diff --git a/benchmark/CMakeLists.txt b/benchmark/CMakeLists.txt
index 728590c410..1f3e857f57 100644
--- a/benchmark/CMakeLists.txt
+++ b/benchmark/CMakeLists.txt
@@ -36,6 +36,10 @@ if(SOURCEMETA_CORE_HTML)
   list(APPEND BENCHMARK_SOURCES html.cc)
 endif()
 
+if(SOURCEMETA_CORE_MARKDOWN)
+  list(APPEND BENCHMARK_SOURCES markdown.cc)
+endif()
+
 if(SOURCEMETA_CORE_GZIP)
   list(APPEND BENCHMARK_SOURCES gzip.cc)
 endif()
@@ -102,6 +106,11 @@ if(BENCHMARK_SOURCES)
       PRIVATE sourcemeta::core::html)
   endif()
 
+  if(SOURCEMETA_CORE_MARKDOWN)
+    target_link_libraries(sourcemeta_core_benchmark
+      PRIVATE sourcemeta::core::markdown)
+  endif()
+
   if(SOURCEMETA_CORE_GZIP)
     target_link_libraries(sourcemeta_core_benchmark
       PRIVATE sourcemeta::core::gzip sourcemeta::core::io)
diff --git a/benchmark/markdown.cc b/benchmark/markdown.cc
new file mode 100644
index 0000000000..ae3ed16d90
--- /dev/null
+++ b/benchmark/markdown.cc
@@ -0,0 +1,103 @@
+#include <benchmark/benchmark.h>
+
+#include <sourcemeta/core/markdown.h>
+
+#include <cstddef> // std::size_t
+#include <string>  // std::string, std::to_string
+
+static auto repeat(const std::string &pattern, const std::size_t count)
+    -> std::string {
+  std::string result;
+  result.reserve(pattern.size() * count);
+  for (std::size_t index = 0; index < count; ++index) {
+    result.append(pattern);
+  }
+
+  return result;
+}
+
+static auto increasing_backtick_runs(const std::size_t count) -> std::string {
+  std::string result;
+  for (std::size_t length = 1; length <= count; ++length) {
+    result.push_back('x');
+    result.append(length, '`');
+  }
+
+  return result;
+}
+
+static auto staircase_list(const std::size_t depth) -> std::string {
+  std::string result;
+  for (std::size_t level = 0; level < depth; ++level) {
+    result.append(level * 2, ' ');
+    result.append("- level\n");
+  }
+
+  return result;
+}
+
+// NOLINTNEXTLINE(readability-identifier-naming)
+static void Markdown_To_HTML_Realistic_Document(benchmark::State &state) {
+  std::string input;
+  for (std::size_t index = 0; index < 500; ++index) {
+    const auto number{std::to_string(index)};
+    input.append("# Section ").append(number).append("\n\n");
+    input.append("This paragraph has *emphasis*, **strong emphasis**, ")
+        .append("`inline code`, a [link](https://sourcemeta.com/")
+        .append(number)
+        .append(" \"Title\"), an autolink to www.sourcemeta.com, and ")
+        .append("~~deleted text~~ with an entity &copy; and a footnote[^")
+        .append(number)
+        .append("].\n\n");
+    input.append("> A block quote with a [reference link][ref")
+        .append(number)
+        .append("]\n> spanning two lines.\n\n");
+    input.append("- First item\n  - Nested *item*\n  - Another `item`\n"
+                 "- [x] Completed task\n- [ ] Pending task\n\n");
+    input.append("1. One\n2. Two\n3. Three\n\n");
+    input.append("| Name | Value | Notes |\n| :--- | ---: | :---: |\n"
+                 "| alpha | 1 | *first* |\n| beta | 2 | `second` |\n"
+                 "| gamma | 3 | [third](/third) |\n\n");
+    input.append("```cpp\nauto main() -> int {\n  return 0;\n}\n```\n\n");
+    input.append("    indented code line\n\n---\n\n");
+    input.append("[ref")
+        .append(number)
+        .append("]: https://sourcemeta.com/reference/")
+        .append(number)
+        .append("\n[^")
+        .append(number)
+        .append("]: Footnote ")
+        .append(number)
+        .append(".\n\n");
+  }
+
+  for (auto iteration : state) {
+    auto result{sourcemeta::core::markdown_to_html(input)};
+    benchmark::DoNotOptimize(result);
+  }
+}
+
+// Inputs that make naive delimiter, bracket, and container handling
+// quadratic or worse, which a linear parser renders almost instantly
+// NOLINTNEXTLINE(readability-identifier-naming)
+static void Markdown_To_HTML_Pathological(benchmark::State &state) {
+  const std::string input{
+      repeat("_x **y ", 5000) + "z" + repeat(" y** x_", 5000) + "\n\n" +
+      repeat("x_. ", 10000) + "\n\n" + repeat("__y ", 10000) + "\n\n" +
+      repeat("]b", 10000) + "\n\n" + repeat("![b", 10000) + "\n\n" +
+      repeat("_b* ", 10000) + "\n\n" + "x***y" + repeat("z* ", 10000) + "\n\n" +
+      repeat("[ b*", 10000) + "\n\n" + repeat("[ x](", 10000) + "\n\n" +
+      repeat("![", 5000) + "x" + repeat("]", 5000) + "\n\n" +
+      repeat("![x](<y", 5000) + "\n\nx" + repeat("<![CDATA[", 5000) + "\n\nx" +
+      repeat("<?", 5000) + "\n\n" + increasing_backtick_runs(2000) + "\n\n" +
+      repeat("> - ", 50) + "deep\n\n" + staircase_list(200) + "\n" +
+      "| a | b | c |\n|---|---|---|\n" + repeat("| x | y | z |\n", 5000)};
+
+  for (auto iteration : state) {
+    auto result{sourcemeta::core::markdown_to_html(input)};
+    benchmark::DoNotOptimize(result);
+  }
+}
+
+BENCHMARK(Markdown_To_HTML_Realistic_Document);
+BENCHMARK(Markdown_To_HTML_Pathological);
diff --git a/test/markdown/CMakeLists.txt b/test/markdown/CMakeLists.txt
index 3c406d735f..96f9fdd72d 100644
--- a/test/markdown/CMakeLists.txt
+++ b/test/markdown/CMakeLists.txt
@@ -1,5 +1,28 @@
 sourcemeta_test(NAMESPACE sourcemeta PROJECT core NAME markdown
-  SOURCES markdown_test.cc)
+  SOURCES
+    markdown_autolinks_test.cc
+    markdown_blockquotes_test.cc
+    markdown_characters_test.cc
+    markdown_code_blocks_test.cc
+    markdown_code_spans_test.cc
+    markdown_concurrency_test.cc
+    markdown_emphasis_test.cc
+    markdown_entities_test.cc
+    markdown_escapes_test.cc
+    markdown_footnotes_test.cc
+    markdown_headings_test.cc
+    markdown_images_test.cc
+    markdown_line_breaks_test.cc
+    markdown_links_test.cc
+    markdown_lists_test.cc
+    markdown_paragraphs_test.cc
+    markdown_pathological_test.cc
+    markdown_safety_test.cc
+    markdown_strikethrough_test.cc
+    markdown_tables_test.cc
+    markdown_task_lists_test.cc
+    markdown_thematic_breaks_test.cc
+    markdown_unsafe_test.cc)
 
 target_link_libraries(sourcemeta_core_markdown_unit
   PRIVATE sourcemeta::core::markdown)
diff --git a/test/markdown/markdown_autolinks_test.cc b/test/markdown/markdown_autolinks_test.cc
new file mode 100644
index 0000000000..bd2ebd78e7
--- /dev/null
+++ b/test/markdown/markdown_autolinks_test.cc
@@ -0,0 +1,306 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(autolink_url) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Visit https://example.com today")};
+  EXPECT_EQ(result,
+            "<p>Visit <a href=\"https://example.com\">https://example.com</a>"
+            " today</p>\n");
+}
+
+TEST(autolink_http) {
+  const auto result{sourcemeta::core::markdown_to_html("http://example.com")};
+  EXPECT_EQ(result,
+            "<p><a href=\"http://example.com\">http://example.com</a></p>\n");
+}
+
+TEST(autolink_www) {
+  const auto result{sourcemeta::core::markdown_to_html("www.example.com")};
+  EXPECT_EQ(result,
+            "<p><a href=\"http://www.example.com\">www.example.com</a></p>\n");
+}
+
+TEST(autolink_email) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Contact user@example.com")};
+  EXPECT_EQ(result, "<p>Contact <a href=\"mailto:user@example.com\">"
+                    "user@example.com</a></p>\n");
+}
+
+TEST(angle_bracket_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://example.com>")};
+  EXPECT_EQ(result,
+            "<p><a href=\"https://example.com\">https://example.com</a></p>\n");
+}
+
+TEST(autolink_inside_list) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- visit https://example.com\n- done")};
+  EXPECT_EQ(result, "<ul>\n<li>visit <a href=\"https://example.com\">"
+                    "https://example.com</a></li>\n<li>done</li>\n</ul>\n");
+}
+
+TEST(multiple_autolinks_in_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "See https://one.com and https://two.com")};
+  EXPECT_EQ(result,
+            "<p>See <a href=\"https://one.com\">https://one.com</a> and "
+            "<a href=\"https://two.com\">https://two.com</a></p>\n");
+}
+
+TEST(autolink_with_trailing_punctuation) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("See https://example.com.")};
+  EXPECT_EQ(
+      result,
+      "<p>See <a href=\"https://example.com\">https://example.com</a>.</p>\n");
+}
+
+TEST(autolink_in_parentheses) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("(see https://example.com)")};
+  EXPECT_EQ(
+      result,
+      "<p>(see <a href=\"https://example.com\">https://example.com</a>)</p>\n");
+}
+
+TEST(autolink_takes_precedence_over_code_span) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://sourcemeta.com/`x>`")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/%60x\">https://"
+                    "sourcemeta.com/`x</a>`</p>\n");
+}
+
+TEST(autolink_uri_schemes) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<irc://chat.example>\n\n<x-custom+scheme.1:thing>\n\n<ab:c>")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"irc://chat.example\">irc://chat.example</a></p>\n"
+      "<p><a href=\"x-custom+scheme.1:thing\">x-custom+scheme.1:thing</a></p>\n"
+      "<p><a href=\"ab:c\">ab:c</a></p>\n");
+}
+
+TEST(autolink_uri_scheme_too_short_is_not_autolink) {
+  const auto result{sourcemeta::core::markdown_to_html("<z:thing>")};
+  EXPECT_EQ(result, "<p>&lt;z:thing&gt;</p>\n");
+}
+
+TEST(autolink_uri_with_space_is_not_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://sourcemeta.com/a b>")};
+  EXPECT_EQ(result, "<p>&lt;<a "
+                    "href=\"https://sourcemeta.com/a\">https://sourcemeta.com/"
+                    "a</a> b&gt;</p>\n");
+}
+
+TEST(autolink_uri_backslash_is_literal) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://sourcemeta.com/\\_>")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/%5C_\">https://"
+                    "sourcemeta.com/\\_</a></p>\n");
+}
+
+TEST(autolink_email_in_angle_brackets) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<team@sourcemeta.com>")};
+  EXPECT_EQ(
+      result,
+      "<p><a "
+      "href=\"mailto:team@sourcemeta.com\">team@sourcemeta.com</a></p>\n");
+}
+
+TEST(autolink_email_with_dots_plus_and_hyphen) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<first.last+tag@sub-domain.sourcemeta.com>")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"mailto:first.last+tag@sub-domain.sourcemeta.com\">"
+                    "first.last+tag@sub-domain.sourcemeta.com</a></p>\n");
+}
+
+TEST(autolink_email_with_backslash_is_not_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<team\\@sourcemeta.com>")};
+  EXPECT_EQ(
+      result,
+      "<p>&lt;<a "
+      "href=\"mailto:team@sourcemeta.com\">team@sourcemeta.com</a>&gt;</p>\n");
+}
+
+TEST(autolink_blank_or_trailing_space_angle_brackets) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("< >\n\n<https://sourcemeta.com >")};
+  EXPECT_EQ(
+      result,
+      "<p>&lt; &gt;</p>\n"
+      "<p>&lt;<a href=\"https://sourcemeta.com\">https://sourcemeta.com</a> "
+      "&gt;</p>\n");
+}
+
+TEST(autolink_without_scheme_is_not_autolink) {
+  const auto result{sourcemeta::core::markdown_to_html("<sourcemeta.com>")};
+  EXPECT_EQ(result, "<p>&lt;sourcemeta.com&gt;</p>\n");
+}
+
+TEST(extended_autolink_www_with_path) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("see www.sourcemeta.com/docs/intro")};
+  EXPECT_EQ(result, "<p>see <a "
+                    "href=\"http://www.sourcemeta.com/docs/"
+                    "intro\">www.sourcemeta.com/docs/intro</a></p>\n");
+}
+
+TEST(extended_autolink_trailing_punctuation_excluded) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Go to www.sourcemeta.com/x.y!")};
+  EXPECT_EQ(result, "<p>Go to <a "
+                    "href=\"http://www.sourcemeta.com/x.y\">www.sourcemeta.com/"
+                    "x.y</a>!</p>\n");
+}
+
+TEST(extended_autolink_balanced_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "https://sourcemeta.com/wiki/Thing_(disambiguation)")};
+  EXPECT_EQ(
+      result,
+      "<p><a "
+      "href=\"https://sourcemeta.com/wiki/Thing_(disambiguation)\">https://"
+      "sourcemeta.com/wiki/Thing_(disambiguation)</a></p>\n");
+}
+
+TEST(extended_autolink_unbalanced_closing_parentheses) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("https://sourcemeta.com/a_(b)))")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/a_(b)\">https://"
+                    "sourcemeta.com/a_(b)</a>))</p>\n");
+}
+
+TEST(extended_autolink_inside_parentheses) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("(see https://sourcemeta.com/a_(b))")};
+  EXPECT_EQ(result, "<p>(see <a "
+                    "href=\"https://sourcemeta.com/a_(b)\">https://"
+                    "sourcemeta.com/a_(b)</a>)</p>\n");
+}
+
+TEST(extended_autolink_entity_like_suffix_excluded) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "https://sourcemeta.com/?x=1&amp;\n\nhttps://sourcemeta.com/?x=1&y=2")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/?x=1\">https://"
+                    "sourcemeta.com/?x=1</a>&amp;</p>\n"
+                    "<p><a "
+                    "href=\"https://sourcemeta.com/?x=1&amp;y=2\">https://"
+                    "sourcemeta.com/?x=1&amp;y=2</a></p>\n");
+}
+
+TEST(extended_autolink_ends_at_less_than) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("https://sourcemeta.com/a<b")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/a\">https://sourcemeta.com/"
+                    "a</a>&lt;b</p>\n");
+}
+
+TEST(extended_autolink_underscore_in_final_domain_segments) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "www.sourcemeta._com\n\nwww.source_meta.com")};
+  EXPECT_EQ(result, "<p>www.sourcemeta._com</p>\n"
+                    "<p>www.source_meta.com</p>\n");
+}
+
+TEST(extended_autolink_underscore_in_earlier_domain_segment) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("www.docs_site.sourcemeta.com")};
+  EXPECT_EQ(
+      result,
+      "<p><a "
+      "href=\"http://"
+      "www.docs_site.sourcemeta.com\">www.docs_site.sourcemeta.com</a></p>\n");
+}
+
+TEST(extended_autolink_http_with_query_and_fragment) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "https://sourcemeta.com/search?q=json+schema#results")};
+  EXPECT_EQ(
+      result,
+      "<p><a "
+      "href=\"https://sourcemeta.com/search?q=json+schema#results\">https://"
+      "sourcemeta.com/search?q=json+schema#results</a></p>\n");
+}
+
+TEST(extended_autolink_email_local_and_domain_symbols) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "team@sourcemeta.com\n\nteam@source+meta.com\n\nteam+tag@sourcemeta."
+      "com")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"mailto:team@sourcemeta.com\">team@sourcemeta.com</a></p>\n"
+      "<p>team@source+meta.com</p>\n"
+      "<p><a "
+      "href=\"mailto:team+tag@sourcemeta.com\">team+tag@sourcemeta.com</a></"
+      "p>\n");
+}
+
+TEST(extended_autolink_email_trailing_symbols) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "first.last@sourcemeta.com.\n\nfirst.last@sourcemeta.com-\n\nfirst.last@"
+      "sourcemeta.com_")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"mailto:first.last@sourcemeta.com\">first.last@"
+                    "sourcemeta.com</a>.</p>\n"
+                    "<p>first.last@sourcemeta.com-</p>\n"
+                    "<p>first.last@sourcemeta.com_</p>\n");
+}
+
+TEST(extended_autolink_mailto_and_xmpp) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "mailto:team@sourcemeta.com\n\nxmpp:team@sourcemeta.com/resource")};
+  EXPECT_EQ(
+      result,
+      "<p><a "
+      "href=\"mailto:team@sourcemeta.com\">mailto:team@sourcemeta.com</a></p>\n"
+      "<p><a "
+      "href=\"xmpp:team@sourcemeta.com/resource\">xmpp:team@sourcemeta.com/"
+      "resource</a></p>\n");
+}
+
+TEST(extended_autolink_not_after_word_character) {
+  const auto result{sourcemeta::core::markdown_to_html("xwww.sourcemeta.com")};
+  EXPECT_EQ(result, "<p>xwww.sourcemeta.com</p>\n");
+}
+
+TEST(extended_autolink_inside_emphasis) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("_https://sourcemeta.com_")};
+  EXPECT_EQ(
+      result,
+      "<p><em><a "
+      "href=\"https://sourcemeta.com\">https://sourcemeta.com</a></em></p>\n");
+}
+
+TEST(extended_autolink_ftp_scheme) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("ftp://files.sourcemeta.com/archive")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"ftp://files.sourcemeta.com/archive\">ftp://"
+                    "files.sourcemeta.com/archive</a></p>\n");
+}
+
+TEST(extended_autolink_inside_link_text) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[https://sourcemeta.com](/x)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">https://sourcemeta.com</a></p>\n");
+}
+
+TEST(extended_autolink_inside_code_span) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("`https://sourcemeta.com`")};
+  EXPECT_EQ(result, "<p><code>https://sourcemeta.com</code></p>\n");
+}
diff --git a/test/markdown/markdown_blockquotes_test.cc b/test/markdown/markdown_blockquotes_test.cc
new file mode 100644
index 0000000000..54dac695e9
--- /dev/null
+++ b/test/markdown/markdown_blockquotes_test.cc
@@ -0,0 +1,259 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(simple_blockquote) {
+  const auto result{sourcemeta::core::markdown_to_html("> quoted text")};
+  EXPECT_EQ(result, "<blockquote>\n<p>quoted text</p>\n</blockquote>\n");
+}
+
+TEST(multiline_blockquote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> line one\n> line two")};
+  EXPECT_EQ(result, "<blockquote>\n<p>line one\nline two</p>\n</blockquote>\n");
+}
+
+TEST(nested_blockquote) {
+  const auto result{sourcemeta::core::markdown_to_html("> outer\n>> inner")};
+  EXPECT_EQ(result, "<blockquote>\n<p>outer</p>\n<blockquote>\n<p>inner</p>\n"
+                    "</blockquote>\n</blockquote>\n");
+}
+
+TEST(blockquote_with_formatting) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> **bold** and *italic*")};
+  EXPECT_EQ(result,
+            "<blockquote>\n<p><strong>bold</strong> and <em>italic</em></p>\n"
+            "</blockquote>\n");
+}
+
+TEST(blockquote_with_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> items:\n> - one\n> - two")};
+  EXPECT_EQ(result,
+            "<blockquote>\n<p>items:</p>\n<ul>\n<li>one</li>\n<li>two</li>\n"
+            "</ul>\n</blockquote>\n");
+}
+
+TEST(blockquote_with_code_block) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> example:\n>\n>     code here")};
+  EXPECT_EQ(result, "<blockquote>\n<p>example:</p>\n"
+                    "<pre><code>code here\n</code></pre>\n</blockquote>\n");
+}
+
+TEST(blockquote_with_heading) {
+  const auto result{sourcemeta::core::markdown_to_html("> ## Quoted heading")};
+  EXPECT_EQ(result, "<blockquote>\n<h2>Quoted heading</h2>\n</blockquote>\n");
+}
+
+TEST(deeply_nested_blockquote) {
+  const auto result{sourcemeta::core::markdown_to_html("> a\n>> b\n>>> c")};
+  EXPECT_EQ(result, "<blockquote>\n<p>a</p>\n<blockquote>\n<p>b</p>\n"
+                    "<blockquote>\n<p>c</p>\n</blockquote>\n</blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_followed_by_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> quote\n\n- item one\n- item two")};
+  EXPECT_EQ(result, "<blockquote>\n<p>quote</p>\n</blockquote>\n"
+                    "<ul>\n<li>item one</li>\n<li>item two</li>\n</ul>\n");
+}
+
+TEST(blockquote_with_strikethrough) {
+  const auto result{sourcemeta::core::markdown_to_html("> ~~deleted~~")};
+  EXPECT_EQ(result, "<blockquote>\n<p><del>deleted</del></p>\n</blockquote>\n");
+}
+
+TEST(blockquote_marker_without_following_space) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(">## Title\n>text\n> more")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<h2>Title</h2>\n"
+                    "<p>text\n"
+                    "more</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_marker_indented_up_to_three_spaces) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("  > one\n > two\n   > three")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one\n"
+                    "two\n"
+                    "three</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_marker_indented_four_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    > one\n    > two")};
+  EXPECT_EQ(result, "<pre><code>&gt; one\n"
+                    "&gt; two\n"
+                    "</code></pre>\n");
+}
+
+TEST(blockquote_lazy_paragraph_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\ntwo")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one\n"
+                    "two</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_lazy_continuation_between_marked_lines) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\ntwo\n> three")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one\n"
+                    "two\n"
+                    "three</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_laziness_does_not_apply_to_thematic_break) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n***")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one</p>\n"
+                    "</blockquote>\n"
+                    "<hr />\n");
+}
+
+TEST(blockquote_laziness_does_not_apply_to_list) {
+  const auto result{sourcemeta::core::markdown_to_html("> * one\n* two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "</blockquote>\n"
+                    "<ul>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(blockquote_laziness_does_not_apply_to_indented_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(">     code\n     more")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</blockquote>\n"
+                    "<pre><code> more\n"
+                    "</code></pre>\n");
+}
+
+TEST(blockquote_laziness_does_not_apply_to_fenced_code) {
+  const auto result{sourcemeta::core::markdown_to_html("> ~~~\ncode\n~~~")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<pre><code></code></pre>\n"
+                    "</blockquote>\n"
+                    "<p>code</p>\n"
+                    "<pre><code></code></pre>\n");
+}
+
+TEST(blockquote_lazy_line_that_looks_like_list_item) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n    * two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one\n"
+                    "* two</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_empty_indented_marker) {
+  const auto result{sourcemeta::core::markdown_to_html(" >")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_empty_multiple_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(">\n>\n>   ")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_blank_first_and_last_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(">  \n> text\n>")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>text</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_blank_line_separates_blockquotes) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n\n> two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one</p>\n"
+                    "</blockquote>\n"
+                    "<blockquote>\n"
+                    "<p>two</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_empty_marker_line_joins_paragraphs) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n> \n> two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one</p>\n"
+                    "<p>two</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_interrupts_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("text\n>quote")};
+  EXPECT_EQ(result, "<p>text</p>\n"
+                    "<blockquote>\n"
+                    "<p>quote</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_ended_by_thematic_break) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n- - -\n> two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one</p>\n"
+                    "</blockquote>\n"
+                    "<hr />\n"
+                    "<blockquote>\n"
+                    "<p>two</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_lazy_line_after_blank_marker_line) {
+  const auto result{sourcemeta::core::markdown_to_html("> one\n>\ntwo")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>one</p>\n"
+                    "</blockquote>\n"
+                    "<p>two</p>\n");
+}
+
+TEST(blockquote_nested_lazy_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html(">> one\ntwo")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<blockquote>\n"
+                    "<p>one\n"
+                    "two</p>\n"
+                    "</blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_nested_markers_without_spaces) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(">>one\n>two\n>>>three")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<blockquote>\n"
+                    "<p>one\n"
+                    "two</p>\n"
+                    "<blockquote>\n"
+                    "<p>three</p>\n"
+                    "</blockquote>\n"
+                    "</blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(blockquote_indented_code_needs_five_spaces) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(">      code\n\n>   text")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<pre><code> code\n"
+                    "</code></pre>\n"
+                    "</blockquote>\n"
+                    "<blockquote>\n"
+                    "<p>text</p>\n"
+                    "</blockquote>\n");
+}
diff --git a/test/markdown/markdown_characters_test.cc b/test/markdown/markdown_characters_test.cc
new file mode 100644
index 0000000000..45f9059805
--- /dev/null
+++ b/test/markdown/markdown_characters_test.cc
@@ -0,0 +1,487 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+#include <string_view> // std::string_view
+
+using namespace std::literals::string_view_literals;
+
+TEST(ampersand_in_text) {
+  const auto result{sourcemeta::core::markdown_to_html("AT&T")};
+  EXPECT_EQ(result, "<p>AT&amp;T</p>\n");
+}
+
+TEST(angle_brackets_in_text) {
+  const auto result{sourcemeta::core::markdown_to_html("1 < 2 and 3 > 2")};
+  EXPECT_EQ(result, "<p>1 &lt; 2 and 3 &gt; 2</p>\n");
+}
+
+TEST(unicode_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Hello \xC3\xA9\xC3\xA0\xC3\xBC")};
+  EXPECT_EQ(result, "<p>Hello \xC3\xA9\xC3\xA0\xC3\xBC</p>\n");
+}
+
+TEST(cjk_characters) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\xE4\xBD\xA0\xE5\xA5\xBD")};
+  EXPECT_EQ(result, "<p>\xE4\xBD\xA0\xE5\xA5\xBD</p>\n");
+}
+
+TEST(emoji) {
+  const auto result{sourcemeta::core::markdown_to_html("\xF0\x9F\x98\x80")};
+  EXPECT_EQ(result, "<p>\xF0\x9F\x98\x80</p>\n");
+}
+
+TEST(invalid_utf8_is_replaced) {
+  const auto result{sourcemeta::core::markdown_to_html("hello \xFF world")};
+  EXPECT_EQ(result, "<p>hello \xEF\xBF\xBD world</p>\n");
+}
+
+TEST(tab_indented_code_block) {
+  const auto result{sourcemeta::core::markdown_to_html("\tlime\tpear\t\tplum")};
+  EXPECT_EQ(result, "<pre><code>lime\tpear\t\tplum\n"
+                    "</code></pre>\n");
+}
+
+TEST(tab_after_space_indented_code_block) {
+  const auto result{sourcemeta::core::markdown_to_html(" \tlime\tpear")};
+  EXPECT_EQ(result, "<pre><code>lime\tpear\n"
+                    "</code></pre>\n");
+}
+
+TEST(tab_list_item_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html(" - kiwi\n\n\tmango")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>kiwi</p>\n"
+                    "<p>mango</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(tab_list_item_indented_code) {
+  const auto result{sourcemeta::core::markdown_to_html("* kiwi\n\n\t\tmango")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>kiwi</p>\n"
+                    "<pre><code>  mango\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(tab_after_blockquote_marker) {
+  const auto result{sourcemeta::core::markdown_to_html(">\t\tcedar\n>\t\toak")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<pre><code>  cedar\n"
+                    "  oak\n"
+                    "</code></pre>\n"
+                    "</blockquote>\n");
+}
+
+TEST(tab_after_list_marker) {
+  const auto result{sourcemeta::core::markdown_to_html("+\t\tcedar")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<pre><code>  cedar\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(tab_after_heading_marker) {
+  const auto result{sourcemeta::core::markdown_to_html("##\tTitle")};
+  EXPECT_EQ(result, "<h2>Title</h2>\n");
+}
+
+TEST(tab_between_thematic_break_characters) {
+  const auto result{sourcemeta::core::markdown_to_html("-\t-\t-")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(crlf_line_endings) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## Title\r\ntext\r\n\r\nmore")};
+  EXPECT_EQ(result, "<h2>Title</h2>\n"
+                    "<p>text</p>\n"
+                    "<p>more</p>\n");
+}
+
+TEST(cr_line_endings) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## Title\rtext\r\rmore")};
+  EXPECT_EQ(result, "<h2>Title</h2>\n"
