v4: a dump or playlist going public notifies its followers — a private dump notified no one when posted, and nothing told its followers when it was made public: the poster's followers never learnt of it, nor did the followers of the public playlists holding it. Likewise, the dumps added to a playlist while it was private were never notified to its followers. updateDump and replaceFileDump now call notifyIfWentPublic, which notifies the poster's followers (user_dump_posted) and, through the new notifyPlaylistFollowersNowPublic, the followers of each public playlist holding the dump (playlist_dump_added). updatePlaylist calls the same function when a playlist goes public, for each public dump in it, from the bottom up. A follower hears of a dump once both it and the playlist are public; the source keys stop a dump made private and public again from notifying twice. 256 backend tests pass, and deno check, deno fmt and doc:lint are clean.

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

api/services/dump-service.ts

@@ -34,6 +34,7 @@ import { isValidHttpUrl } from "../remote/fetch.ts";
 import { broadcastDumpChange } from "./ws-service.ts";
 import {
   notifyMentions,
+  notifyPlaylistFollowersNowPublic,
   notifyUserFollowersNewDump,
 } from "./notification-service.ts";
 import { changeSlug, newSlug, resolveSlug } from "./slug-service.ts";
@@ -91,6 +92,19 @@ function titleFromUrl(url: string): string {
   }
 }
 
+/**
+ * Notifies the followers of a dump that went public, `before` being private
+ * and `after` public: the poster's, as if it were just posted, and those of
+ * each public playlist holding it, as if it were just added. A private dump's
+ * followers were never told of it, so an edit that makes it public is when
+ * they learn of it.
+ */
+function notifyIfWentPublic(before: Dump, after: Dump): void {
+  if (!before.isPrivate || after.isPrivate) return;
+  notifyUserFollowersNewDump(after.userId, after.id, after.title);
+  notifyPlaylistFollowersNowPublic({ dumpId: after.id });
+}
+
 /**
  * Posts a link as `userId`, for `POST /api/dumps`, with its preview fetched
  * from the page. A public dump is broadcast as `dump_created` and notified to
@@ -427,7 +441,8 @@ export function findDumpsByUrl(
  * which `exempt` (a moderator) frees from its rate limit; a new title leaves
  * the slug as it is. Clients get the dump as `dump_updated`, or a
  * `dump_deleted` when it turns private and a `dump_created` when it turns
- * public. Anyone @mentioned in the note is notified.
+ * public. Anyone @mentioned in the note is notified, and when it turns public,
+ * its followers are as when it is posted ({@link notifyIfWentPublic}).
  *
  * @throws {APIException} 404 when there is no such dump, 400 when a new URL
  * isn't a public http(s) URL, a category doesn't exist or the slug isn't
@@ -484,6 +499,7 @@ export async function updateDump(
       attachCategoryIds([updatedDump]);
     }
     broadcastDumpChange(dump, updatedDump);
+    notifyIfWentPublic(dump, updatedDump);
     if (updatedDump.comment) {
       if (!updatedDump.isPrivate) {
         notifyMentions(
@@ -555,6 +571,7 @@ export async function updateDump(
   }
 
   broadcastDumpChange(dump, updatedDump);
+  notifyIfWentPublic(dump, updatedDump);
   if (updatedDump.comment) {
     if (!updatedDump.isPrivate) {
       notifyMentions(
@@ -577,8 +594,8 @@ export async function updateDump(
  * `isPrivate` left out stays as it is. Visibility is taken here so that a new
  * file and a change of visibility land together. The slug changes as in
  * {@link updateDump}, before the file is written. The old file is put back if
- * the database update fails, and clients are told as {@link updateDump} tells
- * them.
+ * the database update fails, and clients and followers are told as
+ * {@link updateDump} tells them.
  *
  * @throws {APIException} 404 when there is no such dump, 400 when it isn't a
  * file dump, the title or comment is too long, the file's type isn't allowed,
@@ -683,6 +700,7 @@ export async function replaceFileDump(
     updatedAt: now,
   };
   broadcastDumpChange(dump, updatedDump);
+  notifyIfWentPublic(dump, updatedDump);
   return updatedDump;
 }
 

