v3: the profile page is split by one rule, and what it re-invented is shared across the app — UserPublicProfile was 1,949 lines because it held its data, six tabs, seven subcomponents and hand-rolled copies of things the app already had or repeated elsewhere. The page now only picks the tab and puts the pieces together (253 lines); useProfile holds the user and the three lists with their live sync, cache and scroll; each tab and header piece is one file under components/profile/; the followed and invitees tabs load on first open through the new useFetchState, keyed by username, which keeps them across tab switches. Every piece taken out replaces its copies: DumpCardList, which reads the votes from WSContext, is every list of dump cards (the index feeds, followed, search, related dumps, UserDumps, UserUpvoted, the profile), so Index no longer threads vote props into the feeds; PlaylistCardList every list of playlist cards; FeedFooter the eight sentinel/loading-more/end blocks; ListState the loading/error/empty chains; Segmented the settings toggles, RoleSwitcher and the playlist edit form, with SegmentedField built on it; LoadMoreButton the three load-more buttons; NewDumpButton UserDumps' and the profile's; useScrollRestore four copies of the scroll restore, and the profile uses useScrollSave instead of saving its whole cache on every scroll. useFading takes an onFaded callback, which replaces PlaylistDetail's copy of its timers; useUpvotedList is the vote tracking UserUpvoted and the profile each had, and a withdrawn upvote now leaves the list and the cache once faded (it was only hidden, and came back after a tab switch). usePlaylistMemberships is the membership load and toggle AddToPlaylistModal and DumpCreateModal each had. pagedList.ts (PagedList, firstPage, restoredList, fetchFirstPage, withFirst), fetchPublicUser and dataOr are shared by the profile, UserPlaylists and useUserDumpFeed; a refused side list still shows empty, as documented, and only the user fails the page. FollowedFeed's two sections are one local hook, and its readPage is expectOk. A card is its owner's when the item is the signed-in user's, everywhere: the profile's upvoted column marked every dump as the owner's on one's own profile. No message changed; the catalogs only move their references. 643 frontend tests pass (11 new for useFetchState, useFading's onFaded and pagedList), and tsc, eslint, doc:lint, deno check and deno fmt are clean.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/hooks/dump/useUpvotedList.ts

@@ -0,0 +1,142 @@
+/**
+ * Keeps a list of the dumps a user upvoted in step with their votes.
+ *
+ * @module
+ */
+
+import { useCallback, useEffect, useLayoutEffect, useRef } from "react";
+
+import { API_URL } from "../../config/api.ts";
+import type { Dump } from "../../../shared/dump.ts";
+import type { Wire } from "../../../shared/api.ts";
+import { expectOk } from "../../utils/shared/api.ts";
+import { deserializeDump } from "../../utils/shared/deserialize.ts";
+import { useAuth } from "../auth/useAuth.ts";
+import { useWS } from "../ws/useWS.ts";
+import { fadeClassName, useFading } from "../feed/useFading.ts";
+
+/** Passed to {@link useUpvotedList} by `UserUpvoted` and the profile. */
+export interface UseUpvotedListOptions {
+  /** Whose upvotes the list holds, null while their profile loads. */
+  profileUserId: string | null;
+  /** Does nothing until the list is loaded. */
+  setItems: (fn: (prev: Dump[]) => Dump[]) => void;
+  /**
+   * Dumps already at hand, which a vote of the signed-in user on their own
+   * list puts first at once, before the socket's vote event. The profile
+   * passes its first page of the user's dumps.
+   */
+  source?: Dump[];
+}
+
+/** Returned by {@link useUpvotedList}. */
+export interface UseUpvotedListResult {
+  /** For `DumpCardList`'s `cardClassName`. */
+  cardClassName: (dump: Dump) => string | undefined;
+  /**
+   * Whether the vote on dump `id` was withdrawn since the list loaded. The
+   * profile's `usePositionAwareSync` keeps such a dump from coming back.