+                    "<p>text</p>\n"
+                    "<p>more</p>\n");
+}
+
+TEST(mixed_line_endings) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("one\rtwo\r\nthree\nfour")};
+  EXPECT_EQ(result, "<p>one\n"
+                    "two\n"
+                    "three\n"
+                    "four</p>\n");
+}
+
+TEST(byte_order_mark_before_list) {
+  const auto result{sourcemeta::core::markdown_to_html("\xEF\xBB\xBF"
+                                                       "* item")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>item</li>\n"
+                    "</ul>\n");
+}
+
+TEST(text_with_special_characters) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("cost: $5 + 10% ; done?")};
+  EXPECT_EQ(result, "<p>cost: $5 + 10% ; done?</p>\n");
+}
+
+TEST(text_with_greek_characters) {
+  const auto result{sourcemeta::core::markdown_to_html("λέξη και φράση")};
+  EXPECT_EQ(result,
+            "<p>\xce\xbb\xce\xad\xce\xbe\xce\xb7 \xce\xba\xce\xb1\xce\xb9 "
+            "\xcf\x86\xcf\x81\xce\xac\xcf\x83\xce\xb7</p>\n");
+}
+
+TEST(text_internal_spaces_preserved) {
+  const auto result{sourcemeta::core::markdown_to_html("wide     gap")};
+  EXPECT_EQ(result, "<p>wide     gap</p>\n");
+}
+
+TEST(invalid_utf8_truncated_two_byte_sequence_at_end) {
+  const auto result{sourcemeta::core::markdown_to_html("caf\xC3")};
+  EXPECT_EQ(result, "<p>caf\xef\xbf\xbd</p>\n");
+}
+
+TEST(invalid_utf8_truncated_three_byte_sequence_mid_text) {
+  const auto result{sourcemeta::core::markdown_to_html("x\xE2\x82"
+                                                       "b")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbd"
+                    "b</p>\n");
+}
+
+TEST(invalid_utf8_truncated_four_byte_sequence_before_newline) {
+  const auto result{sourcemeta::core::markdown_to_html("x\xF0\x9F\x98\ny")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbd\n"
+                    "y</p>\n");
+}
+
+TEST(invalid_utf8_stray_continuation_byte) {
+  const auto result{sourcemeta::core::markdown_to_html("x\x80y")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbdy</p>\n");
+}
+
+TEST(invalid_utf8_consecutive_continuation_bytes) {
+  const auto result{sourcemeta::core::markdown_to_html("\x80\x81\xBF")};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd</p>\n");
+}
+
+TEST(invalid_utf8_overlong_encoded_slash) {
+  const auto result{sourcemeta::core::markdown_to_html("path\xC0\xAF"
+                                                       "etc")};
+  EXPECT_EQ(result, "<p>path\xef\xbf\xbd"
+                    "etc</p>\n");
+}
+
+TEST(invalid_utf8_overlong_encoded_nul) {
+  const auto result{sourcemeta::core::markdown_to_html("x\xE0\x80\x80y")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbdy</p>\n");
+}
+
+TEST(invalid_utf8_encoded_surrogate) {
+  const auto result{sourcemeta::core::markdown_to_html("x\xED\xA0\x80y")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbdy</p>\n");
+}
+
+TEST(invalid_utf8_code_point_above_unicode_range) {
+  const auto result{sourcemeta::core::markdown_to_html("x\xF4\x90\x80\x80y")};
+  EXPECT_EQ(result, "<p>x\xef\xbf\xbdy</p>\n");
+}
+
+TEST(invalid_utf8_five_byte_sequence) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x\xF8\x88\x80\x80\x80y")};
+  EXPECT_EQ(result,
+            "<p>x\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbd\xef\xbf\xbdy<"
+            "/p>\n");
+}
+
+TEST(invalid_utf8_lead_byte_followed_by_ascii) {
+  const auto result{sourcemeta::core::markdown_to_html("\xE4"
+                                                       "abc")};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbd"
+                    "abc</p>\n");
+}
+
+TEST(invalid_utf8_bytes_fe_and_ff) {
+  const auto result{sourcemeta::core::markdown_to_html("\xFE\xFF text")};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbd\xef\xbf\xbd text</p>\n");
+}
+
+TEST(invalid_utf8_in_heading) {
+  const auto result{sourcemeta::core::markdown_to_html("# t\xFFitle")};
+  EXPECT_EQ(result, "<h1>t\xef\xbf\xbditle</h1>\n");
+}
+
+TEST(invalid_utf8_in_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("`a\xFF"
+                                                       "b`")};
+  EXPECT_EQ(result, "<p><code>a\xef\xbf\xbd"
+                    "b</code></p>\n");
+}
+
+TEST(invalid_utf8_in_fenced_code) {
+  const auto result{sourcemeta::core::markdown_to_html("```\n\xC3\n```")};
+  EXPECT_EQ(result, "<pre><code>\xef\xbf\xbd\n"
+                    "</code></pre>\n");
+}
+
+TEST(invalid_utf8_in_fenced_code_info_string) {
+  const auto result{sourcemeta::core::markdown_to_html("```l\xFF"
+                                                       "ang\ncode\n```")};
+  EXPECT_EQ(result, "<pre lang=\"l\xef\xbf\xbd"
+                    "ang\"><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(invalid_utf8_in_indented_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    \xE2\x82\n    next")};
+  EXPECT_EQ(result, "<pre><code>\xef\xbf\xbd\n"
+                    "next\n"
+                    "</code></pre>\n");
+}
+
+TEST(invalid_utf8_in_link_destination) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](/a\xFF"
+                                                       "b)")};
+  EXPECT_EQ(result, "<p><a href=\"/a%EF%BF%BDb\">x</a></p>\n");
+}
+
+TEST(invalid_utf8_in_link_title) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](/a 't\xC3')")};
+  EXPECT_EQ(result, "<p><a href=\"/a\" title=\"t\xef\xbf\xbd\">x</a></p>\n");
+}
+
+TEST(invalid_utf8_in_reference_label) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[l\xFF]\n\n[l\xFF]: /x")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">l\xef\xbf\xbd</a></p>\n");
+}
+
+TEST(invalid_utf8_in_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://sourcemeta.com/\xFF>")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/%EF%BF%BD\">https://"
+                    "sourcemeta.com/\xef\xbf\xbd</a></p>\n");
+}
+
+TEST(invalid_utf8_in_extended_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("www.sourcemeta.com/\xC3path")};
+  EXPECT_EQ(result,
+            "<p><a "
+            "href=\"http://www.sourcemeta.com/"
+            "%EF%BF%BDpath\">www.sourcemeta.com/\xef\xbf\xbdpath</a></p>\n");
+}
+
+TEST(invalid_utf8_in_table_cell) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a |\n| - |\n| \xFF |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>\xef\xbf\xbd</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(invalid_utf8_in_image_description) {
+  const auto result{sourcemeta::core::markdown_to_html("![\xC3](/i.png)")};
+  EXPECT_EQ(result, "<p><img src=\"/i.png\" alt=\"\xef\xbf\xbd\" /></p>\n");
+}
+
+TEST(invalid_utf8_between_emphasis_delimiters) {
+  const auto result{sourcemeta::core::markdown_to_html("*\xFF*")};
+  EXPECT_EQ(result, "<p><em>\xef\xbf\xbd</em></p>\n");
+}
+
+TEST(invalid_utf8_in_footnote_label) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x[^\xFF]\n\n[^\xFF]: note")};
+  EXPECT_EQ(result,
+            "<p>x<sup class=\"footnote-ref\"><a href=\"#fn-%EF%BF%BD\" "
+            "id=\"fnref-%EF%BF%BD\" data-footnote-ref>1</a></sup></p>\n"
+            "<section class=\"footnotes\" data-footnotes>\n"
+            "<ol>\n"
+            "<li id=\"fn-%EF%BF%BD\">\n"
+            "<p>note <a href=\"#fnref-%EF%BF%BD\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"1\" "
+            "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "</ol>\n"
+            "</section>\n");
+}
+
+TEST(invalid_utf8_inside_entity_like_text) {
+  const auto result{sourcemeta::core::markdown_to_html("&\xFF"
+                                                       "amp;")};
+  EXPECT_EQ(result, "<p>&amp;\xef\xbf\xbd"
+                    "amp;</p>\n");
+}
+
+TEST(nul_character_at_start) {
+  const auto result{sourcemeta::core::markdown_to_html("\0text"sv)};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbdtext</p>\n");
+}
+
+TEST(nul_character_in_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("`x\0y`"sv)};
+  EXPECT_EQ(result, "<p><code>x\xef\xbf\xbdy</code></p>\n");
+}
+
+TEST(nul_character_in_fenced_code) {
+  const auto result{sourcemeta::core::markdown_to_html("```\nx\0y\n```"sv)};
+  EXPECT_EQ(result, "<pre><code>x\xef\xbf\xbdy\n"
+                    "</code></pre>\n");
+}
+
+TEST(nul_character_in_link_destination) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](/a\0z)"sv)};
+  EXPECT_EQ(result, "<p><a href=\"/a%EF%BF%BDz\">x</a></p>\n");
+}
+
+TEST(nul_character_in_heading) {
+  const auto result{sourcemeta::core::markdown_to_html("# a\0"sv)};
+  EXPECT_EQ(result, "<h1>a\xef\xbf\xbd</h1>\n");
+}
+
+TEST(nul_character_in_table_cell) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a |\n| - |\n| \0 |"sv)};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>\xef\xbf\xbd</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(start_of_heading_control_character_preserved) {
+  const auto result{sourcemeta::core::markdown_to_html("x\x01y")};
+  EXPECT_EQ(result, "<p>x\x01y</p>\n");
+}
+
+TEST(delete_character_preserved) {
+  const auto result{sourcemeta::core::markdown_to_html("x\x7Fy")};
+  EXPECT_EQ(result, "<p>x\x7fy</p>\n");
+}
+
+TEST(form_feed_between_words) {
+  const auto result{sourcemeta::core::markdown_to_html("a\fz")};
+  EXPECT_EQ(result, "<p>a\x0cz</p>\n");
+}
+
+TEST(vertical_tab_between_words) {
+  const auto result{sourcemeta::core::markdown_to_html("a\vz")};
+  EXPECT_EQ(result, "<p>a\x0bz</p>\n");
+}
+
+TEST(form_feed_between_thematic_break_characters) {
+  const auto result{sourcemeta::core::markdown_to_html("-\f-\f-")};
+  EXPECT_EQ(result, "<p>-\x0c-\x0c-</p>\n");
+}
+
+TEST(lone_carriage_return_at_end) {
+  const auto result{sourcemeta::core::markdown_to_html("text\r")};
+  EXPECT_EQ(result, "<p>text</p>\n");
+}
+
+TEST(carriage_return_before_list_item) {
+  const auto result{sourcemeta::core::markdown_to_html("a\r* b")};
+  EXPECT_EQ(result, "<p>a</p>\n"
+                    "<ul>\n"
+                    "<li>b</li>\n"
+                    "</ul>\n");
+}
+
+TEST(crlf_after_trailing_spaces_is_hard_break) {
+  const auto result{sourcemeta::core::markdown_to_html("a  \r\nb")};
+  EXPECT_EQ(result, "<p>a<br />\n"
+                    "b</p>\n");
+}
+
+TEST(non_breaking_space_after_list_marker_is_not_list) {
+  const auto result{sourcemeta::core::markdown_to_html("*\xC2\xA0item")};
+  EXPECT_EQ(result, "<p>*\xc2\xa0item</p>\n");
+}
+
+TEST(em_spaces_do_not_indent_code) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "\xE2\x80\x83\xE2\x80\x83\xE2\x80\x83\xE2\x80\x83"
+      "code")};
+  EXPECT_EQ(result, "<p>\xe2\x80\x83\xe2\x80\x83\xe2\x80\x83\xe2\x80\x83"
+                    "code</p>\n");
+}
+
+TEST(zero_width_joiner_sequence_preserved) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "\xF0\x9F\x91\xA8\xE2\x80\x8D\xF0\x9F\x92\xBB")};
+  EXPECT_EQ(result, "<p>\xf0\x9f\x91\xa8\xe2\x80\x8d\xf0\x9f\x92\xbb</p>\n");
+}
+
+TEST(combining_accent_preserved) {
+  const auto result{sourcemeta::core::markdown_to_html("e\xCC\x81")};
+  EXPECT_EQ(result, "<p>e\xcc\x81</p>\n");
+}
+
+TEST(right_to_left_text_preserved) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\xD7\xA9\xD7\x9C\xD7\x95\xD7\x9D")};
+  EXPECT_EQ(result, "<p>\xd7\xa9\xd7\x9c\xd7\x95\xd7\x9d</p>\n");
+}
+
+TEST(byte_order_mark_after_first_line) {
+  const auto result{sourcemeta::core::markdown_to_html("a\n\xEF\xBB\xBF"
+                                                       "b")};
+  EXPECT_EQ(result, "<p>a\n"
+                    "\xef\xbb\xbf"
+                    "b</p>\n");
+}
+
+TEST(four_byte_character_in_link_destination) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](/\xF0\x9F\x98\x80)")};
+  EXPECT_EQ(result, "<p><a href=\"/%F0%9F%98%80\">x</a></p>\n");
+}
+
+TEST(non_ascii_link_destination_is_percent_encoded) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](/caf\xC3\xA9)")};
+  EXPECT_EQ(result, "<p><a href=\"/caf%C3%A9\">x</a></p>\n");
+}
+
+TEST(quotes_in_text_are_escaped) {
+  const auto result{sourcemeta::core::markdown_to_html("say \"hi\" and 'bye'")};
+  EXPECT_EQ(result, "<p>say &quot;hi&quot; and 'bye'</p>\n");
+}
+
+TEST(nul_characters_are_replaced) {
+  const auto result{sourcemeta::core::markdown_to_html("one\0two\0"sv)};
+  EXPECT_EQ(result, "<p>one\xef\xbf\xbdtwo\xef\xbf\xbd</p>\n");
+}
diff --git a/test/markdown/markdown_code_blocks_test.cc b/test/markdown/markdown_code_blocks_test.cc
new file mode 100644
index 0000000000..b41f7eae28
--- /dev/null
+++ b/test/markdown/markdown_code_blocks_test.cc
@@ -0,0 +1,284 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(fenced_code_block_backticks) {
+  const auto result{sourcemeta::core::markdown_to_html("```\ncode here\n```")};
+  EXPECT_EQ(result, "<pre><code>code here\n</code></pre>\n");
+}
+
+TEST(fenced_code_block_tildes) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~\ncode here\n~~~")};
+  EXPECT_EQ(result, "<pre><code>code here\n</code></pre>\n");
+}
+
+TEST(fenced_code_block_with_language) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("```cpp\nint x = 0;\n```")};
+  EXPECT_EQ(result, "<pre lang=\"cpp\"><code>int x = 0;\n</code></pre>\n");
+}
+
+TEST(fenced_code_block_html_escaped) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("```\n<div>&amp;</div>\n```")};
+  EXPECT_EQ(result,
+            "<pre><code>&lt;div&gt;&amp;amp;&lt;/div&gt;\n</code></pre>\n");
+}
+
+TEST(indented_code_block) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    int x = 0;\n    return x;")};
+  EXPECT_EQ(result, "<pre><code>int x = 0;\nreturn x;\n</code></pre>\n");
+}
+
+TEST(fenced_code_block_with_empty_lines) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("```\nline one\n\nline three\n```")};
+  EXPECT_EQ(result, "<pre><code>line one\n\nline three\n</code></pre>\n");
+}
+
+TEST(github_pre_lang_format) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("```python\nprint()\n```")};
+  EXPECT_EQ(result, "<pre lang=\"python\"><code>print()\n</code></pre>\n");
+}
+
+TEST(indented_code_chunks_separated_by_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "    first\n\n    second\n \n  \n    third")};
+  EXPECT_EQ(result, "<pre><code>first\n"
+                    "\n"
+                    "second\n"
+                    "\n"
+                    "\n"
+                    "third\n"
+                    "</code></pre>\n");
+}
+
+TEST(indented_code_keeps_extra_indentation_on_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "    first\n        \n        second")};
+  EXPECT_EQ(result, "<pre><code>first\n"
+                    "    \n"
+                    "    second\n"
+                    "</code></pre>\n");
+}
+
+TEST(indented_code_cannot_interrupt_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("Text\n        code")};
+  EXPECT_EQ(result, "<p>Text\n"
+                    "code</p>\n");
+}
+
+TEST(indented_code_ends_at_unindented_line) {
+  const auto result{sourcemeta::core::markdown_to_html("    code\ntext")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<p>text</p>\n");
+}
+
+TEST(indented_code_between_headings) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "## Top\n    code\nBottom\n===\n    code\n***")};
+  EXPECT_EQ(result, "<h2>Top</h2>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<h1>Bottom</h1>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<hr />\n");
+}
+
+TEST(indented_code_first_line_extra_indentation) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("      alpha\n    beta")};
+  EXPECT_EQ(result, "<pre><code>  alpha\n"
+                    "beta\n"
+                    "</code></pre>\n");
+}
+
+TEST(indented_code_surrounding_blank_lines_dropped) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    \n\n    code\n\n    \n")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(indented_code_trailing_whitespace_kept) {
+  const auto result{sourcemeta::core::markdown_to_html("    code\t  ")};
+  EXPECT_EQ(result, "<pre><code>code\t  \n"
+                    "</code></pre>\n");
+}
+
+TEST(indented_code_content_is_not_parsed) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "    **bold**\n    [link](/x)\n\n    1. item")};
+  EXPECT_EQ(result, "<pre><code>**bold**\n"
+                    "[link](/x)\n"
+                    "\n"
+                    "1. item\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_closing_fence_longer_than_opening) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~\ncode\n~~~~~")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_tildes_not_closed_by_backticks) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("~~~~\ncode\n````\n~~~~")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "````\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_backticks_not_closed_by_tildes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("````\ncode\n~~~~\n````")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "~~~~\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_unclosed_empty) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~")};
+  EXPECT_EQ(result, "<pre><code></code></pre>\n");
+}
+
+TEST(fenced_code_unclosed_runs_to_end_of_document) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~~\n\n~~~\ntext")};
+  EXPECT_EQ(result, "<pre><code>\n"
+                    "~~~\n"
+                    "text\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_unclosed_ends_with_blockquote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> ~~~\n> code\n\ntext")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</blockquote>\n"
+                    "<p>text</p>\n");
+}
+
+TEST(fenced_code_only_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~\n \n\n~~~")};
+  EXPECT_EQ(result, "<pre><code> \n"
+                    "\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_empty) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~\n~~~")};
+  EXPECT_EQ(result, "<pre><code></code></pre>\n");
+}
+
+TEST(fenced_code_indentation_removed_from_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("  ~~~\n  one\n two\nthree\n  ~~~")};
+  EXPECT_EQ(result, "<pre><code>one\n"
+                    "two\n"
+                    "three\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_indentation_removed_up_to_fence_indentation) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(" ```\n   one\n  two\n```")};
+  EXPECT_EQ(result, "<pre><code>  one\n"
+                    " two\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_fence_indented_four_spaces_is_indented_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    ~~~\n    code\n    ~~~")};
+  EXPECT_EQ(result, "<pre><code>~~~\n"
+                    "code\n"
+                    "~~~\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_closing_fence_indented_differently) {
+  const auto result{sourcemeta::core::markdown_to_html("  ~~~\ncode\n   ~~~")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_closing_fence_indented_four_spaces_is_content) {
+  const auto result{sourcemeta::core::markdown_to_html("~~~\ncode\n    ~~~")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "    ~~~\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_closing_fence_with_internal_space_is_content) {
+  const auto result{sourcemeta::core::markdown_to_html("```\ncode\n`` ``")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "`` ``\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_backtick_info_with_backticks_is_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("``` x ```\ncode")};
+  EXPECT_EQ(result, "<p><code>x</code>\n"
+                    "code</p>\n");
+}
+
+TEST(fenced_code_interrupts_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("text\n~~~\ncode\n~~~\nmore")};
+  EXPECT_EQ(result, "<p>text</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<p>more</p>\n");
+}
+
+TEST(fenced_code_info_string_first_word_is_language) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "~~~ python extra words here\nprint(1)\n~~~")};
+  EXPECT_EQ(result, "<pre lang=\"python\"><code>print(1)\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_info_string_of_symbols) {
+  const auto result{sourcemeta::core::markdown_to_html("```#!\n```")};
+  EXPECT_EQ(result, "<pre lang=\"#!\"><code></code></pre>\n");
+}
+
+TEST(fenced_code_backtick_fence_info_cannot_contain_backticks) {
+  const auto result{sourcemeta::core::markdown_to_html("```js`\ncode")};
+  EXPECT_EQ(result, "<p>```js`\n"
+                    "code</p>\n");
+}
+
+TEST(fenced_code_tilde_fence_info_can_contain_backticks) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("~~~ `js` ~~~\ncode\n~~~")};
+  EXPECT_EQ(result, "<pre lang=\"`js`\"><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_closing_fence_cannot_have_info) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("~~~\n~~~ closing\n~~~")};
+  EXPECT_EQ(result, "<pre><code>~~~ closing\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_info_string_entities_decoded) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("```c&#43;&#43;\ncode\n```")};
+  EXPECT_EQ(result, "<pre lang=\"c++\"><code>code\n"
+                    "</code></pre>\n");
+}
+
+TEST(fenced_code_info_string_backslash_escapes) {
+  const auto result{sourcemeta::core::markdown_to_html("```c\\#\ncode\n```")};
+  EXPECT_EQ(result, "<pre lang=\"c#\"><code>code\n"
+                    "</code></pre>\n");
+}
diff --git a/test/markdown/markdown_code_spans_test.cc b/test/markdown/markdown_code_spans_test.cc
new file mode 100644
index 0000000000..6d1412d6ff
--- /dev/null
+++ b/test/markdown/markdown_code_spans_test.cc
@@ -0,0 +1,97 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(inline_code) {
+  const auto result{sourcemeta::core::markdown_to_html("Use `printf()`")};
+  EXPECT_EQ(result, "<p>Use <code>printf()</code></p>\n");
+}
+
+TEST(inline_code_with_backticks_inside) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("`` there is a ` here ``")};
+  EXPECT_EQ(result, "<p><code>there is a ` here</code></p>\n");
+}
+
+TEST(inline_code_preserves_html) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("`<div class=\"foo\">`")};
+  EXPECT_EQ(result, "<p><code>&lt;div class=&quot;foo&quot;&gt;</code></p>\n");
+}
+
+TEST(code_span_with_double_backticks) {
+  const auto result{sourcemeta::core::markdown_to_html("``a`b``")};
+  EXPECT_EQ(result, "<p><code>a`b</code></p>\n");
+}
+
+TEST(code_span_strips_one_surrounding_space) {
+  const auto result{sourcemeta::core::markdown_to_html("`` `x` ``")};
+  EXPECT_EQ(result, "<p><code>`x`</code></p>\n");
+}
+
+TEST(code_span_strips_only_one_space_per_side) {
+  const auto result{sourcemeta::core::markdown_to_html("``   x   ``")};
+  EXPECT_EQ(result, "<p><code>  x  </code></p>\n");
+}
+
+TEST(code_span_space_on_one_side_is_kept) {
+  const auto result{sourcemeta::core::markdown_to_html("`x `")};
+  EXPECT_EQ(result, "<p><code>x </code></p>\n");
+}
+
+TEST(code_span_non_breaking_space_is_kept) {
+  const auto result{sourcemeta::core::markdown_to_html("`\xC2\xA0"
+                                                       "x`")};
+  EXPECT_EQ(result, "<p><code>\xc2\xa0x</code></p>\n");
+}
+
+TEST(code_span_of_only_spaces_is_kept) {
+  const auto result{sourcemeta::core::markdown_to_html("`   `")};
+  EXPECT_EQ(result, "<p><code>   </code></p>\n");
+}
+
+TEST(code_span_line_endings_become_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("`one\ntwo\nthree`")};
+  EXPECT_EQ(result, "<p><code>one two three</code></p>\n");
+}
+
+TEST(code_span_interior_spaces_are_kept) {
+  const auto result{sourcemeta::core::markdown_to_html("`a    b  \n  c`")};
+  EXPECT_EQ(result, "<p><code>a    b   c</code></p>\n");
+}
+
+TEST(code_span_backslash_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("`a\\`b")};
+  EXPECT_EQ(result, "<p><code>a\\</code>b</p>\n");
+}
+
+TEST(code_span_backtick_run_lengths_must_match) {
+  const auto result{sourcemeta::core::markdown_to_html("``x```")};
+  EXPECT_EQ(result, "<p>``x```</p>\n");
+}
+
+TEST(code_span_unmatched_opening_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("``x")};
+  EXPECT_EQ(result, "<p>``x</p>\n");
+}
+
+TEST(code_span_longer_closing_run_does_not_close) {
+  const auto result{sourcemeta::core::markdown_to_html("``x```y``")};
+  EXPECT_EQ(result, "<p><code>x```y</code></p>\n");
+}
+
+TEST(code_span_takes_precedence_over_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("_x`_`")};
+  EXPECT_EQ(result, "<p>_x<code>_</code></p>\n");
+}
+
+TEST(code_span_takes_precedence_over_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[text `code](/url`)")};
+  EXPECT_EQ(result, "<p>[text <code>code](/url</code>)</p>\n");
+}
+
+TEST(code_span_takes_precedence_over_autolink) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("`<https://sourcemeta.com/`x>`")};
+  EXPECT_EQ(result, "<p><code>&lt;https://sourcemeta.com/</code>x&gt;`</p>\n");
+}
diff --git a/test/markdown/markdown_concurrency_test.cc b/test/markdown/markdown_concurrency_test.cc
new file mode 100644
index 0000000000..36d35822f0
--- /dev/null
+++ b/test/markdown/markdown_concurrency_test.cc
@@ -0,0 +1,42 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+#include <cstddef> // std::size_t
+#include <string>  // std::string
+#include <thread>  // std::thread
+#include <vector>  // std::vector
+
+TEST(concurrent_calls) {
+  static constexpr std::size_t THREAD_COUNT{16};
+  std::vector<std::thread> threads;
+  threads.reserve(THREAD_COUNT);
+  std::vector<std::string> results(THREAD_COUNT);
+
+  for (std::size_t index{0}; index < THREAD_COUNT; ++index) {
+    threads.emplace_back([&results, index]() {
+      results[index] = sourcemeta::core::markdown_to_html("**hello** world");
+    });
+  }
+
+  for (auto &thread : threads) {
+    thread.join();
+  }
+
+  EXPECT_EQ(results[0], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[1], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[2], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[3], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[4], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[5], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[6], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[7], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[8], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[9], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[10], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[11], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[12], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[13], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[14], "<p><strong>hello</strong> world</p>\n");
+  EXPECT_EQ(results[15], "<p><strong>hello</strong> world</p>\n");
+}
diff --git a/test/markdown/markdown_emphasis_test.cc b/test/markdown/markdown_emphasis_test.cc
new file mode 100644
index 0000000000..d0a7327967
--- /dev/null
+++ b/test/markdown/markdown_emphasis_test.cc
@@ -0,0 +1,312 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(italic_with_asterisks) {
+  const auto result{sourcemeta::core::markdown_to_html("*italic*")};
+  EXPECT_EQ(result, "<p><em>italic</em></p>\n");
+}
+
+TEST(italic_with_underscores) {
+  const auto result{sourcemeta::core::markdown_to_html("_italic_")};
+  EXPECT_EQ(result, "<p><em>italic</em></p>\n");
+}
+
+TEST(bold_with_asterisks) {
+  const auto result{sourcemeta::core::markdown_to_html("**bold**")};
+  EXPECT_EQ(result, "<p><strong>bold</strong></p>\n");
+}
+
+TEST(bold_with_underscores) {
+  const auto result{sourcemeta::core::markdown_to_html("__bold__")};
+  EXPECT_EQ(result, "<p><strong>bold</strong></p>\n");
+}
+
+TEST(bold_and_italic) {
+  const auto result{sourcemeta::core::markdown_to_html("***bold italic***")};
+  EXPECT_EQ(result, "<p><em><strong>bold italic</strong></em></p>\n");
+}
+
+TEST(bold_inside_italic) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("*this is **bold** inside italic*")};
+  EXPECT_EQ(result,
+            "<p><em>this is <strong>bold</strong> inside italic</em></p>\n");
+}
+
+TEST(italic_inside_bold) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("**this is *italic* inside bold**")};
+  EXPECT_EQ(result,
+            "<p><strong>this is <em>italic</em> inside bold</strong></p>\n");
+}
+
+TEST(emphasis_across_words) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("this is **all bold** here")};
+  EXPECT_EQ(result, "<p>this is <strong>all bold</strong> here</p>\n");
+}
+
+TEST(bold_and_italic_in_list_item) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- ***bold italic item***\n- normal")};
+  EXPECT_EQ(result,
+            "<ul>\n<li><em><strong>bold italic item</strong></em></li>\n"
+            "<li>normal</li>\n</ul>\n");
+}
+
+TEST(emphasis_does_not_cross_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("*start `code* end`")};
+  EXPECT_EQ(result, "<p>*start <code>code* end</code></p>\n");
+}
+
+TEST(single_character_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("*a*")};
