From 7bfe1c18fc658a0b8a239c938aed3e0b684b6120 Mon Sep 17 00:00:00 2001
From: Oleg Samarin <osamarin@openintegration.inc>
Date: Thu, 7 May 2026 22:48:27 +0300
Subject: [PATCH] Fixed markdown preview not rendering nested list structure

Replaced flat ordered/unordered list rendering with a stack-based
nested renderer that respects indentation levels, producing proper
nested <ol>/<ul> HTML tags.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 CHANGELOG.md                                  |  1 +
 pom.xml                                       |  2 +-
 .../ui/common/MarkdownRenderer.java           | 92 ++++++++++++++-----
 .../ui/common/MarkdownRendererTest.java       | 43 +++++++++
 4 files changed, 112 insertions(+), 26 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2709898..ace28740 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,4 @@
+- Fixed markdown preview not rendering nested list structure (multi-level indented lists now display with proper nesting)
 - Fixed "Continue last" and "Resume specific" staying enabled (and selected) when a directory or profile with no sessions is chosen in the session selector
 - Fixed model list showing garbled names (e.g. "Mtoket 4.6 with 1M context") when the /model menu includes 1M-context variants and cost annotations
 
diff --git a/pom.xml b/pom.xml
index 3ce8db4b..3bec908f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>io.github.nbclaudecodegui</groupId>
     <artifactId>netbeans-claude-code-gui</artifactId>
-    <version>0.22.48-SNAPSHOT</version>
+    <version>0.22.49-SNAPSHOT</version>
     <packaging>nbm</packaging>
     <name>Netbeans Plugin Claude Code GUI</name>
     <description>NetBeans plugin that provides a GUI for Claude Code CLI — run claude code sessions directly inside the IDE.</description>
diff --git a/src/main/java/io/github/nbclaudecodegui/ui/common/MarkdownRenderer.java b/src/main/java/io/github/nbclaudecodegui/ui/common/MarkdownRenderer.java
index bb4d829e..ecfc8957 100644
--- a/src/main/java/io/github/nbclaudecodegui/ui/common/MarkdownRenderer.java
+++ b/src/main/java/io/github/nbclaudecodegui/ui/common/MarkdownRenderer.java
@@ -299,31 +299,9 @@ && isSeparatorRow(lines[i + 1])) {
                 continue;
             }
 
-            // --- Unordered list ---
-            if (isUnordered(line)) {
-                html.append("<ul>");
-                while (i < lines.length && isUnordered(lines[i])) {
-                    html.append("<li>")
-                            .append(inlineToHtml(lines[i]
-                                    .replaceFirst("^\\s*[-*]\\s+", "")))
-                            .append("</li>");
-                    i++;
-                }
-                html.append("</ul>");
-                continue;
-            }
-
-            // --- Ordered list ---
-            if (isOrdered(line)) {
-                html.append("<ol>");
-                while (i < lines.length && isOrdered(lines[i])) {
-                    html.append("<li>")
-                            .append(inlineToHtml(lines[i]
-                                    .replaceFirst("^\\s*\\d+\\.\\s+", "")))
-                            .append("</li>");
-                    i++;
-                }
-                html.append("</ol>");
+            // --- List (nested ordered/unordered) ---
+            if (isUnordered(line) || isOrdered(line)) {
+                i = renderNestedList(lines, i, html);
                 continue;
             }
 
@@ -531,5 +509,69 @@ private static void appendHtml(JEditorPane pane, String html) {
         }
     }
 
