Items written in Markdown show formatted (#284)

A description with Markdown and no HTML tag is rendered to HTML with
pulldown-cmark, and an item with no text but RSS's <source:markdown>
(https://source.scripting.com/, as Scripting News sends beside its HTML) uses
that. HTML is left alone, and plain text without Markdown in it stays as it
was, so a line like "1984. ..." is not made a list. ammonia cleans the result
as any feed's HTML. Stored items keep what they have: the scanner does not
rewrite an item it has.

Reference: http://scripting.com/2026/10/06/005559.html

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/feed/Cargo.toml

@@ -9,6 +9,7 @@ anyhow.workspace = true
 atom_syndication.workspace = true
 chrono.workspace = true
 opml.workspace = true
+pulldown-cmark.workspace = true
 quick-xml.workspace = true
 reqwest.workspace = true
 rss.workspace = true

crates/feed/src/lib.rs

@@ -767,8 +767,9 @@ fn from_rss(ch: rss::Channel, bytes: &[u8]) -> ParsedFeed {
                 title: title_text(item.title()),
                 link: non_empty(item.link()),
                 published: item.pub_date().and_then(parse_date),
-                // Content wins over description, as __getEntries preferred entry.content.
-                description: body(item.content(), item.description()),
+                // Content wins over description, as __getEntries preferred entry.content. The
+                // source namespace's Markdown copy only when there is neither (#284).
+                description: notes(item.content(), item.description(), source_markdown(item)),
                 categories: item
                     .categories()
                     .iter()
@@ -837,7 +838,7 @@ fn from_atom(feed: atom_syndication::Feed) -> ParsedFeed {
                 title: title_text(Some(e.title().as_str())),
                 link: alt.map(str::to_owned),
                 published: e.published().or(Some(e.updated())).map(|d| d.timestamp()),
-                description: body(e.content().and_then(|c| c.value()), e.summary().map(|s| s.as_str())),
+                description: notes(e.content().and_then(|c| c.value()), e.summary().map(|s| s.as_str()), None),
                 categories: e.categories().iter().map(|c| c.term().to_owned()).collect(),
                 explicit: false,
                 image: None,
@@ -936,6 +937,42 @@ fn title_text(s: Option<&str>) -> Option<String> {
     non_empty(Some(&out))
 }
 
+/// An item's notes as HTML: `body`, with Markdown made HTML, whether the feed wrote its text in
+/// Markdown or sent only a Markdown copy (#284). The page cleans it as it does any feed's HTML.
+fn notes(content: Option<&str>, description: Option<&str>, markdown: Option<&str>) -> Option<String> {
+    match body(content, description) {
+        Some(b) if is_markdown(&b) => Some(markdown_html(&b)),
+        Some(b) => Some(b),
+        None => non_empty(markdown).map(|m| markdown_html(&m)),
+    }
+}
+
+/// `<source:markdown>`, from https://source.scripting.com/: the item's text in Markdown.
+///
+/// shortcut: found by the `source` prefix the namespace's own docs and feeds use; a feed binding
+/// it to another prefix is not read, until one turns up.
+fn source_markdown(item: &rss::Item) -> Option<&str> {
+    item.extensions().get("source")?.get("markdown")?.first()?.value()
+}
+
+/// Text with no HTML tag and some Markdown: a link, a heading, a list, a quote, code or bold.
+/// Plain text without any is left as it was, since rendering it would change nothing but
+/// could still read a line starting "1984." as a list.
+fn is_markdown(s: &str) -> bool {
+    let tag = s
+        .match_indices('<')
+        .any(|(i, _)| s[i + 1..].starts_with(|c: char| c.is_ascii_alphabetic() || c == '/' || c == '!'));
+    let block = |l: &str| ["# ", "## ", "### ", "- ", "* ", "> ", "```"].iter().any(|m| l.trim_start().starts_with(m));
+    !tag && (s.contains("](") || s.contains("**") || s.lines().any(block))
+}
+
+fn markdown_html(md: &str) -> String {
+    use pulldown_cmark::{Options, Parser, html};
+    let mut out = String::new();
+    html::push_html(&mut out, Parser::new_ext(md, Options::ENABLE_TABLES | Options::ENABLE_STRIKETHROUGH));
+    out
+}
+
 /// An item's show notes: its full body when that is whole, else its description.
 ///
 /// libsyn served Daily Meditation Podcast's `content:encoded` cut at the `>` inside a class name
@@ -1361,6 +1398,31 @@ mod tests {
         assert_eq!(parse(atom).unwrap().description.as_deref(), Some("Or here."));
     }
 
+    #[test]
+    fn markdown_notes_are_made_html_and_html_is_left_alone() {
+        let feed = |items: &str| {
+            let xml = format!(
+                r#"<?xml version="1.0"?><rss version="2.0" xmlns:source="https://source.scripting.com/"><channel><title>R</title>{items}</channel></rss>"#
+            );
+            parse(xml.as_bytes()).unwrap().entries.into_iter().map(|e| e.description).collect::<Vec<_>>()
+        };
+        let got = feed(
+            r#"<item><guid>a</guid><description># Hi
+
+Some **bold** and [a link](https://x.example/).</description></item>
+            <item><guid>b</guid><source:markdown>Only *Markdown* here.</source:markdown></item>
+            <item><guid>c</guid><description>&lt;p&gt;HTML **as sent**&lt;/p&gt;</description><source:markdown>ignored</source:markdown></item>
+            <item><guid>d</guid><description>1984. Plain text, left as it is.</description></item>"#,
+        );
+        assert_eq!(
+            got[0].as_deref(),
+            Some("<h1>Hi</h1>\n<p>Some <strong>bold</strong> and <a href=\"https://x.example/\">a link</a>.</p>\n")
+        );
+        assert_eq!(got[1].as_deref(), Some("<p>Only <em>Markdown</em> here.</p>\n"), "the Markdown copy, alone");
+        assert_eq!(got[2].as_deref(), Some("<p>HTML **as sent**</p>"), "HTML wins, untouched");
+        assert_eq!(got[3].as_deref(), Some("1984. Plain text, left as it is."));
+    }
+
     #[test]
     fn a_file_wordpress_lists_twice_is_one_enclosure() {
         let xml = br#"<?xml version="1.0"?><rss version="2.0"><channel><title>R</title>