+  EXPECT_EQ(result, "<p><em>a</em></p>\n");
+}
+
+TEST(emphasis_opening_followed_by_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html("x _ y z_")};
+  EXPECT_EQ(result, "<p>x _ y z_</p>\n");
+}
+
+TEST(emphasis_opening_between_letter_and_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("x*(y)*")};
+  EXPECT_EQ(result, "<p>x*(y)*</p>\n");
+}
+
+TEST(emphasis_opening_followed_by_non_breaking_space) {
+  const auto result{sourcemeta::core::markdown_to_html("_\xC2\xA0"
+                                                       "x\xC2\xA0_")};
+  EXPECT_EQ(result, "<p>_\xc2\xa0x\xc2\xa0_</p>\n");
+}
+
+TEST(emphasis_intraword_with_asterisks) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("un*frigging*believable")};
+  EXPECT_EQ(result, "<p>un<em>frigging</em>believable</p>\n");
+}
+
+TEST(emphasis_intraword_with_underscores_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("snake_case_name")};
+  EXPECT_EQ(result, "<p>snake_case_name</p>\n");
+}
+
+TEST(emphasis_intraword_with_underscores_in_cyrillic) {
+  const auto result{sourcemeta::core::markdown_to_html("река_течёт_быстро")};
+  EXPECT_EQ(result, "<p>\xd1\x80\xd0\xb5\xd0\xba\xd0\xb0_"
+                    "\xd1\x82\xd0\xb5\xd1\x87\xd1\x91\xd1\x82_"
+                    "\xd0\xb1\xd1\x8b\xd1\x81\xd1\x82\xd1\x80\xd0\xbe</p>\n");
+}
+
+TEST(emphasis_between_digits) {
+  const auto result{sourcemeta::core::markdown_to_html("1*2*3\n\n1_2_3")};
+  EXPECT_EQ(result, "<p>1<em>2</em>3</p>\n"
+                    "<p>1_2_3</p>\n");
+}
+
+TEST(emphasis_underscore_between_letters_and_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("x_(y)_z")};
+  EXPECT_EQ(result, "<p>x_(y)_z</p>\n");
+}
+
+TEST(emphasis_underscore_after_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("x._[y]_")};
+  EXPECT_EQ(result, "<p>x.<em>[y]</em></p>\n");
+}
+
+TEST(emphasis_mismatched_delimiter_characters) {
+  const auto result{sourcemeta::core::markdown_to_html("*x_")};
+  EXPECT_EQ(result, "<p>*x_</p>\n");
+}
+
+TEST(emphasis_closing_preceded_by_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html("_x y _")};
+  EXPECT_EQ(result, "<p>_x y _</p>\n");
+}
+
+TEST(emphasis_closing_on_new_line) {
+  const auto result{sourcemeta::core::markdown_to_html("_x y\n_")};
+  EXPECT_EQ(result, "<p>_x y\n"
+                    "_</p>\n");
+}
+
+TEST(emphasis_closing_not_right_flanking) {
+  const auto result{sourcemeta::core::markdown_to_html("_[_x]")};
+  EXPECT_EQ(result, "<p>_[_x]</p>\n");
+}
+
+TEST(emphasis_nested_with_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("_[_x_]_")};
+  EXPECT_EQ(result, "<p><em>[<em>x</em>]</em></p>\n");
+}
+
+TEST(emphasis_closing_followed_by_letter) {
+  const auto result{sourcemeta::core::markdown_to_html("*x*y")};
+  EXPECT_EQ(result, "<p><em>x</em>y</p>\n");
+}
+
+TEST(emphasis_underscore_closing_followed_by_letter) {
+  const auto result{sourcemeta::core::markdown_to_html("_x_y\n\n_x_y_z_")};
+  EXPECT_EQ(result, "<p>_x_y</p>\n"
+                    "<p><em>x_y_z</em></p>\n");
+}
+
+TEST(emphasis_underscore_followed_by_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("_[x]_!")};
+  EXPECT_EQ(result, "<p><em>[x]</em>!</p>\n");
+}
+
+TEST(strong_emphasis_opening_followed_by_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html("__ x y__")};
+  EXPECT_EQ(result, "<p>__ x y__</p>\n");
+}
+
+TEST(strong_emphasis_between_letter_and_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("x__(y)__")};
+  EXPECT_EQ(result, "<p>x__(y)__</p>\n");
+}
+
+TEST(strong_emphasis_intraword_with_asterisks) {
+  const auto result{sourcemeta::core::markdown_to_html("x**y**z")};
+  EXPECT_EQ(result, "<p>x<strong>y</strong>z</p>\n");
+}
+
+TEST(strong_emphasis_nested_asterisks) {
+  const auto result{sourcemeta::core::markdown_to_html("**x, **y**, z**")};
+  EXPECT_EQ(result, "<p><strong>x, y, z</strong></p>\n");
+}
+
+TEST(strong_emphasis_underscore_after_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html("x.__[y]__")};
+  EXPECT_EQ(result, "<p>x.<strong>[y]</strong></p>\n");
+}
+
+TEST(emphasis_rule_of_three_nested_strong) {
+  const auto result{sourcemeta::core::markdown_to_html("_x__y__z_")};
+  EXPECT_EQ(result, "<p><em>x__y__z</em></p>\n");
+}
+
+TEST(emphasis_rule_of_three_unmatched) {
+  const auto result{sourcemeta::core::markdown_to_html("_x__y_")};
+  EXPECT_EQ(result, "<p><em>x__y</em></p>\n");
+}
+
+TEST(emphasis_rule_of_three_triple_opening) {
+  const auto result{sourcemeta::core::markdown_to_html("___x__ y_")};
+  EXPECT_EQ(result, "<p><em><strong>x</strong> y</em></p>\n");
+}
+
+TEST(emphasis_rule_of_three_triple_closing) {
+  const auto result{sourcemeta::core::markdown_to_html("_x __y___")};
+  EXPECT_EQ(result, "<p><em>x <strong>y</strong></em></p>\n");
+}
+
+TEST(emphasis_rule_of_three_intraword) {
+  const auto result{sourcemeta::core::markdown_to_html("a***b***c")};
+  EXPECT_EQ(result, "<p>a<em><strong>b</strong></em>c</p>\n");
+}
+
+TEST(emphasis_rule_of_three_long_runs) {
+  const auto result{sourcemeta::core::markdown_to_html("a****b*******c")};
+  EXPECT_EQ(result, "<p>a<strong>b</strong>***c</p>\n");
+}
+
+TEST(emphasis_containing_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("_see [docs](/manual)_")};
+  EXPECT_EQ(result, "<p><em>see <a href=\"/manual\">docs</a></em></p>\n");
+}
+
+TEST(emphasis_empty_delimiters_are_literal) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "__ empty strong\n\n____ empty double")};
+  EXPECT_EQ(result, "<p>__ empty strong</p>\n"
+                    "<p>____ empty double</p>\n");
+}
+
+TEST(emphasis_spanning_lines) {
+  const auto result{sourcemeta::core::markdown_to_html("_one\ntwo_")};
+  EXPECT_EQ(result, "<p><em>one\n"
+                    "two</em></p>\n");
+}
+
+TEST(strong_emphasis_nested_inside_itself) {
+  const auto result{sourcemeta::core::markdown_to_html("**x **y** z**")};
+  EXPECT_EQ(result, "<p><strong>x y z</strong></p>\n");
+}
+
+TEST(strong_emphasis_quadruple_delimiters) {
+  const auto result{sourcemeta::core::markdown_to_html("****x****")};
+  EXPECT_EQ(result, "<p><strong>x</strong></p>\n");
+}
+
+TEST(strong_emphasis_quintuple_delimiters) {
+  const auto result{sourcemeta::core::markdown_to_html("*****x*****")};
+  EXPECT_EQ(result, "<p><em><strong>x</strong></em></p>\n");
+}
+
+TEST(emphasis_with_escaped_delimiters) {
+  const auto result{sourcemeta::core::markdown_to_html("x _\\__\n\nx __\\___")};
+  EXPECT_EQ(result, "<p>x <em>_</em></p>\n"
+                    "<p>x <strong>_</strong></p>\n");
+}
+
+TEST(emphasis_with_excess_delimiters) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("_x__\n\n__x_\n\n_x____")};
+  EXPECT_EQ(result, "<p><em>x</em>_</p>\n"
+                    "<p>_<em>x</em></p>\n"
+                    "<p><em>x</em>___</p>\n");
+}
+
+TEST(emphasis_overlapping_delimiters) {
+  const auto result{sourcemeta::core::markdown_to_html("_x *y_ z*")};
+  EXPECT_EQ(result, "<p><em>x *y</em> z*</p>\n");
+}
+
+TEST(emphasis_overlapping_strong_and_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("_x **y _z w** v_")};
+  EXPECT_EQ(result, "<p><em>x <strong>y _z w</strong> v</em></p>\n");
+}
+
+TEST(emphasis_unclosed_outer_strong) {
+  const auto result{sourcemeta::core::markdown_to_html("__x __y z__")};
+  EXPECT_EQ(result, "<p>__x <strong>y z</strong></p>\n");
+}
+
+TEST(emphasis_unclosed_outer_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("_x _y z_")};
+  EXPECT_EQ(result, "<p>_x <em>y z</em></p>\n");
+}
+
+TEST(emphasis_does_not_span_link_brackets) {
+  const auto result{sourcemeta::core::markdown_to_html("_[x_](/url)")};
+  EXPECT_EQ(result, "<p>_<a href=\"/url\">x_</a></p>\n");
+}
+
+TEST(emphasis_asterisk_does_not_span_link_brackets) {
+  const auto result{sourcemeta::core::markdown_to_html("*x [y*](/url)")};
+  EXPECT_EQ(result, "<p>*x <a href=\"/url\">y*</a></p>\n");
+}
+
+TEST(strong_emphasis_does_not_span_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("**x `**` y**")};
+  EXPECT_EQ(result, "<p><strong>x <code>**</code> y</strong></p>\n");
+}
+
+TEST(emphasis_does_not_span_autolink) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "_x<https://sourcemeta.com/?a=_>\n\n**x<https://sourcemeta.com/?b=**>")};
+  EXPECT_EQ(result, "<p>_x<a "
+                    "href=\"https://sourcemeta.com/?a=_\">https://"
+                    "sourcemeta.com/?a=_</a></p>\n"
+                    "<p>**x<a "
+                    "href=\"https://sourcemeta.com/?b=**\">https://"
+                    "sourcemeta.com/?b=**</a></p>\n");
+}
+
+TEST(emphasis_does_not_span_link_text_brackets) {
+  const auto result{sourcemeta::core::markdown_to_html("_a [b_ c]")};
+  EXPECT_EQ(result, "<p><em>a [b</em> c]</p>\n");
+}
diff --git a/test/markdown/markdown_entities_test.cc b/test/markdown/markdown_entities_test.cc
new file mode 100644
index 0000000000..b8159d413b
--- /dev/null
+++ b/test/markdown/markdown_entities_test.cc
@@ -0,0 +1,114 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(html_entity_named) {
+  const auto result{sourcemeta::core::markdown_to_html("&copy; 2025")};
+  EXPECT_EQ(result, "<p>\xC2\xA9 2025</p>\n");
+}
+
+TEST(html_entity_numeric) {
+  const auto result{sourcemeta::core::markdown_to_html("&#169; 2025")};
+  EXPECT_EQ(result, "<p>\xC2\xA9 2025</p>\n");
+}
+
+TEST(entity_named_references) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "&lt; &gt; &quot; &apos; &euro; &hellip;\n&rightarrow; "
+      "&NotNestedLessLess; &bigstar;")};
+  EXPECT_EQ(result, "<p>&lt; &gt; &quot; ' \xe2\x82\xac \xe2\x80\xa6\n"
+                    "\xe2\x86\x92 \xe2\xaa\xa1\xcc\xb8 \xe2\x98\x85</p>\n");
+}
+
+TEST(entity_decimal_references) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("&#65; &#8364; &#128512;")};
+  EXPECT_EQ(result, "<p>A \xe2\x82\xac \xf0\x9f\x98\x80</p>\n");
+}
+
+TEST(entity_hexadecimal_references) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("&#x41; &#X20AC; &#x1F600;")};
+  EXPECT_EQ(result, "<p>A \xe2\x82\xac \xf0\x9f\x98\x80</p>\n");
+}
+
+TEST(entity_invalid_references_are_literal) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "&euro &y; &#z; &#xz;\n&#12345678;\n&#x1234567;\n&NotARealEntity;")};
+  EXPECT_EQ(result, "<p>&amp;euro &amp;y; &amp;#z; &amp;#xz;\n"
+                    "\xef\xbf\xbd\n"
+                    "\xef\xbf\xbd\n"
+                    "&amp;NotARealEntity;</p>\n");
+}
+
+TEST(entity_without_semicolon_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("&amp")};
+  EXPECT_EQ(result, "<p>&amp;amp</p>\n");
+}
+
+TEST(entity_unknown_name_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("&notreal;")};
+  EXPECT_EQ(result, "<p>&amp;notreal;</p>\n");
+}
+
+TEST(entity_code_point_beyond_unicode_range) {
+  const auto result{sourcemeta::core::markdown_to_html("&#x110000;")};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbd</p>\n");
+}
+
+TEST(entity_surrogate_code_point) {
+  const auto result{sourcemeta::core::markdown_to_html("&#56320;")};
+  EXPECT_EQ(result, "<p>\xef\xbf\xbd</p>\n");
+}
+
+TEST(entity_in_link_destination_and_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](/caf&eacute; 'caf&eacute;')")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/caf%C3%A9\" title=\"caf\xc3\xa9\">docs</a></p>\n");
+}
+
+TEST(entity_in_reference_definition) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]\n\n[docs]: /caf&eacute; 'caf&eacute;'")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/caf%C3%A9\" title=\"caf\xc3\xa9\">docs</a></p>\n");
+}
+
+TEST(entity_inside_code_span_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("`&eacute;`")};
+  EXPECT_EQ(result, "<p><code>&amp;eacute;</code></p>\n");
+}
+
+TEST(entity_inside_indented_code_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("    &eacute;&amp;")};
+  EXPECT_EQ(result, "<pre><code>&amp;eacute;&amp;amp;\n"
+                    "</code></pre>\n");
+}
+
+TEST(entity_cannot_create_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("&#95;word&#95;")};
+  EXPECT_EQ(result, "<p>_word_</p>\n");
+}
+
+TEST(entity_cannot_create_list) {
+  const auto result{sourcemeta::core::markdown_to_html("&#45; item")};
+  EXPECT_EQ(result, "<p>- item</p>\n");
+}
+
+TEST(entity_newline_is_not_line_break) {
+  const auto result{sourcemeta::core::markdown_to_html("one&#xA;two")};
+  EXPECT_EQ(result, "<p>one\n"
+                    "two</p>\n");
+}
+
+TEST(entity_tabs_are_not_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("&#x9;&#x9;code")};
+  EXPECT_EQ(result, "<p>\t\tcode</p>\n");
+}
+
+TEST(entity_quotes_do_not_delimit_link_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](/manual &#34;Title&#34;)")};
+  EXPECT_EQ(result, "<p>[docs](/manual &quot;Title&quot;)</p>\n");
+}
diff --git a/test/markdown/markdown_escapes_test.cc b/test/markdown/markdown_escapes_test.cc
new file mode 100644
index 0000000000..1ce9327360
--- /dev/null
+++ b/test/markdown/markdown_escapes_test.cc
@@ -0,0 +1,98 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(escape_asterisk) {
+  const auto result{sourcemeta::core::markdown_to_html("\\*not italic\\*")};
+  EXPECT_EQ(result, "<p>*not italic*</p>\n");
+}
+
+TEST(escape_hash) {
+  const auto result{sourcemeta::core::markdown_to_html("\\# not a heading")};
+  EXPECT_EQ(result, "<p># not a heading</p>\n");
+}
+
+TEST(escape_brackets) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\\[not a link\\](url)")};
+  EXPECT_EQ(result, "<p>[not a link](url)</p>\n");
+}
+
+TEST(escape_backtick) {
+  const auto result{sourcemeta::core::markdown_to_html("\\`not code\\`")};
+  EXPECT_EQ(result, "<p>`not code`</p>\n");
+}
+
+TEST(backslash_escapes_every_ascii_punctuation) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "a\\~b\\}c\\|d\\{e\\`f\\_g\\^h\\]i\\\\j\\[k\\@l\\?m\\>n\\=o\\<p\\;q\\:"
+      "r\\/s\\.t\\-u\\,v\\+w\\*x\\)y\\(z\\'1\\&2\\%3\\$4\\#5\\\"6\\!")};
+  EXPECT_EQ(result, "<p>a~b}c|d{e`f_g^h]i\\j[k@l?m&gt;n=o&lt;p;q:r/"
+                    "s.t-u,v+w*x)y(z'1&amp;2%3$4#5&quot;6!</p>\n");
+}
+
+TEST(backslash_before_other_characters_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("\\Z \\9 \\é \\€ \\\t")};
+  EXPECT_EQ(result, "<p>\\Z \\9 \\\xc3\xa9 \\\xe2\x82\xac \\</p>\n");
+}
+
+TEST(backslash_escaped_markup_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "\\_no emphasis_\n\\<em> no tag\n\\![no image](/x.png)\n2\\) no "
+      "list\n\\+ no list\n\\> no quote\n\\&amp; no entity")};
+  EXPECT_EQ(result, "<p>_no emphasis_\n"
+                    "&lt;em&gt; no tag\n"
+                    "!<a href=\"/x.png\">no image</a>\n"
+                    "2) no list\n"
+                    "+ no list\n"
+                    "&gt; no quote\n"
+                    "&amp;amp; no entity</p>\n");
+}
+
+TEST(backslash_escaped_backslash_before_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("\\\\_emphasis_")};
+  EXPECT_EQ(result, "<p>\\<em>emphasis</em></p>\n");
+}
+
+TEST(backslash_at_end_of_line_is_hard_break) {
+  const auto result{sourcemeta::core::markdown_to_html("one\\\ntwo")};
+  EXPECT_EQ(result, "<p>one<br />\n"
+                    "two</p>\n");
+}
+
+TEST(backslash_inside_code_span_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("`\\*\\_`")};
+  EXPECT_EQ(result, "<p><code>\\*\\_</code></p>\n");
+}
+
+TEST(backslash_inside_indented_code_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("    \\*\\_")};
+  EXPECT_EQ(result, "<pre><code>\\*\\_\n"
+                    "</code></pre>\n");
+}
+
+TEST(backslash_inside_fenced_code_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("```\n\\*\\_\n```")};
+  EXPECT_EQ(result, "<pre><code>\\*\\_\n"
+                    "</code></pre>\n");
+}
+
+TEST(backslash_inside_autolink_is_literal) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<https://sourcemeta.com/\\_\\*>")};
+  EXPECT_EQ(result, "<p><a "
+                    "href=\"https://sourcemeta.com/%5C_%5C*\">https://"
+                    "sourcemeta.com/\\_\\*</a></p>\n");
+}
+
+TEST(backslash_escapes_in_link_destination_and_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](/a\\_b 'c\\_d')")};
+  EXPECT_EQ(result, "<p><a href=\"/a_b\" title=\"c_d\">docs</a></p>\n");
+}
+
+TEST(backslash_escapes_in_reference_definition) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]\n\n[docs]: /a\\_b 'c\\_d'")};
+  EXPECT_EQ(result, "<p><a href=\"/a_b\" title=\"c_d\">docs</a></p>\n");
+}
diff --git a/test/markdown/markdown_footnotes_test.cc b/test/markdown/markdown_footnotes_test.cc
new file mode 100644
index 0000000000..f253a34a26
--- /dev/null
+++ b/test/markdown/markdown_footnotes_test.cc
@@ -0,0 +1,241 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(footnote_basic) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Text[^1]\n\n[^1]: Footnote content")};
+  EXPECT_EQ(
+      result,
+      "<p>Text<sup class=\"footnote-ref\"><a href=\"#fn-1\" id=\"fnref-1\""
+      " data-footnote-ref>1</a></sup></p>\n"
+      "<section class=\"footnotes\" data-footnotes>\n<ol>\n"
+      "<li id=\"fn-1\">\n<p>Footnote content "
+      "<a href=\"#fnref-1\" class=\"footnote-backref\""
+      " data-footnote-backref data-footnote-backref-idx=\"1\""
+      " aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+      "</li>\n</ol>\n</section>\n");
+}
+
+TEST(footnote_multiple) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "A[^1] and B[^2]\n\n[^1]: First\n\n[^2]: Second")};
+  EXPECT_EQ(result,
+            "<p>A<sup class=\"footnote-ref\"><a href=\"#fn-1\" id=\"fnref-1\""
+            " data-footnote-ref>1</a></sup> and "
+            "B<sup class=\"footnote-ref\"><a href=\"#fn-2\" id=\"fnref-2\""
+            " data-footnote-ref>2</a></sup></p>\n"
+            "<section class=\"footnotes\" data-footnotes>\n<ol>\n"
+            "<li id=\"fn-1\">\n<p>First "
+            "<a href=\"#fnref-1\" class=\"footnote-backref\""
+            " data-footnote-backref data-footnote-backref-idx=\"1\""
+            " aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "<li id=\"fn-2\">\n<p>Second "
+            "<a href=\"#fnref-2\" class=\"footnote-backref\""
+            " data-footnote-backref data-footnote-backref-idx=\"2\""
+            " aria-label=\"Back to reference 2\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n</ol>\n</section>\n");
+}
+
+TEST(footnote_referenced_multiple_times) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "one[^n] two[^n] three[^n]\n\n[^n]: shared")};
+  EXPECT_EQ(
+      result,
+      "<p>one<sup class=\"footnote-ref\"><a href=\"#fn-n\" id=\"fnref-n\" "
+      "data-footnote-ref>1</a></sup> two<sup class=\"footnote-ref\"><a "
+      "href=\"#fn-n\" id=\"fnref-n-2\" data-footnote-ref>1</a></sup> three<sup "
+      "class=\"footnote-ref\"><a href=\"#fn-n\" id=\"fnref-n-3\" "
+      "data-footnote-ref>1</a></sup></p>\n"
+      "<section class=\"footnotes\" data-footnotes>\n"
+      "<ol>\n"
+      "<li id=\"fn-n\">\n"
+      "<p>shared <a href=\"#fnref-n\" class=\"footnote-backref\" "
+      "data-footnote-backref data-footnote-backref-idx=\"1\" aria-label=\"Back "
+      "to reference 1\">\xe2\x86\xa9</a> <a href=\"#fnref-n-2\" "
+      "class=\"footnote-backref\" data-footnote-backref "
+      "data-footnote-backref-idx=\"1-2\" aria-label=\"Back to reference "
+      "1-2\">\xe2\x86\xa9<sup class=\"footnote-ref\">2</sup></a> <a "
+      "href=\"#fnref-n-3\" class=\"footnote-backref\" data-footnote-backref "
+      "data-footnote-backref-idx=\"1-3\" aria-label=\"Back to reference "
+      "1-3\">\xe2\x86\xa9<sup class=\"footnote-ref\">3</sup></a></p>\n"
+      "</li>\n"
+      "</ol>\n"
+      "</section>\n");
+}
+
+TEST(footnote_unreferenced_definition_omitted) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("body\n\n[^orphan]: unused")};
+  EXPECT_EQ(result, "<p>body</p>\n");
+}
+
+TEST(footnote_reference_without_definition) {
+  const auto result{sourcemeta::core::markdown_to_html("body[^ghost]")};
+  EXPECT_EQ(result, "<p>body[^ghost]</p>\n");
+}
+
+TEST(footnote_label_case_insensitive) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("body[^LABEL]\n\n[^label]: text")};
+  EXPECT_EQ(result,
+            "<p>body<sup class=\"footnote-ref\"><a href=\"#fn-label\" "
+            "id=\"fnref-label\" data-footnote-ref>1</a></sup></p>\n"
+            "<section class=\"footnotes\" data-footnotes>\n"
+            "<ol>\n"
+            "<li id=\"fn-label\">\n"
+            "<p>text <a href=\"#fnref-label\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"1\" "
+            "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "</ol>\n"
+            "</section>\n");
+}
+
+TEST(footnote_definition_with_multiple_blocks) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "body[^m]\n\n[^m]: first\n\n    > quoted\n\n    * item")};
+  EXPECT_EQ(result, "<p>body<sup class=\"footnote-ref\"><a href=\"#fn-m\" "
+                    "id=\"fnref-m\" data-footnote-ref>1</a></sup></p>\n"
+                    "<section class=\"footnotes\" data-footnotes>\n"
+                    "<ol>\n"
+                    "<li id=\"fn-m\">\n"
+                    "<p>first</p>\n"
+                    "<blockquote>\n"
+                    "<p>quoted</p>\n"
+                    "</blockquote>\n"
+                    "<ul>\n"
+                    "<li>item</li>\n"
+                    "</ul>\n"
+                    "<a href=\"#fnref-m\" class=\"footnote-backref\" "
+                    "data-footnote-backref data-footnote-backref-idx=\"1\" "
+                    "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a>\n"
+                    "</li>\n"
+                    "</ol>\n"
+                    "</section>\n");
+}
+
+TEST(footnote_numbering_follows_references) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "x[^z] y[^y] z[^x]\n\n[^x]: X\n[^y]: Y\n[^z]: Z")};
+  EXPECT_EQ(result,
+            "<p>x<sup class=\"footnote-ref\"><a href=\"#fn-z\" id=\"fnref-z\" "
+            "data-footnote-ref>1</a></sup> y<sup class=\"footnote-ref\"><a "
+            "href=\"#fn-y\" id=\"fnref-y\" data-footnote-ref>2</a></sup> z<sup "
+            "class=\"footnote-ref\"><a href=\"#fn-x\" id=\"fnref-x\" "
+            "data-footnote-ref>3</a></sup></p>\n"
+            "<section class=\"footnotes\" data-footnotes>\n"
+            "<ol>\n"
+            "<li id=\"fn-z\">\n"
+            "<p>Z <a href=\"#fnref-z\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"1\" "
+            "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "<li id=\"fn-y\">\n"
+            "<p>Y <a href=\"#fnref-y\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"2\" "
+            "aria-label=\"Back to reference 2\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "<li id=\"fn-x\">\n"
+            "<p>X <a href=\"#fnref-x\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"3\" "
+            "aria-label=\"Back to reference 3\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "</ol>\n"
+            "</section>\n");
+}
+
+TEST(footnote_label_with_special_characters) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("body[^a&b<c>]\n\n[^a&b<c>]: text")};
+  EXPECT_EQ(
+      result,
+      "<p>body<sup class=\"footnote-ref\"><a href=\"#fn-a&amp;b%3Cc%3E\" "
+      "id=\"fnref-a&amp;b%3Cc%3E\" data-footnote-ref>1</a></sup></p>\n"
+      "<section class=\"footnotes\" data-footnotes>\n"
+      "<ol>\n"
+      "<li id=\"fn-a&amp;b%3Cc%3E\">\n"
+      "<p>text <a href=\"#fnref-a&amp;b%3Cc%3E\" class=\"footnote-backref\" "
+      "data-footnote-backref data-footnote-backref-idx=\"1\" aria-label=\"Back "
+      "to reference 1\">\xe2\x86\xa9</a></p>\n"
+      "</li>\n"
+      "</ol>\n"
+      "</section>\n");
+}
+
+TEST(footnote_reference_in_table_cell) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| h |\n| - |\n| c[^t] |\n\n[^t]: table note")};
+  EXPECT_EQ(result,
+            "<table>\n"
+            "<thead>\n"
+            "<tr>\n"
+            "<th>h</th>\n"
+            "</tr>\n"
+            "</thead>\n"
+            "<tbody>\n"
+            "<tr>\n"
+            "<td>c<sup class=\"footnote-ref\"><a href=\"#fn-t\" id=\"fnref-t\" "
+            "data-footnote-ref>1</a></sup></td>\n"
+            "</tr>\n"
+            "</tbody>\n"
+            "</table>\n"
+            "<section class=\"footnotes\" data-footnotes>\n"
+            "<ol>\n"
+            "<li id=\"fn-t\">\n"
+            "<p>table note <a href=\"#fnref-t\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"1\" "
+            "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "</ol>\n"
+            "</section>\n");
+}
+
+TEST(footnote_reference_inside_definition) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "body[^a]\n\n[^a]: refers[^b]\n\n[^b]: nested")};
+  EXPECT_EQ(result, "<p>body<sup class=\"footnote-ref\"><a href=\"#fn-a\" "
+                    "id=\"fnref-a\" data-footnote-ref>1</a></sup></p>\n"
+                    "<section class=\"footnotes\" data-footnotes>\n"
+                    "<ol>\n"
+                    "<li id=\"fn-a\">\n"
+                    "<p>refers<sup class=\"footnote-ref\"><a href=\"#fn-b\" "
+                    "id=\"fnref-b\" data-footnote-ref>2</a></sup> <a "
+                    "href=\"#fnref-a\" class=\"footnote-backref\" "
+                    "data-footnote-backref data-footnote-backref-idx=\"1\" "
+                    "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+                    "</li>\n"
+                    "<li id=\"fn-b\">\n"
+                    "<p>nested <a href=\"#fnref-b\" class=\"footnote-backref\" "
+                    "data-footnote-backref data-footnote-backref-idx=\"2\" "
+                    "aria-label=\"Back to reference 2\">\xe2\x86\xa9</a></p>\n"
+                    "</li>\n"
+                    "</ol>\n"
+                    "</section>\n");
+}
+
+TEST(footnote_definition_inside_blockquote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("body[^q]\n\n> [^q]: inside quote")};
+  EXPECT_EQ(result,
+            "<p>body<sup class=\"footnote-ref\"><a href=\"#fn-q\" "
+            "id=\"fnref-q\" data-footnote-ref>1</a></sup></p>\n"
+            "<blockquote>\n"
+            "</blockquote>\n"
+            "<section class=\"footnotes\" data-footnotes>\n"
+            "<ol>\n"
+            "<li id=\"fn-q\">\n"
+            "<p>inside quote <a href=\"#fnref-q\" class=\"footnote-backref\" "
+            "data-footnote-backref data-footnote-backref-idx=\"1\" "
+            "aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
+            "</li>\n"
+            "</ol>\n"
+            "</section>\n");
+}
+
+TEST(footnote_label_with_space_is_not_footnote) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "body[^two words]\n\n[^two words]: text")};
+  EXPECT_EQ(result, "<p>body<a href=\"text\">^two words</a></p>\n");
+}
diff --git a/test/markdown/markdown_headings_test.cc b/test/markdown/markdown_headings_test.cc
new file mode 100644
index 0000000000..401cf225d4
--- /dev/null
+++ b/test/markdown/markdown_headings_test.cc
@@ -0,0 +1,360 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(atx_heading_level_1) {
+  const auto result{sourcemeta::core::markdown_to_html("# Heading 1")};
+  EXPECT_EQ(result, "<h1>Heading 1</h1>\n");
+}
+
+TEST(atx_heading_level_2) {
+  const auto result{sourcemeta::core::markdown_to_html("## Heading 2")};
+  EXPECT_EQ(result, "<h2>Heading 2</h2>\n");
+}
+
+TEST(atx_heading_level_3) {
+  const auto result{sourcemeta::core::markdown_to_html("### Heading 3")};
+  EXPECT_EQ(result, "<h3>Heading 3</h3>\n");
+}
+
+TEST(atx_heading_level_4) {
+  const auto result{sourcemeta::core::markdown_to_html("#### Heading 4")};
+  EXPECT_EQ(result, "<h4>Heading 4</h4>\n");
+}
+
+TEST(atx_heading_level_5) {
+  const auto result{sourcemeta::core::markdown_to_html("##### Heading 5")};
+  EXPECT_EQ(result, "<h5>Heading 5</h5>\n");
+}
+
+TEST(atx_heading_level_6) {
+  const auto result{sourcemeta::core::markdown_to_html("###### Heading 6")};
+  EXPECT_EQ(result, "<h6>Heading 6</h6>\n");
+}
+
+TEST(atx_heading_with_closing_hashes) {
+  const auto result{sourcemeta::core::markdown_to_html("## Heading ##")};
+  EXPECT_EQ(result, "<h2>Heading</h2>\n");
+}
+
+TEST(setext_heading_level_1) {
+  const auto result{sourcemeta::core::markdown_to_html("Heading 1\n=========")};
+  EXPECT_EQ(result, "<h1>Heading 1</h1>\n");
+}
+
+TEST(setext_heading_level_2) {
+  const auto result{sourcemeta::core::markdown_to_html("Heading 2\n---------")};
+  EXPECT_EQ(result, "<h2>Heading 2</h2>\n");
+}
+
+TEST(heading_followed_by_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("# Title\n\nSome text here.")};
+  EXPECT_EQ(result, "<h1>Title</h1>\n<p>Some text here.</p>\n");
+}
+
+TEST(link_inside_heading) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## [Link](https://example.com)")};
+  EXPECT_EQ(result, "<h2><a href=\"https://example.com\">Link</a></h2>\n");
+}
+
+TEST(inline_code_inside_heading) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## The `main` function")};
