[Repo Assist] fix: Markdown.ToMd preserves DirectLink and DirectImage titles (#1150)

* fix: Markdown.ToMd preserves DirectLink and DirectImage titles

When serialising a document with ToMd, link and image titles were
silently dropped.  A Markdown fragment such as

    [text](url "My Title")

would round-trip as

    [text](url)

because the `DirectLink` / `DirectImage` formatSpan cases matched the
title field with a wildcard.

Fix: give DirectLink and DirectImage their own branches so the optional
title can be appended in CommonMark form (  \"title\").

Three new round-trip tests cover:
  - DirectLink with title
  - DirectLink without title (unchanged behaviour)
  - DirectImage with title

All 284 Markdown tests pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* ci: trigger checks

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Don Syme <dsyme@users.noreply.github.com>

Author: 3 people

RELEASE_NOTES.md

@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 ### Fixed
+* Fix `Markdown.ToMd` dropping link titles in `DirectLink` and `DirectImage` spans. Links with a title attribute (e.g. `[text](url "title")`) now round-trip correctly; without this fix the title was silently discarded on serialisation.
 * Fix `Markdown.ToMd` serialising inline code spans that contain backtick characters. Previously, `InlineCode` was always wrapped in single backticks, producing syntactically incorrect Markdown when the code body contained backticks. Now the serialiser selects the shortest backtick fence that does not collide with the body content (e.g. a double-backtick fence for bodies containing single backticks, triple for double, etc.), matching the CommonMark spec.
 
 ## [22.0.0] - 2026-04-03

src/FSharp.Formatting.Markdown/MarkdownUtils.fs

@@ -106,13 +106,27 @@ module internal MarkdownUtils =
         | HardLineBreak(_) -> "\n"
 
         | AnchorLink _ -> ""
+        | DirectLink(body, link, title, _) ->
+            let t =
+                title
+                |> Option.map (fun t -> sprintf " \"%s\"" (t.Replace("\"", "\\\"")))
+                |> Option.defaultValue ""
+
+            "[" + formatSpans ctx body + "](" + link + t + ")"
+
         | IndirectLink(body, _, LookupKey ctx.Links (link, _), _)
-        | DirectLink(body, link, _, _)
         | IndirectLink(body, link, _, _) -> "[" + formatSpans ctx body + "](" + link + ")"
 
         | IndirectImage(body, _, LookupKey ctx.Links (link, _), _) -> sprintf "![%s](%s)" body link
         | IndirectImage(body, _, key, _) -> sprintf "![%s][%s]" body key
-        | DirectImage(body, link, _, _) -> sprintf "![%s](%s)" body link
+
+        | DirectImage(body, link, title, _) ->
+            let t =
+                title
+                |> Option.map (fun t -> sprintf " \"%s\"" (t.Replace("\"", "\\\"")))
+                |> Option.defaultValue ""
+
+            sprintf "![%s](%s)" body (link + t)
         | Strong(body, _) -> "**" + formatSpans ctx body + "**"
         | InlineCode(body, _) ->
             // Pick the shortest backtick fence that does not appear in the body.

tests/FSharp.Markdown.Tests/Markdown.fs

@@ -1269,10 +1269,32 @@ let ``ToMd preserves a direct link`` () =
     |> toMd
     |> should contain "[FSharp](https://fsharp.org)"
 
+[<Test>]
+let ``ToMd preserves a direct link with title`` () =
+    let md = "[FSharp](https://fsharp.org \"F# language\")"
+    let result = toMd md
+    result |> should contain "[FSharp]("
+    result |> should contain "https://fsharp.org"
+    result |> should contain "\"F# language\""
+
+[<Test>]
+let ``ToMd preserves a direct link without title unchanged`` () =
+    let result = "[link](http://example.com)" |> toMd
+    result |> should contain "[link](http://example.com)"
+    result |> should not' (contain "\"")
+
 [<Test>]
 let ``ToMd preserves a direct image`` () =
     "![alt text](image.png)" |> toMd |> should contain "![alt text](image.png)"
 
+[<Test>]
+let ``ToMd preserves a direct image with title`` () =
+    let md = "![photo](image.png \"My Photo\")"
+    let result = toMd md
+    result |> should contain "![photo]("
+    result |> should contain "image.png"
+    result |> should contain "\"My Photo\""
+
 [<Test>]
 let ``ToMd preserves an unordered list`` () =
     let md = "* apple\n* banana\n* cherry"