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Pre-flight the post-length guard so an over-limit publish can't orphan a document
The 300-grapheme backstop lived inside buildBskyPost, which publish() calls
at step 2 — after step 1 has already created the document record. If it fired,
the PDS kept a published-but-postless document (and a retry minted a second
orphan). Hoist the check into a shared assertBskyPostWithinLimit() and run it
in publish() before any record is written; buildBskyPost keeps calling it as a
final backstop. Adds a regression test asserting an over-limit publish rejects
with zero records written.
author
Jeremy Herve
date
(Jun 12, 2026, 7:19 PM +0200)
commit
a4493d20
a4493d209dc678346082619b63cabe4c2a9bdbf0
parent
59fc8ed7
59fc8ed78178a3d29109791475bf15b408221f8f
+55
-7
+20
src/lib/publish/publisher.test.ts
+20
src/lib/publish/publisher.test.ts
···
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] );
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expect( docWrites.at( -1 )!.record.bskyPostRef ).toBeDefined();
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} );
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+
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it( 'rejects an over-limit post before writing ANY record (no orphan document)', async () => {
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const { agent, created } = fakeAgent();
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await expect(
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publish(
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agent,
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{ did: 'did:plc:me', handle: 'me.bsky.social' },
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{
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title: 'Hello',
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description: 'x'.repeat( 320 ),
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blocks: BLOCKS,
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publicationUri: 'at://did:plc:me/site.standard.publication/pub',
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publicationCid: 'cidpub',
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publicationSlug: 'pub',
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}
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)
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).rejects.toThrow( /300/ );
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// The grapheme guard must fire pre-flight: nothing was written to the PDS.
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expect( created ).toHaveLength( 0 );
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} );
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} );
+6
src/lib/publish/publisher.ts
+6
src/lib/publish/publisher.ts
···
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import {
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buildDocumentRecord,
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buildBskyPost,
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assertBskyPostWithinLimit,
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canonicalArticleUrl,
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type StrongRef,
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} from './records';
···
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const mentions = collectMentions( input.blocks );
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// The post BODY uses the writer-typed lede only (never the derived excerpt).
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const bodyLede = input.description?.trim() || undefined;
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+
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// Pre-flight the companion post's length BEFORE writing anything: if it's over the
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// grapheme limit, fail here rather than after step 1 has already created an orphan
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// document with no post (buildBskyPost repeats this check as a backstop).
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assertBskyPostWithinLimit( { title: input.title, articleUrl, bodyLede, mentions } );
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// 1. Document first (no bskyPostRef yet) so the post can embed its strongRef.
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const docRes = await agent.com.atproto.repo.createRecord( {
+29
-7
src/lib/publish/records.ts
+29
-7
src/lib/publish/records.ts
···
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}
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/** Bluesky rejects posts longer than this many graphemes. */
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-
const BSKY_POST_MAX_GRAPHEMES = 300;
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export const BSKY_POST_MAX_GRAPHEMES = 300;
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/**
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* Throw if the companion post would exceed Bluesky's grapheme limit. Call this as a
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* PRE-FLIGHT in `publish()` (before any record is written) so the guard can't leave an
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* orphaned document; `buildBskyPost` also calls it as a final backstop. Inputs match
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* `assemblePostText`, so the assembled text is identical to what gets published.
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*/
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export function assertBskyPostWithinLimit( input: {
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title: string;
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articleUrl: string;
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bodyLede?: string;
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mentions?: Mention[];
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} ): void {
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const { text } = assemblePostText( input );
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const length = graphemeLength( text );
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if ( length > BSKY_POST_MAX_GRAPHEMES ) {
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throw new Error(
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`Bluesky post is ${ length } characters; the limit is ${ BSKY_POST_MAX_GRAPHEMES }. Shorten the subtitle or remove a mention.`
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);
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}
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}
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/**
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* Build the companion Bluesky post (Decision 0005). Body text + facets come from
···
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mentions: input.mentions,
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} );
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-
const length = graphemeLength( text );
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if ( length > BSKY_POST_MAX_GRAPHEMES ) {
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throw new Error(
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`Bluesky post is ${ length } characters; the limit is ${ BSKY_POST_MAX_GRAPHEMES }. Shorten the subtitle or remove a mention.`
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);
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}
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// Backstop: `publish()` already pre-flights this before writing any record.
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assertBskyPostWithinLimit( {
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title: input.title,
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articleUrl: input.articleUrl,
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bodyLede: input.bodyLede,
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mentions: input.mentions,
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} );
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return {
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$type: 'app.bsky.feed.post',