+  EXPECT_EQ(result, "<h2>The <code>main</code> function</h2>\n");
+}
+
+TEST(consecutive_headings) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("# One\n\n## Two\n\n### Three")};
+  EXPECT_EQ(result, "<h1>One</h1>\n<h2>Two</h2>\n<h3>Three</h3>\n");
+}
+
+TEST(heading_with_thematic_break) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("# Title\n\n---\n\nContent")};
+  EXPECT_EQ(result, "<h1>Title</h1>\n<hr />\n<p>Content</p>\n");
+}
+
+TEST(heading_with_bold_and_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## **Bold** and `code`")};
+  EXPECT_EQ(result, "<h2><strong>Bold</strong> and <code>code</code></h2>\n");
+}
+
+TEST(dashes_after_paragraph_make_setext_heading) {
+  const auto result{sourcemeta::core::markdown_to_html("alpha\n-----\nbeta")};
+  EXPECT_EQ(result, "<h2>alpha</h2>\n"
+                    "<p>beta</p>\n");
+}
+
+TEST(atx_heading_eight_hashes_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("######## title")};
+  EXPECT_EQ(result, "<p>######## title</p>\n");
+}
+
+TEST(atx_heading_without_space_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("#1 fan\n\n##tag")};
+  EXPECT_EQ(result, "<p>#1 fan</p>\n"
+                    "<p>##tag</p>\n");
+}
+
+TEST(atx_heading_escaped_hash_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("\\# title")};
+  EXPECT_EQ(result, "<p># title</p>\n");
+}
+
+TEST(atx_heading_inline_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## plain *em* \\*raw\\*")};
+  EXPECT_EQ(result, "<h2>plain <em>em</em> *raw*</h2>\n");
+}
+
+TEST(atx_heading_surrounding_spaces_ignored) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("###      spaced out      ")};
+  EXPECT_EQ(result, "<h3>spaced out</h3>\n");
+}
+
+TEST(atx_heading_indented_up_to_three_spaces) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("   #### deep\n  # shallow")};
+  EXPECT_EQ(result, "<h4>deep</h4>\n"
+                    "<h1>shallow</h1>\n");
+}
+
+TEST(atx_heading_indented_four_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    ## code")};
+  EXPECT_EQ(result, "<pre><code>## code\n"
+                    "</code></pre>\n");
+}
+
+TEST(atx_heading_indented_four_spaces_continues_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("text\n    ## more")};
+  EXPECT_EQ(result, "<p>text\n"
+                    "## more</p>\n");
+}
+
+TEST(atx_heading_closing_sequence_of_any_length) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## title #######\n#### title #")};
+  EXPECT_EQ(result, "<h2>title</h2>\n"
+                    "<h4>title</h4>\n");
+}
+
+TEST(atx_heading_closing_sequence_followed_by_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("## title ##   ")};
+  EXPECT_EQ(result, "<h2>title</h2>\n");
+}
+
+TEST(atx_heading_hashes_followed_by_text_are_content) {
+  const auto result{sourcemeta::core::markdown_to_html("## title ## tail")};
+  EXPECT_EQ(result, "<h2>title ## tail</h2>\n");
+}
+
+TEST(atx_heading_closing_sequence_needs_preceding_space) {
+  const auto result{sourcemeta::core::markdown_to_html("## title##")};
+  EXPECT_EQ(result, "<h2>title##</h2>\n");
+}
+
+TEST(atx_heading_escaped_closing_hashes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("## title \\##\n# title #\\#")};
+  EXPECT_EQ(result, "<h2>title ##</h2>\n"
+                    "<h1>title ##</h1>\n");
+}
+
+TEST(atx_heading_between_thematic_breaks) {
+  const auto result{sourcemeta::core::markdown_to_html("---\n# title\n---")};
+  EXPECT_EQ(result, "<hr />\n"
+                    "<h1>title</h1>\n"
+                    "<hr />\n");
+}
+
+TEST(atx_heading_interrupts_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("one line\n## heading\nnext line")};
+  EXPECT_EQ(result, "<p>one line</p>\n"
+                    "<h2>heading</h2>\n"
+                    "<p>next line</p>\n");
+}
+
+TEST(atx_heading_empty) {
+  const auto result{sourcemeta::core::markdown_to_html("#\n## \n#### ####")};
+  EXPECT_EQ(result, "<h1></h1>\n"
+                    "<h2></h2>\n"
+                    "<h4></h4>\n");
+}
+
+TEST(setext_heading_single_character_underline) {
+  const auto result{sourcemeta::core::markdown_to_html("Title *em*\n=")};
+  EXPECT_EQ(result, "<h1>Title <em>em</em></h1>\n");
+}
+
+TEST(setext_heading_multiline_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("First *line\nsecond* line\n---")};
+  EXPECT_EQ(result, "<h2>First <em>line\n"
+                    "second</em> line</h2>\n");
+}
+
+TEST(setext_heading_content_surrounding_spaces_stripped) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(" Title *em\ntext*  \n===")};
+  EXPECT_EQ(result, "<h1>Title <em>em\n"
+                    "text</em></h1>\n");
+}
+
+TEST(setext_heading_indented_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("  Title\n  ===\n\n   Other\n-")};
+  EXPECT_EQ(result, "<h1>Title</h1>\n"
+                    "<h2>Other</h2>\n");
+}
+
+TEST(setext_heading_content_indented_four_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    Title\n    ===")};
+  EXPECT_EQ(result, "<pre><code>Title\n"
+                    "===\n"
+                    "</code></pre>\n");
+}
+
+TEST(setext_heading_underline_indented_up_to_three_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("Title\n  ===   ")};
+  EXPECT_EQ(result, "<h1>Title</h1>\n");
+}
+
+TEST(setext_heading_underline_indented_four_spaces_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("Title\n    ===")};
+  EXPECT_EQ(result, "<p>Title\n"
+                    "===</p>\n");
+}
+
+TEST(setext_heading_underline_with_internal_space_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("Title\n== ==")};
+  EXPECT_EQ(result, "<p>Title\n"
+                    "== ==</p>\n");
+}
+
+TEST(setext_heading_trailing_spaces_are_not_hard_break) {
+  const auto result{sourcemeta::core::markdown_to_html("Title   \n===")};
+  EXPECT_EQ(result, "<h1>Title</h1>\n");
+}
+
+TEST(setext_heading_trailing_backslash_is_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("Title\\\n===")};
+  EXPECT_EQ(result, "<h1>Title\\</h1>\n");
+}
+
+TEST(setext_heading_underline_breaks_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("`code\n===\n`")};
+  EXPECT_EQ(result, "<h1>`code</h1>\n"
+                    "<p>`</p>\n");
+}
+
+TEST(setext_heading_equals_underline_is_lazy_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html("> Title\n===")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>Title\n"
+                    "===</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(setext_heading_dashes_after_lazy_line_are_thematic_break) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> quote\ncontinued\n---")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>quote\n"
+                    "continued</p>\n"
+                    "</blockquote>\n"
+                    "<hr />\n");
+}
+
+TEST(setext_heading_equals_after_list_item_is_lazy_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html("* Item\n===")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>Item\n"
+                    "===</li>\n"
+                    "</ul>\n");
+}
+
+TEST(setext_heading_multiline_paragraph_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Line one\nLine two\n===")};
+  EXPECT_EQ(result, "<h1>Line one\n"
+                    "Line two</h1>\n");
+}
+
+TEST(setext_heading_equals_line_then_heading) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("===\nTitle\n===\nText\n---")};
+  EXPECT_EQ(result, "<h1>===\n"
+                    "Title</h1>\n"
+                    "<h2>Text</h2>\n");
+}
+
+TEST(setext_heading_underline_without_content_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("\n==")};
+  EXPECT_EQ(result, "<p>==</p>\n");
+}
+
+TEST(setext_heading_dashes_after_thematic_break) {
+  const auto result{sourcemeta::core::markdown_to_html("***\n---")};
+  EXPECT_EQ(result, "<hr />\n"
+                    "<hr />\n");
+}
+
+TEST(setext_heading_dashes_after_list_item) {
+  const auto result{sourcemeta::core::markdown_to_html("* item\n---")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>item</li>\n"
+                    "</ul>\n"
+                    "<hr />\n");
+}
+
+TEST(setext_heading_equals_after_indented_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    code\n===")};
+  EXPECT_EQ(result, "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<p>===</p>\n");
+}
+
+TEST(setext_heading_escaped_content) {
+  const auto result{sourcemeta::core::markdown_to_html("\\- not a list\n---")};
+  EXPECT_EQ(result, "<h2>- not a list</h2>\n");
+}
+
+TEST(setext_heading_after_blank_line_separated_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Intro\n\nTitle\n===\nBody")};
+  EXPECT_EQ(result, "<p>Intro</p>\n"
+                    "<h1>Title</h1>\n"
+                    "<p>Body</p>\n");
+}
+
+TEST(setext_heading_spaced_dashes_after_blank_line) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("One\ntwo\n\n- - -\n\nthree")};
+  EXPECT_EQ(result, "<p>One\n"
+                    "two</p>\n"
+                    "<hr />\n"
+                    "<p>three</p>\n");
+}
+
+TEST(setext_heading_underscores_are_thematic_break) {
+  const auto result{sourcemeta::core::markdown_to_html("One\ntwo\n___\nthree")};
+  EXPECT_EQ(result, "<p>One\n"
+                    "two</p>\n"
+                    "<hr />\n"
+                    "<p>three</p>\n");
+}
+
+TEST(setext_heading_escaped_equals_are_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("One\ntwo\n\\===\nthree")};
+  EXPECT_EQ(result, "<p>One\n"
+                    "two\n"
+                    "===\n"
+                    "three</p>\n");
+}
diff --git a/test/markdown/markdown_images_test.cc b/test/markdown/markdown_images_test.cc
new file mode 100644
index 0000000000..bfb60d0864
--- /dev/null
+++ b/test/markdown/markdown_images_test.cc
@@ -0,0 +1,85 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(image) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![alt text](image.png)")};
+  EXPECT_EQ(result, "<p><img src=\"image.png\" alt=\"alt text\" /></p>\n");
+}
+
+TEST(image_with_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![alt](image.png \"My Image\")")};
+  EXPECT_EQ(
+      result,
+      "<p><img src=\"image.png\" alt=\"alt\" title=\"My Image\" /></p>\n");
+}
+
+TEST(image_as_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[![logo](logo.png)](https://example.com)")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\">"
+                    "<img src=\"logo.png\" alt=\"logo\" /></a></p>\n");
+}
+
+TEST(image_with_empty_alt) {
+  const auto result{sourcemeta::core::markdown_to_html("![](image.png)")};
+  EXPECT_EQ(result, "<p><img src=\"image.png\" alt=\"\" /></p>\n");
+}
+
+TEST(image_description_containing_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![a [b](/inner)](/image.png)")};
+  EXPECT_EQ(result, "<p><img src=\"/image.png\" alt=\"a b\" /></p>\n");
+}
+
+TEST(image_alt_text_is_plain_text) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![_italic_ and `code`](/i.png)")};
+  EXPECT_EQ(result, "<p><img src=\"/i.png\" alt=\"italic and code\" /></p>\n");
+}
+
+TEST(image_alt_text_from_nested_image) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "![outer ![inner](/in.png)](/out.png)")};
+  EXPECT_EQ(result, "<p><img src=\"/out.png\" alt=\"outer inner\" /></p>\n");
+}
+
+TEST(image_alt_text_from_nested_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![outer [inner](/in)](/out.png)")};
+  EXPECT_EQ(result, "<p><img src=\"/out.png\" alt=\"outer inner\" /></p>\n");
+}
+
+TEST(image_collapsed_and_shortcut_references) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "![logo][]\n\n![LOGO]\n\n[logo]: /logo.png 'Logo'")};
+  EXPECT_EQ(result,
+            "<p><img src=\"/logo.png\" alt=\"logo\" title=\"Logo\" /></p>\n"
+            "<p><img src=\"/logo.png\" alt=\"LOGO\" title=\"Logo\" /></p>\n");
+}
+
+TEST(image_escaped_bracket_is_literal) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("!\\[logo]\n\n[logo]: /logo.png")};
+  EXPECT_EQ(result, "<p>![logo]</p>\n");
+}
+
+TEST(image_escaped_exclamation_is_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\\![logo]\n\n[logo]: /logo.png")};
+  EXPECT_EQ(result, "<p>!<a href=\"/logo.png\">logo</a></p>\n");
+}
+
+TEST(image_angle_bracket_destination_with_space) {
+  const auto result{sourcemeta::core::markdown_to_html("![logo](</a b.png>)")};
+  EXPECT_EQ(result, "<p><img src=\"/a%20b.png\" alt=\"logo\" /></p>\n");
+}
+
+TEST(image_title_with_escaped_quote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![logo](/l.png 'it\\'s')")};
+  EXPECT_EQ(result,
+            "<p><img src=\"/l.png\" alt=\"logo\" title=\"it's\" /></p>\n");
+}
diff --git a/test/markdown/markdown_line_breaks_test.cc b/test/markdown/markdown_line_breaks_test.cc
new file mode 100644
index 0000000000..fd024fbf67
--- /dev/null
+++ b/test/markdown/markdown_line_breaks_test.cc
@@ -0,0 +1,58 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(soft_line_break) {
+  const auto result{sourcemeta::core::markdown_to_html("line one\nline two")};
+  EXPECT_EQ(result, "<p>line one\nline two</p>\n");
+}
+
+TEST(hard_line_break_with_two_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("line one  \nline two")};
+  EXPECT_EQ(result, "<p>line one<br />\nline two</p>\n");
+}
+
+TEST(hard_line_break_with_backslash) {
+  const auto result{sourcemeta::core::markdown_to_html("line one\\\nline two")};
+  EXPECT_EQ(result, "<p>line one<br />\nline two</p>\n");
+}
+
+TEST(hard_break_with_many_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("one     \ntwo")};
+  EXPECT_EQ(result, "<p>one<br />\n"
+                    "two</p>\n");
+}
+
+TEST(hard_break_leading_spaces_on_next_line_ignored) {
+  const auto result{sourcemeta::core::markdown_to_html("one  \n        two")};
+  EXPECT_EQ(result, "<p>one<br />\n"
+                    "two</p>\n");
+}
+
+TEST(hard_break_inside_emphasis) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("_one  \ntwo_\n\n__one\\\ntwo__")};
+  EXPECT_EQ(result, "<p><em>one<br />\n"
+                    "two</em></p>\n"
+                    "<p><strong>one<br />\n"
+                    "two</strong></p>\n");
+}
+
+TEST(hard_break_not_inside_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("`one  \ntwo`")};
+  EXPECT_EQ(result, "<p><code>one   two</code></p>\n");
+}
+
+TEST(hard_break_not_at_end_of_block) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("text\\\n\ntext   \n\n## title\\")};
+  EXPECT_EQ(result, "<p>text\\</p>\n"
+                    "<p>text</p>\n"
+                    "<h2>title\\</h2>\n");
+}
+
+TEST(soft_break_surrounding_spaces_stripped) {
+  const auto result{sourcemeta::core::markdown_to_html("one \n  two")};
+  EXPECT_EQ(result, "<p>one\n"
+                    "two</p>\n");
+}
diff --git a/test/markdown/markdown_links_test.cc b/test/markdown/markdown_links_test.cc
new file mode 100644
index 0000000000..682a6fa1a7
--- /dev/null
+++ b/test/markdown/markdown_links_test.cc
@@ -0,0 +1,589 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(inline_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[click here](https://example.com)")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\">click here</a></p>\n");
+}
+
+TEST(inline_link_with_title) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[click](https://example.com \"My Title\")")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"https://example.com\" title=\"My Title\">click</a></p>\n");
+}
+
+TEST(reference_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[click][ref]\n\n[ref]: https://example.com")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\">click</a></p>\n");
+}
+
+TEST(reference_link_with_title) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[click][ref]\n\n[ref]: https://example.com \"Title\"")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"https://example.com\" title=\"Title\">click</a></p>\n");
+}
+
+TEST(collapsed_reference_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[example][]\n\n[example]: https://example.com")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\">example</a></p>\n");
+}
+
+TEST(shortcut_reference_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[example]\n\n[example]: https://example.com")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\">example</a></p>\n");
+}
+
+TEST(link_with_emphasis_inside) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[**bold link**](https://example.com)")};
+  EXPECT_EQ(result, "<p><a href=\"https://example.com\"><strong>bold "
+                    "link</strong></a></p>\n");
+}
+
+TEST(code_inside_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[`code`](https://example.com)")};
+  EXPECT_EQ(result,
+            "<p><a href=\"https://example.com\"><code>code</code></a></p>\n");
+}
+
+TEST(link_with_special_chars_in_url) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[search](https://example.com/q?a=1&b=2)")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"https://example.com/q?a=1&amp;b=2\">search</a></p>\n");
+}
+
+TEST(link_reference_definition_title_on_next_line) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]: /manual\n\"The manual\"\n\n[docs]")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/manual\" title=\"The manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_spread_over_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "  [docs]:\n    /manual\n     (Manual)  \n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\" title=\"Manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_multiline_title) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]: /manual \"\nfirst\nsecond\n\"\n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\" title=\"\n"
+                    "first\n"
+                    "second\n"
+                    "\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_title_with_blank_line_is_invalid) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]: /manual \"first\n\nsecond\"\n\n[docs]")};
+  EXPECT_EQ(result, "<p>[docs]: /manual &quot;first</p>\n"
+                    "<p>second&quot;</p>\n"
+                    "<p>[docs]</p>\n");
+}
+
+TEST(link_reference_definition_destination_on_next_line) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]:\n  /manual\n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_missing_destination) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]:\n\ntext [docs]")};
+  EXPECT_EQ(result, "<p>[docs]:</p>\n"
+                    "<p>text [docs]</p>\n");
+}
+
+TEST(link_reference_definition_empty_angle_destination) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs]: <>\n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_title_without_separating_space) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]: /manual\"title\"\n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual%22title%22\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_backslash_escapes) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]: /a\\b\\#c 'it\\'s'\n\n[docs]")};
+  EXPECT_EQ(result, "<p><a href=\"/a%5Cb#c\" title=\"it's\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_after_its_use) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("See [docs].\n\n[docs]: /manual")};
+  EXPECT_EQ(result, "<p>See <a href=\"/manual\">docs</a>.</p>\n");
+}
+
+TEST(link_reference_definition_first_one_wins) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]\n\n[docs]: /one\n\n[docs]: /two")};
+  EXPECT_EQ(result, "<p><a href=\"/one\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_label_case_insensitive) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[DoCs]: /manual\n\n[dOcS]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">dOcS</a></p>\n");
+}
+
+TEST(link_reference_definition_label_full_case_folding) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[STRASSE]: /road\n\n[straße]")};
+  EXPECT_EQ(result, "<p><a href=\"/road\">stra\xc3\x9f"
+                    "e</a></p>\n");
+}
+
+TEST(link_reference_definition_alone_renders_nothing) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]: /manual 'Manual'")};
+  EXPECT_EQ(result, "");
+}
+
+TEST(link_reference_definition_with_trailing_text_is_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]: /manual 'Manual' trailing")};
+  EXPECT_EQ(result, "<p>[docs]: /manual 'Manual' trailing</p>\n");
+}
+
+TEST(link_reference_definition_title_with_trailing_text_on_next_line) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs]: /manual\n'Manual' trailing\n\n[docs]")};
+  EXPECT_EQ(result, "<p>'Manual' trailing</p>\n"
+                    "<p><a href=\"/manual\" title=\"Manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_indented_four_spaces_is_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    [docs]: /manual\n\n[docs]")};
+  EXPECT_EQ(result, "<pre><code>[docs]: /manual\n"
+                    "</code></pre>\n"
+                    "<p>[docs]</p>\n");
+}
+
+TEST(link_reference_definition_inside_fenced_code_is_content) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "~~~\n[docs]: /manual\n~~~\n\n[docs]")};
+  EXPECT_EQ(result, "<pre><code>[docs]: /manual\n"
+                    "</code></pre>\n"
+                    "<p>[docs]</p>\n");
+}
+
+TEST(link_reference_definition_cannot_interrupt_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Intro\n[docs]: /manual\n\n[docs]")};
+  EXPECT_EQ(result, "<p>Intro\n"
+                    "[docs]: /manual</p>\n"
+                    "<p>[docs]</p>\n");
+}
+
+TEST(link_reference_definition_between_heading_and_blockquote) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "## [Docs]\n[docs]: /manual\n> quoted")};
+  EXPECT_EQ(result, "<h2><a href=\"/manual\">Docs</a></h2>\n"
+                    "<blockquote>\n"
+                    "<p>quoted</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(link_reference_definition_followed_by_dashes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs]: /manual\n---\n[docs]")};
+  EXPECT_EQ(result, "<p>---\n"
+                    "<a href=\"/manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definitions_consecutive) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[one]: /1 'One'\n[two]: /2\n  'Two'\n[three]: </3>\n\n[one] [two] "
+      "[three]")};
+  EXPECT_EQ(result, "<p><a href=\"/1\" title=\"One\">one</a> <a href=\"/2\" "
+                    "title=\"Two\">two</a> <a href=\"/3\">three</a></p>\n");
+}
+
+TEST(link_reference_definition_inside_blockquote_is_global) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> [docs]: /manual\n\n[docs]")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "</blockquote>\n"
+                    "<p><a href=\"/manual\">docs</a></p>\n");
+}
+
+TEST(link_reference_definition_label_whitespace_normalized) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[the   long\n label]: /manual\n\n[The long label]")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">The long label</a></p>\n");
+}
+
+TEST(link_reference_definition_empty_label_is_invalid) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[]: /manual\n\n[] text")};
+  EXPECT_EQ(result, "<p>[]: /manual</p>\n"
+                    "<p>[] text</p>\n");
+}
+
+TEST(link_reference_definition_whitespace_label_is_invalid) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[  ]: /manual\n\n[  ]")};
+  EXPECT_EQ(result, "<p>[  ]: /manual</p>\n"
+                    "<p>[  ]</p>\n");
+}
+
+TEST(link_destination_single_space) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs]( )")};
+  EXPECT_EQ(result, "<p><a href=\"\">docs</a></p>\n");
+}
+
+TEST(link_destination_empty_angle_brackets_with_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs]( <> )")};
+  EXPECT_EQ(result, "<p><a href=\"\">docs</a></p>\n");
+}
+
+TEST(link_destination_angle_brackets_with_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](<a b c>)")};
+  EXPECT_EQ(result, "<p><a href=\"a%20b%20c\">docs</a></p>\n");
+}
+
+TEST(link_destination_with_space_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](/a b)")};
+  EXPECT_EQ(result, "<p>[docs](/a b)</p>\n");
+}
+
+TEST(link_destination_with_newline_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](/a\n/b)")};
+  EXPECT_EQ(result, "<p>[docs](/a\n"
+                    "/b)</p>\n");
+}
+
+TEST(link_destination_angle_brackets_with_newline_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](</a\nb>)")};
+  EXPECT_EQ(result, "<p>[docs](&lt;/a\n"
+                    "b&gt;)</p>\n");
+}
+
+TEST(link_destination_angle_brackets_with_closing_paren) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](<a)b>)")};
+  EXPECT_EQ(result, "<p><a href=\"a)b\">docs</a></p>\n");
+}
+
+TEST(link_destination_unmatched_angle_bracket) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](<a\\>)")};
+  EXPECT_EQ(result, "<p>[docs](&lt;a&gt;)</p>\n");
+}
+
+TEST(link_destination_invalid_angle_bracket_forms) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](<y)z\n[x](<y>z)")};
+  EXPECT_EQ(result, "<p>[x](&lt;y)z\n"
+                    "[x](<!-- raw HTML omitted -->z)</p>\n");
+}
+
+TEST(link_destination_escaped_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](\\(a\\)b)")};
+  EXPECT_EQ(result, "<p><a href=\"(a)b\">docs</a></p>\n");
+}
+
+TEST(link_destination_balanced_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](a(b(c)d)e)")};
+  EXPECT_EQ(result, "<p><a href=\"a(b(c)d)e\">docs</a></p>\n");
+}
+
+TEST(link_destination_unbalanced_parentheses_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](a(b(c)d)")};
+  EXPECT_EQ(result, "<p>[docs](a(b(c)d)</p>\n");
+}
+
+TEST(link_destination_escaped_unbalanced_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](a\\(b\\(c)")};
+  EXPECT_EQ(result, "<p><a href=\"a(b(c\">docs</a></p>\n");
+}
+
+TEST(link_destination_angle_brackets_unbalanced_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](<a(b(c>)")};
+  EXPECT_EQ(result, "<p><a href=\"a(b(c\">docs</a></p>\n");
+}
+
+TEST(link_destination_backslash_escapes) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](a\\]\\!)")};
+  EXPECT_EQ(result, "<p><a href=\"a%5D!\">docs</a></p>\n");
+}
+
+TEST(link_destination_fragments_and_queries) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[x](#top)\n\n[y](https://sourcemeta.com/?q=1#top)")};
+  EXPECT_EQ(result,
+            "<p><a href=\"#top\">x</a></p>\n"
+            "<p><a href=\"https://sourcemeta.com/?q=1#top\">y</a></p>\n");
+}
+
+TEST(link_destination_backslash_before_letter) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](a\\zb)")};
+  EXPECT_EQ(result, "<p><a href=\"a%5Czb\">docs</a></p>\n");
+}
+
+TEST(link_destination_percent_encoding_and_entities) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](caf%C3%A9&eacute;)")};
+  EXPECT_EQ(result, "<p><a href=\"caf%C3%A9%C3%A9\">docs</a></p>\n");
+}
+
+TEST(link_destination_that_looks_like_title) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs]('Title')")};
+  EXPECT_EQ(result, "<p><a href=\"&#x27;Title&#x27;\">docs</a></p>\n");
+}
+
+TEST(link_title_quote_styles) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[a](/x 'one') [b](/y (two)) [c](/z \"three\")")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/x\" title=\"one\">a</a> <a href=\"/y\" "
+            "title=\"two\">b</a> <a href=\"/z\" title=\"three\">c</a></p>\n");
+}
+
+TEST(link_title_escaped_quotes_and_entities) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](/x 'it\\'s &amp; more')")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/x\" title=\"it's &amp; more\">docs</a></p>\n");
+}
+
+TEST(link_title_separated_by_non_breaking_space) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](/x\xC2\xA0'title')")};
+  EXPECT_EQ(result, "<p><a href=\"/x%C2%A0&#x27;title&#x27;\">docs</a></p>\n");
+}
+
+TEST(link_title_with_unescaped_inner_quote_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs](/x 'a'b')")};
+  EXPECT_EQ(result, "<p>[docs](/x 'a'b')</p>\n");
+}
+
+TEST(link_title_parentheses_with_quotes_inside) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[docs](/x (with 'single' and \"double\"))")};
+  EXPECT_EQ(result, "<p><a href=\"/x\" title=\"with 'single' and "
+                    "&quot;double&quot;\">docs</a></p>\n");
+}
+
+TEST(link_whitespace_around_destination_and_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[docs](\n  /x\n  'title'\n)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\" title=\"title\">docs</a></p>\n");
+}
+
+TEST(link_spaces_before_parentheses_is_not_link) {
+  const auto result{sourcemeta::core::markdown_to_html("[docs]  (/x)")};
+  EXPECT_EQ(result, "<p>[docs]  (/x)</p>\n");
+}
+
+TEST(link_text_with_balanced_brackets) {
+  const auto result{sourcemeta::core::markdown_to_html("[a [b] [c [d]]](/x)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">a [b] [c [d]]</a></p>\n");
+}
+
+TEST(link_text_with_unbalanced_closing_bracket) {
+  const auto result{sourcemeta::core::markdown_to_html("[a] b](/x)")};
