Make syndication available to file at creation for webmention based syndication

[aciccarello]

Is your feature request related to a problem?

Related to #581, I would like to have a syndication plugin for indienews. My current flow is to include frontmatter of syndication: ["https://news.indieweb.org/en/"] on my post, then my webmention sending process forwards it to indienews. I can add config to pass IndieNews as a target but due to 0eb3fd5 that doesn't get passed to the file.

Describe the solution you’d like

mp-syndicate-to is available to file

Describe alternatives you’ve considered

Syndication plugins have a hook to pre-process metadata

Additional context

A key limitation in my setup is that I don't have a database so async processing is not an option. Also I'd like to avoid separate file updates anyway.

[rmdes]

I’ve hit exactly this, from a slightly different direction, and can offer a working implementation if it’s useful.

The case that makes this hard to work around is IndieNews. Submitting a post there means sending a webmention, but IndieNews then fetches the post and requires it to already contain a link to the target:

<a href="https://news.indieweb.org/en" class="u-syndication">IndieNews</a>

That creates an ordering problem that can’t be solved after the fact. The syndication property only exists after syndication has run, so it isn’t available when the file is written. The only thing known at creation time is the intent — which targets were selected — and that’s mp-syndicate-to, which getPostTemplateProperties strips along with the other server commands.

So on stock Indiekit there’s no point at which a template can render that link, and IndieNews rejects every submission with no_link_found. This isn’t awkward so much as structurally impossible, and it applies regardless of whether the webmention is sent by a build step (as @aciccarello does) or by a syndicator plug-in.

What I’ve been running

I’ve been running a fork of endpoint-micropub that preserves just that one property:

// mp-syndicate-to must appear in frontmatter so themes can render
// u-syndication links BEFORE the syndication webmention is sent
const preserveMpProperties = ["mp-syndicate-to"];

for (let key in templateProperties) {
  if (key.startsWith("mp-") && !preserveMpProperties.includes(key)) {
    delete templateProperties[key];
  }
}

The template then renders a u-syndication link for any pending target that needs one, and the syndicator sends the webmention once the post is published.

I realise 0eb3fd5 was deliberate, and I’m not suggesting the general principle is wrong — server commands mostly have no business in a post template. But mp-syndicate-to seems to be a genuine exception, because it’s the only record of intent that exists before syndication happens, and at least two of us have now needed it for the same reason.

Working IndieNews syndication

For what it’s worth, this does work in practice. I have an IndieNews syndicator (submits the webmention, handles the language-specific endpoints, returns the permalink) running against this, and posts land on the aggregator normally:

• https://news.indieweb.org/en/rmendes.net/articles/2026/05/20/building-plume/
• https://news.indieweb.org/en/rmendes.net/articles/2026/03/27/building-newsdiff-tracking-how-news-changes-after-publication/

Happy to open a PR for the endpoint-micropub change on its own, with tests — it’s small and self-contained. And if an IndieNews syndicator is something you’d want in Indiekit rather than as a third-party plug-in, I’m glad to contribute that too, though I’d rather agree the approach with you first than arrive with a finished thing.

One implementation note in case it’s useful to anyone else finding this: IndieNews fetches the source URL exactly as submitted and doesn’t follow redirects to find the markup, so the URL in properties.url needs to match the address the post is actually served from, trailing slash and all.

[aciccarello]

My workaround was to add a wrapper to the micropub endpoint that changes the mp-syndicate-to to a syndication property. It works but even at under 250 lines is more complex than I would like.

I think the original change that stripped mp-* server action fields makes sense. In this case I would like to see a way for syndication plugins to hook into this command and modify the post output synchronously. Something like a getSyndicationUrl() method specifically for these webmention based syndicators that would ad the syndication property to the object that the file formatters ingest. I'll play around with what the implementation looks like to see if it makes sense.

It's more complex than passing though the mp-* properties but seems more logically consistent and avoids pushing extra logic into the file formatters.

[aciccarello]

I opened two related PRs, one adds a hook for syndicators. The other adds an indienews plugin that works for my flow but I'm not sure it's a good general syndicator. But I included it as an example.