diff --git a/src-tauri/src/pdf.rs b/src-tauri/src/pdf.rs
index 9df94fb..2032d05 100644
--- a/src-tauri/src/pdf.rs
+++ b/src-tauri/src/pdf.rs
@@ -65,3 +65,53 @@ fn format_source_diagnostics(diagnostics: &[SourceDiagnostic]) -> String {
         .collect::<Vec<_>>()
         .join("\n")
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // A faithful single-chapter preview source produced by chapterToPdfInputs
+    // (preamble #let macros + page numbering reset + opener + body).
+    const CHAPTER_PREVIEW: &str = r##"#set document(title: "The Lighthouse", author: "")
+#set page(
+  width: 6in + 0.125in,
+  height: 9in + 0.125in * 2,
+  margin: (inside: 0.875in, outside: 0.625in + 0.125in, top: 0.8in + 0.125in, bottom: 0.8in + 0.125in),
+  binding: left,
+)
+#set text(font: "Literata", size: 11pt, lang: "en", hyphenate: true)
+#set par(justify: true, leading: 0.72em, spacing: 0.72em, first-line-indent: (amount: 1.3em, all: false))
+#show heading: set text(font: "Literata", weight: "medium")
+#show heading.where(level: 1): set text(size: 22pt)
+
+#let scenebreak = align(center)[#v(0.5em) #line(length: 13%, stroke: 0.5pt + rgb("#d6cfbd")) #v(0.5em)]
+#let blockquote(body) = pad(left: 1.2em)[#set text(style: "italic", fill: rgb("#6b6458")); #body]
+#let chapteropener(num, title) = {
+  pagebreak(weak: true)
+  v(2.1in)
+  align(center)[
+    #text(font: "Hanken Grotesk", size: 8.5pt, weight: "semibold", tracking: 0.28em)[#upper("Chapter " + num)]
+    #v(0.7em)
+    #heading(level: 1, numbering: none, outlined: true)[#title]
+  ]
+  v(1.5em)
+}
+
+#set page(numbering: "1")
+#counter(page).update(1)
+
+#chapteropener("1", [The Lighthouse])
+
+The lamp had not been lit in thirty years.
+
+#scenebreak
+
+Morning came the color of pewter.
+"##;
+
+    #[test]
+    fn compiles_a_single_chapter_preview() {
+        let pdf = compile(CHAPTER_PREVIEW.to_string(), &[]).expect("chapter preview should compile");
+        assert!(pdf.starts_with(b"%PDF"), "output should be a PDF");
+    }
+}