[Repo Assist] fix: Markdown.ToMd preserves unresolved IndirectLink in reference notation

RELEASE_NOTES.md

@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 ### Fixed
+* Fix `Markdown.ToMd` emitting invalid `[text]([key])` for unresolved reference-style links. Unresolved `IndirectLink` spans now serialise as `[text][key]` (preserving the reference notation) instead of incorrectly inserting the key string with its brackets as a URL.
 * 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.
 

src/FSharp.Formatting.Markdown/MarkdownUtils.fs

@@ -115,6 +115,7 @@ module internal MarkdownUtils =
             "[" + formatSpans ctx body + "](" + link + t + ")"
 
         | IndirectLink(body, _, LookupKey ctx.Links (link, _), _)
+        | DirectLink(body, link, _, _) -> "[" + formatSpans ctx body + "](" + link + ")"
         | IndirectLink(body, link, _, _) -> "[" + formatSpans ctx body + "](" + link + ")"
 
         | IndirectImage(body, _, LookupKey ctx.Links (link, _), _) -> sprintf "![%s](%s)" body link

tests/FSharp.Markdown.Tests/Markdown.fs

@@ -1417,3 +1417,27 @@ 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]"
+
+// --------------------------------------------------------------------------------------
+// ToMd round-trip: unresolved indirect links
+// --------------------------------------------------------------------------------------
+
+[<Test>]
+let ``ToMd preserves unresolved indirect link in reference notation`` () =
+    // Indirect link with NO matching reference definition in the document.
+    // Before fix: emitted [link text]([unknown-key]) — invalid Markdown.
+    // After fix:  emits   [link text][unknown-key]   — valid reference link.
+    let input = "[link text][unknown-key]"
+    let doc = Markdown.Parse(input)
+    let result = Markdown.ToMd(doc)
+    // Must use reference notation, not inline notation with [key] as the URL
+    result |> should contain "[link text][unknown-key]"
+    result |> should not' (contain "[link text]([")
+
+[<Test>]
+let ``ToMd resolves indirect link when reference is present`` () =
+    // Indirect link whose reference definition IS present — key resolves to a URL.
+    let input = "[FSharp][fs-link]\n\n[fs-link]: https://fsharp.org"
+    let result = toMd input
+    result |> should contain "[FSharp]("
+    result |> should contain "https://fsharp.org"