From afa465f8691f5d0d970acec4d87995cdd0a234ff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Mond=C3=A9jar=20Rubio?=
 <mondejar1994@gmail.com>
Date: Fri, 13 Jun 2025 20:04:30 +0200
Subject: [PATCH] Fix internal anchor in included file incorrectly rewritten

---
 examples/internal-anchors/docs/index.md       |  3 +++
 examples/internal-anchors/mkdocs.yml          |  5 +++++
 examples/internal-anchors/test.md             |  7 +++++++
 pyproject.toml                                |  2 +-
 src/mkdocs_include_markdown_plugin/process.py | 13 ++++++++++++-
 tests/test_unit/test_process.py               | 15 ++++++++++++---
 6 files changed, 40 insertions(+), 5 deletions(-)
 create mode 100644 examples/internal-anchors/docs/index.md
 create mode 100644 examples/internal-anchors/mkdocs.yml
 create mode 100644 examples/internal-anchors/test.md

diff --git a/examples/internal-anchors/docs/index.md b/examples/internal-anchors/docs/index.md
new file mode 100644
index 0000000..8515d2f
--- /dev/null
+++ b/examples/internal-anchors/docs/index.md
@@ -0,0 +1,3 @@
+{%
+   include-markdown "../test.md"
+%}
diff --git a/examples/internal-anchors/mkdocs.yml b/examples/internal-anchors/mkdocs.yml
new file mode 100644
index 0000000..422f47f
--- /dev/null
+++ b/examples/internal-anchors/mkdocs.yml
@@ -0,0 +1,5 @@
+site_name: My Docs
+site_url: https://example.com/org-name/repo-name/
+
+plugins:
+  - include-markdown
diff --git a/examples/internal-anchors/test.md b/examples/internal-anchors/test.md
new file mode 100644
index 0000000..1670adc
--- /dev/null
+++ b/examples/internal-anchors/test.md
@@ -0,0 +1,7 @@
+# First level heading
+
+Example data
+
+## Second level heading
+
+Link to [second level heading](#second-level-heading).
diff --git a/pyproject.toml b/pyproject.toml
index ec376f9..089338c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "mkdocs-include-markdown-plugin"
-version = "7.1.5"
+version = "7.1.6"
 description = "Mkdocs Markdown includer plugin."
 readme = "README.md"
 license = "Apache-2.0"
diff --git a/src/mkdocs_include_markdown_plugin/process.py b/src/mkdocs_include_markdown_plugin/process.py
index b7318a3..f16eedd 100644
--- a/src/mkdocs_include_markdown_plugin/process.py
+++ b/src/mkdocs_include_markdown_plugin/process.py
@@ -291,7 +291,7 @@ def rewrite_relative_urls(
     ``destination_path``.
     """
     def rewrite_url(url: str) -> str:
-        if is_url(url) or is_absolute_path(url):
+        if is_url(url) or is_absolute_path(url) or is_anchor(url):
             return url
 
         new_path = os.path.relpath(
@@ -583,6 +583,17 @@ def is_absolute_path(string: str) -> bool:
         return False
 
 
+def is_anchor(string: str) -> bool:
+    """Check if a string looks like an anchor.
+
+    An anchor is a string that starts with `#` and is not a relative path.
+    """
+    try:
+        return string[0] == '#'
+    except IndexError:  # pragma: no cover
+        return False
+
+
 def read_file(file_path: str, encoding: str) -> str:
     """Read a file and return its content."""
     f = open(file_path, encoding=encoding)  # noqa: SIM115
diff --git a/tests/test_unit/test_process.py b/tests/test_unit/test_process.py
index 064ea86..3bf5034 100644
--- a/tests/test_unit/test_process.py
+++ b/tests/test_unit/test_process.py
@@ -125,7 +125,7 @@
              " class='bar'>example</a>"),
             id='html-anchor-single-quote',
         ),
-        # HTML Relative Links Adverarial tests:
+        # HTML Relative Links Adversarial tests:
         # (attribute contains >, attribute without value, multiple tag in line)
         pytest.param(
             ('<img id="foo" attr="3>2" attr2 src="assets/diagram.png"'
@@ -136,7 +136,7 @@
             ('<img id="foo" attr="3>2" attr2 src="../assets/diagram.png"'
              ' alt="diagram" class="bar" /><img id="foo" attr="3>2"'
              ' src="../assets/diagram.png" alt="diagram" class="bar" />'),
-            id='html-image-adverarial-test',
+            id='html-image-adversarial-test',
         ),
         pytest.param(
             ('<a id="foo" attr="3>2" attr2 href="badge.png" class="bar">'
@@ -147,7 +147,7 @@
             ('<a id="foo" attr="3>2" attr2 href="../badge.png" class="bar">'
              'foo</a><a id="foo" attr="3>2" href="../badge.png" class="bar">'
              'bar</a>'),
-            id='html-anchor-adverarial-test',
+            id='html-anchor-adversarial-test',
         ),
         # HTML Relative Links Adversarial test: img no end slash
         pytest.param(
@@ -362,6 +362,15 @@
             # https://spec.commonmark.org/0.28/#indented-code-blocks
             id='no-exclude-indented-code-blocks-missing-newline-after',
         ),
+        # Internal anchor in included file
+        # https://github.com/mondeja/mkdocs-include-markdown-plugin/issues/266
+        pytest.param(
+            'This is a link to an [internal anchor](#internal-anchor).',
+            'README',
+            'docs/nav.md',
+            'This is a link to an [internal anchor](#internal-anchor).',
+            id='internal-anchor',
+        ),
     ),
 )
 def test_rewrite_relative_urls(