rss: render score head as HTML paragraph

Descriptions render as sanitized HTML in readers, where bare newlines
collapse and the feed/score line ran into the article text. Wrap the
headline in <p><em> so it breaks cleanly and reads as metadata, escaped
on the wire by encoding/xml as description-carried HTML should be.

2 files changed, 18 insertions, 11 deletions

diff --git a/cmds/rss.go b/cmds/rss.go
index 8679f6f..30be578 100644
--- a/cmds/rss.go
+++ b/cmds/rss.go
@@ -49,8 +49,9 @@ type rssDocument struct {
 // RSS 2.0 document. Each item title gets the source feed as a rune-capped
 // suffix (readers show the channel title as the source of every item, so
 // this is the only in-list provenance), and the description body opens
-// with feed + model score + the batch-wide median score. Item content was
-// already cleaned when the run row was written.
+// with feed + model score + the batch-wide median score as an emphasized
+// HTML paragraph (bare newlines collapse where descriptions render as
+// HTML). Item content was already cleaned when the run row was written.
 func RenderRSS(runs []core.RunRow) ([]byte, error) {
 	doc := rssDocument{
 		Version: "2.0",
@@ -95,9 +96,14 @@ func truncateRunes(s string, max int) string {
 	return string([]rune(s)[:max]) + "…"
 }
 
-// rssDescription builds the item body: first a headline line with the
-// source feed, model score, and batch-wide median (omitted for run rows
-// written before the median was logged), then the cleaned content (if any).
+// rssDescription builds the item body: first a headline with the source
+// feed, model score, and batch-wide median (omitted for run rows written
+// before the median was logged), then the cleaned content (if any). The
+// headline is wrapped in an emphasized HTML paragraph: descriptions render
+// as sanitized HTML in most readers, where bare newlines collapse and the
+// metadata line would run into the article text. encoding/xml escapes the
+// tags on the wire, which is exactly how description-carried HTML is meant
+// to be transported.
 func rssDescription(k core.KeptItem, median *float64) string {
 	head := fmt.Sprintf("score %.2f", k.Score)
 	if median != nil {
@@ -106,8 +112,9 @@ func rssDescription(k core.KeptItem, median *float64) string {
 	if k.FeedTitle != "" {
 		head = k.FeedTitle + " · " + head
 	}
-	if k.Content == "" {
-		return head
+	body := "<p><em>" + head + "</em></p>"
+	if k.Content != "" {
+		body += "\n" + k.Content
 	}
-	return head + "\n\n" + k.Content
+	return body
 }
diff --git a/cmds/rss_test.go b/cmds/rss_test.go
index ca216ca..79d6d37 100644
--- a/cmds/rss_test.go
+++ b/cmds/rss_test.go
@@ -51,21 +51,21 @@ func TestRenderRSSGolden(t *testing.T) {
       <link>https://example.com/c</link>
       <guid isPermaLink="false">mf:103</guid>
       <pubDate>Fri, 01 Mar 2024 11:00:00 +0000</pubDate>
-      <description>Feed A · score 0.80</description>
+      <description>&lt;p&gt;&lt;em&gt;Feed A · score 0.80&lt;/em&gt;&lt;/p&gt;</description>
     </item>
     <item>
       <title>Alpha &amp; Omega — Feed A</title>
       <link>https://example.com/a?x=1&amp;y=2</link>
       <guid isPermaLink="false">mf:101</guid>
       <pubDate>Fri, 01 Mar 2024 05:00:00 +0000</pubDate>
-      <description>Feed A · score 0.90 · batch median 0.55&#xA;&#xA;x &lt; y</description>
+      <description>&lt;p&gt;&lt;em&gt;Feed A · score 0.90 · batch median 0.55&lt;/em&gt;&lt;/p&gt;&#xA;x &lt; y</description>
     </item>
     <item>
       <title>Beta — A Feed With An Extremely Long And Descri…</title>
       <link>https://example.com/b</link>
       <guid isPermaLink="false">mf:102</guid>
       <pubDate>Fri, 01 Mar 2024 05:30:00 +0000</pubDate>
-      <description>A Feed With An Extremely Long And Descriptive Title Here · score 0.20 · batch median 0.55&#xA;&#xA;second body</description>
+      <description>&lt;p&gt;&lt;em&gt;A Feed With An Extremely Long And Descriptive Title Here · score 0.20 · batch median 0.55&lt;/em&gt;&lt;/p&gt;&#xA;second body</description>
     </item>
   </channel>
 </rss>`