSlotContract,
+} from "@dndbeyond/character-rules-engine/es";
+
+import SpellSlotManagerLevel from "../SpellSlotManagerLevel";
+
+interface Props {
+  heading: string;
+  slots: Array<SpellSlotContract>;
+  onSlotSet?: (level: number, used: number) => void;
+  isReadonly: boolean;
+}
+export default class SpellSlotManagerGroup extends React.PureComponent<Props> {
+  renderCallout = (): React.ReactNode => {
+    const { slots } = this.props;
+
+    return (
+      <div className="ct-spell-slot-manager__group-summary">
+        {slots.map((levelSlots) => (
+          <div
+            className="ct-spell-slot-manager__group-level"
+            key={levelSlots.level}
+          >
+            <div className="ct-spell-slot-manager__group-level-name">
+              {FormatUtils.ordinalize(levelSlots.level)}
+            </div>
+            <div className="ct-spell-slot-manager__group-level-available">
+              {levelSlots.available === 0 ? "-" : levelSlots.available}
+            </div>
+          </div>
+        ))}
+      </div>
+    );
+  };
+
+  render() {
+    const { slots, onSlotSet, heading, isReadonly } = this.props;
+
+    let headerNode: React.ReactNode = (
+      <CollapsibleHeaderContent
+        heading={heading}
+        callout={this.renderCallout()}
+      />
+    );
+
+    if (!slots.length) {
+      return null;
+    }
+
+    return (
+      <Collapsible header={headerNode} className="ct-spell-slot-manager__group">
+        <div className="ct-spell-slot-manager__levels">
+          {slots.map((levelSlots) => {
+            if (levelSlots.available === 0) {
+              return null;
+            }
+            return (
+              <SpellSlotManagerLevel
+                key={levelSlots.level}
+                {...levelSlots}
+                onSlotSet={onSlotSet}
+                isInteractive={!isReadonly}
+              />
+            );
+          })}
+        </div>
+      </Collapsible>
+    );
+  }
+}

ddb_main/tools/js/CharacterSheet/containers/SpellSlotManager/SpellSlotManagerGroup/index.ts

@@ -0,0 +1,4 @@
+import SpellSlotManagerGroup from "./SpellSlotManagerGroup";
+
+export default SpellSlotManagerGroup;
+export { SpellSlotManagerGroup };