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/db/migrations/0016_performance_indexes.ts

@@ -1,24 +1,21 @@
 /**
- * Indexes for the queries that ran as full scans.
- *
- * - feeds page by created_at (newest first), a user's dumps and upvotes by
- *   (user_id, created_at) — these replace the bare user_id indexes;
- * - dump and playlist pages are looked up by slug;
- * - the child side of every ON DELETE CASCADE / SET NULL foreign key, which
- *   SQLite otherwise scans on each parent delete (a comment's replies, a user's
- *   comments, follows, chat messages, invites, reset tokens), and the
- *   followers of a user or playlist, read on every new dump;
- * - @mentions resolve usernames case-insensitively, by lower(username).
- *
- * Idempotent: also runs against fresh databases created from schema.sql, where
- * these indexes already exist.
+ * Adds indexes for the queries that scanned a whole table. The feeds page
+ * dumps by `created_at`, and a user's dumps and upvotes by `(user_id,
+ * created_at)`, which replace the indexes on `user_id` alone. Dumps and
+ * playlists are looked up by slug. Each foreign key with ON DELETE gets an
+ * index on its child column, which SQLite otherwise scans on every delete of
+ * a parent row, and the followers of a user or playlist are read on every new
+ * dump. Mentions look usernames up by `lower(username)`.
  *
  * @module
  */
 
 import type { DatabaseSync } from "node:sqlite";
 
-/** Applies this migration to `db`. */
+/**
+ * Run once by `runMigrations`. A database made from schema.sql already has
+ * these indexes.
+ */
 export function up(db: DatabaseSync): void {
   db.exec(`
     DROP INDEX IF EXISTS idx_dumps_user;