From 2158d480aba89f5587ecde7e9f6d77d01bc82dac Mon Sep 17 00:00:00 2001
From: Miodrag Obradovic <99922455+Kjubikstronk@users.noreply.github.com>
Date: Tue, 18 Aug 2026 14:35:00 +0200
Subject: [PATCH] Strip blockquote markers from a setext heading's continuation
 lines (#19878)

---
 changelog_unreleased/markdown/19878.md        | 20 +++++++++++
 src/language-markdown/print/preprocess.js     |  5 ++-
 .../setext/__snapshots__/format.test.js.snap  | 35 +++++++++++++++++++
 .../markdown/heading/setext/blockquote.md     | 12 +++++++
 4 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 changelog_unreleased/markdown/19878.md
 create mode 100644 tests/format/markdown/heading/setext/blockquote.md

diff --git a/changelog_unreleased/markdown/19878.md b/changelog_unreleased/markdown/19878.md
new file mode 100644
index 000000000..61af67a38
--- /dev/null
+++ b/changelog_unreleased/markdown/19878.md
@@ -0,0 +1,20 @@
+#### Strip blockquote markers from a setext heading's continuation lines (#19878 by @Kjubikstronk)
+
+A setext heading spanning multiple lines inside a blockquote kept the `>` marker of its continuation lines as literal text.
+
+<!-- prettier-ignore -->
+```md
+<!-- Input -->
+> Multi
+> Line
+> ===
+
+<!-- Prettier stable -->
+> Multi > Line
+> ===
+
+<!-- Prettier main -->
+> Multi
+> Line
+> ===
+```
diff --git a/src/language-markdown/print/preprocess.js b/src/language-markdown/print/preprocess.js
index d521e31cc..bffce2cf3 100644
--- a/src/language-markdown/print/preprocess.js
+++ b/src/language-markdown/print/preprocess.js
@@ -183,8 +183,11 @@ function splitTextIntoSentences(ast) {
     // Using `node.value`, we don't need to care about markers like `\n > ` in `blockquote`s.
     let text = node.raw;
 
+    // A setext heading's text can span multiple raw source lines too, e.g.
+    // `> Title\n> continued\n> ===`.
     const paragraphIndex = parentStack.findIndex(
-      (ancestor) => ancestor?.type === "paragraph",
+      (ancestor) =>
+        ancestor?.type === "paragraph" || ancestor?.type === "heading",
     );
 
     const paragraphNode =
diff --git a/tests/format/markdown/heading/setext/__snapshots__/format.test.js.snap b/tests/format/markdown/heading/setext/__snapshots__/format.test.js.snap
index 420cd2cd8..e266385a6 100644
--- a/tests/format/markdown/heading/setext/__snapshots__/format.test.js.snap
+++ b/tests/format/markdown/heading/setext/__snapshots__/format.test.js.snap
@@ -1,5 +1,40 @@
 // Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
+exports[`blockquote.md format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+> Multi
+> Line
+> ===
+
+> Multi
+> Line
+> Three
+> ---
+
+> > Multi
+> > Line
+> > ===
+
+=====================================output=====================================
+> Multi
+> Line
+> ===
+
+> Multi
+> Line
+> Three
+> ---
+
+> > Multi
+> > Line
+> > ===
+
+================================================================================
+`;
+
 exports[`child.md format 1`] = `
 ====================================options=====================================
 parsers: ["markdown"]
diff --git a/tests/format/markdown/heading/setext/blockquote.md b/tests/format/markdown/heading/setext/blockquote.md
new file mode 100644
index 000000000..ca9f11e4f
--- /dev/null
+++ b/tests/format/markdown/heading/setext/blockquote.md
@@ -0,0 +1,12 @@
+> Multi
+> Line
+> ===
+
+> Multi
+> Line
+> Three
+> ---
+
+> > Multi
+> > Line
+> > ===