From 314fe4600f598848b1dd9d1075900dc3a533a737 Mon Sep 17 00:00:00 2001
From: luxick <git@luxick.de>
Date: Thu, 23 Apr 2026 08:46:36 +0200
Subject: [PATCH] Ensure newlines between sections

---
 sections.go | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/sections.go b/sections.go
index bca603b..4b26820 100644
--- a/sections.go
+++ b/sections.go
@@ -26,6 +26,15 @@ func splitSections(raw []byte) [][]byte {
 }
 
 // joinSections reassembles sections produced by splitSections.
+// Inserts a newline between sections when a non-empty section lacks a
+// trailing newline, so an edited section cannot inline the next heading.
 func joinSections(sections [][]byte) []byte {
-	return bytes.Join(sections, nil)
+	var buf bytes.Buffer
+	for i, s := range sections {
+		buf.Write(s)
+		if i < len(sections)-1 && len(s) > 0 && s[len(s)-1] != '\n' {
+			buf.WriteByte('\n')
+		}
+	}
+	return buf.Bytes()
 }