fix: color Markdown heading markers with heading text

docs/editing.md

@@ -176,4 +176,6 @@ Buffers highlight automatically using [Tree-sitter](https://tree-sitter.github.i
 
 Colors retain the terminal palette: comments dark gray, strings green, keywords magenta, numbers yellow, types/markup cyan, and functions light blue. Grammar queries handle multiline/nested constructs, even when their opening is above the viewport. Markdown uses its inline grammar and named fenced-code injections; HTML script/style content uses JavaScript/CSS. Known tagged-template and raw-string injections use the same selected grammar registry; unknown injected languages retain host highlighting or plain text. Highlighting styles whole graphemes and expanded tab cells; partially clipped wide placeholders remain unchanged. Search, Visual selections, and secondary carets retain foreground/background precedence.
 
+Markdown heading markers (`#` through `######`, or Setext underlines) share the heading text's markup color. Plain-text hashes and other punctuation keep their existing styling.
+
 An enabled supporting LSP server supplies semantic tokens automatically, overriding syntax colors only on recognized spans. Variables/parameters use light cyan, properties blue, and readonly variables/properties yellow; declarations/definitions are bold, documentation comments italic, and deprecated symbols struck through. Tree-sitter fills gaps and remains available while new tokens are pending after edits. Search, Visual selections, diagnostics, and carets keep their existing precedence. See [native LSP configuration](configuration.md#native-lsp) for provider support and server-stack routing.

src/syntax.rs

@@ -1263,6 +1263,25 @@ mod tests {
         assert_token(&cache, source, 3, "42", SyntaxKind::Number);
     }
 
+    #[test]
+    fn markdown_heading_markers_share_title_colors_without_coloring_plain_hashes() {
+        let source = "# One\n## Two\n### Three\n#### Four\n##### Five\n###### Six\n\nSetext\n======\n\nplain # text";
+        let cache = self::cache(source, "headings.md");
+        for row in 0..6 {
+            assert_token(
+                &cache,
+                source,
+                row,
+                &"#".repeat(row + 1),
+                SyntaxKind::Markup,
+            );
+        }
+        assert_token(&cache, source, 0, "One", SyntaxKind::Markup);
+        assert_token(&cache, source, 7, "Setext", SyntaxKind::Markup);
+        assert_token(&cache, source, 8, "======", SyntaxKind::Markup);
+        assert_eq!(kind_at(&cache, 10, 6), None);
+    }
+
     #[test]
     fn markdown_inline_and_fences_inject_known_languages_and_update_incrementally() {
         let original = "A **bold** and `code` link.\n\n```rust\nfn main() { let n = 42; }\n```\n\n```python\ndef hello():\n    return 7\n```\n\n```not-a-language\nfn not_rust() { 99; }\n```";

src/syntax/languages.rs

@@ -46,6 +46,24 @@ static CPP_HIGHLIGHTS: LazyLock<String> = LazyLock::new(|| {
     ]
     .join("\n")
 });
+static MD_HIGHLIGHTS: LazyLock<String> = LazyLock::new(|| {
+    [
+        tree_sitter_md::HIGHLIGHT_QUERY_BLOCK,
+        "
+[
+  (atx_h1_marker)
+  (atx_h2_marker)
+  (atx_h3_marker)
+  (atx_h4_marker)
+  (atx_h5_marker)
+  (atx_h6_marker)
+  (setext_h1_underline)
+  (setext_h2_underline)
+] @text.title
+",
+    ]
+    .join("\n")
+});
 
 // The MIT-licensed upstream C++ crate bundles, but does not export, injections.scm.
 // This minimal AST query uses its raw-string delimiter/content nodes:
@@ -129,7 +147,7 @@ static LANGUAGES: LazyLock<[LanguageSpec; 18]> = LazyLock::new(|| {
         spec(
             "Markdown",
             tree_sitter_md::LANGUAGE.into(),
-            tree_sitter_md::HIGHLIGHT_QUERY_BLOCK,
+            MD_HIGHLIGHTS.as_str(),
             tree_sitter_md::INJECTION_QUERY_BLOCK,
             "",
         ),