From c4d636594ed6e408d84eb4511ff20bbd75bd93f4 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 13 Apr 2026 11:10:23 +0000
Subject: [PATCH 1/2] fix: Markdown.ToMd preserves YAML frontmatter

When Markdown.ToMd serialises a parsed MarkdownDocument back to Markdown
text, YamlFrontmatter paragraphs were silently dropped. Documents
containing a YAML front-matter block (--- ... ---) would lose that block
on round-trip.

Fix: emit the --- delimiters and frontmatter lines in formatParagraph so
round-trips are lossless.

Add two new tests: one with populated frontmatter and one with an empty
block.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 RELEASE_NOTES.md                                |  3 +++
 src/FSharp.Formatting.Markdown/MarkdownUtils.fs |  9 ++++++++-
 tests/FSharp.Markdown.Tests/Markdown.fs         | 16 ++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 33214cbc..e75a4d5e 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+### Fixed
+* Fix `Markdown.ToMd` silently dropping YAML frontmatter when serialising a parsed `MarkdownDocument` back to Markdown text. Frontmatter is now preserved with its `---` delimiters.
+
 ## [22.0.0] - 2026-04-03
 
 ### Fixed
diff --git a/src/FSharp.Formatting.Markdown/MarkdownUtils.fs b/src/FSharp.Formatting.Markdown/MarkdownUtils.fs
index 59bf09a3..1ad7bc40 100644
--- a/src/FSharp.Formatting.Markdown/MarkdownUtils.fs
+++ b/src/FSharp.Formatting.Markdown/MarkdownUtils.fs
@@ -235,7 +235,14 @@ module internal MarkdownUtils =
               let lines = code.Replace("\r\n", "\n").Split('\n') |> Array.toList
               yield! lines
           //yield ""
-          | YamlFrontmatter _ -> ()
+          | YamlFrontmatter(lines, _) ->
+              yield "---"
+
+              for line in lines do
+                  yield line
+
+              yield "---"
+              yield ""
           | Span(body = body) -> yield formatSpans ctx body
           | QuotedBlock(paragraphs = paragraphs) ->
               for paragraph in paragraphs do
diff --git a/tests/FSharp.Markdown.Tests/Markdown.fs b/tests/FSharp.Markdown.Tests/Markdown.fs
index 984047f7..b9559702 100644
--- a/tests/FSharp.Markdown.Tests/Markdown.fs
+++ b/tests/FSharp.Markdown.Tests/Markdown.fs
@@ -1371,3 +1371,19 @@ let ``ToMd round-trip: indirect image with unresolved reference`` () =
     let result = Markdown.ToMd(doc)
     // When key is not resolved, should preserve the indirect form
     result |> should contain "![alt text][unknown-ref]"
+
+[<Test>]
+let ``ToMd preserves YAML frontmatter`` () =
+    let input = "---\ntitle: My Page\ndate: 2024-01-01\n---\n\nHello world.\n"
+    let result = input |> toMd
+    result |> should contain "---"
+    result |> should contain "title: My Page"
+    result |> should contain "date: 2024-01-01"
+    result |> should contain "Hello world."
+
+[<Test>]
+let ``ToMd preserves empty YAML frontmatter`` () =
+    let input = "---\n---\n\nHello.\n"
+    let result = input |> toMd
+    result |> should contain "---"
+    result |> should contain "Hello."

From b2a8e4bce9af073bdc465e28efd36f16fb9e5ff3 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 13 Apr 2026 11:10:26 +0000
Subject: [PATCH 2/2] ci: trigger checks