fix Mastodon link verification

the top element must be a single <a> in order for verification to work, so MfmService has gained an 'inline' argument to remove the <p> added by default

packages/backend/src/core/MfmService.ts

@@ -377,7 +377,7 @@ export class MfmService {
 	}
 
 	@bindThis
-	public toHtml(nodes: mfm.MfmNode[] | null, mentionedRemoteUsers: IMentionedRemoteUsers = [], additionalAppenders: Appender[] = []) {
+	public toHtml(nodes: mfm.MfmNode[] | null, mentionedRemoteUsers: IMentionedRemoteUsers = [], additionalAppenders: Appender[] = [], inline = false) {
 		if (nodes == null) {
 			return null;
 		}
@@ -626,9 +626,15 @@ export class MfmService {
 			additionalAppender(doc, body);
 		}
 
-		return domserializer.render(body, {
+		let result = domserializer.render(body, {
 			encodeEntities: 'utf8'
 		});
+
+		if (inline) {
+			result = result.replace(/^<p>/, '').replace(/<\/p>$/, '');
+		}
+
+		return result;
 	}
 
 	// the toMastoApiHtml function was taken from Iceshrimp and written by zotan and modified by marie to work with the current MK version

packages/backend/src/core/activitypub/ApRendererService.ts

@@ -584,7 +584,7 @@ export class ApRendererService {
 		const attachment = profile.fields.map(field => ({
 			type: 'PropertyValue',
 			name: field.name,
-			value: this.mfmService.toHtml(mfm.parse(field.value)),
+			value: this.mfmService.toHtml(mfm.parse(field.value), [], [], true),
 		}));
 
 		const emojis = await this.getEmojis(user.emojis);

packages/backend/test/unit/MfmService.ts

@@ -63,6 +63,12 @@ describe('MfmService', () => {
 			const output = '<p><ruby><span><i>some</i> text</span><rp>(</rp><rt>ignore me</rt><rp>)</rp></ruby></p>';
 			assert.equal(mfmService.toHtml(mfm.parse(input)), output);
 		});
+
+		test('inline', () => {
+			const input = 'https://example.com';
+			const output = '<a href="https://example.com">https://example.com</a>';
+			assert.equal(mfmService.toHtml(mfm.parse(input), [], [], true), output);
+		});
 	});
 
 	describe('toMastoApiHtml', () => {