From 6edc2b16367e4f412458642abb9720a669d29a02 Mon Sep 17 00:00:00 2001
From: Hashim1999164 <64767361+Hashim1999164@users.noreply.github.com>
Date: Sat, 8 Aug 2026 01:35:06 +0500
Subject: [PATCH] fix: place task checkboxes after list loose is finalized

Loose nested task lists could leave checkboxes outside <p> because
checkbox placement used list.loose before spacer detection finished.
Compute the final loose state first, then place checkboxes.

Fixes #4045
---
 src/Tokenizer.ts                            | 21 +++++++++++++--------
 test/specs/new/list_loose_nested_tasks.html | 20 ++++++++++++++++++++
 test/specs/new/list_loose_nested_tasks.md   | 11 +++++++++++
 3 files changed, 44 insertions(+), 8 deletions(-)
 create mode 100644 test/specs/new/list_loose_nested_tasks.html
 create mode 100644 test/specs/new/list_loose_nested_tasks.md

diff --git a/src/Tokenizer.ts b/src/Tokenizer.ts
index d4176e0650..b651849810 100644
--- a/src/Tokenizer.ts
+++ b/src/Tokenizer.ts
@@ -416,9 +416,22 @@ export class _Tokenizer<ParserOutput = string, RendererOutput = string> {
       list.raw = list.raw.trimEnd();
 
       // Item child tokens handled here at end because we needed to have the final item to trim it first
+      // First pass: tokenize items and finalize list.loose from spacers before placing checkboxes
       for (const item of list.items) {
         this.lexer.state.top = false;
         item.tokens = this.lexer.blockTokens(item.text, []);
+
+        if (!list.loose) {
+          // Check if list should be loose
+          const spacers = item.tokens.filter(t => t.type === 'space');
+          const hasMultipleLineBreaks = spacers.length > 0 && spacers.some(t => this.rules.other.anyLine.test(t.raw));
+
+          list.loose = hasMultipleLineBreaks;
+        }
+      }
+
+      // Second pass: place task checkboxes using the final list.loose
+      for (const item of list.items) {
         const itemToken = item.tokens[0];
         if (item.task && (itemToken?.type === 'text' || itemToken?.type === 'paragraph')) {
           // Remove checkbox markdown from item tokens
@@ -460,14 +473,6 @@ export class _Tokenizer<ParserOutput = string, RendererOutput = string> {
         } else if (item.task) {
           item.task = false;
         }
-
-        if (!list.loose) {
-          // Check if list should be loose
-          const spacers = item.tokens.filter(t => t.type === 'space');
-          const hasMultipleLineBreaks = spacers.length > 0 && spacers.some(t => this.rules.other.anyLine.test(t.raw));
-
-          list.loose = hasMultipleLineBreaks;
-        }
       }
 
       // Set all items to loose if list is loose
diff --git a/test/specs/new/list_loose_nested_tasks.html b/test/specs/new/list_loose_nested_tasks.html
new file mode 100644
index 0000000000..5a5ee8c5f1
--- /dev/null
+++ b/test/specs/new/list_loose_nested_tasks.html
@@ -0,0 +1,20 @@
+<ul>
+<li><p><input disabled="" type="checkbox"> Prepare the project</p>
+<ul>
+<li><input disabled="" type="checkbox"> Install dependencies</li>
+<li><input checked="" disabled="" type="checkbox"> Update Marked</li>
+<li><input disabled="" type="checkbox"> Check the rendering</li>
+</ul>
+</li>
+<li><p><input checked="" disabled="" type="checkbox"> Run the tests</p>
+<ul>
+<li><p><input checked="" disabled="" type="checkbox"> Test lists</p>
+</li>
+<li><p><input disabled="" type="checkbox"> Test tables</p>
+<ul>
+<li><input disabled="" type="checkbox"> Test nested cases</li>
+</ul>
+</li>
+</ul>
+</li>
+</ul>
diff --git a/test/specs/new/list_loose_nested_tasks.md b/test/specs/new/list_loose_nested_tasks.md
new file mode 100644
index 0000000000..aef580af2d
--- /dev/null
+++ b/test/specs/new/list_loose_nested_tasks.md
@@ -0,0 +1,11 @@
+* [ ] Prepare the project
+
+  * [ ] Install dependencies
+  * [x] Update Marked
+  * [ ] Check the rendering
+* [x] Run the tests
+
+  * [x] Test lists
+  * [ ] Test tables
+
+    * [ ] Test nested cases