fix: use link text as URL fallback when href is invalid (#3392)

Co-authored-by: Claude <noreply@anthropic.com>

Author: idoshamun

AGENTS.md

@@ -90,6 +90,7 @@ This file provides guidance to coding agents when working with code in this repo
 - Database reset before each test run via pretest hook
 - Fixtures in `__tests__/fixture/` for test data
 - Mercurius integration testing for GraphQL endpoints
+- Avoid creating multiple overlapping tests for the same scenario; a single test per key scenario is preferred
 
 **Infrastructure Concerns:**
 - OpenTelemetry for distributed tracing and metrics
@@ -114,4 +115,4 @@ Hooks are configured in `.claude/settings.json`:
 
 - **File Protection** (PreToolUse): Blocks edits to `pnpm-lock.yaml`, `src/migration/`, `.infra/Pulumi.*`, `.env`, `.git/`
 - **Prevent Force Push** (PreToolUse): Blocks `git push --force` and `git push -f`
-- **Auto-Lint** (PostToolUse): Runs `eslint --fix` on TypeScript files after edits
+- **Auto-Lint** (PostToolUse): Runs `eslint --fix` on TypeScript files after edits

__tests__/comments.ts

@@ -710,6 +710,18 @@ describe('query commentPreview', () => {
     );
   });
 
+  it('should use link text as URL fallback when href is invalid', async () => {
+    loggedUser = '1';
+    const res = await client.query(QUERY, {
+      variables: {
+        content: '[www.google.com](url)',
+      },
+    });
+    expect(res.errors).toBeFalsy();
+    // The invalid "url" href should be replaced with the link text
+    expect(res.data.commentPreview).toContain('href="https://www.google.com"');
+  });
+
   it('should only render markdown not HTML', async () => {
     loggedUser = '1';
     await saveCommentMentionFixtures();

src/common/markdown.ts

@@ -6,6 +6,7 @@ import { DataSource, EntityManager } from 'typeorm';
 import { MentionedUser } from '../schema/comments';
 import { EntityTarget } from 'typeorm/common/EntityTarget';
 import { ghostUser } from './utils';
+import { isValidHttpUrl } from './links';
 
 export const markdown: MarkdownIt = MarkdownIt({
   html: false,
@@ -126,7 +127,61 @@ markdown.renderer.rules.text = function (tokens, idx, options, env, self) {
   return renderMentions(content, mentions);
 };
 
+/**
+ * Extracts the text content from a link by looking at tokens following link_open.
+ * The link text appears in 'text' tokens between link_open and link_close.
+ */
+const getLinkText = (tokens: Token[], linkOpenIdx: number): string => {
+  let text = '';
+  for (let i = linkOpenIdx + 1; i < tokens.length; i++) {
+    if (tokens[i].type === 'link_close') {
+      break;
+    }
+    if (tokens[i].type === 'text') {
+      text += tokens[i].content;
+    }
+  }
+  return text.trim();
+};
+
+/**
+ * Attempts to convert text to a valid HTTP URL.
+ * Handles cases like "www.example.com" by prepending "https://".
+ */
+const toValidHttpUrl = (text: string): string | null => {
+  if (!text) return null;
+
+  // Already a valid HTTP URL
+  if (isValidHttpUrl(text)) {
+    return text;
+  }
+
+  // Try adding https:// prefix for URLs like www.example.com or example.com
+  const withProtocol = `https://${text}`;
+  if (isValidHttpUrl(withProtocol)) {
+    return withProtocol;
+  }
+
+  return null;
+};
+
 markdown.renderer.rules.link_open = function (tokens, idx, options, env, self) {
+  const token = tokens[idx];
+  const hrefIndex = token.attrIndex('href');
+
+  if (hrefIndex >= 0 && token.attrs) {
+    const href = token.attrs[hrefIndex][1];
+
+    // If the href is not a valid HTTP URL, try using the link text as the URL
+    if (!isValidHttpUrl(href)) {
+      const linkText = getLinkText(tokens, idx);
+      const validUrl = toValidHttpUrl(linkText);
+      if (validUrl) {
+        token.attrs[hrefIndex][1] = validUrl;
+      }
+    }
+  }
+
   tokens[idx] = setTokenAttribute(tokens[idx], 'target', '_blank');
   tokens[idx] = setTokenAttribute(tokens[idx], 'rel', 'noopener nofollow');
   return defaultRender(tokens, idx, options, env, self);