Query with limit=1 returns empty for non-empty feed - app.bsky.feed.getAuthorFeed

[oestradiol]

Describe the bug

If you pass the query filters...

• limit=1;
• filter=posts_and_author_threads
• no cursor (although I didn't test with a cursor, but the idea is fetching the latest post, so I don't think this will be particularly relevant)

...to app.bsky.feed.getAuthorFeed, and the last post the person made was deleted, it returns an empty feed (as if they had 0 posts) instead of their actual last available post.

To Reproduce

Steps to reproduce the behavior:

1. Make sure you have at least one post;
2. Post or Repost anything;
3. Undo the previous action;
4. Issue a request: {{your_pds}}/xrpc/app.bsky.feed.getAuthorFeed?actor={{your_did}}&filter=posts_and_author_threads&limit=1

Expected behavior

One would expect the XRPC to return an array containing the last available post.

Additional context

I'm not sure because haven't read much of this codebase, but I think it might be related to this:
The field nullsLast is undefined by default...

atproto/packages/bsky/src/data-plane/server/db/pagination.ts

Lines 135 to 152 in c5b765d

	opts: {
	limit?: number
	cursor?: string
	direction?: 'asc' | 'desc'
	keyset: K
	tryIndex?: boolean
	// By default, pg does nullsFirst
	nullsLast?: boolean
	},
	): QB => {
	const {
	limit,
	cursor,
	keyset,
	direction = 'desc',
	tryIndex,
	nullsLast,
	} = opts

...and should be for getAuthorFeed too, since it's not set here:

atproto/packages/bsky/src/data-plane/server/routes/feeds.ts

Lines 48 to 52 in c5b765d

	builder = paginate(builder, {
	limit,
	cursor,
	keyset,
	})

Because of that, it reaches this query if statement:

atproto/packages/bsky/src/data-plane/server/db/pagination.ts

Lines 156 to 158 in c5b765d

	.if(!nullsLast, (q) =>
	q.orderBy(keyset.primary, direction).orderBy(keyset.secondary, direction),
	)

According to the Postgres documentation (and as mentioned on line 141 of pagination.ts above):

[oestradiol]

Update: Mary (@mary-ext) mentioned something relevant, so I'm adding this here.

"posts_and_author_threads have an additional filter that's done outside of a db query so part of it could be that"