v3: comments say what the code can't — the documentation pass wanted JSDoc on every export and every field of an exported interface, which filled the code with restatements ("The dump.", "Whether it is loading.", "The props of X.", "Renders the X.") and module docs that told a reader nothing ("The hot and new feeds, and the props every main feed of the index takes."); some were wrong as well as vague. Every comment in api/, shared/ and src/ is rewritten under one rule, now stated in the README's "Comments" section: every module and export still has a JSDoc, and it gives context (who uses it and where), usage (what a caller must know: a precondition, what it leaves to the caller, a side effect) or its place in the chain (where its input comes from, where its output goes); a field, parameter, private function or local gets one only when it adds to its parent's, and context about a whole type goes on the type; a type's doc is phrased from the value's side ("Returned to Y by X when Z", "Passed to Y by X"); full sentences, as short as they can be, no label-colon-list; // goes wherever the code isn't obvious and says why, and the section banners and narration go. Every claim was checked against the code, which turned up some forty comments that were wrong: DumpCard's claimed it was only used by the hot and new feeds, the WebSocket welcome claimed to be a socket's first message (presence comes first), UpdateUserRequest said null removes a description (it keeps it), deletedDumpIds leaves out that it also holds dumps made private, THEME_COLOR claimed to mirror index.html's, and the like. The routers' JSDoc now says where they are mounted and what becomes of a thrown APIException. doc-lint.ts lets a field without a doc through; a module or export without one still fails. No code changes; 204 backend and 628 frontend tests pass, and doc:lint, deno check, deno lint and tsc are clean.

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

api/lib/playlist-members.ts

@@ -1,26 +1,30 @@
 /**
- * Which of a playlist's dumps a given viewer may see.
+ * Decides which of a playlist's dumps a viewer may see. The playlist service
+ * filters its listings with it, and the WebSocket service filters each
+ * client's `playlist_dumps_updated` message the same way.
  *
  * @module
  */
 
 import type { Playlist } from "../../shared/playlist.ts";
 
-/** A playlist's dump, with what deciding who may see it takes. */
+/**
+ * The fields of a playlist's dump that {@link isMemberVisibleTo} needs. A
+ * `Dump` has them. For its broadcasts, the playlist service reads only these.
+ */
 export interface PlaylistMember {
-  /** The dump's id. */
   id: string;
-  /** Whether the dump is private. */
   isPrivate: boolean;
-  /** The id of the dump's poster. */
+  /** The dump's poster, not the playlist's owner. */
   userId: string;
 }
 
 /**
- * Checks whether `viewerId` sees this member when the playlist is shown to them: a
- * public dump, or a private one of the owner's own, to the owner. Everyone
- * else — moderators too — doesn't see private dumps, and neither does the
- * owner see someone else's dump once it has gone private.
+ * Checks whether `viewerId` may see `member` in `playlist`. A public dump is
+ * visible to all. A private dump is visible only to the playlist's owner, and
+ * only if they posted it: moderators don't see it, and neither does the owner
+ * once someone else's dump in their playlist goes private. A null or undefined
+ * `viewerId` is a signed-out viewer.
  */
 export function isMemberVisibleTo(
   member: PlaylistMember,