api/services/notification-service.ts

@@ -230,7 +230,9 @@ export function notifyPlaylistOwnerNewFollower(
 
 /**
  * Notifies everyone following `dumperId` that they posted a dump. The dump
- * service calls it for a public dump only, when it is created.
+ * service calls it for a public dump only, when it is created or goes public.
+ * A follower is told of a dump once, however often it goes private and public
+ * again.
  */
 export function notifyUserFollowersNewDump(
   dumperId: string,
@@ -473,3 +475,46 @@ export function notifyPlaylistFollowersNewDump(
     }
   });
 }
+
+/**
+ * Notifies the followers of each playlist of the dumps in it that became
+ * visible to them: a playlist's followers are told of a dump once both are
+ * public. The dump service calls it with `dumpId` when a dump goes public, for
+ * each public playlist holding it; the playlist service with `playlistId`
+ * when a playlist goes public, for each public dump in it, from the bottom of
+ * the playlist up. A dump the followers were told of before either went
+ * private isn't notified again. Adding a dump to a public playlist calls
+ * {@link notifyPlaylistFollowersNewDump} directly.
+ */
+export function notifyPlaylistFollowersNowPublic(
+  of: { dumpId: string } | { playlistId: string },
+): void {
+  const [column, id] = "dumpId" in of
+    ? ["pd.dump_id", of.dumpId]
+    : ["pd.playlist_id", of.playlistId];
+  const rows = db.prepare(
+    `SELECT p.id AS playlist_id, p.title AS playlist_title,
+            d.id AS dump_id, d.title AS dump_title
+       FROM playlist_dumps pd
+       JOIN playlists p ON p.id = pd.playlist_id
+       JOIN dumps d ON d.id = pd.dump_id
+      WHERE ${column} = ? AND p.is_public = 1 AND d.is_private = 0
+      ORDER BY pd.position DESC;`,
+  ).all(id) as {
+    playlist_id: string;
+    playlist_title: string;
+    dump_id: string;
+    dump_title: string;
+  }[];
+
+  transaction(() => {
+    for (const row of rows) {
+      notifyPlaylistFollowersNewDump(
+        row.playlist_id,
+        row.playlist_title,
+        row.dump_id,
+        row.dump_title,
+      );
+    }
+  });
+}

api/services/playlist-service.ts

@@ -33,6 +33,7 @@ import {
 import {
   notifyMentions,
   notifyPlaylistFollowersNewDump,
+  notifyPlaylistFollowersNowPublic,
 } from "./notification-service.ts";
 import { changeSlug, newSlug, resolveSlug } from "./slug-service.ts";
 import { linkAttachments } from "./attachment-service.ts";
@@ -207,8 +208,9 @@ export function listPlaylistsByUser(
  * moderator is exempt from its rate limit; a new title leaves the slug as it
  * is. `canModerate` lets someone other than the owner edit it. If the
  * playlist is public, it notifies, in the owner's name, the users the
- * description mentions. It links the description's attachments and
- * broadcasts `playlist_updated`.
+ * description mentions. When it goes public, its followers are notified of
+ * its public dumps they weren't yet told of. It links the description's
+ * attachments and broadcasts `playlist_updated`.
  *
  * @throws {APIException} 404 when there is no such playlist, 403 when the user
  * is neither its owner nor a moderator, 400 when the slug isn't valid, 409
@@ -270,6 +272,10 @@ export function updatePlaylist(
     linkAttachments(newDescription, "playlist", playlist.id);
   }
   broadcastPlaylistUpdated(updated, playlist.isPublic);
+  // Its followers weren't told of the dumps added while it was private.
+  if (!playlist.isPublic && newIsPublic) {
+    notifyPlaylistFollowersNowPublic({ playlistId: playlist.id });
+  }
   return updated;
 }
 

api/test/routes/dumps.test.ts

@@ -601,6 +601,46 @@ test("PUT /api/dumps/:id: going private hides the dump from everyone else", asyn
   assertEquals((await get(`/api/dumps/${id}`)).status, 200);
 });
 