+   */
+  isWithdrawn: (id: string) => boolean;
+}
+
+/**
+ * Follows the votes of `profileUserId` into their upvoted list. A dump they
+ * upvote is fetched and put first. One whose vote they withdraw fades out
+ * (`useFading`), then leaves the list, unless they vote again meanwhile. The
+ * socket's vote events report every browser's votes; on one's own list,
+ * `myVotes` also reports this tab's at once.
+ */
+export function useUpvotedList(
+  { profileUserId, setItems, source }: UseUpvotedListOptions,
+): UseUpvotedListResult {
+  const { user: me, token } = useAuth();
+  const { myVotes, lastVoteEvent } = useWS();
+  const isOwn = !!profileUserId && me?.id === profileUserId;
+
+  const withdrawnRef = useRef<Set<string>>(new Set());
+  const prevMyVotesRef = useRef<Set<string> | null>(null);
+  // A ref, so that a new first page doesn't count as new votes.
+  const sourceRef = useRef(source);
+  useLayoutEffect(() => {
+    sourceRef.current = source;
+  });
+
+  const { fading, startFading, cancelFading, cancelAll } = useFading((id) =>
+    setItems((items) => items.filter((d) => d.id !== id))
+  );
+
+  const withdraw = useCallback((id: string) => {
+    withdrawnRef.current.add(id);
+    startFading(id);
+  }, [startFading]);
+  const recast = useCallback((id: string) => {
+    withdrawnRef.current.delete(id);
+    cancelFading(id);
+  }, [cancelFading]);
+
+  // Another user's list starts afresh. This runs before the effect below that
+  // diffs the votes, so its baseline resets in time.
+  useEffect(() => {
+    withdrawnRef.current = new Set();
+    prevMyVotesRef.current = null;
+    cancelAll();
+  }, [profileUserId, cancelAll]);
+
+  useEffect(() => {
+    if (!isOwn) return;
+    const prev = prevMyVotesRef.current;
+    prevMyVotesRef.current = new Set(myVotes);
+    // Only a baseline: the list as loaded stands. myVotes may still be the
+    // empty set from before the socket's welcome (or the socket may never
+    // connect), and taking it as the truth here would hide every dump.
+    if (prev === null) return;
+    for (const id of prev) if (!myVotes.has(id)) withdraw(id);
+    const added = new Set([...myVotes].filter((id) => !prev.has(id)));
+    for (const id of added) recast(id);
+    const known = (sourceRef.current ?? []).filter((d) => added.has(d.id));
+    if (known.length === 0) return;
+    setItems((items) => {
+      const ids = new Set(items.map((d) => d.id));
+      const toAdd = known.filter((d) => !ids.has(d.id));
+      return toAdd.length === 0 ? items : [...toAdd, ...items];
+    });
+  }, [myVotes, isOwn, withdraw, recast, setItems]);
+
+  useEffect(() => {
+    if (!lastVoteEvent || !profileUserId) return;
+    const { dumpId, voterId, action } = lastVoteEvent;
+    if (voterId !== profileUserId) return;
+    if (action === "remove") {
+      withdraw(dumpId);
+      return;
+    }
+    recast(dumpId);
+    // Fetched signed in, or a private dump the viewer owns would be refused.
+    fetch(`${API_URL}/api/dumps/${dumpId}`, {
+      headers: token ? { Authorization: `Bearer ${token}` } : {},
+    })
+      .then(expectOk<Wire<Dump>>)
+      .then((wire) => {
+        const dump = deserializeDump(wire);
+        setItems((items) =>
+          // A withdrawn vote cast again before its dump left the list.
+          items.some((d) => d.id === dumpId)
+            ? items.map((d) => d.id === dumpId ? dump : d)
+            : [dump, ...items]
+        );
+      })
+      .catch(() => {});
+  }, [lastVoteEvent, profileUserId, token, withdraw, recast, setItems]);
+
+  const cardClassName = useCallback(
+    (dump: Dump) => fadeClassName(fading[dump.id]),
+    [fading],
+  );
+  const isWithdrawn = useCallback(
+    (id: string) => withdrawnRef.current.has(id),
+    [],
+  );
+
+  return { cardClassName, isWithdrawn };
+}