Add some explanation comments.

src/reactions/RaisedHandIndicator.tsx

@@ -21,6 +21,7 @@ export function RaisedHandIndicator({
 }): ReactNode {
   const [raisedHandDuration, setRaisedHandDuration] = useState("");
 
+  // This effect creates a simple timer effect.
   useEffect(() => {
     if (!raisedHandTime || !showTimer) {
       return;

src/useReactions.test.tsx

@@ -26,6 +26,13 @@ import { randomUUID } from "crypto";
 
 import { ReactionsProvider, useReactions } from "./useReactions";
 
+/**
+ * Test explanation.
+ * This test suite checks that the useReactions hook appropriately reacts
+ * to new reactions, redactions and membership changesin the room. There is
+ * a large amount of test structure used to construct a mock environment.
+ */
+
 const memberUserIdAlice = "@alice:example.org";
 const memberEventAlice = "$membership-alice:example.org";
 const memberUserIdBob = "@bob:example.org";
@@ -198,7 +205,7 @@ describe("useReactions", () => {
     rerender(<TestComponentWrapper rtcSession={rtcSession} />);
     expect(queryByRole("list")?.children).to.have.lengthOf(0);
   });
-  test("handles loading events from cold", () => {
+  test("handles loading prior raised hand events", () => {
     const room = new MockRoom([createReaction(memberEventAlice)]);
     const rtcSession = new MockRTCSession(room);
     const { queryByRole } = render(
@@ -206,6 +213,8 @@ describe("useReactions", () => {
     );
     expect(queryByRole("list")?.children).to.have.lengthOf(1);
   });
+  // If the membership event changes for a user, we want to remove
+  // the raised hand event.
   test("will remove reaction when a member leaves the call", () => {
     const room = new MockRoom([createReaction(memberEventAlice)]);
     const rtcSession = new MockRTCSession(room);
@@ -224,6 +233,7 @@ describe("useReactions", () => {
       <TestComponentWrapper rtcSession={rtcSession} />,
     );
     expect(queryByRole("list")?.children).to.have.lengthOf(1);
+    // Simulate leaving and rejoining
     rtcSession.testRemoveMember(memberUserIdAlice);
     rtcSession.testAddMember(memberUserIdAlice);
     rerender(<TestComponentWrapper rtcSession={rtcSession} />);

src/useReactions.tsx

@@ -72,6 +72,7 @@ export const ReactionsProvider = ({
     clientState?.state === "valid" && clientState.supportedFeatures.reactions;
   const room = rtcSession.room;
 
+  // Calculate our own reaction event.
   const myReactionId = useMemo((): string | null => {
     const myUserId = room.client.getUserId();
     if (myUserId) {
@@ -80,6 +81,15 @@ export const ReactionsProvider = ({
     return null;
   }, [raisedHands, room]);
 
+  // Reduce the data down for the consumers.
+  const resultRaisedHands = useMemo(
+    () =>
+      Object.fromEntries(
+        Object.entries(raisedHands).map(([uid, data]) => [uid, data.time]),
+      ),
+    [raisedHands],
+  );
+
   const addRaisedHand = useCallback(
     (userId: string, info: RaisedHandInfo) => {
       setRaisedHands({
@@ -98,7 +108,7 @@ export const ReactionsProvider = ({
     [raisedHands],
   );
 
-  // Load any existing reactions.
+  // This effect will check the state whenever the membership of the session changes.
   useEffect(() => {
     const getLastReactionEvent = (eventId: string): MatrixEvent | undefined => {
       const relations = room.relations.getChildEventsForEvent(
@@ -148,6 +158,7 @@ export const ReactionsProvider = ({
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [room, memberships]);
 
+  // This effect handles any *live* reaction/redactions in the room.
   useEffect(() => {
     const handleReactionEvent = (event: MatrixEvent): void => {
       const sender = event.getSender();
@@ -201,15 +212,6 @@ export const ReactionsProvider = ({
     };
   }, [room, addRaisedHand, removeRaisedHand, memberships, raisedHands]);
 
-  // Reduce the data down for the consumers.
-  const resultRaisedHands = useMemo(
-    () =>
-      Object.fromEntries(
-        Object.entries(raisedHands).map(([uid, data]) => [uid, data.time]),
-      ),
-    [raisedHands],
-  );
-
   return (
     <ReactionsContext.Provider
       value={{