feat: the extension picks a Discord source's posters from who posts in the channel, stored by id (#4488)

On a Discord channel page the Add panel lists who posted in the newest 200
messages, the creator the server is named for (or owned by) ticked. On a
channel FabledCurator already follows, the chip opens the same list with Save
and Open artist. The list is kept as user ids, so a rename never quietly stops
it matching; the name each was picked under rides beside it for display, and
the Subscriptions dialog shows it.

- DiscordClient.recent_posters + rank_posters (owner / name-matches-server;
  bots never suggested; it suggests, the operator ticks).
- GET/POST /api/extension/discord/posters; quick-add takes discord_authors.

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

extension/background/background.js

@@ -276,11 +276,26 @@ browser.runtime.onMessage.addListener(async (msg) => {
           artistId: msg.artistId ?? null,
           artistName: msg.artistName ?? null,
           usePlatformName: msg.usePlatformName === true,
+          discordAuthors: Array.isArray(msg.discordAuthors) ? msg.discordAuthors : null,
         });
       } catch (e) {
         return { error: e.message };
       }
 
+    case 'DISCORD_POSTERS':
+      try {
+        return await api.getDiscordPosters(msg.url);
+      } catch (e) {
+        return { error: e.message };
+      }
+
+    case 'SET_DISCORD_POSTERS':
+      try {
+        return await api.setDiscordPosters(msg.url, msg.authors || []);
+      } catch (e) {
+        return { error: e.message };
+      }
+
     case 'SEARCH_ARTISTS':
       try {
         return { artists: await api.searchArtists(msg.q || '') };

extension/content/content-script.css

@@ -100,3 +100,7 @@
 /* The panel's own [hidden] — its rows are display:flex, which beats the UA's. */
 .fc-panel [hidden] { display: none !important; }
 .fc-panel__rename { margin-top: 8px; font-size: 13px; }
+/* Poster picker (#4488): who posts in the channel, the likely creator ticked. */
+.fc-panel__posters { max-height: 220px; overflow-y: auto; }
+.fc-panel__poster { flex-wrap: wrap; }
+.fc-panel__poster-meta { flex-basis: 100%; padding-left: 21px; font-size: 11px; color: rgb(170, 166, 156); }

extension/content/content-script.js

@@ -81,6 +81,13 @@
     const probe = currentProbe;
 
     if (probe?.state === 'source_match') {
+      // A followed Discord channel opens its poster list (#4488); the artist
+      // page is one click further, in that panel.
+      if (probe.platform === 'discord' && probe.discord?.channel_id) {
+        if (document.getElementById('fc-add-panel')) closePanel();
+        else openPostersPanel(btn, probe);
+        return;
+      }
       await openArtist(btn, probe.artist?.slug);
       return;
     }
@@ -158,6 +165,120 @@
     document.getElementById('fc-add-panel')?.remove();
   }
 