+    private static int renderNestedList(String[] lines, int start, StringBuilder html) {
+        List<Integer> indentStack = new ArrayList<>();
+        List<Boolean> typeStack = new ArrayList<>();
+
+        int i = start;
+        while (i < lines.length) {
+            String line = lines[i];
+
+            if (line.isBlank()) {
+                int j = i + 1;
+                while (j < lines.length && lines[j].isBlank()) j++;
+                if (j < lines.length && (isOrdered(lines[j]) || isUnordered(lines[j]))) {
+                    i = j;
+                    continue;
+                }
+                break;
+            }
+
+            if (!isOrdered(line) && !isUnordered(line)) break;
+
+            int indent = leadingSpaces(line);
+            boolean ordered = isOrdered(line);
+
+            if (indentStack.isEmpty()) {
+                html.append(ordered ? "<ol>" : "<ul>");
+                indentStack.add(indent);
+                typeStack.add(ordered);
+            } else {
+                int topIndent = indentStack.get(indentStack.size() - 1);
+                if (indent > topIndent) {
+                    html.append(ordered ? "<ol>" : "<ul>");
+                    indentStack.add(indent);
+                    typeStack.add(ordered);
+                } else if (indent < topIndent) {
+                    while (indentStack.size() > 1 && indentStack.get(indentStack.size() - 1) > indent) {
+                        html.append(typeStack.get(typeStack.size() - 1) ? "</ol>" : "</ul>");
+                        indentStack.remove(indentStack.size() - 1);
+                        typeStack.remove(typeStack.size() - 1);
+                    }
+                }
+                if (!typeStack.isEmpty() && typeStack.get(typeStack.size() - 1) != ordered) {
+                    html.append(typeStack.get(typeStack.size() - 1) ? "</ol>" : "</ul>");
+                    typeStack.set(typeStack.size() - 1, ordered);
+                    html.append(ordered ? "<ol>" : "<ul>");
+                }
+            }
+
+            String content = line.replaceFirst("^\\s*(?:\\d+\\.|[-*])\\s+", "");
+            html.append("<li>").append(inlineToHtml(content)).append("</li>");
+            i++;
+        }
+
+        for (int k = typeStack.size() - 1; k >= 0; k--) {
+            html.append(typeStack.get(k) ? "</ol>" : "</ul>");
+        }
+        return i;
+    }
+
+    private static int leadingSpaces(String line) {
+        int n = 0;
+        while (n < line.length() && line.charAt(n) == ' ') n++;
+        return n;
+    }
+
     private MarkdownRenderer() {}
 }
diff --git a/src/test/java/io/github/nbclaudecodegui/ui/common/MarkdownRendererTest.java b/src/test/java/io/github/nbclaudecodegui/ui/common/MarkdownRendererTest.java
index 443ad51c..0ea16901 100644
--- a/src/test/java/io/github/nbclaudecodegui/ui/common/MarkdownRendererTest.java
+++ b/src/test/java/io/github/nbclaudecodegui/ui/common/MarkdownRendererTest.java
@@ -266,6 +266,49 @@ void testHeadingSlugStripNonAlphanumeric() {
         assertTrue(html.contains("<a name=\"hello-world-2024\">"), "slug strips punctuation");
     }
 
+    // -------------------------------------------------------------------------
+    // toHtml() — nested lists
+    // -------------------------------------------------------------------------
+
+    @Test
+    void testNestedOrderedList() {
+        String md = "1. first\n    1. sub-first\n    2. sub-second\n2. second";
+        String html = MarkdownRenderer.toHtml(md);
+        // outer ol must contain an inner ol
+        int outerOl = html.indexOf("<ol>");
+        int innerOl = html.indexOf("<ol>", outerOl + 1);
+        assertTrue(innerOl > outerOl, "inner <ol> must exist inside outer <ol>");
+        assertTrue(html.contains("<li>first</li>") || html.contains("<li>first"),
+                "outer first item");
+        assertTrue(html.contains("sub-first"), "sub-first item");
+        assertTrue(html.contains("sub-second"), "sub-second item");
+        assertTrue(html.contains("second"), "outer second item");
+        // must have at least 2 </ol> closing tags
+        long closeCount = html.chars().filter(c -> c == '<').count();
+        assertTrue(html.indexOf("</ol>", html.indexOf("</ol>") + 1) > 0,
+                "at least 2 </ol> tags expected");
+    }
+
+    @Test
+    void testNestedUnorderedList() {
+        String md = "- alpha\n    - sub-alpha\n    - sub-beta\n- beta";
+        String html = MarkdownRenderer.toHtml(md);
+        int outerUl = html.indexOf("<ul>");
+        int innerUl = html.indexOf("<ul>", outerUl + 1);
+        assertTrue(innerUl > outerUl, "inner <ul> must exist inside outer <ul>");
+        assertTrue(html.contains("alpha"), "outer alpha");
+        assertTrue(html.contains("sub-alpha"), "sub-alpha");
+    }
+
+    @Test
+    void testMixedNestedList() {
+        String md = "1. item\n    - nested-ul\n2. item2";
+        String html = MarkdownRenderer.toHtml(md);
+        assertTrue(html.contains("<ol>"), "outer ol");
+        assertTrue(html.contains("<ul>"), "inner ul");
+        assertTrue(html.contains("nested-ul"), "nested item text");
+    }
+
     // -------------------------------------------------------------------------
     // resolveImagePaths()
     // -------------------------------------------------------------------------