+test("PUT /api/dumps/:id: going public notifies the poster's and its playlists' followers, once", async () => {
+  const owner = await createUser();
+  const fan = await createUser();
+  const listener = await createUser();
+  db.prepare(
+    `INSERT INTO follows (id, follower_id, followed_user_id, created_at) VALUES (?, ?, ?, ?);`,
+  ).run(crypto.randomUUID(), fan.id, owner.id, new Date().toISOString());
+  const mix = insertPlaylist({ userId: owner.id, title: "Mix" });
+  const hidden = insertPlaylist({
+    userId: owner.id,
+    title: "Hidden",
+    isPublic: false,
+  });
+  await put(`/api/me/follow/playlists/${mix.id}`, { auth: listener.auth });
+  const { id } = insertDump({ userId: owner.id, isPrivate: true });
+  for (const p of [mix, hidden]) {
+    await post(`/api/playlists/${p.id}/dumps/${id}`, { auth: owner.auth });
+  }
+  db.exec(`DELETE FROM notifications;`); // the follow notified the owner
+  const setPrivate = (isPrivate: boolean) =>
+    put(`/api/dumps/${id}`, { auth: owner.auth, json: { isPrivate } });
+
+  await setPrivate(false);
+  const notes = db.prepare(
+    `SELECT user_id, type, data FROM notifications ORDER BY type;`,
+  ).all() as { user_id: string; type: string; data: string }[];
+  assertEquals(
+    notes.map((n) => [n.user_id, n.type, JSON.parse(n.data).playlistId]),
+    [
+      [listener.id, "playlist_dump_added", mix.id],
+      [fan.id, "user_dump_posted", undefined],
+    ],
+  );
+  // Neither going private and public again nor an edit notifies twice.
+  await setPrivate(true);
+  await setPrivate(false);
+  await put(`/api/dumps/${id}`, { auth: owner.auth, json: { title: "New" } });
+  assertEquals(count(`SELECT COUNT(*) as n FROM notifications;`), 2);
+});
+
 test("PUT /api/dumps/:id: a file dump edits title, comment and privacy", async () => {
   const owner = await createUser();
   const { id } = insertDump({

api/test/routes/playlists.test.ts

@@ -320,6 +320,33 @@ test("adding to a followed public playlist notifies followers, private dumps exc
   });
 });
 
+test("a playlist going public notifies its followers of the public dumps added meanwhile", async () => {
+  const owner = await createUser();
+  const follower = await createUser();
+  const { id } = insertPlaylist({ userId: owner.id, title: "Mix" });
+  await put(`/api/me/follow/playlists/${id}`, { auth: follower.auth });
+  const before = insertDump({ userId: owner.id, title: "Before" });
+  await post(`/api/playlists/${id}/dumps/${before.id}`, { auth: owner.auth });
+  db.prepare(`DELETE FROM notifications WHERE user_id = ?;`).run(owner.id);
+  const setPublic = (isPublic: boolean) =>
+    put(`/api/playlists/${id}`, { auth: owner.auth, json: { isPublic } });
+
+  await setPublic(false);
+  const during = insertDump({ userId: owner.id, title: "During" });
+  const priv = insertDump({ userId: owner.id, isPrivate: true });
+  for (const d of [during, priv]) {
+    await post(`/api/playlists/${id}/dumps/${d.id}`, { auth: owner.auth });
+  }
+  assertEquals(count(`SELECT COUNT(*) as n FROM notifications;`), 1);
+  await setPublic(true);
+  const titles = (db.prepare(
+    `SELECT data FROM notifications WHERE user_id = ? ORDER BY created_at;`,
+  ).all(follower.id) as { data: string }[]).map((n) =>
+    JSON.parse(n.data).dumpTitle
+  );
+  assertEquals(titles, ["Before", "During"]);
+});
+
 test("playlist covers: upload and serve", async () => {
   const owner = await createUser();
   const other = await createUser();