From 031101c382b8a05575cf0ab66dc8764d43301c46 Mon Sep 17 00:00:00 2001
From: James Griffin <james@unsupervised.ca>
Date: Thu, 27 Aug 2026 16:19:25 -0300
Subject: [PATCH] Show a picture whose address was typed without a scheme

`preview.redd.it/lz4drsqh0clh1.jpeg?width=1290&...` was rendering as plain
text -- not a picture, and not even a link. The bare-address rule has always
insisted on `https://`, so anything copied out of an address bar, where the
browser hides the scheme, fell through to nothing at all. That predates the
inline images from the last commit; it just did not matter until pictures
started being worth placing.

The rule is deliberately narrow: a host with a dot, a path, and an image
extension. Widening it to every schemeless address would be the obvious move
and is wrong, because a comment thread is full of dotted, slashed prose --
`src/render/post.ts` would become a link to a website in Tonga, and
`node_modules/foo/bar.js` a website in Jersey. Requiring the extension costs
nothing here, since the only thing worth guessing a scheme for is a picture.

https is assumed. Every host that serves these redirects to it anyway.

Checked both ways: the four address shapes that should become pictures do,
and nine pieces of ordinary prose that must not -- file paths, a Windows
drive letter, a relative path, an email address followed by a filename, a
version number -- still do not.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017nMQ2eDKnqALYhAibpTKTu
---
 CLAUDE.md              |  5 ++++-
 src/render/markdown.ts | 16 +++++++++++++---
 test/markdown.test.ts  | 31 +++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/CLAUDE.md b/CLAUDE.md
index 2366241..da93618 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -153,7 +153,10 @@ Things worth knowing before editing:
   a key in that same comment's own `media_metadata`, so `resolveInlineImages` is one
   lookup rather than three special cases. A bare `preview.redd.it` address pasted into a
   comment is in there too, keyed by the id inside the URL. Prefer `s.gif` over `s.mp4`
-  for an animated one: a GIF moves in an `<img>` and an MP4 needs a player.
+  for an animated one: a GIF moves in an `<img>` and an MP4 needs a player. An address
+  typed without a scheme counts as well, but only when it ends in an image extension —
+  the rule wants a host, a path *and* that extension, because comments are full of
+  dotted, slashed prose that must not turn into links.
 - **Threads** — same media schema as Instagram (`src/platforms/meta-media.ts`). Its
   payloads are full of empty stub nodes, so the finder only accepts a node with actual
   candidates in it. The page ships the linked post, the author's follow-ups, other
diff --git a/src/render/markdown.ts b/src/render/markdown.ts
index 4f519e4..cd1c0c4 100644
--- a/src/render/markdown.ts
+++ b/src/render/markdown.ts
@@ -69,7 +69,12 @@ const INLINE = new RegExp(
     '(?<![\\w*])\\*([^*\\n]+)\\*(?![\\w*])', // 8 em with asterisks
     '(?<![\\w_])_([^_\\n]+)_(?![\\w_])', // 9 em with underscores
     '(https?://[^\\s<>]+)', // 10 bare url
-    '(?<![\\w/])(/?[ru]/[A-Za-z0-9_][A-Za-z0-9_-]{1,30})', // 11 r/sub and u/name
+    // 11 the same thing with the scheme left off, which is how people type
+    // them. Narrow on purpose: a host, a path, and an image extension. Prose
+    // is full of dotted words, and `src/render/post.ts` must not become a
+    // link to a website in Tonga.
+    '(?<![\\w@/.])((?:[a-z0-9-]+\\.)+[a-z]{2,}/[^\\s<>]*\\.(?:jpe?g|png|gif|webp|avif)(?:\\?[^\\s<>]*)?)',
+    '(?<![\\w/])(/?[ru]/[A-Za-z0-9_][A-Za-z0-9_-]{1,30})', // 12 r/sub and u/name
   ].join('|'),
   'g',
 );
@@ -80,8 +85,8 @@ function inline(text: string, image?: ImageRenderer): string {
   let cursor = 0;
 
   for (const match of text.matchAll(INLINE)) {
-    const [whole, code, alt, src, label, href, strong, strike, emStar, emScore, url, subOrUser] =
-      match;
+    const [whole, code, alt, src, label, href, strong, strike, emStar, emScore, url, schemeless,
+      subOrUser] = match;
     out += escapeHtml(text.slice(cursor, match.index));
     cursor = match.index + whole.length;
 
@@ -113,6 +118,11 @@ function inline(text: string, image?: ImageRenderer): string {
       } else {
         out += anchor(safe, trimmed.replace(/^https?:\/\/(www\.)?/, '')) + tail;
       }
+    } else if (schemeless !== undefined) {
+      // Assumed https: every host that serves these redirects to it anyway,
+      // and a picture is the one thing worth guessing a scheme for.
+      const safe = safeHref(`https://${schemeless}`);
+      out += safe ? (image ? image(safe, '') : anchor(safe, schemeless)) : escapeHtml(whole);
     } else if (subOrUser !== undefined) {
       const path = subOrUser.startsWith('/') ? subOrUser : `/${subOrUser}`;
       out += anchor(`${REDDIT}${path}`, subOrUser);
diff --git a/test/markdown.test.ts b/test/markdown.test.ts
index ae7baa2..7d7576e 100644
--- a/test/markdown.test.ts
+++ b/test/markdown.test.ts
@@ -122,3 +122,34 @@ test("an image's alt text is escaped like anything else a stranger wrote", () =>
 test('images inside a quote are still placed', () => {
   assert.match(mdi('> ![](https://i.redd.it/x.gif)'), /<blockquote><p><img/);
 });
+
+test('an image address typed without a scheme is still the picture', () => {
+  // Which is how people type them: no https, straight from the address bar.
+  const out = mdi('preview.redd.it/lz4drsqh0clh1.jpeg?width=1290&s=b27e');
+  assert.ok(out.includes('<img src="https://preview.redd.it/lz4drsqh0clh1.jpeg?width=1290&amp;s=b27e"'), out);
+});
+
+test('a schemeless image address mid-sentence keeps the sentence', () => {
+  const out = mdi('look at i.redd.it/x.png nice one');
+  assert.ok(out.startsWith('<p>look at <img'), out);
+  assert.ok(out.endsWith(' nice one</p>'), out);
+});
+
+test('prose full of dots and slashes is not mistaken for an address', () => {
+  // The reason this rule insists on a host, a path and an image extension.
+  for (const text of [
+    'the file is at src/render/post.ts',
+    'see node_modules/foo/bar.js',
+    'a path like ./images/cat.jpg',
+    'C:/Users/x/cat.png',
+    'email someone@example.com/nope.jpg',
+    'version 1.2.3/4.png',
+  ]) {
+    assert.ok(!mdi(text).includes('<img'), `treated as an image: ${text}`);
+  }
+});
+
+test('a schemeless address that is not an image is left alone', () => {
+  // Guessing a scheme is worth it for a picture and not for prose.
+  assert.equal(mdi('example.com/article'), '<p>example.com/article</p>');
+});