Self-hosted diagrams.net URLs never match the embed — settings key mismatch

Is there an existing issue for this?

• I have searched the existing issues

This is not related to configuring Outline

• The issue is not related to self-hosting config

This is a code-level key mismatch, not a configuration problem: the settings screen writes one key shape and the embed matcher reads another, so a correctly configured value can never be used.

Current Behavior

With a self-hosted diagrams.net instance configured under Settings → Integrations → Diagrams.net, pasting a URL from that instance into a document shows "Embed · not supported" (disabled) in the paste menu. Only viewer.diagrams.net URLs are recognized.

Expected Behavior

A URL from the configured self-hosted instance should be offered as an embed, the same way viewer.diagrams.net URLs are.

Steps To Reproduce

1. Settings → Integrations → Diagrams.net → set installation URL to e.g. https://drawio.example.com/
2. Open any document, paste https://drawio.example.com/?lightbox=1#R<compressed-xml> on its own line
3. The paste menu shows "Embed · not supported"; pasting https://viewer.diagrams.net/?lightbox=1#R<...> in the same document offers "Embed" normally

Root cause

The settings screen stores the URL nested under the service name:

// plugins/diagrams/client/Settings.tsx
await integrations.save({
  service: IntegrationService.Diagrams,
  settings: {
    diagrams: { url: data.url.replace(/\/?$/, "/") },
  },
});

useEmbeds assigns those settings to the descriptor verbatim:

// app/hooks/useEmbeds.ts
if (integration?.settings) {
  e.settings = integration.settings;   // => { diagrams: { url } }
}

but the matcher reads a flat url:

// shared/editor/embeds/index.tsx
matcher(url) {
  const settingsDomainRegex = this.settings?.url      // always undefined
    ? urlRegex(this.settings?.url)
    : undefined;
  ...
}

So settingsDomainRegex is never built and only the built-in /^https:\/\/viewer\.diagrams\.net\/(?!proxy).*/ regex remains.

I verified this against a live instance: rewriting the stored settings to the flat shape ({"url": "https://drawio.example.com/"}) via integrations.update did not help either, which suggests a second factor — useEmbeds(loadIfMissing = false) means the document editor never fetches embed integrations, so the settings may not reach the descriptor at all in that view. I could not confirm the second part conclusively; the key mismatch above is unambiguous from the source.

Suggested fix

Make the two sides agree — either

// shared/editor/embeds/index.tsx
const settingsDomainRegex = this.settings?.diagrams?.url ? urlRegex(this.settings.diagrams.url) : undefined;

or store the flat shape in plugins/diagrams/client/Settings.tsx.

Environment

• Version: 1.9.2 (self-hosted); the same code is present on main as of 2026-08
• Browser: Chrome