+  EXPECT_EQ(result, "<p>[a] b](/x)</p>\n");
+}
+
+TEST(link_text_with_unbalanced_opening_bracket) {
+  const auto result{sourcemeta::core::markdown_to_html("[a [b](/x)")};
+  EXPECT_EQ(result, "<p>[a <a href=\"/x\">b</a></p>\n");
+}
+
+TEST(link_text_with_escaped_bracket) {
+  const auto result{sourcemeta::core::markdown_to_html("[a \\] b](/x)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">a ] b</a></p>\n");
+}
+
+TEST(link_text_with_inline_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[_a_ __b__ `c` ~~d~~](/x)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\"><em>a</em> <strong>b</strong> "
+                    "<code>c</code> <del>d</del></a></p>\n");
+}
+
+TEST(link_text_with_image) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[![logo](/logo.png 'Logo')](/home)")};
+  EXPECT_EQ(result, "<p><a href=\"/home\"><img src=\"/logo.png\" alt=\"logo\" "
+                    "title=\"Logo\" /></a></p>\n");
+}
+
+TEST(link_inside_link_text_is_not_allowed) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a [b](/inner) c](/outer)")};
+  EXPECT_EQ(result, "<p>[a <a href=\"/inner\">b</a> c](/outer)</p>\n");
+}
+
+TEST(link_inside_emphasis_inside_link_text) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a _[b](/inner)_](/outer)")};
+  EXPECT_EQ(result, "<p>[a <em><a href=\"/inner\">b</a></em>](/outer)</p>\n");
+}
+
+TEST(link_text_brackets_take_precedence_over_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("_[a_](/x)")};
+  EXPECT_EQ(result, "<p>_<a href=\"/x\">a_</a></p>\n");
+}
+
+TEST(link_brackets_take_precedence_over_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html("[a _b](/x_)")};
+  EXPECT_EQ(result, "<p><a href=\"/x_\">a _b</a></p>\n");
+}
+
+TEST(link_code_span_takes_precedence) {
+  const auto result{sourcemeta::core::markdown_to_html("[a`](/x)`")};
+  EXPECT_EQ(result, "<p>[a<code>](/x)</code></p>\n");
+}
+
+TEST(link_autolink_takes_precedence) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[a<https://sourcemeta.com/?q=](/x)>")};
+  EXPECT_EQ(result, "<p>[a<a "
+                    "href=\"https://sourcemeta.com/?q=%5D(/x)\">https://"
+                    "sourcemeta.com/?q=](/x)</a></p>\n");
+}
+
+TEST(reference_link_full) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[the docs][manual]\n\n[manual]: /manual 'Manual'")};
+  EXPECT_EQ(result,
+            "<p><a href=\"/manual\" title=\"Manual\">the docs</a></p>\n");
+}
+
+TEST(reference_link_text_with_nested_brackets) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a [b] c][ref]\n\n[ref]: /ref")};
+  EXPECT_EQ(result, "<p><a href=\"/ref\">a [b] c</a></p>\n");
+}
+
+TEST(reference_link_label_case_folding) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[text][MaNuAl]\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">text</a></p>\n");
+}
+
+TEST(reference_link_label_titlecase_digraph_folding) {
+  const auto result{sourcemeta::core::markdown_to_html("[Dž]\n\n[dž]: /digraph")};
+  EXPECT_EQ(result, "<p><a href=\"/digraph\">\xc7\x85</a></p>\n");
+}
+
+TEST(reference_link_space_between_labels_is_shortcut) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a] [ref]\n\n[ref]: /ref")};
+  EXPECT_EQ(result, "<p>[a] <a href=\"/ref\">ref</a></p>\n");
+}
+
+TEST(reference_link_newline_between_labels_is_shortcut) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a]\n[ref]\n\n[ref]: /ref")};
+  EXPECT_EQ(result, "<p>[a]\n"
+                    "<a href=\"/ref\">ref</a></p>\n");
+}
+
+TEST(reference_link_uses_first_definition) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[a][ref]\n\n[ref]: /first\n[ref]: /second")};
+  EXPECT_EQ(result, "<p><a href=\"/first\">a</a></p>\n");
+}
+
+TEST(reference_link_label_escapes_are_literal) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a][ref\\*]\n\n[ref*]: /ref")};
+  EXPECT_EQ(result, "<p>[a][ref*]</p>\n");
+}
+
+TEST(reference_link_label_with_unescaped_bracket_is_invalid) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a][b]c]\n\n[b]c]: /x")};
+  EXPECT_EQ(result, "<p>[a][b]c]</p>\n"
+                    "<p>[b]c]: /x</p>\n");
+}
+
+TEST(reference_link_label_with_escaped_bracket) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a][b\\]c]\n\n[b\\]c]: /x")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">a</a></p>\n");
+}
+
+TEST(reference_link_label_with_escaped_backslash) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a\\\\b]: /x\n\n[a\\\\b]")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">a\\b</a></p>\n");
+}
+
+TEST(reference_link_empty_brackets_are_literal) {
+  const auto result{sourcemeta::core::markdown_to_html("[][]\n\n[]: /x")};
+  EXPECT_EQ(result, "<p>[][]</p>\n"
+                    "<p>[]: /x</p>\n");
+}
+
+TEST(collapsed_reference_link_case_insensitive) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[MANUAL][]\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">MANUAL</a></p>\n");
+}
+
+TEST(collapsed_reference_link_across_lines_is_shortcut) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[manual]\n[]\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">manual</a>\n"
+                    "[]</p>\n");
+}
+
+TEST(shortcut_reference_link_with_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[_the_ manual]\n\n[_the_ manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\"><em>the</em> manual</a></p>\n");
+}
+
+TEST(shortcut_reference_link_escaped) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\\[manual\\]\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p>[manual]</p>\n");
+}
+
+TEST(shortcut_reference_link_label_with_underscore) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[manual_]: /manual\n\n_[manual_]")};
+  EXPECT_EQ(result, "<p>_<a href=\"/manual\">manual_</a></p>\n");
+}
+
+TEST(reference_link_full_takes_precedence_over_shortcut) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a][b][c]\n\n[b]: /b\n[c]: /c")};
+  EXPECT_EQ(result, "<p><a href=\"/b\">a</a><a href=\"/c\">c</a></p>\n");
+}
+
+TEST(reference_link_undefined_label_falls_back) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[a][b][c]\n\n[a]: /a\n[c]: /c")};
+  EXPECT_EQ(result, "<p>[a]<a href=\"/c\">b</a></p>\n");
+}
+
+TEST(inline_link_takes_precedence_over_reference) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[manual]()\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"\">manual</a></p>\n");
+}
+
+TEST(inline_link_invalid_falls_back_to_reference) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[manual](a b)\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<p><a href=\"/manual\">manual</a>(a b)</p>\n");
+}
diff --git a/test/markdown/markdown_lists_test.cc b/test/markdown/markdown_lists_test.cc
new file mode 100644
index 0000000000..c7cd696ec6
--- /dev/null
+++ b/test/markdown/markdown_lists_test.cc
@@ -0,0 +1,793 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(unordered_list_with_dashes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- one\n- two\n- three")};
+  EXPECT_EQ(result,
+            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
+}
+
+TEST(unordered_list_with_asterisks) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* one\n* two\n* three")};
+  EXPECT_EQ(result,
+            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
+}
+
+TEST(unordered_list_with_plus) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("+ one\n+ two\n+ three")};
+  EXPECT_EQ(result,
+            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
+}
+
+TEST(nested_unordered_list) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- outer\n  - inner\n  - inner2\n- outer2")};
+  EXPECT_EQ(result, "<ul>\n<li>outer\n<ul>\n<li>inner</li>\n<li>inner2</li>\n"
+                    "</ul>\n</li>\n<li>outer2</li>\n</ul>\n");
+}
+
+TEST(ordered_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("1. one\n2. two\n3. three")};
+  EXPECT_EQ(result,
+            "<ol>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ol>\n");
+}
+
+TEST(ordered_list_starting_at_nonone) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("3. three\n4. four\n5. five")};
+  EXPECT_EQ(result,
+            "<ol start=\"3\">\n<li>three</li>\n<li>four</li>\n<li>five</li>\n"
+            "</ol>\n");
+}
+
+TEST(nested_ordered_in_unordered) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- item\n  1. sub one\n  2. sub two\n- item2")};
+  EXPECT_EQ(result, "<ul>\n<li>item\n<ol>\n<li>sub one</li>\n<li>sub two</li>\n"
+                    "</ol>\n</li>\n<li>item2</li>\n</ul>\n");
+}
+
+TEST(loose_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- one\n\n- two\n\n- three")};
+  EXPECT_EQ(result, "<ul>\n<li>\n<p>one</p>\n</li>\n<li>\n<p>two</p>\n</li>\n"
+                    "<li>\n<p>three</p>\n</li>\n</ul>\n");
+}
+
+TEST(list_with_code_block) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- item:\n\n  ```\n  code\n  ```\n\n- next")};
+  EXPECT_EQ(result, "<ul>\n<li>\n<p>item:</p>\n<pre><code>code\n</code></pre>\n"
+                    "</li>\n<li>\n<p>next</p>\n</li>\n</ul>\n");
+}
+
+TEST(deeply_nested_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- a\n  - b\n    - c\n      - d")};
+  EXPECT_EQ(result, "<ul>\n<li>a\n<ul>\n<li>b\n<ul>\n<li>c\n<ul>\n<li>d</li>\n"
+                    "</ul>\n</li>\n</ul>\n</li>\n</ul>\n</li>\n</ul>\n");
+}
+
+TEST(ordered_list_with_paragraphs) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "1. first\n\n   more text\n\n2. second")};
+  EXPECT_EQ(result, "<ol>\n<li>\n<p>first</p>\n<p>more text</p>\n</li>\n"
+                    "<li>\n<p>second</p>\n</li>\n</ol>\n");
+}
+
+TEST(list_item_with_multiple_paragraphs) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- paragraph one\n\n  paragraph two\n\n  paragraph three")};
+  EXPECT_EQ(result, "<ul>\n<li>\n<p>paragraph one</p>\n<p>paragraph two</p>\n"
+                    "<p>paragraph three</p>\n</li>\n</ul>\n");
+}
+
+TEST(list_marker_takes_precedence_over_code_span) {
+  const auto result{sourcemeta::core::markdown_to_html("* `alpha\n* beta`")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>`alpha</li>\n"
+                    "<li>beta`</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_content_needs_marker_width_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n\n two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "<p>two</p>\n");
+}
+
+TEST(list_item_content_with_marker_width_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n\n  two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<p>two</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_wide_marker_content_not_indented_enough) {
+  const auto result{sourcemeta::core::markdown_to_html("1.   one\n\n    two")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>one</li>\n"
+                    "</ol>\n"
+                    "<pre><code>two\n"
+                    "</code></pre>\n");
+}
+
+TEST(list_item_wide_marker_content_indented_enough) {
+  const auto result{sourcemeta::core::markdown_to_html("1.   one\n\n     two")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<p>two</p>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_inside_nested_blockquotes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> > - one\n> >\n> >   two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<blockquote>\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<p>two</p>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(list_item_inside_nested_blockquotes_not_indented_enough) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> > - one\n> >\n> > two")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<blockquote>\n"
+                    "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "<p>two</p>\n"
+                    "</blockquote>\n"
+                    "</blockquote>\n");
+}
+
+TEST(list_item_marker_needs_following_space) {
+  const auto result{sourcemeta::core::markdown_to_html("*one\n\n1)two")};
+  EXPECT_EQ(result, "<p>*one</p>\n"
+                    "<p>1)two</p>\n");
+}
+
+TEST(list_item_multiple_blank_lines_between_blocks) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n\n\n\n  two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<p>two</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_with_several_block_types) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "2. one\n\n   ~~~\n   code\n   ~~~\n\n   two\n\n   > quote")};
+  EXPECT_EQ(result, "<ol start=\"2\">\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<p>two</p>\n"
+                    "<blockquote>\n"
+                    "<p>quote</p>\n"
+                    "</blockquote>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_code_block_with_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "* one\n\n      code\n\n\n      more")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "<pre><code>code\n"
+                    "\n"
+                    "\n"
+                    "more\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_nine_digit_number) {
+  const auto result{sourcemeta::core::markdown_to_html("999999999) max")};
+  EXPECT_EQ(result, "<ol start=\"999999999\">\n"
+                    "<li>max</li>\n"
+                    "</ol>\n");
+}
+
+TEST(ordered_list_ten_digit_number_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("9999999999) over")};
+  EXPECT_EQ(result, "<p>9999999999) over</p>\n");
+}
+
+TEST(ordered_list_starting_at_zero) {
+  const auto result{sourcemeta::core::markdown_to_html("0) zero")};
+  EXPECT_EQ(result, "<ol start=\"0\">\n"
+                    "<li>zero</li>\n"
+                    "</ol>\n");
+}
+
+TEST(ordered_list_number_with_leading_zeros) {
+  const auto result{sourcemeta::core::markdown_to_html("0007. seven")};
+  EXPECT_EQ(result, "<ol start=\"7\">\n"
+                    "<li>seven</li>\n"
+                    "</ol>\n");
+}
+
+TEST(ordered_list_negative_number_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("-5) negative")};
+  EXPECT_EQ(result, "<p>-5) negative</p>\n");
+}
+
+TEST(list_item_indented_code_after_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("* text\n\n      code")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>text</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_item_indented_code_after_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(" 100. text\n\n          code")};
+  EXPECT_EQ(result, "<ol start=\"100\">\n"
+                    "<li>\n"
+                    "<p>text</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_starting_with_indented_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("*     code\n\n  text\n\n      more")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "<p>text</p>\n"
+                    "<pre><code>more\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_starting_with_indented_code_and_extra_space) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("*      code\n\n  text")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<pre><code> code\n"
+                    "</code></pre>\n"
+                    "<p>text</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_starting_with_blank_line) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("*\n  one\n*\n  ~~~\n  code\n  ~~~")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_starting_with_blank_line_and_trailing_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("1.  \n   one")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>one</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_at_most_one_starting_blank_line) {
+  const auto result{sourcemeta::core::markdown_to_html("*\n\n  one")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li></li>\n"
+                    "</ul>\n"
+                    "<p>one</p>\n");
+}
+
+TEST(list_item_empty_between_items) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n*\n* two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li></li>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_empty_with_trailing_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n*  \n* two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li></li>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_item_empty_between_items) {
+  const auto result{sourcemeta::core::markdown_to_html("1) one\n2)\n3) two")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>one</li>\n"
+                    "<li></li>\n"
+                    "<li>two</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_consisting_of_single_empty_item) {
+  const auto result{sourcemeta::core::markdown_to_html("-")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li></li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_empty_cannot_interrupt_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("text\n-\n\ntext\n1)")};
+  EXPECT_EQ(result, "<h2>text</h2>\n"
+                    "<p>text\n"
+                    "1)</p>\n");
+}
+
+TEST(list_item_indented_one_space) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "  1. one\n     two\n\n         code")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>\n"
+                    "<p>one\n"
+                    "two</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_indented_four_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    - one\n      two")};
+  EXPECT_EQ(result, "<pre><code>- one\n"
+                    "  two\n"
+                    "</code></pre>\n");
+}
+
+TEST(list_item_lazy_continuation_lines) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(" * one\ntwo\n\n       code")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>one\n"
+                    "two</p>\n"
+                    "<pre><code>code\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_partially_lazy_continuation) {
+  const auto result{sourcemeta::core::markdown_to_html(" * one\n  two\nthree")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one\n"
+                    "two\n"
+                    "three</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_laziness_inside_nested_containers) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> * > quoted\nlazy line")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<blockquote>\n"
+                    "<p>quoted\n"
+                    "lazy line</p>\n"
+                    "</blockquote>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</blockquote>\n");
+}
+
+TEST(list_nested_with_sufficient_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("* a\n  * b\n    * c")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a\n"
+                    "<ul>\n"
+                    "<li>b\n"
+                    "<ul>\n"
+                    "<li>c</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_not_nested_with_one_space_increments) {
+  const auto result{sourcemeta::core::markdown_to_html("* a\n * b\n  * c")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a</li>\n"
+                    "<li>b</li>\n"
+                    "<li>c</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_nested_needs_marker_width_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("100. a\n     * b")};
+  EXPECT_EQ(result, "<ol start=\"100\">\n"
+                    "<li>a\n"
+                    "<ul>\n"
+                    "<li>b</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(ordered_list_not_nested_with_insufficient_indentation) {
+  const auto result{sourcemeta::core::markdown_to_html("100. a\n    * b")};
+  EXPECT_EQ(result, "<ol start=\"100\">\n"
+                    "<li>a\n"
+                    "* b</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_containing_only_list) {
+  const auto result{sourcemeta::core::markdown_to_html("+ + one")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_containing_nested_ordered_list) {
+  const auto result{sourcemeta::core::markdown_to_html("3) * 4) deep")};
+  EXPECT_EQ(result, "<ol start=\"3\">\n"
+                    "<li>\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<ol start=\"4\">\n"
+                    "<li>deep</li>\n"
+                    "</ol>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_item_containing_headings) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* ## Title\n* Text\n  ===\n  more")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<h2>Title</h2>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<h1>Text</h1>\n"
+                    "more</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_changing_bullet_character_starts_new_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* one\n* two\n- three")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n"
+                    "<ul>\n"
+                    "<li>three</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_changing_delimiter_starts_new_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("1) one\n2) two\n3. three")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>one</li>\n"
+                    "<li>two</li>\n"
+                    "</ol>\n"
+                    "<ol start=\"3\">\n"
+                    "<li>three</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_interrupts_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("Text\n* one\n* two")};
+  EXPECT_EQ(result, "<p>Text</p>\n"
+                    "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_not_starting_at_one_cannot_interrupt_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("We counted\n42. items in total")};
+  EXPECT_EQ(result, "<p>We counted\n"
+                    "42. items in total</p>\n");
+}
+
+TEST(ordered_list_starting_at_one_interrupts_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("We counted\n1. items in total")};
+  EXPECT_EQ(result, "<p>We counted</p>\n"
+                    "<ol>\n"
+                    "<li>items in total</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_items_separated_by_multiple_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n\n\n* two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>one</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>two</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_nested_item_with_blank_lines) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n  * b\n\n\n    c")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "<p>c</p>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_separated_by_html_comment) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* one\n\n<!-- split -->\n\n* two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "<!-- raw HTML omitted -->\n"
+                    "<ul>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_items_with_varying_marker_indentation) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n * b\n  * c\n * d\n* e")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a</li>\n"
+                    "<li>b</li>\n"
+                    "<li>c</li>\n"
+                    "<li>d</li>\n"
+                    "<li>e</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_item_indented_four_spaces_continues_previous_item) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n * b\n  * c\n    * d")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a</li>\n"
+                    "<li>b</li>\n"
+                    "<li>c\n"
+                    "<ul>\n"
+                    "<li>d</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(ordered_list_item_indented_five_spaces_is_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("1) a\n\n 2) b\n\n     3) c")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "<ol start=\"3\">\n"
+                    "<li>c</li>\n"
+                    "</ol>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_loose_with_blank_line_between_items) {
+  const auto result{sourcemeta::core::markdown_to_html("* a\n\n* b\n* c")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>c</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_loose_with_empty_item) {
+  const auto result{sourcemeta::core::markdown_to_html("- a\n-\n\n- b")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "</li>\n"
+                    "<li></li>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_loose_with_blank_line_inside_item) {
+  const auto result{sourcemeta::core::markdown_to_html("* a\n\n  b\n* c")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "<p>b</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>c</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_loose_with_blank_line_before_reference_definition) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n\n  [r]: /r\n* b")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_tight_with_blank_lines_inside_code_block) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n* ~~~\n  x\n\n  ~~~\n* b")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a</li>\n"
+                    "<li>\n"
+                    "<pre><code>x\n"
+                    "\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "<li>b</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_tight_with_loose_sublist) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n  * b\n\n  * c\n* d")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<p>b</p>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>c</p>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "<li>d</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_tight_with_blank_blockquote_line) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- a\n  > b\n  >\n  > c\n- d")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a\n"
+                    "<blockquote>\n"
+                    "<p>b</p>\n"
+                    "<p>c</p>\n"
+                    "</blockquote>\n"
+                    "</li>\n"
+                    "<li>d</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_tight_with_blockquote_and_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n  > b\n  ~~~\n  c\n  ~~~\n* d")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a\n"
+                    "<blockquote>\n"
+                    "<p>b</p>\n"
+                    "</blockquote>\n"
+                    "<pre><code>c\n"
+                    "</code></pre>\n"
+                    "</li>\n"
+                    "<li>d</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_single_tight_nested_ordered_item) {
+  const auto result{sourcemeta::core::markdown_to_html("1. a\n   1. b")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>a\n"
+                    "<ol>\n"
+                    "<li>b</li>\n"
+                    "</ol>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_loose_single_item_with_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* ~~~\n  x\n  ~~~\n\n  y")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<pre><code>x\n"
+                    "</code></pre>\n"
+                    "<p>y</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(list_outer_loose_inner_tight) {
+  const auto result{sourcemeta::core::markdown_to_html("1. a\n   - b\n\n   c")};
+  EXPECT_EQ(result, "<ol>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "<ul>\n"
+                    "<li>b</li>\n"
+                    "</ul>\n"
+                    "<p>c</p>\n"
+                    "</li>\n"
+                    "</ol>\n");
+}
+
+TEST(list_tight_sublist_inside_loose_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a\n  1. b\n  2. c\n\n* d")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<p>a</p>\n"
+                    "<ol>\n"
+                    "<li>b</li>\n"
+                    "<li>c</li>\n"
+                    "</ol>\n"
+                    "</li>\n"
+                    "<li>\n"
+                    "<p>d</p>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
diff --git a/test/markdown/markdown_paragraphs_test.cc b/test/markdown/markdown_paragraphs_test.cc
new file mode 100644
index 0000000000..37ce6a50a6
--- /dev/null
+++ b/test/markdown/markdown_paragraphs_test.cc
@@ -0,0 +1,76 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(simple_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("Hello world")};
+  EXPECT_EQ(result, "<p>Hello world</p>\n");
+}
+
+TEST(multiple_paragraphs) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "First paragraph\n\nSecond paragraph")};
+  EXPECT_EQ(result, "<p>First paragraph</p>\n<p>Second paragraph</p>\n");
+}
+
+TEST(three_paragraphs) {
+  const auto result{sourcemeta::core::markdown_to_html("One\n\nTwo\n\nThree")};
+  EXPECT_EQ(result, "<p>One</p>\n<p>Two</p>\n<p>Three</p>\n");
+}
+
+TEST(empty_input) {
+  const auto result{sourcemeta::core::markdown_to_html("")};
+  EXPECT_TRUE(result.empty());
+}
+
+TEST(whitespace_only) {
+  const auto result{sourcemeta::core::markdown_to_html("   \n\n   ")};
+  EXPECT_TRUE(result.empty());
+}
+
+TEST(paragraph_with_inline_code_and_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "Use `foo()` from [the docs](https://docs.com).")};
+  EXPECT_EQ(result, "<p>Use <code>foo()</code> from "
+                    "<a href=\"https://docs.com\">the docs</a>.</p>\n");
+}
+
+TEST(paragraph_leading_spaces_stripped) {
