From 297117ab77d5d95dad620f2a8300161335efa128 Mon Sep 17 00:00:00 2001
From: Lazizbek Ergashev <lazerg2@gmail.com>
Date: Sat, 12 Sep 2026 06:55:29 +0500
Subject: [PATCH] Fix HTML block indentation drift in markdown list items
 (#19987)

Co-authored-by: fisker Cheung <lionkay@gmail.com>
---
 changelog_unreleased/markdown/19987.md        |  25 ++++
 src/language-markdown/print/list.js           |   2 +-
 .../__snapshots__/format.test.js.snap         | 113 ++++++++++++++++++
 .../markdown/list/html-indent/format.test.js  |   2 +
 .../html-indent/issue-19986-uneven-indent.md  |   5 +
 .../markdown/list/html-indent/issue-19986.md  |  11 ++
 6 files changed, 157 insertions(+), 1 deletion(-)
 create mode 100644 changelog_unreleased/markdown/19987.md
 create mode 100644 tests/format/markdown/list/html-indent/__snapshots__/format.test.js.snap
 create mode 100644 tests/format/markdown/list/html-indent/format.test.js
 create mode 100644 tests/format/markdown/list/html-indent/issue-19986-uneven-indent.md
 create mode 100644 tests/format/markdown/list/html-indent/issue-19986.md

diff --git a/changelog_unreleased/markdown/19987.md b/changelog_unreleased/markdown/19987.md
new file mode 100644
index 000000000..49fcd70ea
--- /dev/null
+++ b/changelog_unreleased/markdown/19987.md
@@ -0,0 +1,25 @@
+#### Fix HTML block indentation drift in markdown list items (#19987 by @lazerg)
+
+<!-- prettier-ignore -->
+```markdown
+<!-- Input -->
+1. Enable images:
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+<!-- Prettier stable (--tab-width=4) -->
+1. Enable images:
+
+     <p align="center">
+       <img alt="example">
+     </p>
+
+<!-- Prettier main (--tab-width=4) -->
+1. Enable images:
+
+    <p align="center">
+      <img alt="example">
+    </p>
+```
diff --git a/src/language-markdown/print/list.js b/src/language-markdown/print/list.js
index eb4c5c673..755d76769 100644
--- a/src/language-markdown/print/list.js
+++ b/src/language-markdown/print/list.js
@@ -99,7 +99,7 @@ function printListItem(path, options, print, listPrefix) {
     prefix,
     printChildren(path, options, print, {
       processor({ node, isFirst }) {
-        if (isFirst && node.type !== "list") {
+        if ((isFirst && node.type !== "list") || node.type === "html") {
           return align(" ".repeat(prefix.length), print());
         }
 
diff --git a/tests/format/markdown/list/html-indent/__snapshots__/format.test.js.snap b/tests/format/markdown/list/html-indent/__snapshots__/format.test.js.snap
new file mode 100644
index 000000000..69e9823ca
--- /dev/null
+++ b/tests/format/markdown/list/html-indent/__snapshots__/format.test.js.snap
@@ -0,0 +1,113 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`issue-19986.md - {"tabWidth":4} format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+tabWidth: 4
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+1. Enable images:
+
+    \`\`\`json
+    {}
+    \`\`\`
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+2. Continue.
+
+=====================================output=====================================
+1. Enable images:
+
+    \`\`\`json
+    {}
+    \`\`\`
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+2. Continue.
+
+================================================================================
+`;
+
+exports[`issue-19986.md format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+1. Enable images:
+
+    \`\`\`json
+    {}
+    \`\`\`
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+2. Continue.
+
+=====================================output=====================================
+1. Enable images:
+
+   \`\`\`json
+   {}
+   \`\`\`
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+2. Continue.
+
+================================================================================
+`;
+
+exports[`issue-19986-uneven-indent.md - {"tabWidth":4} format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+tabWidth: 4
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+1. Enable images:
+
+        <p align="center">
+      <img alt="example">
+    </p>
+
+=====================================output=====================================
+1. Enable images:
+
+        <p align="center">
+
+      <img alt="example">
+    </p>
+
+================================================================================
+`;
+
+exports[`issue-19986-uneven-indent.md format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+1. Enable images:
+
+        <p align="center">
+      <img alt="example">
+    </p>
+
+=====================================output=====================================
+1. Enable images:
+
+        <p align="center">
+
+      <img alt="example">
+    </p>
+
+================================================================================
+`;
diff --git a/tests/format/markdown/list/html-indent/format.test.js b/tests/format/markdown/list/html-indent/format.test.js
new file mode 100644
index 000000000..47801ffa2
--- /dev/null
+++ b/tests/format/markdown/list/html-indent/format.test.js
@@ -0,0 +1,2 @@
+runFormatTest(import.meta, ["markdown"], { tabWidth: 4 });
+runFormatTest(import.meta, ["markdown"]);
diff --git a/tests/format/markdown/list/html-indent/issue-19986-uneven-indent.md b/tests/format/markdown/list/html-indent/issue-19986-uneven-indent.md
new file mode 100644
index 000000000..a9b988e9e
--- /dev/null
+++ b/tests/format/markdown/list/html-indent/issue-19986-uneven-indent.md
@@ -0,0 +1,5 @@
+1. Enable images:
+
+        <p align="center">
+      <img alt="example">
+    </p>
diff --git a/tests/format/markdown/list/html-indent/issue-19986.md b/tests/format/markdown/list/html-indent/issue-19986.md
new file mode 100644
index 000000000..e0872c46e
--- /dev/null
+++ b/tests/format/markdown/list/html-indent/issue-19986.md
@@ -0,0 +1,11 @@
+1. Enable images:
+
+    ```json
+    {}
+    ```
+
+    <p align="center">
+      <img alt="example">
+    </p>
+
+2. Continue.