FIX: avoid inline oneboxing watched words on rich editor (#37349)

Watched link words can generate `link_open` markdown-it tokens with a
`linkify` `markup`. This attribute is used both to allow serialization
back to markdown without the link `[]()` syntax, and also to be captured
by the onebox extension to trigger a oneboxing attempt.

This PR adds a test to only attempt oneboxes to `linkify` links that
also happen to have a URL-like content, avoiding this edge case.

frontend/discourse/app/static/prosemirror/extensions/onebox.js

@@ -5,7 +5,10 @@ import {
 import { load } from "pretty-text/oneboxer";
 import { ajax } from "discourse/lib/ajax";
 import escapeRegExp from "discourse/lib/escape-regexp";
-import { isWhiteSpace } from "discourse/static/prosemirror/lib/markdown-it";
+import {
+  getLinkify,
+  isWhiteSpace,
+} from "discourse/static/prosemirror/lib/markdown-it";
 import { isTopLevel } from "discourse-markdown-it/features/onebox";
 
 /** @type {RichEditorExtension} */
@@ -169,6 +172,8 @@ const extension = {
 
             if (
               link?.attrs.markup === "linkify" &&
+              // Excludes watched word links
+              getLinkify().test(node.text) &&
               set.find(pos, pos + node.nodeSize).length === 0 &&
               isOutsideSelection(pos, node.nodeSize, tr)
             ) {

spec/system/composer/prosemirror_onebox_spec.rb

@@ -180,4 +180,34 @@ describe "Composer - ProseMirror - Oneboxing", type: :system do
 
     expect(composer).to have_value("Hey https://example.com/x and https://example.com/x")
   end
+
+  context "with watched word links" do
+    fab!(:topic) { Fabricate(:topic, user: current_user) }
+    fab!(:post) do
+      Fabricate(:post, topic:, user: current_user, raw: "Check out discourse for more info")
+    end
+    fab!(:watched_word) do
+      Fabricate(
+        :watched_word,
+        action: WatchedWord.actions[:link],
+        word: "discourse",
+        replacement: "https://example.com/x",
+      )
+    end
+
+    it "does not onebox watched word links" do
+      visit "/t/#{topic.slug}/#{topic.id}"
+      find(".post-action-menu__edit").click
+      expect(composer).to be_opened
+      composer.focus
+
+      expect(rich).to have_css("a[href='https://example.com/x']", text: "discourse")
+      expect(rich).to have_no_css("a.inline-onebox")
+      expect(rich).to have_no_css(".inline-onebox-loading")
+
+      composer.toggle_rich_editor
+
+      expect(composer).to have_value("Check out discourse for more info")
+    end
+  end
 end