+  const auto result{sourcemeta::core::markdown_to_html(" one\n  two")};
+  EXPECT_EQ(result, "<p>one\n"
+                    "two</p>\n");
+}
+
+TEST(paragraph_continuation_leading_spaces_stripped) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "one\n          two\n                     three")};
+  EXPECT_EQ(result, "<p>one\n"
+                    "two\n"
+                    "three</p>\n");
+}
+
+TEST(paragraph_first_line_indented_three_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("  first\nsecond")};
+  EXPECT_EQ(result, "<p>first\n"
+                    "second</p>\n");
+}
+
+TEST(paragraph_first_line_indented_five_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("     first\nsecond")};
+  EXPECT_EQ(result, "<pre><code> first\n"
+                    "</code></pre>\n"
+                    "<p>second</p>\n");
+}
+
+TEST(paragraph_final_trailing_spaces_stripped) {
+  const auto result{sourcemeta::core::markdown_to_html("one   \ntwo   ")};
+  EXPECT_EQ(result, "<p>one<br />\n"
+                    "two</p>\n");
+}
+
+TEST(blank_lines_at_start_and_end_ignored) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("\n  \none\n\n \n## two\n\n\n")};
+  EXPECT_EQ(result, "<p>one</p>\n"
+                    "<h2>two</h2>\n");
+}
diff --git a/test/markdown/markdown_pathological_test.cc b/test/markdown/markdown_pathological_test.cc
new file mode 100644
index 0000000000..045c3e64e3
--- /dev/null
+++ b/test/markdown/markdown_pathological_test.cc
@@ -0,0 +1,244 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+#include <cstddef>     // std::size_t
+#include <string>      // std::string, std::to_string
+#include <string_view> // std::string_view
+
+static auto repeat(const std::string_view pattern, const std::size_t count)
+    -> std::string {
+  std::string result;
+  result.reserve(pattern.size() * count);
+  for (std::size_t index = 0; index < count; ++index) {
+    result.append(pattern);
+  }
+
+  return result;
+}
+
+static auto increasing_backtick_runs(const std::size_t count) -> std::string {
+  std::string result;
+  for (std::size_t length = 1; length <= count; ++length) {
+    result.push_back('x');
+    result.append(length, '`');
+  }
+
+  return result;
+}
+
+static auto staircase_list(const std::size_t depth) -> std::string {
+  std::string result;
+  for (std::size_t level = 0; level < depth; ++level) {
+    result.append(level * 2, ' ');
+    result.append("- level\n");
+  }
+
+  return result;
+}
+
+static auto numbered_reference_definitions(const std::size_t count)
+    -> std::string {
+  std::string result;
+  for (std::size_t index = 0; index < count; ++index) {
+    const auto number{std::to_string(index)};
+    result.append("[r").append(number).append("]: /").append(number).append(
+        "\n");
+  }
+
+  return result;
+}
+
+static auto numbered_reference_uses(const std::size_t count) -> std::string {
+  std::string result;
+  for (std::size_t index = 0; index < count; ++index) {
+    if (index > 0) {
+      result.push_back(' ');
+    }
+
+    result.append("[r").append(std::to_string(index)).append("]");
+  }
+
+  return result;
+}
+
+static auto numbered_reference_anchors(const std::size_t count) -> std::string {
+  std::string result;
+  for (std::size_t index = 0; index < count; ++index) {
+    if (index > 0) {
+      result.push_back(' ');
+    }
+
+    const auto number{std::to_string(index)};
+    result.append("<a href=\"/")
+        .append(number)
+        .append("\">r")
+        .append(number)
+        .append("</a>");
+  }
+
+  return result;
+}
+
+TEST(alternating_nested_emphasis) {
+  const auto input{repeat("_x **y ", 5000) + "z" + repeat(" y** x_", 5000)};
+  const auto result{sourcemeta::core::markdown_to_html(input)};
+  EXPECT_EQ(result, "<p>" + repeat("<em>x <strong>y ", 5000) + "z" +
+                        repeat(" y</strong> x</em>", 5000) + "</p>\n");
+}
+
+TEST(underscore_closers_before_punctuation_without_openers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("x_. ", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("x_. ", 9999) + "x_.</p>\n");
+}
+
+TEST(double_underscore_openers_without_closers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("__y ", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("__y ", 9999) + "__y</p>\n");
+}
+
+TEST(link_closers_without_openers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("]b", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("]b", 10000) + "</p>\n");
+}
+
+TEST(image_openers_without_closers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("![b", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("![b", 10000) + "</p>\n");
+}
+
+TEST(mismatched_underscore_openers_and_asterisk_closers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("_b* ", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("_b* ", 9999) + "_b*</p>\n");
+}
+
+TEST(intraword_triple_asterisks_followed_by_single_closers) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x***y" + repeat("z* ", 10000))};
+  EXPECT_EQ(result, "<p>x<em><em><em>yz</em> z</em> z</em> " +
+                        repeat("z* ", 9996) + "z*</p>\n");
+}
+
+TEST(link_openers_with_asterisk_closers) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("[ b*", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("[ b*", 10000) + "</p>\n");
+}
+
+TEST(unclosed_link_destinations_with_open_parentheses) {
+  const auto result{sourcemeta::core::markdown_to_html(repeat("[ x](", 10000))};
+  EXPECT_EQ(result, "<p>" + repeat("[ x](", 10000) + "</p>\n");
+}
+
+TEST(nested_image_brackets) {
+  const auto input{repeat("![", 5000) + "x" + repeat("]", 5000)};
+  const auto result{sourcemeta::core::markdown_to_html(input)};
+  EXPECT_EQ(result, "<p>" + input + "</p>\n");
+}
+
+TEST(unclosed_image_angle_bracket_destinations) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(repeat("![x](<y", 5000))};
+  EXPECT_EQ(result, "<p>" + repeat("![x](&lt;y", 5000) + "</p>\n");
+}
+
+TEST(unclosed_inline_cdata_sections) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x" + repeat("<![CDATA[", 5000))};
+  EXPECT_EQ(result, "<p>x" + repeat("&lt;![CDATA[", 5000) + "</p>\n");
+}
+
+TEST(unclosed_inline_processing_instructions) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x" + repeat("<?", 5000))};
+  EXPECT_EQ(result, "<p>x" + repeat("&lt;?", 5000) + "</p>\n");
+}
+
+TEST(backtick_runs_of_increasing_length) {
+  const auto input{increasing_backtick_runs(2000)};
+  const auto result{sourcemeta::core::markdown_to_html(input)};
+  EXPECT_EQ(result, "<p>" + input + "</p>\n");
+}
+
+TEST(code_span_with_eighty_backticks) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      std::string(80, '`') + "x" + std::string(80, '`'))};
+  EXPECT_EQ(result, "<p><code>x</code></p>\n");
+}
+
+TEST(code_span_with_eighty_one_backticks) {
+  const auto input{std::string(81, '`') + "x" + std::string(81, '`')};
+  const auto result{sourcemeta::core::markdown_to_html(input)};
+  EXPECT_EQ(result, "<p>" + input + "</p>\n");
+}
+
+TEST(alternating_blockquote_and_list_nesting_on_one_line) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(repeat("> - ", 30) + "deep")};
+  EXPECT_EQ(result, repeat("<blockquote>\n<ul>\n<li>\n", 29) +
+                        "<blockquote>\n<ul>\n<li>deep</li>\n</ul>\n"
+                        "</blockquote>\n" +
+                        repeat("</li>\n</ul>\n</blockquote>\n", 29));
+}
+
+TEST(alternating_blockquote_and_list_nesting_on_one_line_beyond_depth_limit) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(repeat("> - ", 50) + "deep")};
+  EXPECT_EQ(result, repeat("<blockquote>\n<ul>\n<li>\n", 49) +
+                        "<blockquote>\n<p>- deep</p>\n</blockquote>\n" +
+                        repeat("</li>\n</ul>\n</blockquote>\n", 49));
+}
+
+TEST(staircase_list_of_one_hundred_fifty_levels) {
+  const auto result{sourcemeta::core::markdown_to_html(staircase_list(150))};
+  EXPECT_EQ(result, repeat("<ul>\n<li>level\n", 149) +
+                        "<ul>\n<li>level</li>\n</ul>\n" +
+                        repeat("</li>\n</ul>\n", 149));
+}
+
+TEST(table_with_many_rows) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| a | b | c |\n|---|---|---|\n" + repeat("| x | y | z |\n", 5000))};
+  EXPECT_EQ(
+      result,
+      "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n<th>c</th>\n"
+      "</tr>\n</thead>\n<tbody>\n" +
+          repeat("<tr>\n<td>x</td>\n<td>y</td>\n<td>z</td>\n</tr>\n", 5000) +
+          "</tbody>\n</table>\n");
+}
+
+TEST(table_with_many_columns) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "|" + repeat(" h |", 1000) + "\n|" + repeat("-|", 1000) + "\n|" +
+      repeat(" c |", 1000))};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n" + repeat("<th>h</th>\n", 1000) +
+                        "</tr>\n</thead>\n<tbody>\n<tr>\n" +
+                        repeat("<td>c</td>\n", 1000) +
+                        "</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(link_reference_label_of_one_thousand_characters) {
+  const std::string label(1000, 'y');
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[" + label + "]: /x\n\n[" + label + "]")};
+  EXPECT_EQ(result, "<p><a href=\"/x\">" + label + "</a></p>\n");
+}
+
+TEST(link_reference_label_of_one_thousand_one_characters) {
+  const std::string label(1001, 'y');
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[" + label + "]: /x\n\n[" + label + "]")};
+  EXPECT_EQ(result, "<p>[" + label + "]: /x</p>\n<p>[" + label + "]</p>\n");
+}
+
+TEST(single_paragraph_line_of_two_hundred_thousand_characters) {
+  const std::string input(200000, 'w');
+  const auto result{sourcemeta::core::markdown_to_html(input)};
+  EXPECT_EQ(result, "<p>" + input + "</p>\n");
+}
+
+TEST(two_thousand_reference_definitions_and_uses) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(numbered_reference_definitions(2000) +
+                                         "\n" + numbered_reference_uses(2000))};
+  EXPECT_EQ(result, "<p>" + numbered_reference_anchors(2000) + "</p>\n");
+}
diff --git a/test/markdown/markdown_safety_test.cc b/test/markdown/markdown_safety_test.cc
new file mode 100644
index 0000000000..0eecb7fd87
--- /dev/null
+++ b/test/markdown/markdown_safety_test.cc
@@ -0,0 +1,218 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(safe_mode_renders_plain_content) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Hello **world**", true)};
+  EXPECT_EQ(result, "<p>Hello <strong>world</strong></p>\n");
+}
+
+TEST(safe_mode_omits_raw_html) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>", true)};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(default_omits_raw_html) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(default_strips_dangerous_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[click](javascript:alert(1))")};
+  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
+}
+
+TEST(inline_html_is_sanitized) {
+  const auto result{sourcemeta::core::markdown_to_html("Hello <em>world</em>")};
+  EXPECT_EQ(
+      result,
+      "<p>Hello <!-- raw HTML omitted -->world<!-- raw HTML omitted --></p>\n");
+}
+
+TEST(raw_html_block_is_sanitized) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<div class=\"foo\">bar</div>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(script_tag_is_sanitized) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<script>alert('xss')</script>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(iframe_is_sanitized) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<iframe src=\"https://evil.com\"></iframe>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(javascript_link_is_sanitized) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[click](javascript:alert('xss'))")};
+  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
+}
+
+TEST(vbscript_link_is_sanitized) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[click](vbscript:MsgBox)")};
+  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
+}
+
+TEST(data_uri_link_is_sanitized) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[click](data:text/html,<h1>hi</h1>)")};
+  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
+}
+
+TEST(safe_mode_strips_mixed_case_javascript_scheme) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[click](JaVaScRiPt:void(0))")};
+  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
+}
+
+TEST(safe_mode_strips_uppercase_file_scheme) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[local](FILE://C:/secrets.txt)")};
+  EXPECT_EQ(result, "<p><a href=\"\">local</a></p>\n");
+}
+
+TEST(safe_mode_strips_data_text_plain) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](data:text/plain,hello)")};
+  EXPECT_EQ(result, "<p><a href=\"\">x</a></p>\n");
+}
+
+TEST(safe_mode_keeps_data_image_gif) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "![pixel](data:image/gif;base64,R0lGODlhAQABAAAAACw=)")};
+  EXPECT_EQ(result,
+            "<p><img src=\"data:image/gif;base64,R0lGODlhAQABAAAAACw=\" "
+            "alt=\"pixel\" /></p>\n");
+}
+
+TEST(safe_mode_keeps_uppercase_data_image_jpeg_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](DATA:IMAGE/JPEG;base64,/9j/)")};
+  EXPECT_EQ(result, "<p><a href=\"DATA:IMAGE/JPEG;base64,/9j/\">x</a></p>\n");
+}
+
+TEST(safe_mode_strips_data_image_bmp) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![x](data:image/bmp;base64,Qk0=)")};
+  EXPECT_EQ(result, "<p><img src=\"\" alt=\"x\" /></p>\n");
+}
+
+TEST(safe_mode_strips_entity_encoded_javascript) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](&#x6A;avascript:void(0))")};
+  EXPECT_EQ(result, "<p><a href=\"\">x</a></p>\n");
+}
+
+TEST(safe_mode_keeps_percent_encoded_colon) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](vbscript%3Amsgbox)")};
+  EXPECT_EQ(result, "<p><a href=\"vbscript%3Amsgbox\">x</a></p>\n");
+}
+
+TEST(safe_mode_strips_dangerous_image_source) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![x](vbscript:msgbox)")};
+  EXPECT_EQ(result, "<p><img src=\"\" alt=\"x\" /></p>\n");
+}
+
+TEST(safe_mode_strips_dangerous_reference_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x][r]\n\n[r]: file:///tmp/a")};
+  EXPECT_EQ(result, "<p><a href=\"\">x</a></p>\n");
+}
+
+TEST(safe_mode_strips_dangerous_autolink) {
+  const auto result{sourcemeta::core::markdown_to_html("<vbscript:msgbox>")};
+  EXPECT_EQ(result, "<p><a href=\"\">vbscript:msgbox</a></p>\n");
+}
+
+TEST(safe_mode_keeps_telephone_relative_and_fragment_links) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[a](tel:+123) [b](../up) [c](#anchor)")};
+  EXPECT_EQ(result, "<p><a href=\"tel:+123\">a</a> <a href=\"../up\">b</a> <a "
+                    "href=\"#anchor\">c</a></p>\n");
+}
+
+TEST(safe_mode_omits_inline_html_comment) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("before <!-- hidden --> after")};
+  EXPECT_EQ(result, "<p>before <!-- raw HTML omitted --> after</p>\n");
+}
+
+TEST(safe_mode_omits_processing_instruction) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "before <?xml version=\"1.0\"?> after")};
+  EXPECT_EQ(result, "<p>before <!-- raw HTML omitted --> after</p>\n");
+}
+
+TEST(safe_mode_omits_cdata_section) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("before <![CDATA[ data ]]> after")};
+  EXPECT_EQ(result, "<p>before <!-- raw HTML omitted --> after</p>\n");
+}
+
+TEST(safe_mode_omits_declaration_block) {
+  const auto result{sourcemeta::core::markdown_to_html("<!ENTITY x \"y\">")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
+}
+
+TEST(safe_mode_omits_html_block_but_parses_markdown_between_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<section>\n\n__strong__\n\n</section>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n"
+                    "<p><strong>strong</strong></p>\n"
+                    "<!-- raw HTML omitted -->\n");
+}
+
+TEST(safe_mode_omits_html_block_with_blank_line_inside) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<div>\n<p>\n__text__\n\n_more_\n</p>\n</div>")};
+  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n"
+                    "<p><em>more</em></p>\n"
+                    "<!-- raw HTML omitted -->\n");
+}
+
+TEST(safe_mode_omits_inline_tag_with_attributes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <span style=\"color:red\"> y")};
+  EXPECT_EQ(result, "<p>x <!-- raw HTML omitted --> y</p>\n");
+}
+
+TEST(safe_mode_escapes_markup_in_link_title) {
+  const auto result{sourcemeta::core::markdown_to_html("[x](/y '<b>&\"</b>')")};
+  EXPECT_EQ(
+      result,
+      "<p><a href=\"/y\" title=\"&lt;b&gt;&amp;&quot;&lt;/b&gt;\">x</a></p>\n");
+}
+
+TEST(safe_mode_escapes_quotes_in_image_title) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(R"MD(![x](/y.png "say \"hi\""))MD")};
+  EXPECT_EQ(
+      result,
+      "<p><img src=\"/y.png\" alt=\"x\" title=\"say &quot;hi&quot;\" /></p>\n");
+}
+
+TEST(safe_mode_omits_raw_html_inside_emphasis) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("_<span title=\"_\">x</span>_")};
+  EXPECT_EQ(
+      result,
+      "<p><em><!-- raw HTML omitted -->x<!-- raw HTML omitted --></em></p>\n");
+}
+
+TEST(safe_mode_omits_raw_html_taking_precedence_over_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x <span data=\"](/y)\">")};
+  EXPECT_EQ(result, "<p>[x <!-- raw HTML omitted --></p>\n");
+}
diff --git a/test/markdown/markdown_strikethrough_test.cc b/test/markdown/markdown_strikethrough_test.cc
new file mode 100644
index 0000000000..ad176606a5
--- /dev/null
+++ b/test/markdown/markdown_strikethrough_test.cc
@@ -0,0 +1,86 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(strikethrough) {
+  const auto result{sourcemeta::core::markdown_to_html("~~deleted~~")};
+  EXPECT_EQ(result, "<p><del>deleted</del></p>\n");
+}
+
+TEST(strikethrough_with_other_formatting) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("~~deleted **bold** text~~")};
+  EXPECT_EQ(result, "<p><del>deleted <strong>bold</strong> text</del></p>\n");
+}
+
+TEST(strikethrough_in_sentence) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("This is ~~wrong~~ correct")};
+  EXPECT_EQ(result, "<p>This is <del>wrong</del> correct</p>\n");
+}
+
+TEST(strikethrough_inside_table_cell) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| h |\n| - |\n| ~~old~~ |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
+                    "<tbody>\n<tr>\n<td><del>old</del></td>\n</tr>\n"
+                    "</tbody>\n</table>\n");
+}
+
+TEST(strikethrough_with_code) {
+  const auto result{sourcemeta::core::markdown_to_html("~~use `old_func()`~~")};
+  EXPECT_EQ(result, "<p><del>use <code>old_func()</code></del></p>\n");
+}
+
+TEST(strikethrough_with_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("~~[removed](https://example.com)~~")};
+  EXPECT_EQ(result,
+            "<p><del><a href=\"https://example.com\">removed</a></del></p>\n");
+}
+
+TEST(strikethrough_bold_italic_combined) {
+  const auto result{sourcemeta::core::markdown_to_html("~~***all three***~~")};
+  EXPECT_EQ(result, "<p><del><em><strong>all three</strong></em></del></p>\n");
+}
+
+TEST(single_tilde_is_not_strikethrough) {
+  const auto result{sourcemeta::core::markdown_to_html("~not deleted~")};
+  EXPECT_EQ(result, "<p>~not deleted~</p>\n");
+}
+
+TEST(strikethrough_spanning_lines) {
+  const auto result{sourcemeta::core::markdown_to_html("~~one\ntwo~~")};
+  EXPECT_EQ(result, "<p><del>one\n"
+                    "two</del></p>\n");
+}
+
+TEST(strikethrough_triple_tildes_inline) {
+  const auto result{sourcemeta::core::markdown_to_html("x ~~~y~~~ z")};
+  EXPECT_EQ(result, "<p>x ~~~y~~~ z</p>\n");
+}
+
+TEST(strikethrough_unclosed) {
+  const auto result{sourcemeta::core::markdown_to_html("x ~~y")};
+  EXPECT_EQ(result, "<p>x ~~y</p>\n");
+}
+
+TEST(strikethrough_with_surrounding_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html("x ~~ y ~~ z")};
+  EXPECT_EQ(result, "<p>x ~~ y ~~ z</p>\n");
+}
+
+TEST(strikethrough_and_emphasis_overlap) {
+  const auto result{sourcemeta::core::markdown_to_html("~~_x~~_")};
+  EXPECT_EQ(result, "<p><del>_x</del>_</p>\n");
+}
+
+TEST(strikethrough_escaped_closing) {
+  const auto result{sourcemeta::core::markdown_to_html("~~x\\~~")};
+  EXPECT_EQ(result, "<p>~~x~~</p>\n");
+}
+
+TEST(strikethrough_inside_link_text) {
+  const auto result{sourcemeta::core::markdown_to_html("[~~old~~ new](/x)")};
+  EXPECT_EQ(result, "<p><a href=\"/x\"><del>old</del> new</a></p>\n");
+}
diff --git a/test/markdown/markdown_tables_test.cc b/test/markdown/markdown_tables_test.cc
new file mode 100644
index 0000000000..920ed27a96
--- /dev/null
+++ b/test/markdown/markdown_tables_test.cc
@@ -0,0 +1,417 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(simple_table) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a | b |\n| - | - |\n| 1 | 2 |")};
+  EXPECT_EQ(
+      result,
+      "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</thead>\n"
+      "<tbody>\n<tr>\n<td>1</td>\n<td>2</td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(table_with_alignment) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| left | center | right |\n| :--- | :---: | ---: |\n| a | b | c |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n"
+                    "<th align=\"left\">left</th>\n"
+                    "<th align=\"center\">center</th>\n"
+                    "<th align=\"right\">right</th>\n"
+                    "</tr>\n</thead>\n<tbody>\n<tr>\n"
+                    "<td align=\"left\">a</td>\n"
+                    "<td align=\"center\">b</td>\n"
+                    "<td align=\"right\">c</td>\n"
+                    "</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(table_with_formatting_in_cells) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| h |\n| - |\n| **bold** |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
+                    "<tbody>\n<tr>\n<td><strong>bold</strong></td>\n</tr>\n"
+                    "</tbody>\n</table>\n");
+}
+
+TEST(table_with_multiple_rows) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| x | y |\n| - | - |\n| 1 | 2 |\n| 3 | 4 |\n| 5 | 6 |")};
+  EXPECT_EQ(result,
+            "<table>\n<thead>\n<tr>\n<th>x</th>\n<th>y</th>\n</tr>\n</thead>\n"
+            "<tbody>\n<tr>\n<td>1</td>\n<td>2</td>\n</tr>\n"
+            "<tr>\n<td>3</td>\n<td>4</td>\n</tr>\n"
+            "<tr>\n<td>5</td>\n<td>6</td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(table_with_pipe_in_cell) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| h |\n| - |\n| a \\| b |")};
+  EXPECT_EQ(result,
+            "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
+            "<tbody>\n<tr>\n<td>a | b</td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(link_inside_table_cell) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| h |\n| - |\n| [click](https://example.com) |")};
+  EXPECT_EQ(result,
+            "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
+            "<tbody>\n<tr>\n<td><a href=\"https://example.com\">click</a>"
+            "</td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(code_inside_table_cell) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| h |\n| - |\n| `code` |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
+                    "<tbody>\n<tr>\n<td><code>code</code></td>\n</tr>\n"
+                    "</tbody>\n</table>\n");
+}
+
+TEST(empty_table_cells) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a | b |\n| - | - |\n|   |   |")};
+  EXPECT_EQ(result,
+            "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</thead>\n"
+            "<tbody>\n<tr>\n<td></td>\n<td></td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(table_header_only) {
+  const auto result{sourcemeta::core::markdown_to_html("| a | b |\n| - | - |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</"
+                    "thead>\n</table>\n");
+}
+
+TEST(table_after_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "Here is a table:\n\n| a |\n| - |\n| 1 |")};
+  EXPECT_EQ(result, "<p>Here is a table:</p>\n"
+                    "<table>\n<thead>\n<tr>\n<th>a</th>\n</tr>\n</thead>\n"
+                    "<tbody>\n<tr>\n<td>1</td>\n</tr>\n</tbody>\n</table>\n");
+}
+
+TEST(table_with_inline_code_in_header) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| `key` | `value` |\n| - | - |\n| a | b |")};
+  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th><code>key</code></th>\n"
+                    "<th><code>value</code></th>\n</tr>\n</thead>\n"
+                    "<tbody>\n<tr>\n<td>a</td>\n<td>b</td>\n</tr>\n"
+                    "</tbody>\n</table>\n");
+}
+
+TEST(table_escaped_pipes_inside_inline_content) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| code |\n| ---- |\n| `a\\|b` |\n| _c\\|d_ |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>code</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td><code>a|b</code></td>\n"
+                    "</tr>\n"
+                    "<tr>\n"
+                    "<td><em>c|d</em></td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_ends_at_blank_line) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| a | b |\n|---|---|\n| 1 | 2 |\n\nafter")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "<th>b</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>1</td>\n"
+                    "<td>2</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(table_ends_at_blockquote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a |\n|---|\n| 1 |\n> quote")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>1</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n"
+                    "<blockquote>\n"
+                    "<p>quote</p>\n"
+                    "</blockquote>\n");
+}
+
+TEST(table_line_without_pipes_is_row) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a | b |\n|---|---|\ntext row")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "<th>b</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>text row</td>\n"
+                    "<td></td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_delimiter_count_mismatch_is_not_table) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a | b | c |\n| - | - |")};
+  EXPECT_EQ(result, "<p>| a | b | c |\n"
+                    "| - | - |</p>\n");
+}
+
+TEST(table_rows_with_fewer_and_more_cells) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| a | b |\n| - | - |\n| 1 |\n| 1 | 2 | 3 |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a</th>\n"
+                    "<th>b</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>1</td>\n"
+                    "<td></td>\n"
+                    "</tr>\n"
+                    "<tr>\n"
+                    "<td>1</td>\n"
+                    "<td>2</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_without_outer_pipes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x | y\n:-- | --:\n1 | 2")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th align=\"left\">x</th>\n"
+                    "<th align=\"right\">y</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td align=\"left\">1</td>\n"
+                    "<td align=\"right\">2</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_single_column_with_pipes) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| only |\n| :-: |\n| one |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th align=\"center\">only</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td align=\"center\">one</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_every_alignment) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| l | r | c | n |\n|:--|--:|:-:|---|\n| 1 | 2 | 3 | 4 |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th align=\"left\">l</th>\n"
+                    "<th align=\"right\">r</th>\n"
+                    "<th align=\"center\">c</th>\n"
+                    "<th>n</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td align=\"left\">1</td>\n"
+                    "<td align=\"right\">2</td>\n"
+                    "<td align=\"center\">3</td>\n"
+                    "<td>4</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_delimiter_row_with_surrounding_spaces) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x|y\n  --- |  :---:  ")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>x</th>\n"
+                    "<th align=\"center\">y</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "</table>\n");
+}
+
+TEST(table_header_cell_with_escaped_pipe) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| a \\| b | c |\n| - | - |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>a | b</th>\n"
+                    "<th>c</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "</table>\n");
+}
+
+TEST(table_cell_with_reference_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "| [manual] |\n| --- |\n\n[manual]: /manual")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th><a href=\"/manual\">manual</a></th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "</table>\n");
