From c981357922aaf544218cb788641018016d61a152 Mon Sep 17 00:00:00 2001
From: Dylan Piercey <pierceydylan@gmail.com>
Date: Mon, 2 Nov 2026 15:41:44 -0700
Subject: [PATCH] feat: only comments may follow a concise `;` line's html
 comment

After a `;` ends a concise line, code after an html comment was read as a
new line indented under the tag (`div; <!-- a --> span` nested `span` in
`div`). Only comments may follow the html comment now, as after the `;`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .changeset/semicolon-html-comment.md            |  5 +++++
 ...de-after-semicolon-html-comment.expected.txt | 17 +++++++++++++++++
 .../input.marko                                 |  2 ++
 src/states/CONCISE_HTML_CONTENT.ts              |  5 +++++
 4 files changed, 29 insertions(+)
 create mode 100644 .changeset/semicolon-html-comment.md
 create mode 100644 src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/__snapshots__/invalid-code-after-semicolon-html-comment.expected.txt
 create mode 100644 src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/input.marko

diff --git a/.changeset/semicolon-html-comment.md b/.changeset/semicolon-html-comment.md
new file mode 100644
index 00000000..3de9e63e
--- /dev/null
+++ b/.changeset/semicolon-html-comment.md
@@ -0,0 +1,5 @@
+---
+"htmljs-parser": minor
+---
+
+Report code after an html comment that follows a concise `;` (eg `div; <!-- a --> span`) as an error, as after any other comment there, instead of reading it as a new line nested in the tag. More comments may still follow.
diff --git a/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/__snapshots__/invalid-code-after-semicolon-html-comment.expected.txt b/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/__snapshots__/invalid-code-after-semicolon-html-comment.expected.txt
new file mode 100644
index 00000000..c4a99c9a
--- /dev/null
+++ b/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/__snapshots__/invalid-code-after-semicolon-html-comment.expected.txt
@@ -0,0 +1,17 @@
+1╭─ div; <!-- a --> <!-- b --> // c
+ │  │   ││   │      │   │      │ ╰─ comment.value " c"
+ │  │   ││   │      │   │      ╰─ comment "// c"
+ │  │   ││   │      │   ╰─ comment.value " b "
+ │  │   ││   │      ╰─ comment "<!-- b -->"
+ │  │   ││   ╰─ comment.value " a "
+ │  │   │╰─ comment "<!-- a -->"
+ │  │   ╰─ openTagEnd
+ ╰─ ╰─ tagName "div"
+2╭─ span; <!-- d --> p
+ │  │    ││   │      ╰─ error(INVALID_CODE_AFTER_SEMICOLON:A semicolon indicates the end of a line. Only comments may follow it.)
+ │  │    ││   ╰─ comment.value " d "
+ │  │    │╰─ comment "<!-- d -->"
+ │  │    ╰─ openTagEnd
+ │  ├─ closeTagEnd(div)
+ ╰─ ╰─ tagName "span"
+3╰─ 
\ No newline at end of file
diff --git a/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/input.marko b/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/input.marko
new file mode 100644
index 00000000..96c6f141
--- /dev/null
+++ b/src/__tests__/fixtures/invalid-code-after-semicolon-html-comment/input.marko
@@ -0,0 +1,2 @@
+div; <!-- a --> <!-- b --> // c
+span; <!-- d --> p
diff --git a/src/states/CONCISE_HTML_CONTENT.ts b/src/states/CONCISE_HTML_CONTENT.ts
index 060189d7..47d92556 100644
--- a/src/states/CONCISE_HTML_CONTENT.ts
+++ b/src/states/CONCISE_HTML_CONTENT.ts
@@ -188,6 +188,11 @@ export const CONCISE_HTML_CONTENT: StateDefinition = {
 
         break;
       }
+      case STATE.HTML_COMMENT:
+        // Only reached after a ";" (a line starting with "<" is an html
+        // block), so only comments may follow it either.
+        STATE.endConciseLine(this, this.data);
+        break;
     }
   },
 };