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/0013_dump_url_canonical.ts

@@ -1,19 +1,12 @@
 /**
- * Adds `dumps.url_canonical` — the lookup key behind the "already dumped?"
- * check on the create form — and backfills it for every existing URL dump.
+ * Adds `dumps.url_canonical`, the key the create form's "already dumped" hint
+ * looks a URL up by, and fills it for every URL dump already posted.
  *
- * Purely local: it re-derives the key from the URL already stored on each row
- * and makes no network calls.
- *
- * The helpers below are a deliberate frozen copy of `api/lib/canonical-url.ts`
- * as it stood when this migration shipped, not an import of it. A migration
- * runs exactly once per database, so importing the live version would mean two
- * databases migrating at different times end up with keys computed under
- * different rules. Improving the shared canonicalizer therefore calls for a new
- * backfill migration rather than an edit here.
- *
- * Idempotent: the column is only added when missing and only rows whose key is
- * still NULL are touched, so a fresh database built from schema.sql is a no-op.
+ * It fills the key from each stored URL and fetches nothing. Its helpers are a
+ * copy of lib/canonical-url.ts as it stood when this shipped: importing the
+ * live one would give two databases migrated at different times keys made by
+ * different rules. A change to lib/canonical-url.ts therefore needs a new
+ * migration that fills the keys again.
  *
  * @module
  */
@@ -98,7 +91,10 @@ function canonicalizeUrl(raw: string): string | null {
   return `https://${host}${path}${query ? `?${query}` : ""}${hash}`;
 }
 
-/** Applies this migration to `db`. */
+/**
+ * Run once by `runMigrations`. It fills only the keys still NULL, and leaves
+ * NULL a URL that isn't http(s).
+ */
 export function up(db: DatabaseSync): void {
   const columns = db.prepare(`PRAGMA table_info(dumps);`).all() as {
     name: string;