+  // ---- Poster picker (#4488) ----
+  // Who posted in this channel lately, read by FabledCurator with its Discord
+  // token, the creator the server is named for (or owned by) ticked. The
+  // source keeps their ids: a username can change on a whim, an id can't, so
+  // the list never quietly stops matching. Names are other people's text —
+  // createElement only.
+
+  function posterSection() {
+    const list = el('div', { class: 'fc-panel__posters' }, [
+      el('div', { class: 'fc-panel__hint', text: 'Reading who posts here…' }),
+    ]);
+    const node = el('div', {}, [
+      el('div', { class: 'fc-panel__label', text: 'Only posts by' }),
+      list,
+    ]);
+    const state = { data: null, picked: new Set() };
+
+    function render() {
+      const posters = withSelected(state.data);
+      if (!posters.length) {
+        list.replaceChildren(el('div', { class: 'fc-panel__hint', text: 'No one has posted here lately.' }));
+        return;
+      }
+      const rows = posters.map((p) => {
+        const id = String(p.id);
+        const box = el('input', { type: 'checkbox', checked: state.picked.has(id) });
+        box.addEventListener('change', () => {
+          if (box.checked) state.picked.add(id);
+          else state.picked.delete(id);
+          hint.textContent = pickHint();
+        });
+        const bits = [`${p.images} image${p.images === 1 ? '' : 's'}`, `${p.messages} message${p.messages === 1 ? '' : 's'}`];
+        if (p.reasons?.length) bits.unshift(p.reasons.join(', '));
+        return el('label', { class: 'fc-panel__radio fc-panel__poster' }, [
+          box,
+          el('span', { text: posterLabel(p) }),
+          el('span', { class: 'fc-panel__poster-meta', text: bits.join(' · ') }),
+        ]);
+      });
+      const hint = el('div', { class: 'fc-panel__hint', text: pickHint() });
+      list.replaceChildren(...rows, hint);
+    }
+
+    function pickHint() {
+      return state.picked.size
+        ? 'Only the ticked people’s posts are taken.'
+        : 'Nothing ticked: everyone’s posts are taken.';
+    }
+
+    async function load() {
+      let r;
+      try {
+        r = await browser.runtime.sendMessage({ type: 'DISCORD_POSTERS', url: window.location.href });
+      } catch (e) {
+        r = { error: e.message };
+      }
+      if (r?.error) {
+        list.replaceChildren(el('div', { class: 'fc-panel__hint', text: `Couldn’t list posters — ${r.error}` }));
+        return;
+      }
+      state.data = r;
+      state.picked = initialPosterPick(r);
+      render();
+    }
+
+    // null until the list has loaded: an add made before then leaves the
+    // source's list as it is instead of clearing it.
+    const request = () => (state.data ? postersRequest(state.data.posters, state.picked) : null);
+    return { node, load, request };
+  }
+
+  function openPostersPanel(btn, probe) {
+    closePanel();
+    const d = probe.discord || {};
+    const posters = posterSection();
+    const saveBtn = el('button', { class: 'fc-panel__btn fc-panel__btn--primary', text: 'Save' });
+    const artistBtn = el('button', { class: 'fc-panel__btn', text: `Open ${probe.artist?.name || 'artist'}` });
+    const cancelBtn = el('button', { class: 'fc-panel__btn', text: 'Close' });
+    const panel = el('div', { id: 'fc-add-panel', class: 'fc-panel' }, [
+      el('div', { class: 'fc-panel__title', text: 'Discord source' }),
+      el('div', { class: 'fc-panel__sub', text: d.channel_id ? channelLabel(d) : serverLabel(d) }),
+      posters.node,
+      el('div', { class: 'fc-panel__actions' }, [artistBtn, cancelBtn, saveBtn]),
+    ]);
+    panel.addEventListener('keydown', (e) => {
+      e.stopPropagation();
+      if (e.key === 'Escape') closePanel();
+    });
+    cancelBtn.addEventListener('click', closePanel);
+    artistBtn.addEventListener('click', () => { closePanel(); openArtist(btn, probe.artist?.slug); });
+    saveBtn.addEventListener('click', async () => {
+      const authors = posters.request();
+      if (!authors) return;
+      saveBtn.disabled = true;
+      try {
+        const r = await browser.runtime.sendMessage({
+          type: 'SET_DISCORD_POSTERS', url: window.location.href, authors,
+        });
+        if (r?.error) {
+          showToast(`Error: ${r.error}`, 'error');
+          return;
+        }
+        showToast(authors.length ? `Only posts by ${authors.map((a) => a.name || a.id).join(', ')}` : 'Taking everyone’s posts', 'success');
+        closePanel();
+      } catch (e) {
+        showToast(`Error: ${e.message}`, 'error');
+      } finally {
+        saveBtn.disabled = false;
+      }
+    });
+    document.body.appendChild(panel);
+    posters.load();
+  }
+
   async function openAddPanel(btn, probe) {
     closePanel();
     const platformName = PLATFORMS[probe.platform]?.name || probe.platform;
@@ -184,6 +305,8 @@
     const d = probe.discord || {};
     const discord = probe.platform === 'discord';
     const choice = panelDefaults(probe, window.location.href);
+    // #4488: on a channel page, pick whose posts the new source takes.
+    const posters = discord && d.channel_id ? posterSection() : null;
 
     const scopeRow = (value, label, disabled) => {
       const input = el('input', {
@@ -234,6 +357,7 @@
       el('div', { class: 'fc-panel__label', text: 'Artist' }),
       el('div', { class: 'fc-panel__combo' }, [nameInput, results]),
       renameRow,
+      ...(posters ? [posters.node] : []),
       hint,
       el('div', { class: 'fc-panel__actions' }, [cancelBtn, addBtn]),
     ]);
@@ -392,6 +516,8 @@
     addBtn.addEventListener('click', async () => {
       const req = addRequest(choice);
       if (!req) return;
+      const authors = posters?.request();
+      if (authors) req.discordAuthors = authors;
       const btn = document.getElementById('fc-add-source-btn');
       addBtn.disabled = true;
       const ok = await add(btn || addBtn, req);
@@ -402,6 +528,7 @@
     document.body.appendChild(panel);
     refresh();
     nameInput.focus();
+    posters?.load();
     nameInput.select();
     // Search what the field opens with — the server's name, usually — so an
     // artist it already matches is picked before the operator types anything.

extension/lib/api.js

@@ -106,8 +106,11 @@ class FabledCuratorAPI {
   // artist from the URL. A Discord channel always sends one.
   // usePlatformName: a Patreon source joining an existing artist renames it
   // to the Patreon display name (Patreon is canon; name only, never the slug).
-  quickAddSource(url, { artistId = null, artistName = null, usePlatformName = false } = {}) {
+  // discordAuthors ([{id, name}], #4488): a Discord source's poster list, set
+  // in the same step.
+  quickAddSource(url, { artistId = null, artistName = null, usePlatformName = false, discordAuthors = null } = {}) {
     const body = { url };
+    if (discordAuthors) body.discord_authors = discordAuthors;
     if (artistId != null) body.artist_id = artistId;
     else if (artistName) body.artist_name = artistName;
     if (usePlatformName) body.use_platform_name = true;
@@ -123,6 +126,15 @@ class FabledCuratorAPI {
     const qs = new URLSearchParams(params).toString();
     return this.request('GET', `/extension/probe?${qs}`);
   }
+  // #4488: who posts in the Discord channel `url` shows, lately, with the
+  // likely creator marked; and setting the list on the source that follows it.
+  getDiscordPosters(url) {
+    const qs = new URLSearchParams({ url }).toString();
+    return this.request('GET', `/extension/discord/posters?${qs}`);
+  }
+  setDiscordPosters(url, authors) {
+    return this.request('POST', '/extension/discord/posters', { url, authors });
+  }
   // Latest published extension version on this instance — drives the in-app
   // update prompt. Public endpoint (no key needed, but request() sends it
   // harmlessly). Returns {version, xpi_url, latest_url, sha256}.