+}
+
+TEST(table_interrupts_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("intro\na | b\n- | -")};
+  EXPECT_EQ(result, "<p>intro\n"
+                    "a | b</p>\n"
+                    "<ul>\n"
+                    "<li>| -</li>\n"
+                    "</ul>\n");
+}
+
+TEST(table_inside_list_item) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* a | b\n  - | -\n  1 | 2")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>a | b\n"
+                    "<ul>\n"
+                    "<li>| -\n"
+                    "1 | 2</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
+
+TEST(table_inside_blockquote) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("> a | b\n> - | -\n> 1 | 2")};
+  EXPECT_EQ(result, "<blockquote>\n"
+                    "<p>a | b</p>\n"
+                    "<ul>\n"
+                    "<li>| -\n"
+                    "1 | 2</li>\n"
+                    "</ul>\n"
+                    "</blockquote>\n");
+}
+
+TEST(table_cell_with_entities) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| &lt;tag&gt; |\n| --- |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>&lt;tag&gt;</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "</table>\n");
+}
+
+TEST(table_empty_header_cells) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("|  |  |\n|--|--|\n| x | y |")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th></th>\n"
+                    "<th></th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>x</td>\n"
+                    "<td>y</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
+
+TEST(table_emphasis_does_not_span_cells) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| _a | b_ |\n|---|---|")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>_a</th>\n"
+                    "<th>b_</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "</table>\n");
+}
+
+TEST(table_invalid_delimiter_row_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("| a |\n| :-:x |")};
+  EXPECT_EQ(result, "<p>| a |\n"
+                    "| :-:x |</p>\n");
+}
+
+TEST(table_delimiter_count_mismatch_without_outer_pipes) {
+  const auto result{sourcemeta::core::markdown_to_html("x | y | z\n- | -")};
+  EXPECT_EQ(result, "<p>x | y | z</p>\n"
+                    "<ul>\n"
+                    "<li>| -</li>\n"
+                    "</ul>\n");
+}
+
+TEST(table_leading_pipe_without_trailing_pipe) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("| x | y\n|---|---\n| 1 | 2")};
+  EXPECT_EQ(result, "<table>\n"
+                    "<thead>\n"
+                    "<tr>\n"
+                    "<th>x</th>\n"
+                    "<th>y</th>\n"
+                    "</tr>\n"
+                    "</thead>\n"
+                    "<tbody>\n"
+                    "<tr>\n"
+                    "<td>1</td>\n"
+                    "<td>2</td>\n"
+                    "</tr>\n"
+                    "</tbody>\n"
+                    "</table>\n");
+}
diff --git a/test/markdown/markdown_task_lists_test.cc b/test/markdown/markdown_task_lists_test.cc
new file mode 100644
index 0000000000..026dc362d1
--- /dev/null
+++ b/test/markdown/markdown_task_lists_test.cc
@@ -0,0 +1,131 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(task_list_unchecked) {
+  const auto result{sourcemeta::core::markdown_to_html("- [ ] todo")};
+  EXPECT_EQ(result,
+            "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> todo</li>\n"
+            "</ul>\n");
+}
+
+TEST(task_list_checked) {
+  const auto result{sourcemeta::core::markdown_to_html("- [x] done")};
+  EXPECT_EQ(result,
+            "<ul>\n<li><input type=\"checkbox\" checked=\"\" disabled=\"\" />"
+            " done</li>\n</ul>\n");
+}
+
+TEST(task_list_mixed) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- [x] done\n- [ ] todo\n- [x] also done")};
+  EXPECT_EQ(
+      result,
+      "<ul>\n"
+      "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> done</li>\n"
+      "<li><input type=\"checkbox\" disabled=\"\" /> todo</li>\n"
+      "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> also "
+      "done</li>\n"
+      "</ul>\n");
+}
+
+TEST(task_list_with_bold) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- [ ] **important** task")};
+  EXPECT_EQ(result, "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> "
+                    "<strong>important</strong> task</li>\n</ul>\n");
+}
+
+TEST(task_list_with_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "- [x] see [docs](https://example.com)")};
+  EXPECT_EQ(result,
+            "<ul>\n<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> "
+            "see <a href=\"https://example.com\">docs</a></li>\n</ul>\n");
+}
+
+TEST(task_list_with_code) {
+  const auto result{sourcemeta::core::markdown_to_html("- [ ] fix `bug`")};
+  EXPECT_EQ(result, "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> "
+                    "fix <code>bug</code></li>\n</ul>\n");
+}
+
+TEST(task_list_uppercase_marker) {
+  const auto result{sourcemeta::core::markdown_to_html("* [X] finished")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" "
+                    "/> finished</li>\n"
+                    "</ul>\n");
+}
+
+TEST(task_list_marker_needs_following_space) {
+  const auto result{sourcemeta::core::markdown_to_html("* [ ]pending")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>[ ]pending</li>\n"
+                    "</ul>\n");
+}
+
+TEST(task_list_marker_with_other_character) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* [-] partial\n* [x] complete")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>[-] partial</li>\n"
+                    "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" "
+                    "/> complete</li>\n"
+                    "</ul>\n");
+}
+
+TEST(task_list_nested) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "* [ ] parent\n  * [x] child\n    * [ ] grandchild")};
+  EXPECT_EQ(result,
+            "<ul>\n"
+            "<li><input type=\"checkbox\" disabled=\"\" /> parent\n"
+            "<ul>\n"
+            "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> child\n"
+            "<ul>\n"
+            "<li><input type=\"checkbox\" disabled=\"\" /> grandchild</li>\n"
+            "</ul>\n"
+            "</li>\n"
+            "</ul>\n"
+            "</li>\n"
+            "</ul>\n");
+}
+
+TEST(task_list_in_ordered_list) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("1) [ ] first\n2) [X] second")};
+  EXPECT_EQ(
+      result,
+      "<ol>\n"
+      "<li><input type=\"checkbox\" disabled=\"\" /> first</li>\n"
+      "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> second</li>\n"
+      "</ol>\n");
+}
+
+TEST(task_list_marker_not_at_item_start) {
+  const auto result{sourcemeta::core::markdown_to_html("* text [ ] later")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>text [ ] later</li>\n"
+                    "</ul>\n");
+}
+
+TEST(task_list_marker_alone) {
+  const auto result{sourcemeta::core::markdown_to_html("* [x]")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>[x]</li>\n"
+                    "</ul>\n");
+}
+
+TEST(task_list_in_loose_list) {
+  const auto result{sourcemeta::core::markdown_to_html("* [x] a\n\n* [ ] b")};
+  EXPECT_EQ(result,
+            "<ul>\n"
+            "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> \n"
+            "<p>a</p>\n"
+            "</li>\n"
+            "<li><input type=\"checkbox\" disabled=\"\" /> \n"
+            "<p>b</p>\n"
+            "</li>\n"
+            "</ul>\n");
+}
diff --git a/test/markdown/markdown_test.cc b/test/markdown/markdown_test.cc
deleted file mode 100644
index ad16573f35..0000000000
--- a/test/markdown/markdown_test.cc
+++ /dev/null
@@ -1,989 +0,0 @@
-#include <sourcemeta/core/markdown.h>
-
-#include <sourcemeta/core/test.h>
-
-#include <cstddef> // std::size_t
-#include <string>  // std::string
-#include <thread>  // std::thread
-#include <vector>  // std::vector
-
-TEST(concurrent_calls) {
-  static constexpr std::size_t THREAD_COUNT{16};
-  std::vector<std::thread> threads;
-  threads.reserve(THREAD_COUNT);
-  std::vector<std::string> results(THREAD_COUNT);
-
-  for (std::size_t index{0}; index < THREAD_COUNT; ++index) {
-    threads.emplace_back([&results, index]() {
-      results[index] = sourcemeta::core::markdown_to_html("**hello** world");
-    });
-  }
-
-  for (auto &thread : threads) {
-    thread.join();
-  }
-
-  EXPECT_EQ(results[0], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[1], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[2], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[3], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[4], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[5], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[6], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[7], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[8], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[9], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[10], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[11], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[12], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[13], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[14], "<p><strong>hello</strong> world</p>\n");
-  EXPECT_EQ(results[15], "<p><strong>hello</strong> world</p>\n");
-}
-
-TEST(simple_paragraph) {
-  const auto result{sourcemeta::core::markdown_to_html("Hello world")};
-  EXPECT_EQ(result, "<p>Hello world</p>\n");
-}
-
-TEST(safe_mode_renders_plain_content) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("Hello **world**", true)};
-  EXPECT_EQ(result, "<p>Hello <strong>world</strong></p>\n");
-}
-
-TEST(safe_mode_omits_raw_html) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>", true)};
-  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
-}
-
-TEST(default_omits_raw_html) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>")};
-  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
-}
-
-TEST(unsafe_mode_passes_raw_html) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>", false)};
-  EXPECT_EQ(result, "<div onclick=\"x\">hi</div>\n");
-}
-
-TEST(default_strips_dangerous_link) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("[click](javascript:alert(1))")};
-  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
-}
-
-TEST(unsafe_mode_keeps_dangerous_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[click](javascript:alert(1))", false)};
-  EXPECT_EQ(result, "<p><a href=\"javascript:alert(1)\">click</a></p>\n");
-}
-
-TEST(multiple_paragraphs) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "First paragraph\n\nSecond paragraph")};
-  EXPECT_EQ(result, "<p>First paragraph</p>\n<p>Second paragraph</p>\n");
-}
-
-TEST(three_paragraphs) {
-  const auto result{sourcemeta::core::markdown_to_html("One\n\nTwo\n\nThree")};
-  EXPECT_EQ(result, "<p>One</p>\n<p>Two</p>\n<p>Three</p>\n");
-}
-
-TEST(empty_input) {
-  const auto result{sourcemeta::core::markdown_to_html("")};
-  EXPECT_TRUE(result.empty());
-}
-
-TEST(whitespace_only) {
-  const auto result{sourcemeta::core::markdown_to_html("   \n\n   ")};
-  EXPECT_TRUE(result.empty());
-}
-
-TEST(soft_line_break) {
-  const auto result{sourcemeta::core::markdown_to_html("line one\nline two")};
-  EXPECT_EQ(result, "<p>line one\nline two</p>\n");
-}
-
-TEST(hard_line_break_with_two_spaces) {
-  const auto result{sourcemeta::core::markdown_to_html("line one  \nline two")};
-  EXPECT_EQ(result, "<p>line one<br />\nline two</p>\n");
-}
-
-TEST(hard_line_break_with_backslash) {
-  const auto result{sourcemeta::core::markdown_to_html("line one\\\nline two")};
-  EXPECT_EQ(result, "<p>line one<br />\nline two</p>\n");
-}
-
-TEST(atx_heading_level_1) {
-  const auto result{sourcemeta::core::markdown_to_html("# Heading 1")};
-  EXPECT_EQ(result, "<h1>Heading 1</h1>\n");
-}
-
-TEST(atx_heading_level_2) {
-  const auto result{sourcemeta::core::markdown_to_html("## Heading 2")};
-  EXPECT_EQ(result, "<h2>Heading 2</h2>\n");
-}
-
-TEST(atx_heading_level_3) {
-  const auto result{sourcemeta::core::markdown_to_html("### Heading 3")};
-  EXPECT_EQ(result, "<h3>Heading 3</h3>\n");
-}
-
-TEST(atx_heading_level_4) {
-  const auto result{sourcemeta::core::markdown_to_html("#### Heading 4")};
-  EXPECT_EQ(result, "<h4>Heading 4</h4>\n");
-}
-
-TEST(atx_heading_level_5) {
-  const auto result{sourcemeta::core::markdown_to_html("##### Heading 5")};
-  EXPECT_EQ(result, "<h5>Heading 5</h5>\n");
-}
-
-TEST(atx_heading_level_6) {
-  const auto result{sourcemeta::core::markdown_to_html("###### Heading 6")};
-  EXPECT_EQ(result, "<h6>Heading 6</h6>\n");
-}
-
-TEST(atx_heading_with_closing_hashes) {
-  const auto result{sourcemeta::core::markdown_to_html("## Heading ##")};
-  EXPECT_EQ(result, "<h2>Heading</h2>\n");
-}
-
-TEST(setext_heading_level_1) {
-  const auto result{sourcemeta::core::markdown_to_html("Heading 1\n=========")};
-  EXPECT_EQ(result, "<h1>Heading 1</h1>\n");
-}
-
-TEST(setext_heading_level_2) {
-  const auto result{sourcemeta::core::markdown_to_html("Heading 2\n---------")};
-  EXPECT_EQ(result, "<h2>Heading 2</h2>\n");
-}
-
-TEST(italic_with_asterisks) {
-  const auto result{sourcemeta::core::markdown_to_html("*italic*")};
-  EXPECT_EQ(result, "<p><em>italic</em></p>\n");
-}
-
-TEST(italic_with_underscores) {
-  const auto result{sourcemeta::core::markdown_to_html("_italic_")};
-  EXPECT_EQ(result, "<p><em>italic</em></p>\n");
-}
-
-TEST(bold_with_asterisks) {
-  const auto result{sourcemeta::core::markdown_to_html("**bold**")};
-  EXPECT_EQ(result, "<p><strong>bold</strong></p>\n");
-}
-
-TEST(bold_with_underscores) {
-  const auto result{sourcemeta::core::markdown_to_html("__bold__")};
-  EXPECT_EQ(result, "<p><strong>bold</strong></p>\n");
-}
-
-TEST(bold_and_italic) {
-  const auto result{sourcemeta::core::markdown_to_html("***bold italic***")};
-  EXPECT_EQ(result, "<p><em><strong>bold italic</strong></em></p>\n");
-}
-
-TEST(bold_inside_italic) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("*this is **bold** inside italic*")};
-  EXPECT_EQ(result,
-            "<p><em>this is <strong>bold</strong> inside italic</em></p>\n");
-}
-
-TEST(italic_inside_bold) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("**this is *italic* inside bold**")};
-  EXPECT_EQ(result,
-            "<p><strong>this is <em>italic</em> inside bold</strong></p>\n");
-}
-
-TEST(inline_code) {
-  const auto result{sourcemeta::core::markdown_to_html("Use `printf()`")};
-  EXPECT_EQ(result, "<p>Use <code>printf()</code></p>\n");
-}
-
-TEST(inline_code_with_backticks_inside) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("`` there is a ` here ``")};
-  EXPECT_EQ(result, "<p><code>there is a ` here</code></p>\n");
-}
-
-TEST(inline_code_preserves_html) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("`<div class=\"foo\">`")};
-  EXPECT_EQ(result, "<p><code>&lt;div class=&quot;foo&quot;&gt;</code></p>\n");
-}
-
-TEST(fenced_code_block_backticks) {
-  const auto result{sourcemeta::core::markdown_to_html("```\ncode here\n```")};
-  EXPECT_EQ(result, "<pre><code>code here\n</code></pre>\n");
-}
-
-TEST(fenced_code_block_tildes) {
-  const auto result{sourcemeta::core::markdown_to_html("~~~\ncode here\n~~~")};
-  EXPECT_EQ(result, "<pre><code>code here\n</code></pre>\n");
-}
-
-TEST(fenced_code_block_with_language) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("```cpp\nint x = 0;\n```")};
-  EXPECT_EQ(result, "<pre lang=\"cpp\"><code>int x = 0;\n</code></pre>\n");
-}
-
-TEST(fenced_code_block_html_escaped) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("```\n<div>&amp;</div>\n```")};
-  EXPECT_EQ(result,
-            "<pre><code>&lt;div&gt;&amp;amp;&lt;/div&gt;\n</code></pre>\n");
-}
-
-TEST(indented_code_block) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("    int x = 0;\n    return x;")};
-  EXPECT_EQ(result, "<pre><code>int x = 0;\nreturn x;\n</code></pre>\n");
-}
-
-TEST(inline_link) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("[click here](https://example.com)")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\">click here</a></p>\n");
-}
-
-TEST(inline_link_with_title) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[click](https://example.com \"My Title\")")};
-  EXPECT_EQ(
-      result,
-      "<p><a href=\"https://example.com\" title=\"My Title\">click</a></p>\n");
-}
-
-TEST(reference_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[click][ref]\n\n[ref]: https://example.com")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\">click</a></p>\n");
-}
-
-TEST(reference_link_with_title) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[click][ref]\n\n[ref]: https://example.com \"Title\"")};
-  EXPECT_EQ(
-      result,
-      "<p><a href=\"https://example.com\" title=\"Title\">click</a></p>\n");
-}
-
-TEST(collapsed_reference_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[example][]\n\n[example]: https://example.com")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\">example</a></p>\n");
-}
-
-TEST(shortcut_reference_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[example]\n\n[example]: https://example.com")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\">example</a></p>\n");
-}
-
-TEST(link_with_emphasis_inside) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[**bold link**](https://example.com)")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\"><strong>bold "
-                    "link</strong></a></p>\n");
-}
-
-TEST(image) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("![alt text](image.png)")};
-  EXPECT_EQ(result, "<p><img src=\"image.png\" alt=\"alt text\" /></p>\n");
-}
-
-TEST(image_with_title) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("![alt](image.png \"My Image\")")};
-  EXPECT_EQ(
-      result,
-      "<p><img src=\"image.png\" alt=\"alt\" title=\"My Image\" /></p>\n");
-}
-
-TEST(simple_blockquote) {
-  const auto result{sourcemeta::core::markdown_to_html("> quoted text")};
-  EXPECT_EQ(result, "<blockquote>\n<p>quoted text</p>\n</blockquote>\n");
-}
-
-TEST(multiline_blockquote) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("> line one\n> line two")};
-  EXPECT_EQ(result, "<blockquote>\n<p>line one\nline two</p>\n</blockquote>\n");
-}
-
-TEST(nested_blockquote) {
-  const auto result{sourcemeta::core::markdown_to_html("> outer\n>> inner")};
-  EXPECT_EQ(result, "<blockquote>\n<p>outer</p>\n<blockquote>\n<p>inner</p>\n"
-                    "</blockquote>\n</blockquote>\n");
-}
-
-TEST(blockquote_with_formatting) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("> **bold** and *italic*")};
-  EXPECT_EQ(result,
-            "<blockquote>\n<p><strong>bold</strong> and <em>italic</em></p>\n"
-            "</blockquote>\n");
-}
-
-TEST(unordered_list_with_dashes) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("- one\n- two\n- three")};
-  EXPECT_EQ(result,
-            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
-}
-
-TEST(unordered_list_with_asterisks) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("* one\n* two\n* three")};
-  EXPECT_EQ(result,
-            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
-}
-
-TEST(unordered_list_with_plus) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("+ one\n+ two\n+ three")};
-  EXPECT_EQ(result,
-            "<ul>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ul>\n");
-}
-
-TEST(nested_unordered_list) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- outer\n  - inner\n  - inner2\n- outer2")};
-  EXPECT_EQ(result, "<ul>\n<li>outer\n<ul>\n<li>inner</li>\n<li>inner2</li>\n"
-                    "</ul>\n</li>\n<li>outer2</li>\n</ul>\n");
-}
-
-TEST(ordered_list) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("1. one\n2. two\n3. three")};
-  EXPECT_EQ(result,
-            "<ol>\n<li>one</li>\n<li>two</li>\n<li>three</li>\n</ol>\n");
-}
-
-TEST(ordered_list_starting_at_nonone) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("3. three\n4. four\n5. five")};
-  EXPECT_EQ(result,
-            "<ol start=\"3\">\n<li>three</li>\n<li>four</li>\n<li>five</li>\n"
-            "</ol>\n");
-}
-
-TEST(nested_ordered_in_unordered) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- item\n  1. sub one\n  2. sub two\n- item2")};
-  EXPECT_EQ(result, "<ul>\n<li>item\n<ol>\n<li>sub one</li>\n<li>sub two</li>\n"
-                    "</ol>\n</li>\n<li>item2</li>\n</ul>\n");
-}
-
-TEST(loose_list) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("- one\n\n- two\n\n- three")};
-  EXPECT_EQ(result, "<ul>\n<li>\n<p>one</p>\n</li>\n<li>\n<p>two</p>\n</li>\n"
-                    "<li>\n<p>three</p>\n</li>\n</ul>\n");
-}
-
-TEST(thematic_break_with_dashes) {
-  const auto result{sourcemeta::core::markdown_to_html("---")};
-  EXPECT_EQ(result, "<hr />\n");
-}
-
-TEST(thematic_break_with_asterisks) {
-  const auto result{sourcemeta::core::markdown_to_html("***")};
-  EXPECT_EQ(result, "<hr />\n");
-}
-
-TEST(thematic_break_with_underscores) {
-  const auto result{sourcemeta::core::markdown_to_html("___")};
-  EXPECT_EQ(result, "<hr />\n");
-}
-
-TEST(thematic_break_with_spaces) {
-  const auto result{sourcemeta::core::markdown_to_html("- - -")};
-  EXPECT_EQ(result, "<hr />\n");
-}
-
-TEST(escape_asterisk) {
-  const auto result{sourcemeta::core::markdown_to_html("\\*not italic\\*")};
-  EXPECT_EQ(result, "<p>*not italic*</p>\n");
-}
-
-TEST(escape_hash) {
-  const auto result{sourcemeta::core::markdown_to_html("\\# not a heading")};
-  EXPECT_EQ(result, "<p># not a heading</p>\n");
-}
-
-TEST(escape_brackets) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("\\[not a link\\](url)")};
-  EXPECT_EQ(result, "<p>[not a link](url)</p>\n");
-}
-
-TEST(escape_backtick) {
-  const auto result{sourcemeta::core::markdown_to_html("\\`not code\\`")};
-  EXPECT_EQ(result, "<p>`not code`</p>\n");
-}
-
-TEST(html_entity_named) {
-  const auto result{sourcemeta::core::markdown_to_html("&copy; 2025")};
-  EXPECT_EQ(result, "<p>\xC2\xA9 2025</p>\n");
-}
-
-TEST(html_entity_numeric) {
-  const auto result{sourcemeta::core::markdown_to_html("&#169; 2025")};
-  EXPECT_EQ(result, "<p>\xC2\xA9 2025</p>\n");
-}
-
-TEST(ampersand_in_text) {
-  const auto result{sourcemeta::core::markdown_to_html("AT&T")};
-  EXPECT_EQ(result, "<p>AT&amp;T</p>\n");
-}
-
-TEST(angle_brackets_in_text) {
-  const auto result{sourcemeta::core::markdown_to_html("1 < 2 and 3 > 2")};
-  EXPECT_EQ(result, "<p>1 &lt; 2 and 3 &gt; 2</p>\n");
-}
-
-TEST(unicode_content) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("Hello \xC3\xA9\xC3\xA0\xC3\xBC")};
-  EXPECT_EQ(result, "<p>Hello \xC3\xA9\xC3\xA0\xC3\xBC</p>\n");
-}
-
-TEST(cjk_characters) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("\xE4\xBD\xA0\xE5\xA5\xBD")};
-  EXPECT_EQ(result, "<p>\xE4\xBD\xA0\xE5\xA5\xBD</p>\n");
-}
-
-TEST(emoji) {
-  const auto result{sourcemeta::core::markdown_to_html("\xF0\x9F\x98\x80")};
-  EXPECT_EQ(result, "<p>\xF0\x9F\x98\x80</p>\n");
-}
-
-TEST(inline_html_is_sanitized) {
-  const auto result{sourcemeta::core::markdown_to_html("Hello <em>world</em>")};
-  EXPECT_EQ(
-      result,
-      "<p>Hello <!-- raw HTML omitted -->world<!-- raw HTML omitted --></p>\n");
-}
-
-TEST(raw_html_block_is_sanitized) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<div class=\"foo\">bar</div>")};
-  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
-}
-
-TEST(script_tag_is_sanitized) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<script>alert('xss')</script>")};
-  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
-}
-
-TEST(iframe_is_sanitized) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "<iframe src=\"https://evil.com\"></iframe>")};
-  EXPECT_EQ(result, "<!-- raw HTML omitted -->\n");
-}
-
-TEST(javascript_link_is_sanitized) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("[click](javascript:alert('xss'))")};
-  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
-}
-
-TEST(simple_table) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| a | b |\n| - | - |\n| 1 | 2 |")};
-  EXPECT_EQ(
-      result,
-      "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</thead>\n"
-      "<tbody>\n<tr>\n<td>1</td>\n<td>2</td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(table_with_alignment) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "| left | center | right |\n| :--- | :---: | ---: |\n| a | b | c |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n"
-                    "<th align=\"left\">left</th>\n"
-                    "<th align=\"center\">center</th>\n"
-                    "<th align=\"right\">right</th>\n"
-                    "</tr>\n</thead>\n<tbody>\n<tr>\n"
-                    "<td align=\"left\">a</td>\n"
-                    "<td align=\"center\">b</td>\n"
-                    "<td align=\"right\">c</td>\n"
-                    "</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(table_with_formatting_in_cells) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| h |\n| - |\n| **bold** |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
-                    "<tbody>\n<tr>\n<td><strong>bold</strong></td>\n</tr>\n"
-                    "</tbody>\n</table>\n");
-}
-
-TEST(table_with_multiple_rows) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "| x | y |\n| - | - |\n| 1 | 2 |\n| 3 | 4 |\n| 5 | 6 |")};
-  EXPECT_EQ(result,
-            "<table>\n<thead>\n<tr>\n<th>x</th>\n<th>y</th>\n</tr>\n</thead>\n"
-            "<tbody>\n<tr>\n<td>1</td>\n<td>2</td>\n</tr>\n"
-            "<tr>\n<td>3</td>\n<td>4</td>\n</tr>\n"
-            "<tr>\n<td>5</td>\n<td>6</td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(table_with_pipe_in_cell) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| h |\n| - |\n| a \\| b |")};
-  EXPECT_EQ(result,
-            "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
-            "<tbody>\n<tr>\n<td>a | b</td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(autolink_url) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("Visit https://example.com today")};
-  EXPECT_EQ(result,
-            "<p>Visit <a href=\"https://example.com\">https://example.com</a>"
-            " today</p>\n");
-}
-
-TEST(autolink_http) {
-  const auto result{sourcemeta::core::markdown_to_html("http://example.com")};
-  EXPECT_EQ(result,
-            "<p><a href=\"http://example.com\">http://example.com</a></p>\n");
-}
-
-TEST(autolink_www) {
-  const auto result{sourcemeta::core::markdown_to_html("www.example.com")};
-  EXPECT_EQ(result,
-            "<p><a href=\"http://www.example.com\">www.example.com</a></p>\n");
-}
-
-TEST(autolink_email) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("Contact user@example.com")};
-  EXPECT_EQ(result, "<p>Contact <a href=\"mailto:user@example.com\">"
-                    "user@example.com</a></p>\n");
-}
-
-TEST(angle_bracket_autolink) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("<https://example.com>")};
-  EXPECT_EQ(result,
-            "<p><a href=\"https://example.com\">https://example.com</a></p>\n");
-}
-
-TEST(strikethrough) {
-  const auto result{sourcemeta::core::markdown_to_html("~~deleted~~")};
-  EXPECT_EQ(result, "<p><del>deleted</del></p>\n");
-}
-
-TEST(strikethrough_with_other_formatting) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("~~deleted **bold** text~~")};
-  EXPECT_EQ(result, "<p><del>deleted <strong>bold</strong> text</del></p>\n");
-}
-
-TEST(strikethrough_in_sentence) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("This is ~~wrong~~ correct")};
-  EXPECT_EQ(result, "<p>This is <del>wrong</del> correct</p>\n");
-}
-
-TEST(task_list_unchecked) {
-  const auto result{sourcemeta::core::markdown_to_html("- [ ] todo")};
-  EXPECT_EQ(result,
-            "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> todo</li>\n"
-            "</ul>\n");
-}
-
-TEST(task_list_checked) {
-  const auto result{sourcemeta::core::markdown_to_html("- [x] done")};
-  EXPECT_EQ(result,
-            "<ul>\n<li><input type=\"checkbox\" checked=\"\" disabled=\"\" />"
-            " done</li>\n</ul>\n");
-}
-
-TEST(task_list_mixed) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- [x] done\n- [ ] todo\n- [x] also done")};
-  EXPECT_EQ(
-      result,
-      "<ul>\n"
-      "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> done</li>\n"
-      "<li><input type=\"checkbox\" disabled=\"\" /> todo</li>\n"
-      "<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> also "
-      "done</li>\n"
-      "</ul>\n");
-}
-
-TEST(heading_followed_by_paragraph) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("# Title\n\nSome text here.")};
