From 6d5adbb16a85bcfe0fb3dfbbb7c6921640253c9d Mon Sep 17 00:00:00 2001
From: Viktor Voropaev <v@vorou.com>
Date: Wed, 11 Mar 2026 12:50:08 -0700
Subject: [PATCH] Fix output block closing fence when content lacks trailing
 newline

Commands like `printf "hello"` produce output without a trailing newline,
causing the closing ``` fence to land on the same line as the output and
breaking the resulting markdown.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 markdown/writer.go      |  6 +++++-
 markdown/writer_test.go | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/markdown/writer.go b/markdown/writer.go
index 06d8593..53a7086 100644
--- a/markdown/writer.go
+++ b/markdown/writer.go
@@ -49,7 +49,11 @@ func writeBlock(w io.Writer, block Block) error {
 		return err
 	case OutputBlock:
 		fence := fenceFor(b.Content)
-		_, err := fmt.Fprintf(w, "%soutput\n%s%s\n", fence, b.Content, fence)
+		sep := ""
+		if b.Content != "" && !strings.HasSuffix(b.Content, "\n") {
+			sep = "\n"
+		}
+		_, err := fmt.Fprintf(w, "%soutput\n%s%s%s\n", fence, b.Content, sep, fence)
 		return err
 	case ImageOutputBlock:
 		_, err := fmt.Fprintf(w, "![%s](%s)\n", b.AltText, b.Filename)
diff --git a/markdown/writer_test.go b/markdown/writer_test.go
index 391a936..7267f70 100644
--- a/markdown/writer_test.go
+++ b/markdown/writer_test.go
@@ -128,6 +128,21 @@ func TestWriteOutputNoBackticks(t *testing.T) {
 	}
 }
 
+func TestWriteOutputNoTrailingNewline(t *testing.T) {
+	var buf strings.Builder
+	blocks := []Block{
+		OutputBlock{Content: "hello"},
+	}
+	err := Write(&buf, blocks)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := "```output\nhello\n```\n"
+	if buf.String() != expected {
+		t.Errorf("expected:\n%q\ngot:\n%q", expected, buf.String())
+	}
+}
+
 func TestWriteTitleWithDocumentID(t *testing.T) {
 	var buf strings.Builder
 	blocks := []Block{