extension/lib/chip.js

@@ -144,3 +144,49 @@ function inlineCompletion(typed, results) {
   if (!t) return null;
   return (results || []).find((a) => a.name.length > t.length && a.name.toLowerCase().startsWith(t)) || null;
 }
+
+// ---- Discord poster picker (#4488) ----
+// /api/extension/discord/posters lists who posted in the channel lately, with
+// the creator the server is named for (or owned by) marked `suggested`. The
+// picker ticks posters; the source keeps their ids, since a username can
+// change on a whim and an id can't.
+
+/** "Todding (@todding)" — the display name, then the handle when it differs. */
+function posterLabel(p) {
+  const shown = p?.global_name || p?.username || p?.id || '';
+  const handle = p?.username && p.username !== shown ? ` (@${p.username})` : '';
+  return `${shown}${handle}`;
+}
+
+/** What the picker starts with: the source's current list when it has one,
+ *  else the suggested creator(s). A set of ids. */
+function initialPosterPick(data) {
+  const current = (data?.selected || []).map(String);
+  if (current.length) return new Set(current);
+  return new Set((data?.posters || []).filter((p) => p.suggested).map((p) => String(p.id)));
+}
+
+/** The checklist's rows: who posted lately, then anyone already on the
+ *  source's list who hasn't — by the name they were picked under — so they
+ *  can still be unticked. */
+function withSelected(data) {
+  const posters = [...(data?.posters || [])];
+  const shown = new Set(posters.map((p) => String(p.id)));
+  const labels = data?.selected_labels || {};
+  for (const id of (data?.selected || []).map(String)) {
+    if (shown.has(id)) continue;
+    posters.push({ id, global_name: labels[id] || null, username: null,
+      messages: 0, images: 0, reasons: ['on the list, not posting lately'] });
+  }
+  return posters;
+}
+
+/** The picked posters as the API takes them: [{id, name}], in list order.
+ *  An id already on the source but no longer posting lately is kept. */
+function postersRequest(posters, picked) {
+  const byId = new Map((posters || []).map((p) => [String(p.id), p]));
+  return [...picked].map((id) => ({
+    id,
+    name: byId.has(id) ? (byId.get(id).global_name || byId.get(id).username || id) : null,
+  }));
+}

extension/test/chip.spec.js

@@ -198,3 +198,46 @@ describe('Add panel on Patreon and SubscribeStar', () => {
     expect(c.artistName).toBe('Tamada')
   })
 })
+
+const { posterLabel, initialPosterPick, postersRequest, withSelected } = loadLib('chip.js', [
+  'posterLabel', 'initialPosterPick', 'postersRequest', 'withSelected',
+])
+
+describe('the poster checklist rows', () => {
+  it('adds someone on the list who has not posted lately, by their saved name', () => {
+    const rows = withSelected({
+      posters: [{ id: '7', username: 'todding', global_name: 'Todding' }],
+      selected: ['7', '42'],
+      selected_labels: { 42: 'Old Name' },
+    })
+    expect(rows.map((r) => r.id)).toEqual(['7', '42'])
+    expect(posterLabel(rows[1])).toBe('Old Name')
+    expect(rows[1].reasons).toEqual(['on the list, not posting lately'])
+  })
+})
+
+describe('the Discord poster picker (#4488)', () => {
+  const posters = [
+    { id: '7', username: 'todding', global_name: 'Todding', suggested: true },
+    { id: '8', username: 'jakeboii', global_name: 'Jake Boii', suggested: false },
+    { id: '9', username: 'plain', global_name: null, suggested: false },
+  ]
+
+  it('labels a poster by display name, then handle', () => {
+    expect(posterLabel(posters[0])).toBe('Todding (@todding)')
+    expect(posterLabel(posters[2])).toBe('plain')
+  })
+
+  it('starts from the source list when it has one, else the suggestion', () => {
+    expect([...initialPosterPick({ posters, selected: [] })]).toEqual(['7'])
+    expect([...initialPosterPick({ posters, selected: ['8'] })]).toEqual(['8'])
+    expect([...initialPosterPick({ posters: [] })]).toEqual([])
+  })
+
+  it('sends ids with the names they were picked under, keeping unknown ids', () => {
+    expect(postersRequest(posters, new Set(['7', '42']))).toEqual([
+      { id: '7', name: 'Todding' },
+      { id: '42', name: null },
+    ])
+  })
+})