-  EXPECT_EQ(result, "<h1>Title</h1>\n<p>Some text here.</p>\n");
-}
-
-TEST(blockquote_with_list) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("> items:\n> - one\n> - two")};
-  EXPECT_EQ(result,
-            "<blockquote>\n<p>items:</p>\n<ul>\n<li>one</li>\n<li>two</li>\n"
-            "</ul>\n</blockquote>\n");
-}
-
-TEST(list_with_code_block) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- item:\n\n  ```\n  code\n  ```\n\n- next")};
-  EXPECT_EQ(result, "<ul>\n<li>\n<p>item:</p>\n<pre><code>code\n</code></pre>\n"
-                    "</li>\n<li>\n<p>next</p>\n</li>\n</ul>\n");
-}
-
-TEST(link_inside_heading) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("## [Link](https://example.com)")};
-  EXPECT_EQ(result, "<h2><a href=\"https://example.com\">Link</a></h2>\n");
-}
-
-TEST(emphasis_across_words) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("this is **all bold** here")};
-  EXPECT_EQ(result, "<p>this is <strong>all bold</strong> here</p>\n");
-}
-
-TEST(paragraph_with_inline_code_and_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "Use `foo()` from [the docs](https://docs.com).")};
-  EXPECT_EQ(result, "<p>Use <code>foo()</code> from "
-                    "<a href=\"https://docs.com\">the docs</a>.</p>\n");
-}
-
-TEST(strikethrough_inside_table_cell) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| h |\n| - |\n| ~~old~~ |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
-                    "<tbody>\n<tr>\n<td><del>old</del></td>\n</tr>\n"
-                    "</tbody>\n</table>\n");
-}
-
-TEST(link_inside_table_cell) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "| h |\n| - |\n| [click](https://example.com) |")};
-  EXPECT_EQ(result,
-            "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
-            "<tbody>\n<tr>\n<td><a href=\"https://example.com\">click</a>"
-            "</td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(code_inside_table_cell) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| h |\n| - |\n| `code` |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>h</th>\n</tr>\n</thead>\n"
-                    "<tbody>\n<tr>\n<td><code>code</code></td>\n</tr>\n"
-                    "</tbody>\n</table>\n");
-}
-
-TEST(empty_table_cells) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("| a | b |\n| - | - |\n|   |   |")};
-  EXPECT_EQ(result,
-            "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</thead>\n"
-            "<tbody>\n<tr>\n<td></td>\n<td></td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(table_header_only) {
-  const auto result{sourcemeta::core::markdown_to_html("| a | b |\n| - | - |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</"
-                    "thead>\n</table>\n");
-}
-
-TEST(task_list_with_bold) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("- [ ] **important** task")};
-  EXPECT_EQ(result, "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> "
-                    "<strong>important</strong> task</li>\n</ul>\n");
-}
-
-TEST(task_list_with_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- [x] see [docs](https://example.com)")};
-  EXPECT_EQ(result,
-            "<ul>\n<li><input type=\"checkbox\" checked=\"\" disabled=\"\" /> "
-            "see <a href=\"https://example.com\">docs</a></li>\n</ul>\n");
-}
-
-TEST(task_list_with_code) {
-  const auto result{sourcemeta::core::markdown_to_html("- [ ] fix `bug`")};
-  EXPECT_EQ(result, "<ul>\n<li><input type=\"checkbox\" disabled=\"\" /> "
-                    "fix <code>bug</code></li>\n</ul>\n");
-}
-
-TEST(code_inside_link) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("[`code`](https://example.com)")};
-  EXPECT_EQ(result,
-            "<p><a href=\"https://example.com\"><code>code</code></a></p>\n");
-}
-
-TEST(inline_code_inside_heading) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("## The `main` function")};
-  EXPECT_EQ(result, "<h2>The <code>main</code> function</h2>\n");
-}
-
-TEST(image_as_link) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[![logo](logo.png)](https://example.com)")};
-  EXPECT_EQ(result, "<p><a href=\"https://example.com\">"
-                    "<img src=\"logo.png\" alt=\"logo\" /></a></p>\n");
-}
-
-TEST(strikethrough_with_code) {
-  const auto result{sourcemeta::core::markdown_to_html("~~use `old_func()`~~")};
-  EXPECT_EQ(result, "<p><del>use <code>old_func()</code></del></p>\n");
-}
-
-TEST(strikethrough_with_link) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("~~[removed](https://example.com)~~")};
-  EXPECT_EQ(result,
-            "<p><del><a href=\"https://example.com\">removed</a></del></p>\n");
-}
-
-TEST(autolink_inside_list) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- visit https://example.com\n- done")};
-  EXPECT_EQ(result, "<ul>\n<li>visit <a href=\"https://example.com\">"
-                    "https://example.com</a></li>\n<li>done</li>\n</ul>\n");
-}
-
-TEST(blockquote_with_code_block) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("> example:\n>\n>     code here")};
-  EXPECT_EQ(result, "<blockquote>\n<p>example:</p>\n"
-                    "<pre><code>code here\n</code></pre>\n</blockquote>\n");
-}
-
-TEST(blockquote_with_heading) {
-  const auto result{sourcemeta::core::markdown_to_html("> ## Quoted heading")};
-  EXPECT_EQ(result, "<blockquote>\n<h2>Quoted heading</h2>\n</blockquote>\n");
-}
-
-TEST(deeply_nested_list) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("- a\n  - b\n    - c\n      - d")};
-  EXPECT_EQ(result, "<ul>\n<li>a\n<ul>\n<li>b\n<ul>\n<li>c\n<ul>\n<li>d</li>\n"
-                    "</ul>\n</li>\n</ul>\n</li>\n</ul>\n</li>\n</ul>\n");
-}
-
-TEST(deeply_nested_blockquote) {
-  const auto result{sourcemeta::core::markdown_to_html("> a\n>> b\n>>> c")};
-  EXPECT_EQ(result, "<blockquote>\n<p>a</p>\n<blockquote>\n<p>b</p>\n"
-                    "<blockquote>\n<p>c</p>\n</blockquote>\n</blockquote>\n"
-                    "</blockquote>\n");
-}
-
-TEST(consecutive_headings) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("# One\n\n## Two\n\n### Three")};
-  EXPECT_EQ(result, "<h1>One</h1>\n<h2>Two</h2>\n<h3>Three</h3>\n");
-}
-
-TEST(consecutive_thematic_breaks) {
-  const auto result{sourcemeta::core::markdown_to_html("---\n\n---")};
-  EXPECT_EQ(result, "<hr />\n<hr />\n");
-}
-
-TEST(link_with_special_chars_in_url) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[search](https://example.com/q?a=1&b=2)")};
-  EXPECT_EQ(
-      result,
-      "<p><a href=\"https://example.com/q?a=1&amp;b=2\">search</a></p>\n");
-}
-
-TEST(image_with_empty_alt) {
-  const auto result{sourcemeta::core::markdown_to_html("![](image.png)")};
-  EXPECT_EQ(result, "<p><img src=\"image.png\" alt=\"\" /></p>\n");
-}
-
-TEST(bold_and_italic_in_list_item) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("- ***bold italic item***\n- normal")};
-  EXPECT_EQ(result,
-            "<ul>\n<li><em><strong>bold italic item</strong></em></li>\n"
-            "<li>normal</li>\n</ul>\n");
-}
-
-TEST(fenced_code_block_with_empty_lines) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("```\nline one\n\nline three\n```")};
-  EXPECT_EQ(result, "<pre><code>line one\n\nline three\n</code></pre>\n");
-}
-
-TEST(ordered_list_with_paragraphs) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "1. first\n\n   more text\n\n2. second")};
-  EXPECT_EQ(result, "<ol>\n<li>\n<p>first</p>\n<p>more text</p>\n</li>\n"
-                    "<li>\n<p>second</p>\n</li>\n</ol>\n");
-}
-
-TEST(heading_with_thematic_break) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("# Title\n\n---\n\nContent")};
-  EXPECT_EQ(result, "<h1>Title</h1>\n<hr />\n<p>Content</p>\n");
-}
-
-TEST(table_after_paragraph) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "Here is a table:\n\n| a |\n| - |\n| 1 |")};
-  EXPECT_EQ(result, "<p>Here is a table:</p>\n"
-                    "<table>\n<thead>\n<tr>\n<th>a</th>\n</tr>\n</thead>\n"
-                    "<tbody>\n<tr>\n<td>1</td>\n</tr>\n</tbody>\n</table>\n");
-}
-
-TEST(blockquote_followed_by_list) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("> quote\n\n- item one\n- item two")};
-  EXPECT_EQ(result, "<blockquote>\n<p>quote</p>\n</blockquote>\n"
-                    "<ul>\n<li>item one</li>\n<li>item two</li>\n</ul>\n");
-}
-
-TEST(multiple_autolinks_in_paragraph) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "See https://one.com and https://two.com")};
-  EXPECT_EQ(result,
-            "<p>See <a href=\"https://one.com\">https://one.com</a> and "
-            "<a href=\"https://two.com\">https://two.com</a></p>\n");
-}
-
-TEST(emphasis_does_not_cross_code_span) {
-  const auto result{sourcemeta::core::markdown_to_html("*start `code* end`")};
-  EXPECT_EQ(result, "<p>*start <code>code* end</code></p>\n");
-}
-
-TEST(vbscript_link_is_sanitized) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("[click](vbscript:MsgBox)")};
-  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
-}
-
-TEST(data_uri_link_is_sanitized) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "[click](data:text/html,<h1>hi</h1>)")};
-  EXPECT_EQ(result, "<p><a href=\"\">click</a></p>\n");
-}
-
-TEST(single_character_emphasis) {
-  const auto result{sourcemeta::core::markdown_to_html("*a*")};
-  EXPECT_EQ(result, "<p><em>a</em></p>\n");
-}
-
-TEST(list_item_with_multiple_paragraphs) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "- paragraph one\n\n  paragraph two\n\n  paragraph three")};
-  EXPECT_EQ(result, "<ul>\n<li>\n<p>paragraph one</p>\n<p>paragraph two</p>\n"
-                    "<p>paragraph three</p>\n</li>\n</ul>\n");
-}
-
-TEST(table_with_inline_code_in_header) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "| `key` | `value` |\n| - | - |\n| a | b |")};
-  EXPECT_EQ(result, "<table>\n<thead>\n<tr>\n<th><code>key</code></th>\n"
-                    "<th><code>value</code></th>\n</tr>\n</thead>\n"
-                    "<tbody>\n<tr>\n<td>a</td>\n<td>b</td>\n</tr>\n"
-                    "</tbody>\n</table>\n");
-}
-
-TEST(strikethrough_bold_italic_combined) {
-  const auto result{sourcemeta::core::markdown_to_html("~~***all three***~~")};
-  EXPECT_EQ(result, "<p><del><em><strong>all three</strong></em></del></p>\n");
-}
-
-TEST(autolink_with_trailing_punctuation) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("See https://example.com.")};
-  EXPECT_EQ(
-      result,
-      "<p>See <a href=\"https://example.com\">https://example.com</a>.</p>\n");
-}
-
-TEST(autolink_in_parentheses) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("(see https://example.com)")};
-  EXPECT_EQ(
-      result,
-      "<p>(see <a href=\"https://example.com\">https://example.com</a>)</p>\n");
-}
-
-TEST(blockquote_with_strikethrough) {
-  const auto result{sourcemeta::core::markdown_to_html("> ~~deleted~~")};
-  EXPECT_EQ(result, "<blockquote>\n<p><del>deleted</del></p>\n</blockquote>\n");
-}
-
-TEST(heading_with_bold_and_code) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("## **Bold** and `code`")};
-  EXPECT_EQ(result, "<h2><strong>Bold</strong> and <code>code</code></h2>\n");
-}
-
-TEST(footnote_basic) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("Text[^1]\n\n[^1]: Footnote content")};
-  EXPECT_EQ(
-      result,
-      "<p>Text<sup class=\"footnote-ref\"><a href=\"#fn-1\" id=\"fnref-1\""
-      " data-footnote-ref>1</a></sup></p>\n"
-      "<section class=\"footnotes\" data-footnotes>\n<ol>\n"
-      "<li id=\"fn-1\">\n<p>Footnote content "
-      "<a href=\"#fnref-1\" class=\"footnote-backref\""
-      " data-footnote-backref data-footnote-backref-idx=\"1\""
-      " aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
-      "</li>\n</ol>\n</section>\n");
-}
-
-TEST(footnote_multiple) {
-  const auto result{sourcemeta::core::markdown_to_html(
-      "A[^1] and B[^2]\n\n[^1]: First\n\n[^2]: Second")};
-  EXPECT_EQ(result,
-            "<p>A<sup class=\"footnote-ref\"><a href=\"#fn-1\" id=\"fnref-1\""
-            " data-footnote-ref>1</a></sup> and "
-            "B<sup class=\"footnote-ref\"><a href=\"#fn-2\" id=\"fnref-2\""
-            " data-footnote-ref>2</a></sup></p>\n"
-            "<section class=\"footnotes\" data-footnotes>\n<ol>\n"
-            "<li id=\"fn-1\">\n<p>First "
-            "<a href=\"#fnref-1\" class=\"footnote-backref\""
-            " data-footnote-backref data-footnote-backref-idx=\"1\""
-            " aria-label=\"Back to reference 1\">\xe2\x86\xa9</a></p>\n"
-            "</li>\n"
-            "<li id=\"fn-2\">\n<p>Second "
-            "<a href=\"#fnref-2\" class=\"footnote-backref\""
-            " data-footnote-backref data-footnote-backref-idx=\"2\""
-            " aria-label=\"Back to reference 2\">\xe2\x86\xa9</a></p>\n"
-            "</li>\n</ol>\n</section>\n");
-}
-
-TEST(single_tilde_is_not_strikethrough) {
-  const auto result{sourcemeta::core::markdown_to_html("~not deleted~")};
-  EXPECT_EQ(result, "<p>~not deleted~</p>\n");
-}
-
-TEST(github_pre_lang_format) {
-  const auto result{
-      sourcemeta::core::markdown_to_html("```python\nprint()\n```")};
-  EXPECT_EQ(result, "<pre lang=\"python\"><code>print()\n</code></pre>\n");
-}
-
-TEST(invalid_utf8_is_replaced) {
-  const auto result{sourcemeta::core::markdown_to_html("hello \xFF world")};
-  EXPECT_EQ(result, "<p>hello \xEF\xBF\xBD world</p>\n");
-}
diff --git a/test/markdown/markdown_thematic_breaks_test.cc b/test/markdown/markdown_thematic_breaks_test.cc
new file mode 100644
index 0000000000..45c31cc640
--- /dev/null
+++ b/test/markdown/markdown_thematic_breaks_test.cc
@@ -0,0 +1,131 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+TEST(thematic_break_with_dashes) {
+  const auto result{sourcemeta::core::markdown_to_html("---")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_with_asterisks) {
+  const auto result{sourcemeta::core::markdown_to_html("***")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_with_underscores) {
+  const auto result{sourcemeta::core::markdown_to_html("___")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_with_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("- - -")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(consecutive_thematic_breaks) {
+  const auto result{sourcemeta::core::markdown_to_html("---\n\n---")};
+  EXPECT_EQ(result, "<hr />\n<hr />\n");
+}
+
+TEST(thematic_break_with_trailing_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html("***\t  ")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_plus_signs_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("++++")};
+  EXPECT_EQ(result, "<p>++++</p>\n");
+}
+
+TEST(thematic_break_equals_signs_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("= = = =")};
+  EXPECT_EQ(result, "<p>= = = =</p>\n");
+}
+
+TEST(thematic_break_two_characters_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("**\n\n__")};
+  EXPECT_EQ(result, "<p>**</p>\n"
+                    "<p>__</p>\n");
+}
+
+TEST(thematic_break_indented_one_to_three_spaces) {
+  const auto result{sourcemeta::core::markdown_to_html("   ___\n  ---\n ***")};
+  EXPECT_EQ(result, "<hr />\n"
+                    "<hr />\n"
+                    "<hr />\n");
+}
+
+TEST(thematic_break_indented_four_spaces_is_code) {
+  const auto result{sourcemeta::core::markdown_to_html("    ---")};
+  EXPECT_EQ(result, "<pre><code>---\n"
+                    "</code></pre>\n");
+}
+
+TEST(thematic_break_indented_four_spaces_continues_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Paragraph text\n    ___")};
+  EXPECT_EQ(result, "<p>Paragraph text\n"
+                    "___</p>\n");
+}
+
+TEST(thematic_break_many_characters) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "-------------------------------------------------")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_spaces_between_characters) {
+  const auto result{sourcemeta::core::markdown_to_html("* * * *")};
+  EXPECT_EQ(result, "<hr />\n");
+}
+
+TEST(thematic_break_with_other_characters_is_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("- - - x\n\nx______\n\n***x***")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<ul>\n"
+                    "<li>\n"
+                    "<ul>\n"
+                    "<li>x</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "</li>\n"
+                    "</ul>\n"
+                    "<p>x______</p>\n"
+                    "<p><em><strong>x</strong></em></p>\n");
+}
+
+TEST(thematic_break_mixed_characters_is_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("-*-")};
+  EXPECT_EQ(result, "<p>-*-</p>\n");
+}
+
+TEST(thematic_break_interrupts_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html("alpha\n___\nbeta")};
+  EXPECT_EQ(result, "<p>alpha</p>\n"
+                    "<hr />\n"
+                    "<p>beta</p>\n");
+}
+
+TEST(thematic_break_takes_precedence_over_list_item) {
+  const auto result{sourcemeta::core::markdown_to_html("- one\n- - -\n- two")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "<hr />\n"
+                    "<ul>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(thematic_break_inside_list_item) {
+  const auto result{sourcemeta::core::markdown_to_html("* one\n* - - -")};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "<li>\n"
+                    "<hr />\n"
+                    "</li>\n"
+                    "</ul>\n");
+}
diff --git a/test/markdown/markdown_unsafe_test.cc b/test/markdown/markdown_unsafe_test.cc
new file mode 100644
index 0000000000..39c94ae604
--- /dev/null
+++ b/test/markdown/markdown_unsafe_test.cc
@@ -0,0 +1,345 @@
+#include <sourcemeta/core/markdown.h>
+
+#include <sourcemeta/core/test.h>
+
+#include <string_view> // std::string_view
+
+using namespace std::literals::string_view_literals;
+
+TEST(html_block_script_with_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<script type=\"module\">\n\nconst x = 1;\n\n</script>\nafter", false)};
+  EXPECT_EQ(result, "&lt;script type=\"module\">\n"
+                    "\n"
+                    "const x = 1;\n"
+                    "\n"
+                    "&lt;/script>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_pre_keeps_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<pre>\nline one\n\n*not emphasis*\n</pre>\nafter", false)};
+  EXPECT_EQ(result, "<pre>\n"
+                    "line one\n"
+                    "\n"
+                    "*not emphasis*\n"
+                    "</pre>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_style_with_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<style>\n\n.x { color: red; }\n\n</style>\nafter", false)};
+  EXPECT_EQ(result, "&lt;style>\n"
+                    "\n"
+                    ".x { color: red; }\n"
+                    "\n"
+                    "&lt;/style>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_comment_with_blank_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<!--\n\n*hidden*\n\n-->\nafter", false)};
+  EXPECT_EQ(result, "<!--\n"
+                    "\n"
+                    "*hidden*\n"
+                    "\n"
+                    "-->\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_processing_instruction) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<?xml\n\nversion=\"1.0\"\n\n?>\nafter", false)};
+  EXPECT_EQ(result, "<?xml\n"
+                    "\n"
+                    "version=\"1.0\"\n"
+                    "\n"
+                    "?>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_declaration) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<!ENTITY example \"value\">", false)};
+  EXPECT_EQ(result, "<!ENTITY example \"value\">\n");
+}
+
+TEST(html_block_cdata_section) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<![CDATA[\nif (a < b) {\n\n  go();\n}\n]]>\nafter", false)};
+  EXPECT_EQ(result, "<![CDATA[\n"
+                    "if (a < b) {\n"
+                    "\n"
+                    "  go();\n"
+                    "}\n"
+                    "]]>\n"
+                    "<p>after</p>\n");
+}
+
+TEST(html_block_ends_at_blank_line) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<div>\n*one*\n\n*two*\n</div>", false)};
+  EXPECT_EQ(result, "<div>\n"
+                    "*one*\n"
+                    "<p><em>two</em></p>\n"
+                    "</div>\n");
+}
+
+TEST(html_block_partial_opening_tag) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<section class=\"a\"\n  id=\"b\">\n</section>", false)};
+  EXPECT_EQ(result, "<section class=\"a\"\n"
+                    "  id=\"b\">\n"
+                    "</section>\n");
+}
+
+TEST(html_block_starting_with_closing_tag) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("</section>\n_text_", false)};
+  EXPECT_EQ(result, "</section>\n"
+                    "_text_\n");
+}
+
+TEST(html_block_complete_inline_tag) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<span class=\"x\">\n_text_\n</span>", false)};
+  EXPECT_EQ(result, "<span class=\"x\">\n"
+                    "_text_\n"
+                    "</span>\n");
+}
+
+TEST(html_block_complete_tag_cannot_interrupt_paragraph) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("Text\n<span>\nmore", false)};
+  EXPECT_EQ(result, "<p>Text\n"
+                    "<span>\n"
+                    "more</p>\n");
+}
+
+TEST(html_block_section_interrupts_paragraph) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "Text\n<section>\nmore\n</section>", false)};
+  EXPECT_EQ(result, "<p>Text</p>\n"
+                    "<section>\n"
+                    "more\n"
+                    "</section>\n");
+}
+
+TEST(html_block_indented_four_spaces_is_code) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("    <div>code</div>", false)};
+  EXPECT_EQ(result, "<pre><code>&lt;div&gt;code&lt;/div&gt;\n"
+                    "</code></pre>\n");
+}
+
+TEST(html_block_inside_list_item) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("* <section>\n* text", false)};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>\n"
+                    "<section>\n"
+                    "</li>\n"
+                    "<li>text</li>\n"
+                    "</ul>\n");
+}
+
+TEST(inline_html_open_tags) {
+  const auto result{sourcemeta::core::markdown_to_html("<x><yy1><z-z>", false)};
+  EXPECT_EQ(result, "<p><x><yy1><z-z></p>\n");
+}
+
+TEST(inline_html_empty_elements) {
+  const auto result{sourcemeta::core::markdown_to_html("<br/><hr />", false)};
+  EXPECT_EQ(result, "<p><br/><hr /></p>\n");
+}
+
+TEST(inline_html_attributes_across_lines) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<span\n  data-x='1'\n  data-y=2>", false)};
+  EXPECT_EQ(result, "<p><span\n"
+                    "data-x='1'\n"
+                    "data-y=2></p>\n");
+}
+
+TEST(inline_html_invalid_tag_names) {
+  const auto result{sourcemeta::core::markdown_to_html("<1x> <-x>", false)};
+  EXPECT_EQ(result, "<p>&lt;1x&gt; &lt;-x&gt;</p>\n");
+}
+
+TEST(inline_html_invalid_attribute_name) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<span 1x=\"y\">", false)};
+  EXPECT_EQ(result, "<p>&lt;span 1x=&quot;y&quot;&gt;</p>\n");
+}
+
+TEST(inline_html_invalid_attribute_values) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<span a=\"b> <span a='b>", false)};
+  EXPECT_EQ(result, "<p>&lt;span a=&quot;b&gt; &lt;span a='b&gt;</p>\n");
+}
+
+TEST(inline_html_invalid_whitespace) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "< span> <span/ > <span a=b\n c!d>", false)};
+  EXPECT_EQ(result, "<p>&lt; span&gt; &lt;span/ &gt; &lt;span a=b\n"
+                    "c!d&gt;</p>\n");
+}
+
+TEST(inline_html_closing_tags) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("</span></section >", false)};
+  EXPECT_EQ(result, "<p></span></section ></p>\n");
+}
+
+TEST(inline_html_closing_tag_with_attributes_is_literal) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("</span class=\"x\">", false)};
+  EXPECT_EQ(result, "<p>&lt;/span class=&quot;x&quot;&gt;</p>\n");
+}
+
+TEST(inline_html_comment_with_double_hyphen) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <!-- a -- b -->", false)};
+  EXPECT_EQ(result, "<p>x <!-- a -- b --></p>\n");
+}
+
+TEST(inline_html_comment_edge_forms) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "x <!--> y -->\n\nx <!---> y -->", false)};
+  EXPECT_EQ(result, "<p>x <!--> y --&gt;</p>\n"
+                    "<p>x <!---> y --&gt;</p>\n");
+}
+
+TEST(inline_html_processing_instruction) {
+  const auto result{sourcemeta::core::markdown_to_html("x <?go run ?>", false)};
+  EXPECT_EQ(result, "<p>x <?go run ?></p>\n");
+}
+
+TEST(inline_html_declaration) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <!DOCTYPE svg>", false)};
+  EXPECT_EQ(result, "<p>x <!DOCTYPE svg></p>\n");
+}
+
+TEST(inline_html_cdata_section) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <![CDATA[a < b & c]]>", false)};
+  EXPECT_EQ(result, "<p>x <![CDATA[a < b & c]]></p>\n");
+}
+
+TEST(inline_html_entity_in_attribute_is_preserved) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <span title=\"&copy;\">", false)};
+  EXPECT_EQ(result, "<p>x <span title=\"&copy;\"></p>\n");
+}
+
+TEST(inline_html_backslash_in_attribute_is_preserved) {
+  const auto result{
+      sourcemeta::core::markdown_to_html(R"MD(x <span title="\_">)MD", false)};
+  EXPECT_EQ(result, "<p>x <span title=\"\\_\"></p>\n");
+}
+
+TEST(tagfilter_every_disallowed_tag) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<plaintext> <script> <noframes> <noembed> <iframe> <xmp> <style> "
+      "<textarea> <title>",
+      false)};
+  EXPECT_EQ(result,
+            "<p>&lt;plaintext> &lt;script> &lt;noframes> &lt;noembed> "
+            "&lt;iframe> &lt;xmp> &lt;style> &lt;textarea> &lt;title></p>\n");
+}
+
+TEST(tagfilter_mixed_allowed_and_disallowed_tags) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<b> <iframe src=\"x\"> <i>", false)};
+  EXPECT_EQ(result, "<p><b> &lt;iframe src=\"x\"> <i></p>\n");
+}
+
+TEST(tagfilter_closing_disallowed_tags) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("</textarea> </xmp>", false)};
+  EXPECT_EQ(result, "<p>&lt;/textarea> &lt;/xmp></p>\n");
+}
+
+TEST(tagfilter_case_insensitive) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<IfRaMe src=\"x\"></iFrAmE>", false)};
+  EXPECT_EQ(result, "&lt;IfRaMe src=\"x\">&lt;/iFrAmE>\n");
+}
+
+TEST(tagfilter_inside_html_block) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "<div>\n<noembed>x</noembed> <TITLE>y</TITLE>\n</div>", false)};
+  EXPECT_EQ(result, "<div>\n"
+                    "&lt;noembed>x&lt;/noembed> &lt;TITLE>y&lt;/TITLE>\n"
+                    "</div>\n");
+}
+
+TEST(unsafe_mode_keeps_uppercase_file_scheme) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x](FILE://C:/secrets.txt)", false)};
+  EXPECT_EQ(result, "<p><a href=\"FILE://C:/secrets.txt\">x</a></p>\n");
+}
+
+TEST(unsafe_mode_keeps_dangerous_image_source) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("![x](vbscript:msgbox)", false)};
+  EXPECT_EQ(result, "<p><img src=\"vbscript:msgbox\" alt=\"x\" /></p>\n");
+}
+
+TEST(unsafe_mode_keeps_raw_html_inside_emphasis) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "_<span title=\"_\">x</span>_", false)};
+  EXPECT_EQ(result, "<p><em><span title=\"_\">x</span></em></p>\n");
+}
+
+TEST(unsafe_mode_raw_html_takes_precedence_over_link) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("[x <span data=\"](/y)\">", false)};
+  EXPECT_EQ(result, "<p>[x <span data=\"](/y)\"></p>\n");
+}
+
+TEST(unsafe_mode_list_separated_by_html_comment) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "* one\n\n<!-- split -->\n\n* two", false)};
+  EXPECT_EQ(result, "<ul>\n"
+                    "<li>one</li>\n"
+                    "</ul>\n"
+                    "<!-- split -->\n"
+                    "<ul>\n"
+                    "<li>two</li>\n"
+                    "</ul>\n");
+}
+
+TEST(unsafe_mode_passes_raw_html) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<div onclick=\"x\">hi</div>", false)};
+  EXPECT_EQ(result, "<div onclick=\"x\">hi</div>\n");
+}
+
+TEST(unsafe_mode_keeps_dangerous_link) {
+  const auto result{sourcemeta::core::markdown_to_html(
+      "[click](javascript:alert(1))", false)};
+  EXPECT_EQ(result, "<p><a href=\"javascript:alert(1)\">click</a></p>\n");
+}
+
+TEST(unsafe_mode_invalid_utf8_inside_html_block) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("<div>\xFF</div>", false)};
+  EXPECT_EQ(result, "<div>\xef\xbf\xbd</div>\n");
+}
+
+TEST(unsafe_mode_invalid_utf8_inside_inline_html_attribute) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <span title=\"\xC3\">", false)};
+  EXPECT_EQ(result, "<p>x <span title=\"\xef\xbf\xbd\"></p>\n");
+}
+
+TEST(unsafe_mode_nul_character_inside_inline_html) {
+  const auto result{
+      sourcemeta::core::markdown_to_html("x <span title=\"a\0z\">"sv, false)};
+  EXPECT_EQ(result, "<p>x <span title=\"a\xef\xbf\xbdz\"></p>\n");
+}